Rfi list by freq

last mod 20mar14

     This is a working list of rfi found at the observatory. It should eventually get merged into the rfi page (when i figure out how to modify it).    Each entry in a list has a link to any further info. The dates are when we (me) became aware of the birdie, not when when it first appeared. A birdie in the list means that it was here at one time. It may have gotten fixed (many of the beeper harmonics). It stays in the list in case in pops up again. The status column is filled in for the  birdies that i'm sure about. The column being blank reflects my ignorance.

By frequency:

327 Mhz birdies
430 Mhz birdies
450 MHz to 1 GHz
lband birdies
birdies above lband

Combs 

Device specific birdies

title 47 part 15 radio frequency devices


    327 Mhz birdies

    The table below comes mainly from azimuth swings done on 28oct05  (more info). If a birdie varies with azimuth, then it is coming from outside of the dome.
 
327 birdies  (top)
freq date stat Comments
308.352 05oct
  • This was the  strongest signal (1600*Tsys). 
  • It was less then 1 frequency channel wide. 
  • It was time variable in time: on for 1 second (may have been shorter than 1 second). 
  • It repeated every 18.6 seconds. 
  • It was present for the first 55 minutes and then turned off.
  • It was not causing the set of frequencies that looked like intermods since they continued after it turned off
308.7
309.9
311.07
313.1
314.3
317.5
318.9
05oct
  • These signals were time variable and got stronger/weaker together.
  • 317.5 was heard to be the FM station 107.3 (on the radio). This may mean that all the others are related to 107.3 (see 321.9/317.5 below).
  • 308.7 is the 3rd harmonic of 102.9. On the whip antenna this is the 2nd strongest fm station (after 107.3).
  • There may be an out of band birdie that is causing all of this birdies to increase?
  • The common frequency difference is about 1.2 Mhz. 
312.3 05oct
  • This the  3rd harmonic of 104.1. We heard the radio station when we listened to the 312.3 birdie in the 2nd IF.
321.9
317.5
05oct
  • 321.9 :This is the 3rd harmonic of 107.3 It is the  strongest fm station at AO. The music was  heard in the IF using the radio.
  • 317.5: 
    • This was heard (with the radio) to be 107.3. 
    • It is 4.4 Mhz below 321.9 Mhz.
    • 4.4 Mhz is the fundamental difference between 107.3 and 102.9. These are the two strongest fm stations. 
320.9
328.1
05oct
  • These came from the alfa motor controller. Turning of the controller made them go away.  Look at 28oct05 swing 1. gif at the bottom. The motor controller was on and then turned off around an az of -50.
309.66
317.04
323.18
330.01*
331.78

324.41
325.64
 
 

05oct
Birdies coming from the azimuth encoder comb (more info).
They all share the same azimuth dependence (although 324.41 and 325.64 look a little different).  The strongest is 324.41 at 1.6 Tsys in a 24 Khz resolution bandwidth.
The encoder comb is spaced at 614.368 Khz (where 1 freq is 320.719). The table below shows the frequencies for the comb in the 327 band. The  resolution in the step is probably hz. The resolution in the offset is 10 to 20 Khz (determined by the rbw):
 
azimuth enc comb freq in 327 band
308.431  309.046  309.660  310.275  310.889  311.503  312.118  312.732  313.346  313.961 
314.575  315.190  315.804  316.418  317.033  317.647  318.261  318.876  319.490  320.104 
320.719  321.333  321.948  322.562  323.176  323.791  324.405  325.019  325.634  326.248 
326.863  327.477  328.091  328.706  329.320  329.934  330.549  331.163  331.777  332.392 
333.006  333.621  334.235  334.849  335.464  336.078  336.692  337.307  337.921  338.536 
319.5 05oct
  • showed repeateable az dependence. This is the 3rd harmonic of 106.5. It is the 5th strongest fm station on the whip antenna. It is also close to the azimuth encoder comb frquencies.
319.93
320.00
320.06
05oct
  •  Same azimuth dependence.
312.3
312.5
313.99
324.00
325.00
327.51
05oct
  • These all showed unique azimuth dependence.
324
04mar14
fixed
meteor video camera on top of antenna test building (more info)
324-328
mar14
found
a birdie drifting up to 4 mhz in 24 hours was seen in the 327 receiver feb,mar14. It was coming from the sbn postamp chassis. (more info)
327.62(3)
331.79
335.95(3)
344.07
352.51(3)

24jan13

ac building 2 during building II  turn off (more info)
There are also weaker birdies from this
(3) --> a triple



 
430 MHZ BIRDIES (top)
FREQ
Mhz
BW DATE STAT COMMENTS
408.6145 <.003 oct02
(more info)
410.5249 <.003 oct02 active Coming from 1000 foot navy tower in aguada.(more info)
410.8118 <.003 oct02
(more info)

418.75
423.5
427.75
432.25
435.75
  mar03 fixed
jan05
tv chn14,22 intermods moreInfo
2*f1Video-f2Audio
2*f1Video-f2Video
2*f1Audio-f2Audio
2*f1Audio-f2Video
alias of 423.5 using 12.5 mhz digital filter
jan05-low loss filters to notch out tv stations inserted in front of dewar. (moreinfo)
422.72
423.18
423.25
423.46
--
429.89
430.31
430.38
430.48
--
432.67
30
Khz
dec05 active These birdies have 1 minute periods (more info).
424.03
420.096
429.550
  aug99   dome camera birdies at 430 mhz when the iflo cabinet door was open. Note seen when the door was closed. (more info)
425-440 6 aug01 radar Airborne radar. customs or navy. Usage decreased since war games at rosy rodes stopped. Can tune to a 6 mhz band between about 420 to 440 Mhz. Easily seen on the hilltop rfi monitoring plots. (more info)
426.25

 

lt 12.5
Khz
jun03

 

active

 

az swing peaks at -59 az. When this signal was baseband samled, it looked like a phase lock loop that was sweeping back and forth thru its input bandwidth as if it was out of lock. The sweep time took 12 seconds to repeat.
moreInfo
429.16
433.32

427.48
430.11
430.49

<.001 aug99
Power meter in dome (429.16,433.32). 433.32 is strongest
Multimeter in dome (427,430)
They were first placed in the shielded iflo rack in the turret room (birdie_Strength)
The power meter and 1 multi meter was then placed in an rfi shielded box within the iflo rack. The 2nd multi meter is still in the iflo rack.(more info)
430-432
chirped
feb14
fixed
strong 430 birdie 10e3*Tsys every 10 secs (lasting 180 millisecs)
coming from a motorola 460 Mhz repeater on tua's tower in utuado (more info)





450 to 1 Ghz (top)
FREQ
Mhz
BW
DATE
STAT
COMMENTS
tvFreq



175-700 MHz
849-851
894-896

jul09
notseen
inflight internet,email: jetblue, gogo
849-851 ground to air
895-896 air to ground
limited towithin 300 miles of mainland because ground stations are used.
ac bidco sister company of aircell.
902-928


notseen
pge smart meter wireless frequencies







LBAND BIRDIES  (top)
FREQ                 
Mhz
BW DATE STAT COMMENTS
1090


secondary surveillance radar (SSR) and air borne collision avoidance systems (ACAS). Seen in hilltop monitoring system.
1176.45



GPS L5 coming.. +/- 12.5 Mhz.
1200.
<.05hz
2001
active
A tone at 1200 Mhz has been present since we began recording the fractional occurrence of rfi from the telescope data.
It is less than .05 Hz wide and it is located at 1200Mhz. It is coming in through the horn since the amplitude repeats with with the same az,za. It looks like it is locked to the station clock. (more info)
1215 to 1400
(freqList)
In modeA:
1228.5 1243.5
1279.5 1294.5
1.15
.625
feb00 active
radar
Punta salinas  frequency hopping radar. 12 sec rotation. short and long pulse lengths: 51.2 and 409.5 usecs. When we request, they will sit in mode A (1232,1247,1241,1256 Mhz) rather than hop thru the entire band. the the complete set of frequences see: (freqList)





1215.6-1239.6
center:1227.6

apr99
gps  l2
1235-1256



glonass L2
Pcode 5.11Mhz bitrate, Satellite spaced .4375 Mhz
Lowest carrier cfr: 1238.9375
1241.75
1244.6
1256.5
1261.25
1.67 jan97-
dec11
active
Radar
Aerostat radar ballon in lajas. dual freq or quad freq modes. 160 usec per pulse, chirped. Rotation rate 11.59 secs. Blanks toward AO. (see aerostat info)
15dec11- tether breaks, balloon rises and then bursts. aerostat offline.
1269.41 F1n
1274.59 F1
1327.41 F2n
1332.59 F2
1-2Mhz
apr13
active
Radar
Punta Borinquen CARSR (Common Air Route Surveillance Radar). Installed 01apr13. They blank when pointing in our direction.   This is a spread spectrum radar with  3 ipps. It transmits 5*ipp0,5*ipp1, then 5*ipp2. The transmitted pulse sequence is:
  • F1 117us
  • 2 usec off
  • F2 117 usecs
  • 2 usec off
  • F2n 19 usec
  • 2 usec off
  • F1n 19 usecs.
 More info

( This radar has replaced the 1270,1290 radar that used to be at punta borinquen/remy radar)
 
1270/1290 .2 feb02 Radar
out of service
Punta Borinquen Remy Radar at the end of the runway .(fps20-93a). 12 sec rotation rate, single ipp of 2781. Runs in 1270 or 1290 mode (not simultaneously). (see radar info)
This radar has been replaced by the 1269,1274,1327,1332 CARSR radar .. see above.
1270+/-20
1290+/-20
.2
mar11
Radar
out of
service
when 1270,1290 are both active they are transmitted simultaneously. These intermods
are created in the receiver (2f1-f2) etc..
1287.5/1299.84
1300,1399.83
1400
1411.52
1412.5
<.025 jan01
apr02

Distomat birdies. Occur every 2 minutes for a few seconds. Az dependent.Distomats have a 27 Mhz clock.
Data was measured in jan01 (before shielding work)
Data was remeasured in apr02 (after some shielding work).
The window was changed 
1349.6/1344.4
1257.6/1252.4
1-2
apr13
faa carsr
radar
faa radar. switched to carsr apr13. more info
1330/1350 .2 jan97 out of service.
switched to carsr
FAA airport radar.12 sec rotation, 5 ipps about 2.5 ms,5 usec pulse, 1350 then 1330 pulse sent each ipp.  (radar info)
1340
narrow
sep10

narrow tone at 1340. this is from the lo of the radar blanker on the platform.
1366.2/1382.66
1324/1340
1387.3/1371.0
  feb01 Radar Radars with 1.94 sec rotation rates. ( more info). These radar were probably associated with military ship practices. Fast rotating radars are needed when objects move far within 1 rotation (planes near aircraft carriers,etc..)
1374.988
<20hz
nov09
fixed
stride 100 mbit 5 port ethernet switch (with fiber converter) that had been installed on top of the platform in a plastic box.
1381.05 1 sep91 active GPS L3 downlink. (more info)
1388.55 .024 98
beeper harmonic (3rd of 462.85)
1388.6 .024 93
beeper harmonic (3rd  of 462.875) (borinquen beepers)
1388.858
1417.495
<190
(hz)
may02
dome camera birides. part of a comb of 14.3185 Mhz. (more info).
1390.8 .024 feb93
beeper harmonic (3rd of 463.6 (mr. beeper)
1407 .3 apr01 fixed tvChan20 arecibo. Drifted around with time. They were having  trouble with their transmitter. (more info)
1408.0x
<500hz
sep11
active
1408.0143,1408.0638 < 500 hz wide. Combs of 50Khz about these.
peaks at az=338.1 (za=15).
coming from new ac unit of top of building I
(Ac also has 80Mhz comb).
1422.5


tvChan54 2nd harmonic
1525-1545   aug03
Inmarsat stdBC ship,portable earch downlinks
Inmarsat stdM ship downlinks
1525-1559   aug03
Inmarsat stdF ship, stdM portable earth downlinks
1530-1559   aug03
Inmarsat airborne downlink
 1535.0 -1543.5    aug03   InmarSat stdA downlink. RHC xmitted. 339 channels. chan1=1535.025, chn339=1543.475. chn spacing 25Khz. signal bw 12 Khz. FM modulation. chan110 is call announcments. position tracking carriers at 3947.0 / 3949.4 / 3950.6 /3953.0. Info 06aug03 
1575.42 1.

GPS L1
1602+.562n   aug98 active GLONAS n= -7 to 13.  more info
1621.35-1626.5
(need to update freq range)


active iridium communications satellites.
66 sat, 6 planes, inclined at 86.4deg to pole.
3*16 beams per sat.
90 millisec rep rate. 
8 8.29 ms tdma slot. 4 uplink, 4 downlink.
band protect guard time of 22.48 ms
interframe guard times:.1ms upl, .28 ms downlink
delay sat to ground: about 2.6 millisecs
120 fdma chan in 5.15 Mhz. Each chan 31.5Khz 
Within each fdma chan there are 8 tdma chan (4upl,4dwnl).
1626-1646.5
aug03
InmarSat stdBC ship earth station, portable mobile earth
InmarSat stdM ship earth station uplinks
1626-1660.5
aug03
Inmarsat stdF ship earth station uplink
Inmarsat stdM portable earth mobile station uplink
Inmarsat airborne uplink
1636.5-1645.0


InmarSat standardA uplink

GNNS  satellites




galileo ..  fundamental freq: Fo=10.23 Mhz
freq
Nm
chiprate
Mcps
Notes
1164-1189
E5a
115*Fo
Fo
115E5a cycles/chip
10.23Mhz
carrier:1176.45. Also gpsL5
1189-1214
E5b
118*Fo
Fo
118E5b cycles/chip
10.23 Mhz
carrier:1207.14.Also glonass L3
1164-1189
ALTBOC
10.23 Mhz
covers E5a and E5b. cfr:1191.975
1260-1300
E6A,B
125*Fo
E6A unknown
E6B Fo
250E6 cycles/chip
5.115 Mhz
1278.75 center. Commerical service . coded
1544-1544.2


SAR downlink
1559-1563
E2


1563-1587
L1

shared with gps L1
1587-1591
E1
Fo/10 (Achan)
616L1 cycles/chip
2.5575 MHz
Fo/10 (B&C chan)
1540cyles/chip
1.023 Mhz
carrier: 1575.42

notes:
  • 1164-1214, 1563-1591 : open service free to public
  • 1260-1300 ,                   : commerical service.. fee charged for usage.
  • giove-A: launched 28dec05: uses L1+E5, L1+E6. E1-boc(1,1) and E6
  • giove-B: launched 27apr08:  uses E1-CBOC & E6
  • 30 satellites, 3 planes of 9 satellites each





Glonass
L1
1602+.562n n=1 to 24. shutting down soon?? but leaving n=12,21,22,24??
L2
1235-1256 1246 + k*Fs  k=-7 to 13  Fs=437.5 KHz
  • standard accuracy code chip
    • 2438.36 L2 cycles/chip
    • .511 MHz
    • pnCode. length=511 code chips, period=1 msec
  • high accuracy code chip
    • 243,836 L2  cycles/chip
    • 5.11 MHz
L3
1202.025
1207.14
glonassK1 launched feb11
glonassKN N>1  will use 1207.14
CDMA
L5
1176.45
GLONASSKm lauch date 2015










COMPASS chinese GNSS system (more info)
1589.74
1561.1
1268.52
1207.14




see also:  Novatel  info on :galileo,gps,glonass,compass (.pdf)

Birdies above lband  (top)
FREQ
Mhz
BW DATE STAT COMMENTS
1990-2110 17Mhz
12Mhz


bas(Broadcast aux serv), LTTS(local television transmission serv), cars cable television relay service. Moving from 17 Mhz chan to 12 Mhz chan (2005). 
1710-1755
2110-2155


aws-1
advanced wireless band plan (.pdf)
Licensee's in PR:

Call
chan Blk
licensee
freq Range
WQGD633
E
T-mobile
1740-1745
2140-2145
WQGA789
D
AT&T mobility
1735-1740
2135-2140
WQGV899
C
triad aws PR
1730-1735
2130-2135
WQGV788
C
triad aws pr
1730-1735
2130-2135
WQNI308
B
PRTC
1720-1730
2120-2130
WQGT859
A
cavalier wireless
caguas
1710-1720
2110-2130
WQGT864
A
cavalier wireless
mayaquez
1710-1720
2110-2130
WQGT865
A
cavalier wireless
arecibo
1710-1720
2110-2130
WQGT866
A
cavalier wireless
aguadilla
1710-1720
2110-2130
B489
BR broadband
radio service (not aws)
clearwire corp
(mayaguez)
2150-2156

1915-1920
1995-2000
2020-2025
2175-2180


aws-2

2155-2175

2007
aws-3

2228.524
.350
jun10

lhcp.sband downlink new gps satellites. As forwards from gps command
2305-2320
2345-2360


2010

Wireless communications services WCS.
Auction #14 wcs 25apr97. PR rights bought by coloma wireless. At&T then bought the rights:

blockname
lower Freqblk
uppper freqblk
A
2305-2310
2350-2355
B
2310-2315
2355-2360
C
2315-2320

D
2345-2350


Note block C,D have limitations within 2.3 Mhz of satellite radio
  • First seen 23jun10 7:29 am 2305-2320 in hillltop monitor.
  • 2345-2350 so att coming from the radio redentor tower above utuado
2320 - 2345
satellite radio



Satellite radio (SDARS). Each satellite has 12.5 Mhz bandwidth

freq
user
2320-2324.54
sirius
2324.54-2327.96
sirius terrestrial repeaters
2327.96-2332.5
sirius
2332.5-2336.225
xm
2335.225-2341.285
xm terrestrial repeaters
2341.285-2345
xm

 sirius xm is coming to pr with terrestrial repeaters (20).
2370-2375
5mhz
30dec15-
25jan16
wcs
blkD
this was the 2345-2350 wcs block D that att owns. It comes from the HQ  tower above utuado. Around 30dec15 it jumped up to 2370-2375. on 25jan16 we talked to the engineer and he turned it off.
2400-2500


ism
ism band unregulated.
wifi 802.11
(b,g,)
2401-2495



wifi freq 802.11 at 2400 mhz ism band
14 channels, 22 Mhz each
centers separated by 5Mhz: 2412,2417...
use chna 12,13,14:2467,2472,2484 not available
chan 14 ok for 802.11b
bluetooth
801.15
2402-2480
1Mhz


band broken up into 87? 1 Mhz channels. Can frequency hop at up to 1600 hz.
Max output power:100mW,2.5mW, 1mW for class 1,2,3 devices.

2700
may96
Faa radar 1350 2nd harmonic (seen in rfi monitor.. probably our system).
2900-3100

radar pico del este sps-48 9 distinct freq. (more info)
3600-3621
aug03
Inmarsat downlinks LHC (*a)
802.11y
3657.5-3690



ieee802.11y in use in use.. freq,chan  , bw same as 802.11a.. 20 Mhz. with overlap
  • 3657.5 . 131
  • 3662.5 . 132
  • 3667.5.   133
  • 3672.4  . 134
  • 3677.4     135
  • 3682.5   136
  • 3687.5 137
  • 3689.5 138
3945.5
aug03
marisat trackin beacon LHC (*a)
 3947.0    aug03   inmarsat tracking beacon LHC  (*a)
3947.5
aug03
intelsat tracking beacon RHC (*a)
3949.4
aug03
inmarsat tracking beacon LHC (*a)
3950.6
aug03
inmarsat tracking beacon LHC (*a)
3952.5
aug03
intelsat tracking beacon RHC (*a)
3953.0
aug03
inmarsat tracking beacon LHC (*a)
3952.5
aug03
marisat tracking beacon linear??(*a)
4188.72
aug03
marecs satellite tracking beacon LHC(*a)
4250-4350

apr13

airplane radio altimeter fm modulated, sweeps between across the band
(more info .pdf)
4505-4660

apr13
active
burst lasting 30 sec to a minute.This band is allocated for space to earth communications limited to international calls. (see us245 footnote).
5010-5150

mar13
fixed
internet communications companies were/are broadcasting outside of the allowed U-NII band.
5010-5130 is now clean (jun13). They are still cheating on the 5150 edge of the band. more info
5.15-5.25 GHz
5.25-5.35
5.47-5.725
5.725-5.85

see fcc title47 part15 rf devices UNII devices
Give power,antenna limits

mar09
info
U-NII Unlicensed National Information Infrastructure
CPE: Customer Premises Equipment
Neptuno Pr wireless network provider with :Axxcelera equipment
AB-MAX 5.47-5.85 wireless access point.5,10,15 Mhz bw. xmit:18dbm access pnt,15dbm cpe.
AB-full Acces. 5.725-5.85 +5 to +23 dbm ism and

jun13: these bands are pretty much full with internet communications (more info)
possible birdies at :5771,5818,5838 in hilltop monitoring.
r.
5350

apr12
launch
info
risat-1 indian radar imaging satellite
polar orbit, sun synchronous, period=96.49 minute.
equatorial crossing 6am/6pm (local time)
14 orbits ;per day
5.725-5.85


info
ISM InIndustrial Scientific, Medial band





5610

sep08

Terminal Doppler Weather radar at punta salinas.
5666-5674
10mhz
18sep09

18sep09 jumped from center 5700 to  5670. an 801.11 band??
been there ever since.
seen in fractional occurence of rfi and in hilltop monitor
5700
10mhz
jun-sep09

saw in hilltop monitor. appeared after hilltop monitor came back on line after a few days offline.
jumped to 5670 on 18sep09..
wifi 802.11a
(a,h,j,n)
5180-5825
FCC new unii band. aug16



ieee 802.11(a,h,j,n) each number is the center of a 20 Mhz band
These are the channels uses in us see table
  • 5180 chan 36
  • 5200 chan 40
  • 5220 chan 44
  • 5240-5580 chan 48,52,56,60,64,100,104,108,112,116
  • 5275 (xpernet from yiyi avila's tower)
  • 5680 chan 136
  • 5700 chan 140
  • 5745 chan 149
  • 5765 chan 153
  • 5785 chan 157
  • 5805 chan 161
  • 5825 chan 165
6255
30Mhz
apr11
ino
seen in hilltop monitoring data. appeared 19apr11 with the 6595 data.probably another microwave link from roncador (yiyi avila)
6595
30Mhz
apr11
info
seen in cbhi. appeared 19apr11. probably att mobility microwave link roncador to arecibo. (more info)
9186.2 narrow nov04 fixed this had sidebands spaced by 85 Khz. It sounded like the dewar refrigerator when plugged into the radio. Turned out to be an
oscillation in the sbw dewar (1 channel). By retuning the bias, it went away.
9410

sep08

mayagueaz weather radars. 9410 +/- 30 mhz
9650
300Mhz


sar radar with up to 300 Mhz chirp.
TerraSar-x satellite radar.
   launched 2007, leo altitude: 514 km, inclination 97.44, repeat 94.92 minutes.
   repeat visit on equator once every 11 days.
tandem-X launch oct09.  two satellites orbiting together
   does bistatic radar. similiar orbit to terraSar??






 
Information sources.
INMARSAT
(*a)
http://ourworld.compuserve.com/homepages/pjmarsh/inmarsat.htm . may be a bit old
L to C  and C to L transponders. Tracking beacons at 39xx Mhz. geostationary satellites.  Path loss to earth 188.5 db. Mainly describes stdA



 
Combs  (top)
COMB 
SPACING
IN
RCVR
DATE STATUS NOTES
1,2 Mhz 327 jul02 resolved This was coming from the power meter on the roof of turret room that reads the power for the 430 Mhz xmter. It is in a huffman box. The edges of the box used a metallic gasket to improve the contact. This gasket contained silver and stopped working do to oxidation. 'resolution: We switched to another gasket material. (more info)
372Khz
744Khz 
(odd harmonics)
327 nov03 resolved This comb was coming from the sb tx rack in the sband tx room above the turret room. The filters and doors of the enclosure were shot. There was also some problems with some of the cables going into the cabinet. These were fixed. (more info).
375/750 Khz
40Khz
327,430 apr06 resolved
(again)
This was the sband console in the dome again. Inside the cabinet are some covers that need to be screwed in place to increase the shielding. They had been left unscrewed because of some maintenance work that was going on. (more info)




Alfa motor controller
16Khz 327 apr05 resolved saw in 327 rcvr.  resolved oct05. coming from the alfa motor controller. It is a modulation on top of the 40 Mhz comb from the controller. Resolution is to turn off the motor controller for low frequency work.  (more info)
7.5 Mhz
327
mar
alfamot
the alfa motor controller is making a 7.5 Mhz comb that drifts to lower frequency when it is power on. (more info)
40 Mhz 327 oct05 resolved saw at 320 Mhz. This is from the alfa motor controller. The 16khz comb is center on this harmonic. (more info)
10 Mhz
327
mar11
alfamot
The alfa motor controller is generating a 10 Mhz comb.
The 40 Mhz comb (oct05) is probably just the stronger parts of this comb.
2 Khz 327 oct05 resolved This is from the alfa motor controller. This comb is centered on the 40 Mhz comb harmonics. (more info). To get rid of it turn off the alfa motor controller.




Dome AC
units
1 Mhz  327
430
oct05 src found This comb was seen at 327 and 430.  It can wander by up to 30Khz in and hour. The birdie width is about 1 hz. It is coming from the AC units in the dome. There are actually 2 combs, 1 from each ac unit. The birdie is coming from the digital communications portion of the ac unit. Turning off the ac unit with the remote does not make it go away. You need to turn the power off to the ac unit. There is a switch downstairs for the old ac unit. The new ac unit can not be switched off. ( more info).




az,dome encoders
614 Khz 327 sep06
a 614 khz comb in the 327 Mhz receiver. Each element was about 1-3 Khz wide. It showed an az and za dependence. The comb was coming from the azimuth 2 (ch side) encoder. This was a new type of encoder that was installed on 02aug06. The old type of encoder was re=installed (more info).
1.65Mhz
327
sep06

coming from az,za encoders.. more info





62.6418Mhz
-
feb11
src
Ethernet transceiver/repeater in 12meter cabinet. Not yet seen outside of cabinet. Extends upwards of 1GHz. This one of our devices so we probably have this at other spots.
The first 24 frequencies of the comb are:
   62.642, 125.284, 187.925, 250.567, 313.209, 375.851, 438.493, 501.134, 563.776,       
 626.418, 689.060, 751.702, 814.343, 876.985, 939.627, 1002.269, 1064.911, 1127.552, 1190.194, 1252.836, 1315.478, 1378.120, 1440.761, 1503.403,

14.3 Mhz
327
mar11
cameras
This is coming from the cameras in the dome (more info).
80Mhz
327,800
sep11
active
ac unit on top of building I.

Device specific birdies

device
strongest birdies
notes
cameras in dome
315.00,329.30, 343.64
02mar11.
sband console in dome


turret control box in dome


alfa motor controller
  • 300,310..10Mhz comb
    • 320,340 the strongest
    • sometimes mistaken for 40 mhz comb
  • 7.5 Mhz comb
    • start at 320Mhz when powered on
      • starting freq probably not stable..
    • drifts to lower freq over time
      • about 2 mhz in first 100 secs
  • 16khz, 2khz, combs.. about the 10/40 Mhz comb frequencies

02mar11.
aug05





 home_~phil