31/Mar/2007 CIMA Comment Observer: RM ML TG CS Project: a2268 Receiver: X-Band Email address for response:csalter The monitor screen that repeats the screen in the if2 room is illegible. Insufficient brightness and contrast. **************************************************************************************************************** 19/Feb/2007 Hi Tapasi, The old L-band flat feed and SETI@Home receiver were dismantled and brought down in June 2006 (http://www.naic.edu/~rxgroup/log/seti.shtml). So, this 1140 MHz can not be the SETI LO. We have to look at other sources to locate this 1140 birdie. The SETI@Home group has been using the ALFA receiver since June '06. - Ganesh dtusr@naic.edu wrote: > CIMA Comment > Observer: tg/nk > Project: a2123 > Receiver: L-Band Wide > Email address for response: tghosh@naic.edu nkanekar@nrao.edu > > We see a single channel (for us) spike exactly at 1140 MHz. It is rather strong -peak > going to about 3*Tsys and fluctuating. This reminds me of the old SETI LO. Is it > still there ? Please check. > > Thanks, **************************************************************************************************************** 17/Feb/2007 CIMA Comment Observer: tg/nk Project: a2123 Receiver: L-Band Wide Email address for response: tghosh@naic.edu nkanekar@nrao.edu We see a single channel (for us) spike exactly at 1140 MHz. It is rather strong -peak going to about 3*Tsys and fluctuating. This reminds me of the old SETI LO. Is it still there ? Please check. Thanks, **************************************************************************************************************** 2/Nov/2006 CIMA Comment Observer: B. Catinella Project: a2010 Receiver: ALFA Email address for response: bcatinel RFI at 1380.0-1380.2 MHz present all night during my observations. It is very weak, strongest in beams 4A and 5A (just visible in the waterfall plots -- but if one looks carefully is present in all beams and both polarizations). It became suddenly very strong for ~1 minute, see file wapp.20061101.a2010.0035.fits. **************************************************************************************************************** 25/Sep/2006 > Hi all, > > This is to bring to your attention to a disturbing RFI occurrence. > > Date: September 5, 2006 > Time: around 2:45 am (for several minutes) > Observer: E. Momjian > Project ID: a2010 > RX: ALFA > > The RFI was around 137**************************************************************************************************************** MHz with a width of about 4 MHz repeating every > ~12 seconds. However, it seems that the width may not have been limited > to 4 MHz, but to much larger value at lower power levels, as the plots > of beam 0 suggest (see attached file, specially pol B's). All ALFA beams > were affected by this RFI, which lasted for several minutes. The wapp > file when this RFI occurred is: > /share/pserverf.sdb1/wappdata/wapp.20060905.a2010.0016.fits > > Emmanuel emanual, I looked at this rfi a little more. It syncs pretty closely with the faa radar.. but then it drifted a little so it can't be the faa radar. I looked at the entire nite and it only showed up this one time for about 430 seconds. You can see the plots at: http://www.naic.edu/~phil/modhistory.html 25sep06 12 seconds radar at 137**************************************************************************************************************** Mhz appears for 430 secs on 05sep06 phil **************************************************************************************************************** 06/Sep/2006 Hi all, This is to bring to your attention to a disturbing RFI occurrence. Date:September 5, 2006 Time: around 2:45 am (for several minutes) Observer: E. Momjian Project ID: a2010 RX: ALFA The RFI was around 137**************************************************************************************************************** MHz with a width of about 4 MHz repeating every ~12 seconds. However, it seems that the width may not have been limited to 4 MHz, but to much larger value at lower power levels, as the plots of beam 0 suggest (see attached file, specially pol B's). All ALFA beams were affected by this RFI, which lasted for several minutes. The wapp file when this RFI occurred is: /share/pserverf.sdb1/wappdata/wapp.20060905.a2010.0016.fits Emmanuel **************************************************************************************************************** 31/Aug/2006 CIMA Comment Observer: tg Project: a2049 Receiver: L-Band Wide Email address for response: Awful RFI between 1340 - 1355 MHz, leaving a plot on Ray Velez's desk TG **************************************************************************************************************** 12/Aug/2006 Results from RFI Report posted Date:12/Aug/2006 Observer:Pisano Project:A2149 Receiver:L-wide Email address for response:pisano@nrl.navy.mil Report/Comments: The 1290 MHz RFI seems to be the Remy Radar. I am not entirely sure about the stuff near 1305 MHz, however. **************************************************************************************************************** 04/Aug/2006 > From jweisber@carleton.edu Fri Aug 4 16:55:17 2006 > Date: Fri, 04 Aug 2006 15:54:56 -0500 > > Last night on P2206, Thurs night ~21-24 h AST Aug 3, we had horrible > interference at > 1419 which seems to wander some up to 1420 MHz. Only just saw it as we > processed our data (see attached). > > The horizontal scale is v in km/s wrt topocentric 1420.4058 (ie NOT > doppler shifted). > To convert horiz scale crudely back to freq, note they (vel and freq) > are inverted wrt each other and the total BW=3.125 MHz. > Joel, A2048 (who ran after you guys) also complained about this. I looked at it and it is a 21.5 Mhz comb that goes all through lband (at least i looked 1332 thru 1480). In the a2048 (and the accompanying galfa) data i saw the birdie at: (1333.0 1354.50 1376.00 1397.50 1419.00 1440.50 1462.00 1483.50 )Mhz These are all multiples of 21.5. For a2048 i first saw it around 1am and it went away around 2:32 am. Did you take any search data? a2048 only has 1 second integrations. I'd like to see if it has any time variations less than 1 second. It is not the punta salinas radar (i called and talked to them.. they were in mode a). . Looking at the time variability with 1 second resolution it does not look like a radar. I looked on the hilltop monitor and didn't see anything funny. It may be that we are generating it internally (although i have know proof of that). We need to go up to the dome and probe around with the spectrum analyzer when the birdie is present. Unfortunately the spectrum analyzer generates enough birdies that it wrecks any experiments going on... In the 10 minute scans of a2048 , it went on/off a few times. I'll try to put the plots i made on the web.. let me know how often you see it... phil **************************************************************************************************************** 04/Aug/2006 RFI Report - email From: Joel Weisberg Subject: awful interference last night (Thurs night) at 1419 (-20) MHz Project: P2206 Last night on P2206, Thurs night ~21-24 h AST Aug 3, we had horrible interference at 1419 which seems to wander some up to 1420 MHz. Only just saw it as we processed our data (see attached). The horizontal scale is v in km/s wrt topocentric 1420.4058 (ie NOT doppler shifted). To convert horiz scale crudely back to freq, note they (vel and freq) are inverted wrt each other and the total BW=3.125 MHz. THerefore the LEFT edge of plot is 1420.4058 PLUS 3.125 / 2 MHz = 1421.97 RIGHT " MINUS = 1418.84 more specifically using channel labelling and doppler eqn, spike is at +300 km/s . v/c = -( delta f) / f =>- f v /c = ( delta f) = -1420.4058 MHz (300 km/s / 300 000 km/s) = -1.42 MHz so spike is at (1420.4058 - 1.420)= 1419 MHz. (anything special about interference being ~exaclty 1/1000 of rf?) The bumps in the middle are galactic HI with T~100K. The spike is several hundred K at 1419 MHz and apparently occasionally wanders up to 1420 which is why the baseline is not flat there (on other nights it is.) isnt this a protected band? anything we can do? we observe at this freq every night for the next week incl tonight. we have had many other nights without it. thanks joel weisberg ******************************************************************************* 04/Aug/2006 CIMA Comment Observer: LCortese Project: a2048 Receiver: ALFA Email address for response: luca.cortese@astro.cf.ac.uk Hi. I'm observing with ALFA and during the first two hours of the run (from AST 00:30 to AST 02:30) I had four strong RFI (GPS?) at the following frequencies: No periodicity. **************************************************************************************************************** 31/Jul/2006 > CIMA Comment > Observer: Michielsen > Project: a2149 > Receiver: L-Band Wide > Email address for response: dolf.michielsen@nottingham.ac.uk > > This is an RFI comment. > I'm observing around frequency 1320 MHz, and there is a quite strong emission peak> at 1330 MHz, and a weaker one at 1324 MHz. It is quite variable. > The TO only sees interference from the Airport at 1350MHz. > He's put a note in the log about it. > We're looking for HI emission at 1320.7 MHz, so I don't think it will be a problem for our observations. > I checked the hilltop monitor for sunday 30jul06. The faa (airport) radar was running at 1330 and 1350 Mhz all day long. phil perillat arecibo observatory ***************************************************************************************** 30/Jul/2006 CIMA Comment Observer: Michielsen Project: a2149 Receiver: L-Band Wide Email address for response: dolf.michielsen@nottingham.ac.uk This is an RFI comment. I'm observing around frequency 1320 MHz, and there is a quite strong emission peak at 1330 MHz, and a weaker one at 1324 MHz. It is quite variable. The TO only sees interference from the Airport at 1350MHz. He's put a note in the log about it. We're looking for HI emission at 1320.7 MHz, so I don't think it will be a problem for our observations. ***************************************************************************************** 17/Jul/2006 > CIMA Comment > Observer: cs > Project: a2049 > Receiver: L-Band Wide > Email address for response: csalter tghosh > Narrow spike at 1200Mhz, both polarizations and always present. Internal ? > > chris, tapasi, This looks like the 100 Mhz harmonic from the wapps but is i'm not positive. It is definitely coming from outside of the dome since it shows an azimuth dependence. It also is not a harmonic since it stayed at 1200 Mhz when you guys moved the frequency by .5 Mhz. take a look at : http://www.naic.edu/~phil/modhistory.html --> 17jul06 1200 Mhz narrow birdie. phil *********************************************************************************************** 15/Jul/2006 CIMA Comment Observer: cs Project: a2049 Receiver: L-Band Wide Email address for response: csalter tghosh Narrow spike at 1200Mhz, both polarizations and always present. Internal ? ************************************************************************************************ 13/Jul/2006 CIMA Comment Observer: hh,tg Project: a2049 Receiver: L-Band Wide Email address for response: tghosh@naic.edu radar-like interference at 1298.4, 1304.5, 1307, 1314 (+ 1290 radar). Scan number, 619400905 ************************************************************************************************* 05/Jun/2006 CIMA Comment Observer: cjs/tg Project: a2049 Receiver: L-Band Wide Email address for response: csalter, tghosh We were running A2049 just now, and looking at a source whose line is expected at 1330.1 MHz. We had the blanker on, but the 1330 MHz airport radar still showed. When we looked at the radar blanker chassis, the "out of lock" red light was flashing (and still is). Could somebody take and look and "lock it up" please? Ta, Chris and Tapasi ******************************************************************************************* 15/May/2006 CIMA Comment Observer: Tapasi Ghosh Project: a2123 Receiver: L-Band Wide Email address for response: tghosh@naic.edu A spiky RFI again at 1293.3032 MHz. It was present only for about 16 mins. Also time variable (may have the same 12 s periodicity), I don't have much time to invetsigate now. ******************************************************************************************* 07/May/2006 CIMA Comment Observer: tg Project: a2123 Receiver: L-Band Wide Email address for response: tghosh@naic.edu Between 10:22 and about 10:37 pm tonight (7May06), there was a strong narrow RFI spike at 1293.3028 MHz. It was stronger in Pol B, and reduced in intensity with time. No periodicity, i.e. always present. One channel wide (0.76 kHz) or narrower. Didn't go when the ALFA motor was turned off. ******************************************************************************************* 01/May/2006 > > CIMA Comment > Observer: RM > Project: a2048 > Receiver: ALFA > Email address for response: rminchin@naic.edu > > Fairly weak (compared to the FAA) RFI seen at 1387.8 MHz with a period of 6s. Presumably a radar, but not one listed on Phil's RFI page. > > Robert, the 1387.8 Mhz radar is the 3rd harmonic of the 1350 faa radar being created at the 250 Mhz IF. see http://www.naic.edu/~phil/ ---> alfa multi beam --> miscellaneous --> 24feb06 harmonics created in the alfa wapp configuration... There is an idl routine to compute these harmonics for a given sky frequency. it is documented in the generic idl routines: http://www.naic.edu/~phil/ --> software documentation --> generic idl routines -->alfawappharm - compute alfa wapp harmonics phil ********************************************************************************** 29/Apr/2006 CIMA Comment Observer: RM Project: a2048 Receiver: ALFA Email address for response: rminchin@naic.edu Fairly weak (compared to the FAA) RFI seen at 1387.8 MHz with a period of 6s. Presumably a radar, but not one listed on Phil's RFI page. ************************************************************************************************ 24/Apr/2006 From: Phil Perillat To: emuller@naic.edu Cc: rfi-grp@naic.edu Subject: Re: Some rfi from Sunday morning.. > From rfi-grp-request Mon Apr 24 13:50:51 2006 > Date: Mon, 24 Apr 2006 13:50:48 -0400 (AST) > From: EM > To: rfi-grp@naic.edu > Subject: Some rfi from Sunday morning.. > MIME-Version: 1.0 > X-Lines: 11 > > During observations for a2055 on the morning of the 23rd Apr, we had some > rfi contamination at approximately 1367 and 1381 MHz in the form of periodic > pulses. However, the period of the pulses was at ~10 sec (not the ~2 sec > that I'd expect at those freqs). > > Is this unusual? Any idea what the source is? > > Thanks. > Erik M > > > erik, The operators log for sunday morning had: ================================================== File: 23APR2006_0800_1600.rad Operator: Wilfredo Portalatin Projects: A2121 / A2154 / A1852 Time: 09:47 Project: A2154r Receiver: lbw In progress. Loris Magnani and Elizabeth Wennerstrom obs remotely. Time: 10:00 Sr. MSgt. Falcon called about the RFI report from Edgardo Cruz. Apparently some contractors had left the equipment on the wrong mode and he switched it to mode A and offered his apologies for any inconvenience. He also stated this will not happen again. ================================================== 1367 and 1381 are channel 18 of punta salinas. So my guess is that you observered while the contractor had left on channel 18 rather than mode A at 1230Mhz. phil ps. The period should be 12 seconds for the rotation rate..... ************************************************************************************************ 24/Apr/2006 From: EM To: rfi-grp@naic.edu Subject: Some rfi from Sunday morning.. During observations for a2055 on the morning of the 23rd Apr, we had some rfi contamination at approximately 1367 and 1381 MHz in the form of periodic pulses. However, the period of the pulses was at ~10 sec (not the ~2 sec that I'd expect at those freqs). Is this unusual? Any idea what the source is? Thanks. Erik M ****************************************************************************************************** 23/Apr/2006 From: E Muller Date: Sun, 23 Apr 2006 20:24:27 +1000 (EST) To: Subject: Odd RFI tonight. Hello Murray, Apologies : There appears to be a problem with the RFI reporting gui on CIMA, so I'm sending this by 'hand'. We had some observations for a2055 this morning, using ALFA. We appeared to be getting periodic RFI at about 1366 and 1382 MHz, although with a period of about 10 sec. That combination of frequencies and the period leaves me a little mystified about the source. Any clues? Thanks Murray. Erik M. ****************************************************************************************************** 04/Apr/2006 CIMA Comment Observer: tg Project: a2123 Receiver: L-Band Wide Email address for response: tghosh@naic.edu Looks like the 1292.9 MHz RFI has a 12 sec periodicity with a "sub pulse" at about 6/7th sec. ******************************************************************************************************* 04/Apr/2006 CIMA Comment Observer: tg Project: a2123 Receiver: L-Band Wide Email address for response: tghosh@naic.edu Strong RFI between 1292.87 -- 1293.08 MHz (one big hump). It is very close to the red-shifted line I am after which is expected at 1293.21 MHz. I haven't seen this before. Turned off the ALFA motor - no change. ******************************************************************************************************* 18/Mar/2006 CIMA Comment Observer: THH JLS EP Project: p1976 Receiver: 327 MHz Email address for response: thankins@nrao.edu We see occasional interference at 308.9 MHz. It lasts for about 1 second and occurs every 2 minutes or so. It has a sharp rise and end time, and is modulated. We have seen this each time we have observed at 327 MHz over the past 9 days. Tim Hankins ******************************************************************************* 03/Jan/2006 CIMA Comment Observer: R Auld Project: a2048 Receiver: ALFA Email address for response: rauld@naic.edu The FAA radar at 1351 MHz seems to be much stronger than during the precursor observations in November 2004. Is this correct or am I imagining things again. *************************************************************************************************** 17/Oct/2005 >CIMA Comment > Observer: KevinDouglas > Project: a2056 > Receiver: ALFA > Email address for response: douglas@ssl.berkeley.edu,christopher.springob@nrl.navy.mil > > I am seeing 12 second periodic RFI spikes in the wideband of the GALFA > spectrometer. A large spike appears at about 1450 MHz, followed 3 seconds > later by a series of spikes near 1423,1430,1440,1450,1460 and 1470 MHz. > Sometimes the 1450 MHz and 1430 MHz spikes have companion spikes about > 2 MHz lower (ie. 1428 and 1448). Assuming these are due to radar, but they > seem to be more prominent the last couple of days (didn't really notice > them before). > > Also, Chris Springob reports a 1383.8 MHz or so persistent spike, changing > in amplitude every few seconds - this is near the center of his band. > > Just thought you should be aware of these birdies > KD > kevin, This is being caused by the 1350 faa radar. I plotted up the location of the aliases versus frequency. There is also a link describing how it is folding in... take a look at: http://www.naic.edu/~phil/modhistory.html --> 17oct05 location of 1350 faa radar alias in alfa phil perillat ********************************************************************************************************************** 17/Oct/2005 CIMA Comment Observer: KevinDouglas Project: a2056 Receiver: ALFA Email address for response: douglas@ssl.berkeley.edu,christopher.springob@nrl.navy.mil I am seeing 12 second periodic RFI spikes in the wideband of the GALFA spectrometer. A large spike appears at about 1450 MHz, followed 3 seconds later by a series of spikes near 1423,1430,1440,1450,1460 and 1470 MHz. Sometimes the 1450 MHz and 1430 MHz spikes have companion spikes about 2 MHz lower (ie. 1428 and 1448). Assuming these are due to radar, but they seem to be more prominent the last couple of days (didn't really notice them before). Also, Chris Springob reports a 1383.8 MHz or so persistent spike, changing in amplitude every few seconds - this is near the center of his band. Just thought you should be aware of these birdies KD ********************************************************************************************************************** 30/Aug/2005 CIMA Comment Observer: Brian Kent Project: a2010 Receiver: ALFA Email address for response: bkent@astro.cornell.edu Strong spurious RFI at 1363.32 MHz in all ALFA pixels. Only one occurance. File: /share/pserverf.sdb1/wappdata/wapp.20050830.a2010.0015.fits Time record / freq plots of central pixel at: http://www.naic.edu/~a2010/2005aug30.jpg http://www.naic.edu/~a2010/2005aug30_2.jpg ******************************************************************************* 29/Jun/2005 CIMA Comment Observer: cs Project: a1653 Receiver: L-Band Wide Email address for response:csalter@naic.edu This is mostly an un-RFI report! The aerostat radar is off tonight, and for the first time in recent a1653 runs I do NOT see the features at about 1200.4 and 1214.4 MHz which I previously reported on April 13th, 2005 as appearing to be "slaved" to the aerostat. Proof positive, I guess. I do still see the narrow RFI (not a radar) at about 1265 MHz also reported on April 13th. The Punto Borinquen radar seems to be at 1270 MHz (as expected), and there is also a strong, narrow RFI at about 1169 MHz (strongest in Poln. B). Chris ******************************************************************************* 25/Jun/2005 CIMA Comment Observer: Pieter Buyle Project: a2047 Receiver: L-Band Wide Email address for response: Pieter.Buyle@UGent.be There is strong RFI at 1295 MHz ************************************************************************* 30/May/2005 CIMA Comment Observer: cs Project: a2057 Receiver: 327 MHz Email address for response: Re-the comb that I just reported; I forgot to say that we switched the multi meter, and the power meter off at times, and the comb was not affected. Chris ************************************************************************* 30/May/2005 CIMA Comment Observer: cs Project: a2057 Receiver: 327 MHz Email address for response: Observing at 327 MHz (Proj A2057) I am getting a 16-kHz comb across my 400 kHz bandwidth! It is much stronger in Poln B. When the spectrum is "blown up" in frequency, the 16-kHz comb appears rather to be the strong component of a 2-kHz comb! The "spikes" are very narrow, probably just a single channel, i.e. 400 Hz. The strength of the RFI seems to vary with time (i.e. with azimuth) We see on Phil's home page that one of the color cameras has been known to give a near 16-kHz comb some time ago!! Chris ************************************************************************* 22/May/2005 Sabrina Stierwalt wrote: >Hello, > For the nights of May 18th, 19th and 20th I have seen very strong RFI >at 1428.2 MHz. Can anyone tell me what this is? >Thank you, >Sabrina from a2010 Saludos, Sabrina. I don't see this frequency in the RFI hits catalog, but it is real close to the second harmonic of chan. 54. Can you tell me at what times you sw this and if it went away after midnight. The reason I ask is that this channel goes off the air from midnight to 6 am local time (AST). Any feedback would be helpfull. Thanks, Rey. Reinaldo Velez ************************************************************************* 21/May/2005 Hello, For the nights of May 18th, 19th and 20th I have seen very strong RFI at 1428.2 MHz. Can anyone tell me what this is? Thank you, Sabrina from a2010 ************************************************************************ /2/May/2005 23:54:23 CIMA Comment Observer: Howell Project: a2031 Receiver: ALFA Email address for response: pixel 4 seems OK tonight. Some RFI around 11:30pm, but then it went away. Did not affect observations, but could see it on the oscilloscope. ************************************************************************ 20/Apr/2005 22:32:00 CIMA Comment Observer: B. Catinella Project: a2008 Receiver: L-Band Wide Email address for response: bcatinel@naic.edu Narrow RFI drifting in frequency between 1195.5 and 1196 MHz, both polarizations, seen for a couple of hours (from about 7 to 8:40pm AST), then I changed freq. range. See for instance scan 511000275 in corfile.21apr05.a2008.1. Sometimes barely visible, but looks like it was always there. ************************************************************* 13/Apr/2005 22:10:29 CIMA Comment Observer: tg/cs Project: a1653 Receiver: L-Band Wide Email address for response:csalter@naic.edu, tghosh@naic.edu A couple of comments on this LBW set of observations tonight. All the usual suspects there, i.e. the Aerostat, Punta Salinas in Mode A, 1270/1290 MHz radar. Slighly unusual is that the 1270/1290 MHz radar seems to be operating at 1270 AND 1290 MHz simultaneously. Both pulses slaved together in phase, and roughly in strength. For the past week or so, we have also noticed two other features at about 1200.4 and 1214.4 MHz. These are slaved to the Aerostat (1241.75 and 1256.5 MHz) in that when the sector blanking of the Aerostat occurs, the other two features also disappear. Also 1200.4 and 1214.4 MHz are at least twice the width of the Aerostat features. Could be intermods? (3 * 1241.75) - (2 * 1256.5) = 1212.3 MHz (4 * 1241.75) - (3 * 1256.5) = 1197.5 MHz Close to 1214.4 and 1202.4 MHz, but a bit too far off methinks? Finally, there is a narrow RFI at about 1265.1 MHz, that is NOT a radar. Pretty constant in amplitude, always there. Hope this helps, Chris. ***************************************************************************** 24/Mar/2005 13:28:39 > > CIMA Comment > Observer: KH, BK > Project: a2010 > Receiver: ALFA > Email address for response:bkent@astro.cornell.edu > > Feature at 1430 MHz present again for second night in Beam 0, Pol B. Increasing >in frequency through the night from 1429 MHz at 11:30PM AST to 1433 MHz >at 3:30AM AST. I looked at the data for 21mar05 thru 23mar05. this looks like the same problem we had back in sep04. Back then the problem was caused by the rf to if converter upstairs. Replacing the converter got rid of the problem (and a birdie was seen in the lab using the bad module). You can see some plots of the data at: http://www.naic.edu/~phil/modhistory.html --> 24mar05 1430Mhz birdie in alfa pixel0b phil ************************************************************************************************************************************************ 24/Mar/2005 04:52:00 CIMA Comment Observer: KH, BK Project: a2010 Receiver: ALFA Email address for response: bkent@astro.cornell.edu Same drifting feature is visible in the spectrum between 1430-1435 MHz as on the nights of March 21 and March 22. The feature moved out of the bandpass during the night. Again, visible only in Pol B of beam 0. *************************************************************************************************************************** 23/Mar/2005 03:42:21 CIMA Comment Observer: KH, BK Project: a2010 Receiver: ALFA Email address for response:bkent@astro.cornell.edu Feature at 1430 MHz present again for second night in Beam 0, Pol B. Increasing in frequency through the night from 1429 MHz at 11:30PM AST to 1433 MHz at 3:30AM AST. ******************************************************************************************************************* 22/Mar/2005 04:40:19 CIMA Comment Observer: BK, KH Project: a2010 Receiver: ALFA Email address for response:bkent@astro.cornell.edu Noticed a feature at 1431 Mhz - present all night in FixedAz Drift Map. Only present in Beam 0,Pol B. Changing in time, but also drifting in frequency. See plots at: http://www.naic.edu/~a2010/march22/ -Brian Kent ****************************************************************************************************** 2/Mar/2005 01:35:02 CIMA Comment Observer: Karen O'Neil Project: a1759 Receiver: L-Band Wide Email address for response:koneil@nrao.edu Hello, I am being hit contonuously (as far as I can tell) be a signal at 1381 - the GPS L3 frequency. This is not the usual GPS signal that is only on for ~30s 2x/day, but as I said is on almost continuously. As I am only occasionally looking at 1381, I cannot state definitively that it is on 100% of the time, but it is certainly present whenever I look at that frequency. Additionally, I am still being hit by the "bad baselines" problem which I reported one month ago (perhaps these two things are related?). This is the second time this project has been rescheduled due to RFI problems. WOULD SOMEONE PLEASE LOOK INTO THIS AND LET ME KNOW IF ANYTHING CAN BE FIXED BEFORE OUR FINAL RUN (March 7). The RFI & baseline probelms are killing this project. ************************************************************************************************* 27/Feb/2005 13:55:55 > CIMA Comment > Observer: Brian Kent > Project: a2010 > Receiver: ALFA > Email address for response: bkent@astro.cornell.edu > > RFI noticed at Frequencies 1382 and 1367 MHz in all 7 beams. E. Mommijan notified >observing team in Ithaca of problem. Puente Salinas was contacted and stated they >were operating in mode A. Cause of RFI unknown. RFI still persists at those two frequencies. > Take a look at http://www.naic.edu/~phil/modhistory.html --> 27feb05 punta salinas does not stay in mode A. It certainly looks like they were not in mode A during the run... phil **************************************************************************************************** 26/Feb/2005 21:58:38 CIMA Comment Observer: Brian Kent Project: a2010 Receiver: ALFA Email address for response: bkent@astro.cornell.edu RFI noticed at Frequencies 1382 and 1367 MHz in all 7 beams. E. Mommijan notified observing team in Ithaca of problem. Puente Salinas was contacted and stated they were operating in mode A. Cause of RFI unknown. RFI still persists at those two frequencies. **************************************************************************************************************** 23/Feb/2005 15:23:59 -0400 CIMA Comment Observer: B. Catinella, M. Krco Project: x111 Receiver: ALFA Email address for response: bcatinel Last Saturday Feb 19 there was a test of commensality of G-ALFA and E-ALFA (A2010) observations during x111 time, under request of Marko Krco for the G-ALFA team. We couldn't test much anyway because of very strong RFI at 1380.0 MHz (w/ peak intensity ~1500). Phil came to look into this. In summary: 1- The RFI was visible with both ALFA and L-wide. 2- When the turret was rotated by 45deg the RFI signal seen by ALFA became *stronger*, so it wasn't coming from the sky. 3- The RFI entered the system before the IF stage. 4- RFI frequency-modulated, hopping b/w two frequencies. You can find a plot in /home/a2010/dump_20050219_1644.ps Phil of course is much more knowledgeable about this. I should also add that I observed later in the night for A2010, and the RFI was still there but very weak, so it wasn't a problem for our observations. Sorry for the late report, but since it was x111 time and Phil and the tel. oper. knew about this I thought you would already know. :) Barbara ************************************************************************************************************** 23/Feb/2005 15:23:59 CIMA Comment Observer: B. Catinella, M. Krco Project: x111 Receiver: ALFA Email address for response: bcatinel Last Saturday Feb 19 there was a test of commensality of G-ALFA and E-ALFA (A2010) observations during x111 time, under request of Marko Krco for the G-ALFA team. We couldn't test much anyway because of very strong RFI at 1380.0 MHz (w/ peak intensity ~1500). Phil came to look into this. In summary: 1- The RFI was visible with both ALFA and L-wide. 2- When the turret was rotated by 45deg the RFI signal seen by ALFA became *stronger*, so it wasn't coming from the sky. 3- The RFI entered the system before the IF stage. 4- RFI frequency-modulated, hopping b/w two frequencies. You can find a plot in /home/a2010/dump_20050219_1644.ps Phil of course is much more knowledgeable about this. I should also add that I observed later in the night for A2010, and the RFI was still there but very weak, so it wasn't a problem for our observations. Sorry for the late report, but since it was x111 time and Phil and the tel. oper. knew about this I thought you would already know. :) Barbara ********************************************************************************* 25/Jan/2005 17:21:09 > > > Hi Karen, > > Your wrote, > > % ...more worrisome is that tonight i has some remarkably crappy data > % for a couple scans. In particular, if you could take a look at the > % on+off pair starting with scan 502500031 (file corfile.25jan05.a1759.1) > % and let me know what you think that would be great. (I saw a similar, > % but not as bad, behavior for the scans starting with 502500027, and i > % can see the wiggle midly in many of the other scans (e.g. 502500035). > > Yes, I took a look at all On/OFF pairs from your last night's data, and > agree with you that the baseline of the On-OFF/OFF spectra between 1389 > - ~1402 has some terrible trouble. Pol B seems to be more affected than > Pol A. The strange thing is that these are weak/invisible on the ONs > and the OFFs themselves. Only when the On-OFF is done, one begins to > see it. Possible nearby source doesn't explain these either (I agree) > as it is seen on various sources that are as far off as about 8 degs in > dec or so! > > Some months ago, Steve Snider had also seen wide (~15 MHz) ratty > baseline around 1400 MHz, and so had Chris. Both of these were reported > at the time of the observations, but as we were terribly bothered > by a "wondering birdie", this problem got moved to a lower priority. > In any case, this is damaging as well, as I can see that much of your > data look corrupted. > > I urge the RFI group to please investigate it, and am alerting Sr. Hector that > some of these lost observing time may be recalimed. > > Bye for now, > > Tapasi > > karen, I looked into these lousy lbw baselines a while back... You can see what they were like then at: http://www.naic.edu/~phil/modhistory.html --> 02aug04 ripples in lbw near 1390 and 1400 Mhz (a1861:may04,a1914:aug04). They seemed to go away after awhile. Back in may04 the only hint i had was that it might be a problem with the 1370 hipass filter.. You used the 1360-1470 filter for the first 6 onoff pairs, then you switched to the 1370 hipass with the 1230-1470 Filter for 3 on/offs, and then you went back to the 1360-1470 filter for the last on/off.. The worst baselines occured with the 1370 hipass filter in. If you have trouble with baselines, you might try switching from the 1370 hipass filter to a different combination that does not use it, and see if the problem goes away... phil *************************************************************************** 25/Jan/05 09:37:15 Hi Karen, Your wrote, % ...more worrisome is that tonight i has some remarkably crappy data % for a couple scans. In particular, if you could take a look at the % on+off pair starting with scan 502500031 (file corfile.25jan05.a1759.1) % and let me know what you think that would be great. (I saw a similar, % but not as bad, behavior for the scans starting with 502500027, and i % can see the wiggle midly in many of the other scans (e.g. 502500035). Yes, I took a look at all On/OFF pairs from your last night's data, and agree with you that the baseline of the On-OFF/OFF spectra between 1389 - ~1402 has some terrible trouble. Pol B seems to be more affected than Pol A. The strange thing is that these are weak/invisible on the ONs and the OFFs themselves. Only when the On-OFF is done, one begins to see it. Possible nearby source doesn't explain these either (I agree) as it is seen on various sources that are as far off as about 8 degs in dec or so! Some months ago, Steve Snider had also seen wide (~15 MHz) ratty baseline around 1400 MHz, and so had Chris. Both of these were reported at the time of the observations, but as we were terribly bothered by a "wondering birdie", this problem got moved to a lower priority. In any case, this is damaging as well, as I can see that much of your data look corrupted. I urge the RFI group to please investigate it, and am alerting Sr. Hector that some of these lost observing time may be recalimed. Bye for now, Tapasi ********************************************************************************* 15/Dec/2004 18:30:21 CIMA Comment Observer: ml Project: a1856/a1909 Receiver: L-Band Wide Email address for response:mlebron The wandering birdy is here. Scan 435000287, 290 2 out of 6 scans. ML ****************************************************************** 14/Dec/2004 18:29:05 CIMA Comment Observer: ml Project: a1856/a1909 Receiver: L-Band Wide Email address for response:mlebron RFI as usual, the wanderdefing birdy. Scans: 434900344, 347 2 of 5 scans with RFI tonight MLebron ****************************************************************** 12/Dec/2004 CIMA Comment Observer: emuller Project: a1856 Receiver: L-Band Wide Email address for response: Wandering Birdy in scans 434700796,799,802 Note that the fact that the birdy is not present in other scans may have more to do with the fact that the bands are very narrow ~3 MHz and ~6 MHz. The rest of this email is trash, generated during idleness I think in future I will apply for exactly twice the length of time for Lband obs. Da birdy is back. Oh yeah, its here It wont cut us slack Im going to get beer. Gimmie a B! Gimmie an I! Gimmie an RDY! ad neaseum. I propose that we rename this thing to 'albatross' or 'pterodactyl'. Or some other airborne behemoth. ****************************************************************** CIMA Comment Observer: ml,em Project: a1856/a1909 Receiver: L-Band Wide Email address for response: Birdy in scans:434700781,784,787 BIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDYBIRDY tweet, tweet, the birdy is back Tweet, tweet, It lives in the shack. Tweet, tweet, I wish it would die Tweet, tweet, I'll have birdy pie. The birdy is here, its is here to stay. The birdy is playing, it plays all day. I hate the Birdy. ****************************************************************** 10/Dec/2004 CIMA Comment Observer: ml,em Project: a1856 Receiver: L-Band Wide Email address for response: RFI observed in .... scans tonight. The very unfamous wandering RFI. scans434500276, 434500279, 434500282. 3 of 4 scans. That is the 9th night out of 9 that we get this RFI. ****************************************************************** 06/Dec/2004 CIMA Comment Observer: Chris_salter Project: a1785 Receiver: L-Band Wide Email address for response:csalter@naic.edu Nope. Wrong again Salter! Having drifted off to lower frequencies on scan 434100116, it reappeared drifting to higher freq. on scan 434100117! Finally drifted to the top of the band on scan 434100120. Sadly, reappeared drifting downward in frequency on 434100121. Drifting upwards again in 434100124 and 125. Drifting down again on 434100128, then back up on 434100129. Scan 434100132 is first clean scan in a long time. Scan 434100133 also almost clean, although birdie reappears drifting down in frequency on last few records. Birdie loud and clear on 434100136 drifting down, turning around, and then drfiting up in freq. Scan 434100137 shows the RFI drifting up. Worst I have yet seen this fellow! Wrecked the session. ****************************************************************** 06/Dec/2004 CIMA Comment Observer: Chris_Salter Project: a1785 Receiver: L-Band Wide Email address for response:csalter@naic.edu And again in scans 434100112 and 3. A little unusual in that it was travelling in the same direction (towards increasing frequency) as a couple of minutes before! Could this "apparition" be the next harmonic down reaching my observing band? It then proceeded to turn around and start off towards lower frequency. Wonder if I'll see the next harmonic up travelling down shortly? ****************************************************************** 06/Dec/2004 CIMA Comment IMA Comment Observer: Chris_Salter Project: a1785 Receiver: L-Band Wide Email address for response:csalter@naic.edu Surprise, surprise, our old friend the "travelling RFI" on scan 434100112. ****************************************************************** Project: a1856 Receiver: L-Band Wide Email address for response:emuller, cpantoja We have the Lband wandering birdy again. Scan number 434000798,807,810 Note: Last night we detected the birdy for proj a1856/a1909 al the way through to the end of LAST session of proj 1961 (i.e. the early morning session). I think I forgot to submit a report. Typically, the birdy is clear on broadband observations for many many hours. ****************************************************************** 04/Dec/2004 CIMA Comment Observer: ml,em Project: a1856/a1909 Receiver: L-Band Wide Email address for response: Wandering RFI is here. Scan 433900806, 433900809, 433900911 Please help!, this is the sixth night in a row, effectively 12% of the data collected for this project so far is destroyed. Is there anything we can do to help track it down - phone anyone? switch on any monitoring? get up on the hill with a yagi? ****************************************************************** 03/Dec/2004 19:14:02 CIMA Comment Observer: EMM Project: a1856 Receiver: L-Band Wide Email address for response:emuller@naic.edu, mlebron@naic.edu Hi folks, We had the Wandering birdy again in our data. These are narrowband obs, centred on the galaxy. EMM+ML. ****************************************************************** 03/Dec/2004 CIMA Comment Observer: EM JD SS SS Project: a1961 Receiver: ALFA Email address for response: The wandering birdie is still wandering... ****************************************************************** 02/Dec/2004 CIMA Comment Observer: EM Project: a1961 Receiver: ALFA Email address for response: We have the wandering birdie around again. ****************************************************************** 2/Dec/2004 CIMA Comment Observer: ml Project: a1856/a1909 Receiver: L-Band Wide Email address for response: The usual RFI of all these days. scan 433700347. Appears in 1/4 scans. We are really move very slow with this map... Mayra ****************************************************************** 02/Dec/2004 CIMA Comment Observer: Barbara Project: a1956 Receiver: ALFA Email address for response: bcatinel@naic.edu Hello RFI experts! During the A1956 observations I noticed RFI at ~1246.4 MHz, ~0.8 MHz wide, variable intensity (weaker than Pta Salinas). It's not a radar, looks like one of those wandering birdies... It seems to be in all of the beams (although with different intensity) and present for most (all?) of the time. Has this been noticed before? Muchas gracias, Barbara ****************************************************************** /02/Dec/2004 CIMA Comment Observer: EM Project: a1961 Receiver: ALFA Email address for response: We have the wandering birdie around again. ****************************************************************** /01/Dec/2004 CIMA Comment Observer: ml Project: a1856/1909 Receiver: L-Band Wide Email address for response:mlebron Scan 433600470 shows some RFI in the Freq. range from 1417 to 1423.5MHz (the complete band width). today we got 4/5 scans clean of RFI. Mayra ****************************************************************** /30/Nov/2004 CIMA Comment Observer: ml Project: a1856/a1909 Receiver: L-Band Wide Email address for response: Here is it again, the wandering RFI. Very bright and clear in scan 433500481. Tonight we managed to get 5 scans on source. The interference also appears in scan 433500486. Mayra ****************************************************************** /29/Nov/2004 CIMA Comment Observer: ml Project: a1856/a1909 Receiver: L-Band Wide Email address for response:mlebron, emuller The wandering RFI appeared in two of our 4 strips that we did today. scans: 433401255 and 433401258 Mayra ****************************************************************************** /27/Nov/2004 Hi All, There were an apparent RFI problem when friending Steve Schneider on a1972 last night. This is an L-band wide experiment using the WAPPs. During the observations, (or at least for the 3 hr when I was there), there was an apparent RFI (or at least a very ratty baseline) for some 15-20 MHz centered closely on 1400 MHz. Its amplitude was about 10 mJy, and would have prevented anything but the strongest of detections within this window. This problem, Tapasi and I have encountered before (and reported) earlier this year in project a1653, as have Emmanuel, Tapasi and I in project a1908. (It is not the wandering birdie, appearing always centered close to 1400 MHz.) Steve will probably also submit a report on this, but I wanted to log it while my recollections were still fresh. Cheers, Chris ****************************************************************************** 21/Nov/2004 CIMA Comment Observer: SS,EM,RA,PH Project: a1961 Receiver: ALFA Email address for response:schneider@astro.umass.edu,emuller,rauld,henning@as.unm.edu Yo! Narrow interference (100 kHz) at 1349.95 MHz. Strong stuff. There in all our data. Too narrow for airport? Local? We hear rumors. Variations, but not periodic. ****************************************************************************** steve, Go take a look at: http://www.naic.edu/~phil/rfi/rfi.html then scroll down to the link at 05oct01: tone at 1350Mhz. This thing has been around for a long time. The azimuth plot shows that it is coming from the general direction of the control room.. The problem with debugging this is that you need to first blank the radar signal before you can see this thing.... hopefully we'll get around to it one of these days... phil ****************************************************************************** /20/Nov/2004 CIMA Comment Observer: cs Project: a1785 Receiver: X-Band Email address for response:csalter@naic.edu Strong birdie (almost 5,000 Tsys in one poln, B), narrow spike (~25 kHz), at 9186.24 MHz. Apparently sidebands on either side of about 10% intensity, offset in frequency by ~85 kHz. Gave up observing this source after a few seconds. Went back 25 min later, and it was just as bad! ****************************************************************************** chris, I looked at the frational occurence of rfi by month and birdie has been around awhile. It would be interesting to plug the IF into the radio receiver and listen to what it sounds like... phil ****************************************************************************** Chris, I put 9186.0 Mhz on the spectrum analyzer and saw a birdie 20 to 30 db above the noise floor. I took the 260 Mhz IF and plugged it into the radio with fm demodulation. It sounded exactly like the refrigerators for the dewars. You could hear both strokes. The period was .8 seconds just like the fridges.. We closed the shutters and it went away. ganesh went upstairs and turned off the fridges one at a time and nothing much happenned. He tried shorting the input to the horn with a metal plate and it got smaller but did not go away completely (probably because the capton was not allowing good contact between the metal plate and the mouth of the horn). ( Here's where we lucked out because ganesh was under the floor ) We closed the shutters again and the signal disappeared immediately. Ganesh noticed (since he was under the floor watching the shutters close) that the xband shutter had barely moved when i said that the birdie had disappeared. The xband shutter moves slowly. The cband and sbw shutters use air and move very fast. We turned off the bias supply to sbw and the birdie went away. Ganesh looked at the output of the dewar for sbw and saw an oscillation at 9186 Mhz with the 85 Khz sidebands in one of the channels. By adjusting the bias , he was able to make the oscillation go away. This thing has been around for along time, so thanks for mentioning it again.. Another moral is that : just because closing the shutters makes it go away, does not mean it is not coming out of one of our other receivers!!! phil ****************************************************************************** /19/Nov/2004 CIMA Comment Observer: SS Project: a1961 Receiver: ALFA Email address for response:schneider@astro.umass.edu,emuller@naic.edu,rauld@naic.edu We are sorry to report the presence of a rather virulent form of interference whose presence has interrupted o ur peace at about 4am. Its presence in all beams is most disturbing. Wandering, wandering, it just cannot make up its mind what frequency it wishes to corrupt. Please peruse wapp.20041119.a1961.0031.fits all the way unto # .0048 at your earliest convenience. Your attention in this matter would be greatly appreciated. Your humble servants, S, E, & R ****************************************************************************** steve, I haven't looked at your data but my guess is that this is the wandering birdie with 60 Mhz harmonics that has been around since last apr04. A lot of effort has been put into tracking this down. The main problem has been that it is intermittant... Today we finally located the problem. It is us... The problem is coming from the dewar monitoring hardware (the thing that keeps track of the dewar temperatures and bias voltage/currents). The problem is in the hardware. Turning off the monitoring software does not make the problem go away. We'll need a little while to nail down which piece of the hardware is causing the problem For now we've turned off the power to the monitoring of the lbw dewar.. This seems to make it stop.. But there may be other pieces that are also causing problems. So the problem may not be completely gone, but we now know where to look to solve it... phil ****************************************************************************************** /17/Nov/2004 CIMA Comment Observer: SS Project: a1961 Receiver: ALFA Email address for response:emuller@naic.edu,schneider@astro.umass.edu 1. Is Punta Salenas running? we have interference at 1382 & 1367 MHz throughout run even though it was suppose d to be off. 2. Broad strong interference (about 1MHz wide) fixed frequency range around 1381 MHz at 7h46 to 7h49 UT ************************************************************************************* % 1. Is Punta Salenas running? we have interference at 1382 & 1367 MHz % throughout run even though it was supposed to be off. This may well be the 1366.2/1382.66 MHz ship-borne radar that we have seen from time to time over the past 3-4 years. It is well documented on Phil's web page. If it is that radar it should have about a 2 sec repetition period (1.94 sec Phil says. Did you dump data at 1 Hz rate? If so, you should be able to see this period.) It seems to often occur at the time of naval exercises in Puerto Rican waters. It also has been know to occur at the frequency pairs of 1324/1340 MHz, 1387.3/1371.0 MHz, (note that the pairs are always separated by about 16 MHz.) % 2. Broad strong interference (about 1MHz wide) fixed frequency range % around 1381 MHz at 7h46 to 7h49 UT This is almost certainly GPS L3. It comes on irregularly for a few minutes every so often. Very strong, and wrecks the data when present. I saw a mail a couple of days back saying there would be L3 tests soon, but don't have the mail to hand at this second. Cheers, Chris ******************************************************************** I took a look at the data and in this case it really was punta salinas that was running. From about midnite to 15:00 on 17nov04 they ran in modes a,b,c, and channel 18 (1367/1382). They had not been doing this on the previous or following days. Maybe we need to call them and let them know that this happened (in case they weren't aware of it..). The operator tried to call punta salinas that night, but they got no response (since no one was there). There is a procedure for contacting someone after hours for punta salinas (some home phone numbers) .. We should review this with the operators to make sure they know about it.. You can see the plots from the data at: http://www.naic.edu/~phil/modhistory.html --> 18nov04: 1367/1382 radar birdies were punta salinas with chn 18 left on phil ********************************************************************************** 08/Nov/04 CIMA Comment Observer: BC, EM Project: a1956 Receiver: ALFA Email address for response: bcatinel, emomjian Pta Salinas seems to be operating in mode A and C at the same time (but mode A is stronger). Guess the coordination (for mode C) didn't work very well... ***************************************************************** I checked the hilltop monitoring and lister's data... pta salinas was in mode C only. The 1242, 1256 frequencies that you saw were from the aero stat radar. they share the same frequencies as mode A of punta salinas. If punta salinas had been in mode A, you should have seen the 4 frequencies: 1232, 1247 , 1242, 1256 not just 1242,, 1256 phil ****************************************************************** 06/Nov/04 CIMA Comment Observer: EM+ML Project: a1856 Receiver: L-Band Wide Email address for response:emuller mlebron We have damage to our data caused by the infamous wandering birdy. Our band is 6 MHz wide and centred on 14 20 MHz at 0 kms. So far, only one of our map strips are affected (out of about 5... )! EM+ML ****************************************************************** CIMA Comment Observer: EM+ML Project: XALFA Receiver: ALFA Email address for response:emuller, mlebron Two bright and persistent interf. peaks at 1430 and 1432 MHz. There is no apparent periodicity although they are somewhat intermittent. They almost always appear together and they don't appear to move around. They disappeared after 10-20 minutes. EM+ML ************************************************************************ 28/Sep/04 Hello Murray et al, I have some very bad news from tonights observing for a1909 (mapping small-scale HVCs). At around 11:30 until I finished at 12:15, I found some very bright, and frequency mobile interference all across my 6.25 and 3.125 MHz bands. Both boards were centred at 1.42GHz and the interference appeared to be somewhat polarized, although the degree of polarisation completely varied. The brightness was as much as half that of the Galaxy! About 40% of our observing time was lost because of these interferences. I have made a little images of my time series, just to show you how horrible the interference is! http://www.naic.edu/~emuller/interf_2_sept.pdf (I hope that is the best way for you to see the images- these are only one pol, with a 6.15MHz band width. Each spectra is one second. Each image is a separate ~4 minute interval. The mode is a drift scan. The centre line is the Galaxy. If you need better resolution images, let me know and I will see what I can do). I am not hopeful that too much can be done now of course, and I will continue observing tomorrow and so on. It appears that this is the same beast as is affecting Chris S, Tapasi, G and Emmanuel M. Enjoy Geneva Murray! Erik M. ********************************************************************** erik, This looks like the wandering lband birdie with 60 Mhz spacing. You can see more info about it at: http://www.naic.edu/~phil/modhistory.html --> 22jun04 drifting birdies in lb system with 60 mhz spacing. phil ps. the link for interf_2_sept.pdf left out the /data/ part of the directory path... **************************************************************************** 25/Sep/04 CIMA Comment Observer: em,cs,tg Project: a1908 Receiver: L-Band Wide Email address for response:emomjian@naic.edu The wandering RFI showed up again around 1400 MHz. The observed target source was 20480+0937. ******************************************************************************* CIMA Comment Observer: em,cs,tg Project: a1908 Receiver: L-Band Wide Email address for response:emomjian@naic.edu,csalter@naic.edu,tghosh@naic.edu Due to the wandering RFI, many other scans were affected in today's run. This problem has been sporadically ruining our observations since we started observing in July. We urge the RFI group to track down the source of this RFI and make this very important band usable again. Thanks! ****************************************************************************** 23/Sep/04 CIMA Comment Observer: Paulo Freire Project: p1733 Receiver: C-Band Email address for response: I see lots of interference in Channel A of the C band receiver. This is very broadband, it looks like a thunderstorm. Surprisingly, beam B is clear of this. This happens both at 4800 MHz and 5800 MHz. Both channels detect strong pulsars in the beam. ************************************************************************************************ 10/Sep/04 CIMA Comment Observer: BC & EMom & EMul Project: a1946 Receiver: ALFA Email address for response: bcatinel, emomjian, emuller The birdy for beam 0B at ~1.38GHz appears to have multiplied and spread into all beams now! This mornings a1946 data showed a persistent birdy at ~1.380GHz for all boards, all pols (and apparently variable between boards, though it is difficult to tell). It does not have the shape of a GPS transmission (which is not scheduled for transmission today anyhow) and appears in every other way to be a smaller and much, much weaker copy of the birdy which was on beam 0B earlier this week. BC, EM, EM. ******************************************************* This is a different birdie from the one caused by the rf to if board in beam 0b. It has been their for awhile. If you look closely at the plots in http://www.naic.edu/~phil/modhistory.html -->08sep04 1380 Mhz birdie in pixel 0b of alfa data on the first page you can see this other 1380 Mhz birdie in all the beams. On page 2 you can see a blowup of it. It is at different frequency from the large birdie in pixel 0b. phil ***************************************************************** CIMA Comment Observer: BC & EMom + Emuller Project: a1946 Receiver: ALFA Email address for response:bcatinel, emomjian, emuller Just a caveat for the previously submitted a1946 RFI report for the 1.38GHz 'birdy': The strength of that 'birdy' at ~1.38GHz appears to be somewhat correlated with the strength of the Airport radar. BC, EM, EM *********************************************************************** 29/Aug/04 CIMA Comment Observer: riccardo Project: a1946 Receiver: ALFA Email address for response: In backend control: WAPP power levels change when Adjust Power button pushed, but values not updated during scan. Power levs are updated on alfaobswin display. *************************************************************************************** 21/Aug/04 Hi Phil and Murray, Jim and I see some unusual RFI in our a1843 observations at 327 MHz. Phil, I know you noticed this when you were looking over the data last month. Just wanted to send over some plots and ask if you had seen this type of interference before or had ideas about what might be causing it. The first plot (scan 0026) shows interference that covers a few MHz and has a regular modulation in time. The second plot (0032) shows a much narrower signal. Kate *********************************************************************************** 2/Aug/04 Tapasi, Just to let you know, everything has gone well so far. The only issue of any sort is a bit of broad interference (about 2 MHz wide) that has been popping up around 1400 MHz in about half of the on-off pairs (5 minutes for each scan). It's obviously variable, but it also looks like it shifts in frequency as well, since some scans have a zig-zag shape near 1400 MHz. It isn't a critical problem, since my line is at 1394 MHz, but it does make for some ugly baselines. Looking at the RFI page, it seems that this could be consistent with the 1400 MHz birdie which was tentatively tied to the WAPPs. Is there a known solution to this issue? thanks. later... --D.J. ---------------------------------------------------------------- D.J. Pisano NSF MPS Distinguished International Postdoctoral Research Fellow CSIRO Australia Telescope National Facility P.O. Box 76 | phone: +61-2-9372-4573 Epping NSW 1710 | fax: +61-2-9372-4310 Australia | DJ.Pisano@csiro.au ---------------------------------------------------------------- *************************************************************************************** Hi Daniel, Yes, this RFI has been seen since the end of May. I am forwarding your mail to the RFI group (I no longer belong to that group), and to Steve Torchinsky, the new Head of Radio Astronomy group. They will have to decide what to do about it. Hope yur observtaion go fine ? Best wishes, Tapasi ****************************************************************************************** d.j, I looked at your data from the last two nites (02aug04,03aug04): This is what i found: 1. There is a narrow birdie at 1400 Mhz from the distomats that comes every two minutes and lasts for a few seconds. I don't think it is bothering your data. 2. There is a broad ripple (a few mhz) in the bandpass around 1400 Mhz that corresponds to what you were talking about. #2 is not from the 1400 Mhz birdie from the wapps. The 1400 Mhz birdie from the wapps is a multiple of the 100 Mhz clock frequency (probably all of the digital logic switching at that rate). It is extremely narrow (since it is tied to the station clock/maser). We have seen a drifting birdie in lband with a 60 MHZ spacing (look at http://www.naic.edu/~phil/modhistory.html, -->22jun04 drifting birdies in lband system with 60 Mhz spacing). It has a narrower bandwidth than what you have. Back in may04 a1861 (john salzer) did have a problem similar to what you see. It looked like we could make the problem go away by not selecting the 1370 hipass filter. We never did any thorough testing of this problem so it may have just been a coincidence that things got better. In the gui, you might want to try selecting just the 1360-1470 bandpass filter rather than the 1370 hipass filter. You may end up getting some intermods from the 1350 radar, but it's worth a try... let me know if it makes a difference.... phil perillat phil@naic.edu **************************************************************************************** 30/Sep/03 CIMA Comment Observer: B. Catinella Project: a1761 Receiver: L-Band Wide Email address: bcatinel@naic.edu, springob@astro.cornell.edu During A1761 observations I had RFI at two frequencies: 1424MHz, ~0.8 MHz wide, lasting maybe 1 or 2 seconds 1396 MHz, ~2 MHz wide, lasting maybe 1 or 2 seconds These RFIs are present in all of the scans, except maybe the first few ones. The worst case is scan 327301064: both RFI are very strong, very regular and with the same periodicity (every 10s), and present in both polarizations. Scans 067 and 070 are pretty bad, too. I looked at Phil's RFI web page but didn't find these frequencies mentioned. **************************************************************************** Barbera, I looked at the data, and the birdies were happening at the same time. This gives you a hint that they are intermods or harmonics of something in our system. The twelve second separation between the rfi looks like a radar rotation rate. I looked at the hilltop rfi monitoring info and saw that the Puntas Salinas frequency-agile radar (lband) was running all night in their all frequency mode. Two of their freq were 1366 and 1381. These were the ones that were probably causing the intermods in the system. This morning they were still running in their all freq mode. They had been running in this mode for a week during the aeronomy experiment. Looks like they didn't switch back to their two frequency mode. Rey Velez had sent them a new schedule, but maybe they didn't get it. Rey will call them today.. phil NB Rey finds Puntas Salinas is having troubles with fax & email, and ours is not getting through their system. To find another way. BML ******************************************************************************* 12/Aug/03 CIMA Comment Observer: cs Project: a1713 Receiver: L-Band Wide Email address for response: Occational narrow spike, at MHz ~ 1637, one channel RFI also, at MHz ~ 1691, spiky interference always present Time: 17-18 EDT, August, 12th, 2003. Simon (and the GB gang + Chris) *************************************************************************** 11Aug/03 Observer: I Stairs Project: P1740 Receiver: Carriage House 430/47 Observing with pspm and mark4. Sometime in the last 5 min or so, a fairly strong, very narrow (about 1 channel) birdie has appeared right at 430 MHz, in the middle of the pspm band. The strength seems to be time-variable. Ingrid *************************************************************************** We've been having intermods caused by tv chan 14,22 in the 430 Mhz receivers. I took some data 19jun03 while doing azimuth spins with the dome and carriage house at high za. You can see the results at: http://www.naic.edu/~phil -->rfi --> rfi measurements. --> 19jun03: 430 birdies... You can see which of the birdies are related by looking at the azimuth dependence of the az swings. I also took 20Khz bandwidth baseband data from both the dome and the carriage house and then beat the two signal together. You could see the doppler shift in the difference frequency caused by the motion of the azimuth arm. This gives the direction of the signal when the doppler goes to zero... phil *************************************************************************** > Observer: ppk > Project: a1731 > Receiver: 430 MHz > > Very strong RFI at 432.5 - 433 MHZ and at 435 - 436 MHz. > Began about 19:20 AST and getting steadily worse (on Monday, Jun 16) > > Phil Kronberg > kronberg@lanl.gov I looked at the rfi for a1731. The 432.5-433 and 435-436 birdies were the same signal. They drifted together starting up at 435, down to 432 and then back up to 435 (pretty lousy oscillator..) The tv station intermods were also visible: ch14_Vid=471.25 ch14_Aud=475.75 ch22_Vid=519.25 ch22_Aud=523.75 The intermods are: ch14_Aud*2 - ch22_Aud= 475.75*2 - 523.75 = 427.75 ch15_Aud*2 - ch22_Vid= 475.75*2 - 519.25 = 432.25 The first intermod at 427.75 was there most of the night and stable. If the other birdie was from the second intermod, then you would have a stable ch22_Aud and a drifting ch22_Vid (since the first intermod was stable). This drift was up to 3 Mhz so i doubt if the birdie 432-435 was the tv intermod. I wonder if we have some ham transmitting video at 430 (slow or fast scan??) phil ************************************************************************** 11/4/03 Observer: dlorimer Project: p1685 Receiver: Carriage House 430/47 The RFI situation is significantly better with 430 carriage house thanks to the recent efforts. Many thanks to all involved. Kristine, I looked at the hilltop monitoring and did not see anything unusual during this time. Unfortunately the hilltop monitoring checks a band once every 20 minutes so it would be easy to miss something. I also went through all of your data. It looks like it is something out of band. I plotted the power counter data (50 Mhz bw) for each sbc. They all looked about the same. So the positioning of the 4 50 Mhz filters for your lo's did not make much difference. I thought it might be gps at 1381 but that's just a guess. I would have expected the 4 sbc to respond a little differently. One thing that would be helpful is to have someone down here look on the spectrum analyzer at the entire rf band you are observing while this is occuring. Since you had the 1370 hipass filter in , we could have looked at least at 1370 to 1650 Mhz. Unfortunately i'm not sure all of the operators know how to do this. If chris is here, he could give it a shot. If you don't see anything on the spectrum analyzer with the 1370 high pass filter in, you might want to take out the 1370 Mhz high pass filter, and look (on the spectrum analyzer) at the whole band to see if there is anything below 1370 that is causing problems in the dewar... phil ************************************************************************* 11/4/03 Observer: Kristine Spe Project: a1705 Receiver: L-Band Narrow *very strong*, intermittent RFI throughout our band (1385-1425 MHz), starting at ~2:20 AST. So strong that we thought something might be wrong with the receiver when it first appeared - asked Miguel to check things out, and everything seemed normal. *Huge* peaks in the RMS power plots (size of galactic HI signal), about 0.2-0.5 MHz wide, and throughout the band. Peaks not coincident in PolA and Polb, although both Pols experienced it. Intermittent; it's difficult to estimate quasi-period since the montoring output was drowned by the RFI when present, but I think it's about 30-60 secs. However, it's very erratic: for example, scan #310105616 is completely contaminated, whereas the next one (310105619) is clear, and then in the scan after that (310105622) it's back with a vengeance... What is this? 05/4/03 Observer: spekkens Project: a1705 Receiver: L-Band Narrow Very narrow RFI (less than our 12kHz channel width) at 1400 MHz, ~ 3K in RMS power plots, from 7:30 - 9:00 pm AST. Did not return for the remainder of the run, which ended at 4:00 AST. 04/4/03 Observer: spekkens Project: a1705 Receiver: L-Band Narrow Persistent RFI at 1424.5 MHz and 1396.5 MHz. RFI at 1424.5 MHz first noticed at around 7:50pm AST; width of RFI about 1 MHz, strength 3-5 times RMS power levs. RFI at 1393.5 MHz became noticeable a few hours later - 2 MHz wide and generally weaker than that at 1424.5 MHz. Worst at around 12:15 AST: many times rms power in strength, both signals have same periodicity of 10-15 seconds and show up at the same time in our scans. 1424.5 Mhz seems to be have 2 widths superposed, one ~1/5 MHz and one ~1 MHz. 1396.5 MHz also has two widths, one ~1.5 MHz and one ~3 MHz wide. Both widths for each signal are seen in a single ~5 min scan. No clear periodicity for which width appears at a particular frequency was noticed. Got better towards end of run (~4:00 am), the 1424.5 MHz RFI being the mors persistent of the two. Could these be harmonics of 1269 and 1290 ramey radars (as mentioned on RFI measurements page, 4oct01) ? *************************************************************************** 29/3/03 Observer: xiluri Project: P1600 Receiver: 430 MHz Hello, this is Kiriaki Xiluri (kx8u@virginia.edu). Today i started at 15:00AST observing with the 430CH, pulsar run. I am aware of the tV stations and after a few runs i switched to the 430dome. Here are my observations and i hope you find them useful. I was observing with the PSPM, a 128 -8MHz filter bank. While with 430-CH, there was always a spike present at about channel #28. The first 1/3 of the band was basically unusable while occasional spikes were seeing at the upper end of the band.. With 430-Dome there were times of tranquility. The spike at #28 made its appearance but not as frequent and i think not as strong. But a new spike appeared at channel 3-4. Occasional spikes were at the end of the band as well. I am not sure if in addition to the stations what i see is radar. with best regars kiriaki 28/3/03 Hi Ingrid, The notch filter is ONLY in the RCP channel (B) and is not in-band. So, the spikes are still present in the LCP channel. It merely attenuates the stronger TV station (470 to 476MHz), while passing the 430 MHz band with a little insertion loss. Unfortunately, it does not have enough bandwidth to cut off the other TV channel #22 (518 to 524 MHz). The in-band 3-rd order intermods from these carriers are at 423.25, 427.75 (strongest), 432.25 & 436.75 MHz. Due to complexities involved with 430 RADAR operation, it is not possible at present to introduce a similar filter in the LCP channel. As the aeronomy program currently uses only about 1 MHz bandwidth, their observations run fine. TV transmitters: The TV channel # 22 went up from 100KW to 4.2 MW at the same time channel #16 restored to high power transmission. Unfortunately, we can not do anything with their power levels, as they have the FCC approval & some paper work has gone thro' our Spectrum Management office. The solution is to filter out these strong signals, before the cooled amplifier or decrease the gain/increase the power handling of our cooled amplifiers. The Bandpass Filter that we have ordered will completely eliminate this problem, but add about 10K (we hope) to the system temperature. Delivery is expected in 3 weeks. In the meantime, If all users agree, we can switch to a room temperature system (high dynamic range), but that will increase the Tsys to about 100 - 110 K. It will be possible to switch to the room temp LNAs next Tuesday after the Monday night RADAR run. I will discuss with Chris & others Monday. Cheers, Ganesh 28/3/03 CIMA Comment Observer: Ingrid Stairs Project: P1740 Receiver: CarriageHouse 430/47 Email address for response:stairs@astro.ubc.ca Hi - Whatever notch filter arrangement was put into the CH to attempt to block the Tv-station rfi doesn't seem to be working, unfortunately. All the trouble is in one polarization, and everything was stable at L-band, so I'm pretty sure I'm right to blame RFI at 430 as opposed to instrument problems. The symptom is that the mark4 levels will able stable for a while (few minutes?) but then increase by 30% or more in one polarization for maybe 20-30 seconds, and then repeat shortly afterwards. In the pspm spectrum I see a couple of narrow lines, one of which is around channel 30 (so around 427.8 MHz - right where Ganesh said) and its strength is obviously correlated with the increase levels on mark4. Unfortunately with mark4 I'm using a 5 MHz bandpass centred on 430 MHz; I can't quite remember how to switch to a different central frequency or I would try to move up a bit. Hope you can persuade the TV station to reduce its power - right now the band is barely usable! Cheers, Ingrid ************************************************************************ 26/3/03 Hi Dunc & Maura, Just to fill in some technical details on the CH430 RFI problems... Yes, the dome shields the receivers better from the TV station signals. The open linefeed is more susceptible to RFI & that is why we see such problems more in the CHouse. Our careful measurements on the platform have shown that the spikes in the passband are caused by the inter-mods in the cooled LNAs by two of the strongest TV stations around; Channel #14 & Channel #22. On the 20th Feb, the Channel #14 signal went up by more than 20 dB & is causing us this problem. -------------------------------------------- Spurii in band 415MHz to 445MHz Fixed1=475.75MHz (audio of Ch #14) Fixed2=523.75MHz (audio of Ch #22) -------------------------------------------- +2*Fixed1-1*Fixed2=(427.75MHz) <----- heard! -------------------------------------------- Fixed1=471.25MHz (video of Ch #14) Fixed2=519.25MHz (video of Ch #22) -------------------------------------------- +2*Fixed1-1*Fixed2=(423.25MHz) <----- seen! -------------------------------------------- The other spurii are at 432.25MHz & 436.75MHz. The monoplexer which protects the receiver during the RADAR observations is on the LCP channel (A) and it acts somewhat like a bandpass filter and reduces the levels at the amplifier input. In addition, we have had some biasing problems with the RCP channel (B) LNA, resulting in lower power handling capacity and hence more intermods. That's why LCP channel is better than RCP channel. As Rey found out, this station was transmitting low power in October 2002, when we replaced with new LNAs & we did not see these intermods then. We are trying to solve this problem in the short term by introducing low loss cavity filters / notches. This will result in a slight increase in the system temperature, but the band should be clean & stable. Sometime in the summer, Carriage House will get a new dewar with NRAO LNAs (same as the ones in the dome) and also a new monoplexer module. Cheers, Ganesh p.s. BTW, Thanks, Dunc for your kind words on our work on the 327MHz Rx. We will continue to reduce the system temperature. We will very soon start designing a dewar for a cooled receiver. That is second in the priority list, after the new 6-8 GHz receiver. ************************************************************************ 24/3/03 > hi guys, > > thought you might like to see these plots from last nights observing > comparing an observation of the same pulsar with both 430-MHz systems. > > http://www.jb.man.ac.uk/~drl/download/430_rfi.gif > > The top plots show a 10-s integrated bandpass and the bottom ones an > integrated pulse profile (the pulse period is about 2.8 s) from 90-s > observations. > > as you can see - the carriage house RFI is really bad! resulting in > very crappy s/n profiles cf the dome. We'd like to keep using the > carriage house as long as possible, for consistency with our previous > timing results, but if this doesn't get much better, we may have to > seriously reconsider this. > > talking to Phil on the chatterbox last night, he suggested that the > RFI was caused by an intermod connected to the TV stations that > would be visible from both receivers, but it's clearly much worse > with the carriage house, which suggests to me that it might be > something internal to the receiver? > > any thoughts on what it could be would be much appreciated > > cheers > > Dunc 09/3/03 Observer: Maura Project: P1682 Receiver: 430 MHz Tonight and during my runs on Thursday and Friday, the RFI situation with the 430 MHz carriage house has been really bad. There are a few huge intermittent spikes in the bandpass which make it almost unusable. The 430 Gregorian is not nearly so bad so it must be something internal. Maura ************************************************************************** 07/3/03 Hi Barbara, Our apologies for your rocky start last night. We will do our best to check out all entries in the relevant catalog in double quick time. You later write; % Project A1726 % % I have been observing from 8:45pm to 3:30am AST. % A narrow RFI was present at 1350 MHz, as it can be seen in the scans % from 306501039 to 306600017. The radar blanker was on all the time. % The data (dumped every second) is in /share/olcor/corfile.07mar03.a1726.1 % % Barbara Indeed, this is a long known birdie, at least since Oct 01. It is probably generated on site, and some work was done on it in 2001, but being "under the FAA radar", it probably got less attention than it deserves. I'll cc: Murray Lewis, our spectrum coordinator, on this mail, and he will doubtless see that it gets a fresh look (and hopefully solution). Phil wrote up some work he did on this RFI in Oct 2001. I'll append the text below, but look at http://www.naic.edu/~phil/rfi/rfi.html#05oct01 1350 Mhz tone for the associated figures. I hope that things went better later in the night? Did you manange any detections for these higher-z targets? Ciao, Chris >From Phil's pages: % 05oct01. tone at 1350 Mhz. % % The FAA radar is at 1330 and 1350 Mhz. When the radar blanker % was used, the radar pulses were blanked but a tone remained at 1350 % Mhz. On 05oct01 an azimuth spin was done with lband narrow (native % circular) with the dome at 19 degrees za to look for any azimuth % dependence of the tone. The correlator was setup for 25 Khz resolution % and was dumped at 1 second intervals. The figures shows the results. % Pol A is black, pol B is red, and the azimuth location of the control % room is flagged with a green vertical line. The top figure shows +/- % 180 degrees azimuth (from north). The center figure smoothes the 1 % second samples (.2 degrees azimuth /sample) by 11. The lower figure % blows up +/- 20 degrees azimuth about the control room position. % Asterisks mark the 1 second samples. The tone is between azimuth -100 % and +10 degrees az. The peak value is close to the control room values % but the center is not. The peaks last for about 8 seconds (or 1.6 % degrees in azimuth). At 25 Khz resolution the tone was not resolved. % % If the control room is causing the problem, then the center % offset may come from the asymmetry in the cliffs adjacent to the % control room blocking the beam. The lidar lab and the rfi shack are % also in this general direction. We need to go up to the azimuth with an % antenna and look around (bringing the data down into the correlator and % using the blanker). processing: x101/011005/1350tone.pro ************************************************************************* 07/03/03 Project A1726 I have been observing from 8:45pm to 3:30am AST. A narrow RFI was present at 1350 MHz, as it can be seen in the scans from 306501039 to 306600017. The radar blanker was on all the time. The data (dumped every second) is in /share/olcor/corfile.07mar03.a1726.1 Barbara