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Cameras, PwrMeter,and MultiMeter rfi August 27, 1999 5
FIGURE 3: Power meter birdie with door closed.
Fri
Aug
27
23:17:58
1999
phil

Cameras, PwrMeter,and MultiMeter rfi August 27, 1999 4
FIGURE 2. Power meter, multimeter birdies with door closed.
Fri
Aug
27
23:14:06
1999
phil

Cameras, PwrMeter,and MultiMeter rfi August 27, 1999 3
FIGURE 1. 5aug99 doors open, turning various devices on/off.
Thu
Aug
26
18:04:22
1999
phil

Cameras, PwrMeter,and MultiMeter rfi August 27, 1999 2
turned off and the integration continued for 6 more minutes. Figure 2 and Figure 3 show
on/off ­ 1 for these birdies (as well as all of the other interference that w as there).

Cameras, PwrMeter,and MultiMeter rfi August 27, 1999 1
Cameras, PwrMeter,and MultiMeter rfi
phil perillat
26aug99
1.0 Summary
The interference from the power meter, multimeters, and camera system in the gregorian
dome was measured in the dome on 5 august 1999 at 430 Mhz with the rf cabinet doors
open and on 26 august 1999 with the cabinet doors closed. The results are shown in table
1:
1. The first column shows the strongest birdies at 430 from the power meter, multi meters,
and the camera system. .
2. The current rf cabinet shielding reduces the levels of the birdies but it needs to be
improved (or the meters that make the interference should be replaced).
2.0 Setup
On 5aug99 the correlator was run with a 12.5 Mhz bw and 1024 channels. The door to
both if/lo cabinets in the gregorian dome were left open. Ten 10 second integrations were
taken at each setting (pwrmeter on, camera on, multimeter on, etc.) The spectra were a
ver­
aged to 30 seconds each and on/off ­ 1 was computed for each of these records. The off
was taken with all the devices shut off and the doors closed. Figure 1 plots the results
where groups of 3 records correspond to a particular device being on. The data was
clipped to .6 Tsys for plotting purposes. Table 1 contains the actual values.
On 26aug99 the correlator was run with a 1.5625 Mhz bandwidth and 1024 channels. The
door to both ifl/o cabinets was shut and the cameras were left on the whole time. Data was
dumped for 12 minutes with the power meter and multimeters on. The devices were then
TABLE 1. Birdies with door open and closed
Birdie Intensity
door open
[% tsys]
Intensity door
closed
[% Tsys]
pwrM 433.325 829 250
pwrM 429.158 17 5
multiM 427.485 43 not measured
multiM 429.74 92 24
multiM 430.11 36 11
multiM 430.49 101 8
camera 424.03 48
camera 429.096 270
camera 429.550 639