05dec11: vlf antenna from SRI.

• vlf antenna
• gps receiver
• active loop vlf antenna

02nov11: test system on top of antenna test lab adjacent to the lidar lab.

• interim correlator, 195 Khz bw with 2048 channels, 9 level giving 95 hz Resolution (190 hz after hanning smoothing). 1 second sampling.
• lbw, with linear polarizations centered at 1400 Mhz.
• The acquisition Sequence was:
• turn on system in plastic box.
• Take data 
  
• Turn system off at 228 secs.
• Move vlfant into huffman box (but cables came out the top, so the box was not securely closed and the cables were not filtered).
  
• Turn system back on 
  
• turn system off at sec 491.

• The birdie is seen at 1400 Mhz till the device was turned off at 228 seconds.
• After placing the vlfant in the huffman box and turning it back on, the birdie moved to 1399.9949 Mhz (it moved by 5100 hz). 1399.9949 was the frequency we saw the birdie in the control room.
• The 1399.9949 birdie disappears at 491 when the device is switched off.
• a Birdie at 1399.981 Mhz pops up every time the vlf antenna is powered on.

• top: spectral average for records 10-200 where the vlfant was on outside the huffman box. The channel resolution was 190 hz. The 1400 Mhz birdies was 1.4 times Tsys.
  
• Bottom: spectral average for records 310-460 when the vlfant was in the huffman box (but not closed correctly). The 1400 Mhz birdie is no .7*Tsys while the 1399.995 birdies is about 40% of Tsys. The 1399.981 birdie is less than 5% (since it was only on for a short period of time).

05nov11: vlf antenna at offsite location.

• az 270-630 degrees at .35 deg/sec. a clockwise (CW) and then counterclockwise (CCW) swing was done.
• lbw was setup for linear polarization centered at 1398.99 Mhz.
  
• the mock spectrometer took data using 8192 channels over 168 Khz bw giving 20 hz resolution. 1 second integrations were done.
  
• to get rid of the mock birdies close to DC, the rf frequency was offset by -1.008 (1400-1.008=1398.99 rf center) and then the digital in the mocks moved the band up by 1.008 so the center of the band was 1400.0 Mhz. This put the A/D sampling junk 1.008 Mhz from 1400. Mhz.

• The processing for the images:
  
• The median bandpass for each swing was computed.
• An 11 order harmonic function was fit to the median bandpass and then used for the bandpass correction.
• polA and polB were averaged.
• A robust sigma for the images was computed and then the images were scaled to 8 sigma
• CW swing.gif
• 1400 Mhz birdie.
• always present. Probably coming from our 100 Mhz reference.
• 1399.98023 birdie.
• 1400.00000 birdie (must be from the 100 Mhz of station clock).
  
• 1400.01425 that drifts down to 1400.01085 over the azwing
• 1400.060 drifting birdie
• CCW azswing.gif
• 1399.98031 birdie
  
• 1400.00000 birdie (from 100 Mhz of station clock).
  
• 1400.01069 976 hz wide. Probably the same as the drifting birdie in the CW spin.
• 1400.060 birdie no longer drifiting.

• Black in the CW swing. Red is the CCw az swing.
  
• Top frame: the average spectra
• 2nd: blowup around the 1399.98 birdie.
• This shifted by about 80 Hz (4 channels) between the cw and CCW spins.
• 3rd: az dependence of 1399.98 birdie
• bottom: blowup around strongest part of 1399.98 biridie
• The az dependence repeats so it is outside the dome.
  
• The peaks are around az=27 and az=37.

Summary:

• vlfantenna:
• The vlfant made rfi when at the lidar lab. Putting it inside the huffman box (without properly closing it) only shifted the frequency (this may have been the device changing the frequency as it powered back up.
• moving to the offsite location:
• 1400 Mhz: probably from station clock since exactly on 1400. vlfant not visible
• 1399.9949 not seen
• 1399.9801 that popped up on startup onsite.
• we did see 1399.9803 and 02 birdies. This may or may not be the same thing.
• The 1400 birdie we saw in the az swings is from the station clock (it's stable). the vlfant 1400 Mhz was not visible.
• So the offsite data is inconclusive since we never cycled the devices power to see any birdies come and go.
  
• Other birdies close to 1400 Mhz
• 1400.01069 976 wide and drifts ..
• 1400.060  also  drifts. Looks like it is part of the 1400.01069 birdie  (they drift together).
  

iLon smartserver (AC control)

• iLon smartserver 2000.
• agilent E4445A spectrum analyzer, 601 channels, and preamp on.
• 1 MHz to 10 Ghz. I've included the data from DC to 3gHz.
  
• ETS model 7405 902 probe: magnetic field. resonant freq 1.5 Ghz
• Move the probe around the device looking for maximum value (spectrum analzyer set to max hold).

• Page 1: spectral density plots Dc to 1500 MHz.
• The different colors show separate measurents. Some plots have a different resolution bandwidth (making the noise floor lower).
• The black and red dotted lines show two combs:
• black: 25 MHz comb
• red : 32.9798 MHz comb
• 1000 to 1100 MHz is filled with emi.
• The largest peaks are:
• 625 : 25, 33 mhz comb
• 1125: 25,33 MHz comb
• 1088.3: 33 MHz comb.
• Page 2: 1500 to 3000 MHz.
• The largest repeatable peaks are:
• 1875 MHz
  
• 2125 MHz
• rfi is visible through 2500 MHz.
• Page 3: a few higher resolution spectra covering 327,430, 800 Rcvrs.
• The spectra with lower noise floor used a higher resolution spectra.
• 327: there are some 2  to 5 MHz combs
  
• 430: 2.5-4 MHz comb
• 750:
• 2380: 2375 comb visible.

Summary:

• The ac unit has a 25 and 33 MHz comb (32.9798)
• The combs extend thru 2500 MHz.
• The largest peaks are:
• 625.0 : 25, 33 mhz comb
• 1125: 25,33 MHz comb
• 1088.3: 33 MHz comb.
• The 327, 430 and 700 MHz bands also show some 2 to 5 MHz combs.

Accurange 3000 distomat:

•  Accurange 3000 sitting out in the screen room (no huffman box).
• agilent E4445A spectrum analyzer, 601 channels, and preamp on.
• 1 MHz to 10 Ghz. I've included the data from DC to 6 gHz.
  
• ETS model 7405 probles:
• 902:magnetic field. resonant freq 1.5 Ghz
• 903:magnetic field. resonant freq 2.3 Ghz
• 904:electric field: resonant freq > 1Ghz
• Move the probes around the device looking for maximum value (spectrum analzyer set to max hold).

• Page 1: 902 probe, 0 to 1.5 Ghz.
• top, middle, bottom are 500 MHz sections of 0 to 1.5 Ghz.
• Each color is a separate measurment with the spectrum analyzer.
• some of the spectra have a lower noise baseline. These have narrower resolution bandwidths.
  
• The dotted vertical lines are a comb ath 36.8789 MHz
• The strongest comb birdies are at:
• 295.031 MHz : -66dbm. This repeats for different measurements.
• 1032.61 MHz : -71dbm, 1069.49 MHz : -74dbm
• Page 2: 902 probe 1.5 Ghz to 6 Ghz
• top,middle, bottom are 1.5 Ghz sections from 1.5 to 6 Ghz.
• There are no obvious birdies that stick out  (but these resolution bandwidths are pretty wide.
• Page 3: compare the response of the 3 probes:
• the colors correspond to the different probes:
• black probe 902 (res freq 1.5 Ghz).
• red     probe 903 (res freq 2.3 Ghz)
• green Electric field > 1Ghz.
• probe 902 and then 903 do the best job showing the comb. 904 does not see things above 300MHz.
• this test does not guarantee that the positions of the 3 combs were exactly the same.

Summary:

• The accurange3000 has a comb with a spacing of 36.8789 MHz
• we saw the comb with the probes up to about 1100 MHz.
  
• The strongest comb elements are:
• 295.031,1032.61,1069.49 MHz.
• probe 902 does the best job showing the probe up to 1.5 Ghz.

Axis 212 ptz  web camera:

Plots:
The 325 and 324 MHz birdies in the shielded room (.ps) (.pdf)
Average of  (camera on)/(camera off) - 1  (on the telescope) (.ps) (.pdf )

Dynamic spectra:
324 MHz dynamic spectra: camera in the parking lot (.gif):
324 MHz dynamic spectra: camera in the control room (.gif):
325 MHz dynamic spectra: camera in the parking lot (.gif):
325 MHz dynamic spectra: camera in the control room (.gif):

    An axis 212ptz  web cam is to be installed in the control room and at the visitor center in oct06. We checked for rfi emissions in the shielded room and on the telescope. When we made the measurements, the ethernet was not connected.

17oct06: looking at the birdies in the shielded room.

More Notes:

• The 650-800 MHz was pretty mess. When the camera was powered off the entire band moved down by about 15 db so there is some continuum emission.
• Most of the birdies that sat on  multiples of 25 MHz had a FWHM of 100 Khz.
• The narrow birdies at 323.997 and 347.996 were not resolved with the 100 Hz RBW.

• Top: this is the 325 MHz birdie. with a 10 Khz rbw. It is one of the stronger comb elements. The black trace has been averaged by 10 sweeps, the red trace is a peak hold.
• Bottom: The 324 MHz narrow birdie. The rbw was 100 hz. This narrow birdie was also seen at 347.996 MHz.

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17oct06: rfi from the axis 212 camera seen through the telescope.

• Interim correlator with 380 hz resolution (after hanning) 324 MHz and 25 Khz resolution.
• 1 second integrations were taken. During this time we turned the camera on and off.
• We used the 327 MHz receiver (Tsys about 130K) for the 324 and 325 MHz birdies. lbw (tsys about 28K) for the 1375 MHz birdie.
• The telescope was parked at az=337.2, za=19. This position gave a maximum when we transmitted from the control room (see az,za dependence of transmitted birdies).
• Data was taken with the camera in the parking lot adjacent to the control room (in the rfi van). It was also taken with the camera in the control room on the desk next to the observer2 workstations. These were the same two positions used for the transmitted birdies test. So hopefully the az,za we picked was close to a maximum. The only difference would be the field pattern of the transmit antenna versus the field pattern of the camera.

• 324 MHz Birdie (narrow band):
• 324 MHz dynamic spectra: camera in the parking lot (.gif):
• 324 MHz dynamic spectra: camera in the control room (.gif):
• You can clearly see the 324 MHz birdie in the parking lot. In the control room there is a birdie close to 324 MHz that lasts from records 30 through 130. During this time i was turning the camera to see if we could find a maximum.
• 325 MHz Birdie (100 Khz fwhm). Part of the 25 MHz comb.
• 325 MHz dynamic spectra: camera in the parking lot (.gif):
• 325 MHz dynamic spectra: camera in the control room (.gif):
• The 325 MHz birdies is clearly seen in the parking lot. With the 25 Khz resolution you can still see the 324 MHz (narrow birdie). You do not see the 325 MHz birdie in the control room with the 25 Khz RBW.

Top:  25 Khz resolution centered at 325 MHz. The dashed green lines are the two birdies. You see them in the parking lot but not in the control room.

Center:  390 Hz resolution spectrum shows that the narrow band birdie is at 323.995 MHz. It is 1.5 times Tsys in a 390 Hz channel when the camera is in the parking lot.

Bottom: blowup of the 390 Hz resolution spectra. You can see a small bump in the control room (red) spectra about 1 Khz above the camera birdie. This is probably the streak we saw in the 324 MHz dynamic spectra from the control room. Since the 323.995 birdie remained relatively stable, my guess is that the birdie we saw in the control room is not coming from the camera.

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Summary:

• The axis 212 camera has a 25 MHz comb at multiples of 25 MHz. It is about 100 Khz wide
• Two narrow birdies were seen at 323.995 and 348 MHz.
• Some of the stronger birdies seen in the screen room  were: 324,325,348,375,700,725,1375 MHz.
• With the camera in the parking lot we see the camera birdies at 323.995 and 325 MHz. The 323.995 birdie is 1.5 times Tsys in a 390 Hz channel. We do not see the birdie at 1375 MHz.
• With a 100 second integration the 325 and 324 MHz birdies were not seen in the control room.
• If the camera is placed at the visitors center, it will have to be put inside a shielded box.
• If the camera is placed in the control room then you probably can use it without a shielded box. The only question is whether there is an az,za and camera position that will be much stronger than the ones we used. If the rfi shielded boxes are not hard (expensive) to build, it might be a good idea to put all of the cameras in a box.