Birdies with 1 minute period in 430 and 327.

last updated 02jun06

29may/12feb06: 430 yagi/linefeed  have 1 minute glitches.                      .
02dec05: birdies at 430 Mhz with 1 minute periods.
28oct05: azimuth swings at 327 Mhz show birdies with 1 minute periodicity.


29may06/12feb06  430 yagi has large 1 minute glitches

    Crosses were done on continuum sources with the 430 Mhz yagi for calibration. The data was taken  on 12feb06 and 29may06. On both dates, positive jumps were seen on the total power output.
    The data was taken in continuum mode with a 1 Mhz bandwidth centered at 430 Mhz. A time constant of 20 milliseconds was used with a sampling rate of 100 Hz. Each leg of the cross lasted for 90 seconds (1 in az, 1 in za). It took 30 seconds to move between the az and za leg. Crosses were also taken with the linefeed for calibration cross reference.
    At first we thought the jumps were a problem with water in the hybrid that converts linear to circular. After plotting the data versus wall time (rather than position along the strip) a 1 minute periodicity was seen. The plots how the results of the measurements:

29may06 yagi glitches (.ps)  (.pdf):

29may06 linefeed glitches (.ps)  (.pdf): 12feb06 yagi glitches (.ps)  (.pdf): 12feb06 linefeed glitches (.ps)  (.pdf):


02dec05: birdies at 430 Mhz with 1 minute periods.  (top)

    Project A2125 was doing mapping at 430 Mhz. The data showed some time dependent birdies. On 02dec05 i took some data with the interim correlator and the 430 dome receiver. The setup was: The plots show the birdies seen during this session:
processing: x101/051202/

28oct05 327 Mhz rcvr azimuth swings show 1 min periods.  (top)

    On 28oct05 5 azimuth swings were done with the 327 receiver to check the azimuth dependence of the birdies in the 327 receiver (see the 327 azimuth spins).

    The az swing dynamic spectra showed some birdies that were coming and going with time. They were centered around 318.6 Mhz and azimuth near 120 degrees (see the az swing dynamic spectra 2,3,4,5). These dynamic spectra were made with polA.  The last 3 azimuth swings in polB turned out to have the strongest    ence of these birdies.

    The plots show that there are 4 birdies with a time variability of 1 minute. Plotting versus azimuth shows that the birdies also have an azimuth dependence. This implies that  they are coming from outside the dome/azimuth arm. The spacing between the 4 frequencies is different from that found at 430. The signal to noise and number of groups is less than the 430 measuremnets (probably because we were swinging the azimuth). Having 4 frequencies and a time dependence of 1 minute probably says that the 327 birdies are coming from the same source as the 430 birdies.

Summary of the 327 birdies:
period 1 minute
freq width about 30 khz
time duration 1-2 secs
birdie frequencies 318.41,318.47,318.56,318.74
az dependence peaks at az 113 and 147 degrees.

processing: x101/Y05/051028/

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