Miscellaneous devices

Links to different devices:
axis 212 ptz web camera.


Axis 212 ptz  web camera:

Sections:
17oct06: looking at the birdies in the shielded room.
17oct06: rfi from the axis 212 camera seen through the telescope.
Summary:

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.

    The rfi output of the camera was measured in the shielded room on 17oct06 using the ybt250 (Tektronix) spectrum analyzer.  The small loop antenna was placed close to the lens of the camera and rotated to give maximum signal.
    We found a  comb with a 25 Mhz spacing sitting at 300,325,350 etc. Mhz. The comb elements seem to be modulated with about a 100 Khz bandwidth. T
    I stepped through 100 Mhz to 1500 Mhz with a 100 Mhz span and then came back and looked at some of the comb elements with a higher resolution (note: RBW is resolution band width). A list of some of the more prominent birdies are:
 
freq  rbw amp (db) Notes
323.997 100 Hz 32  Very narrow
325 10 Khz 25 about 100 Khz fwhm
347.996 100 Hz 32 very narrow
375 100 Khz 20 100 Khz fwhm
400 100 Khz 15
425 1 Khz 10
675 1 Khz 15 The adjacent noise floor moves down by 15 more db when the camera is off.
700
725
30 Khz 25 100 Khz wide birdie
775
800
1 Mhz 20
1375 1 Khz 20 adjacent 1374.9 birdie was from repeater

More Notes:

Plots were made of the 325 and 324 Mhz birdies in the shielded room (.ps) (.pdf). The data was taken with the loop antenna and the Tektronix spectrum analyzer in the screened room:
processing: x101/061017/cameralab.pro


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

    On 17oct06 we looked at the rfi from the axis 212 camera using the telescope. The setup was: The first plots are dynamic spectra for 324 Mhz and 325 Mhz with the camera in the parking lot and in the control room. The horizontal dashed lines surround when the camera was turned off: The average of  (camera on)/(camera off) - 1  (.ps) (.pdf ) is also plotted. Black has the camera in the parking lot, red is in the control room:
  • 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.
  • processing: x101/061017/cam_on_tel.pro


    Summary:


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