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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.