09mar11: 327 Mhz birdies and their Azimuth dependence

09mar11
Links to plots/tables:

Dynamic spectra:

the average and peak hold spectra for the az swings (.ps) (.pdf):
the birdie power versus azimith for the 60 strongest birdies (.ps) (.pdf):
Table summarizing the birdies.

Sections:
Intro
Processing the data
Dynamic spectra of the azimuth swings
Average/PeakHold spectra for each az swing:
The azimuth dependence of the birdies
birdies with common az dependence
Summary
other: azswings done 28oct05 


Introduction (top)

    On 09mar11 2 azimuth swings were done with the 327 Mhz receiver to see if there was an azimuth dependence for the birdies that were seen in the band. The dome was at 15 degrees.
  The setup was:


Processing the data: (top)


Dynamic spectra of the azimuth swings:  (top)

    Dynamic spectra were made for each of the  azimuth swings showing spectra density plotted against azimuth and frequency. The plots were aligned so that azimuth always increased bottom to top (so the swings from 270 to -90  were flipped). At the bottom of each image is a peak hold spectra (maximum in each frequency channel) for the entire spin. 


Average/Peak spectra for each az swing:  (top)

    For each azimuth swing an average spectrum (over the 1029 spectra) was computed as well as a peak hold spectrum (the largest value in each frequency bin was kept). Colors were used to differentiate between azimuth swings. The plots show
the average and peak hold spectra for the az swings (.ps) (.pdf):


The azimuth dependence of the birdies:  (top)

    The frequencies of the 60 strongest birdies were found and then a mask (in frequency) was placed around each one. The largest value in each mask was taken as the value of the birdie at each time sample (this was needed since some birdies drifted in frequency). Birdie power versus azimuth was plotted for each of the 60 birdies (5 birdies per frame). The black trace is the CW azswing while the red trace is the CCW trace. The vertical scale is in Tsys units.

    The plots show the birdie power versus azimith for the 60 strongest birdies (.ps) (.pdf):


The the birdies that have a common azimuth dependence.:  (top)

     Looking at the dynamic spectra, there are a large number of birdies that occur at the same azimuth for the CW and CCW azswings. These are coming from the same az location (and probably the same set of intermods).
The dynamic spectra were blown up to show (300 to 327Mhz, 130 to240 az) how the signals change together:


    The plots show the azimuth dependence:



Summary:  (top)

Table of frequencies
rfi
freq
fm station
Notes:
308.7 102.9
3rd harmonic of HQ . located next to 104.1 radio redentro in utuado
312.3
104.1
3rd harmonic of radio redentor transmitter in utuado
321.9
107.3
3rd harmonic of delta107.3
302.7
303.9
305.1
307.1
309.9
311.1
313.1*
314.3*
317.5*
318.7*

102.9
104.1
  • These all show time/azimuth variation that match that of 308.7 (102.9*3)
  • Many of these are spaced by 1.2 Mhz (104.1-102.9)
  • * these are spaced by 1.2 Mhz but are offset from the other set. They may be related to 107.3 (see below)
 
317.5
313.1
314.3
315.5
318.73

107.3

  • 317.5: 
    • back in 2005 This was heard (with the radio in the control room ) to be 107.3.
  • Looking at the dynamic spectra, the other frequencies look like they may line up in az,time with 317.5 which would also make them related to 107.3
  • 321.9-317.5 =4.4  Mhz. This is the difference 107.3-102.9 ..
other birdies:
350.00
346.53

350.00 comes from the interim correlator in the control building.
346.53 has similar az dependence so it may also come from the same place
313.51,
319.46
327.00
350.39

Little az dependence ..may be in the dome.
processing:  x101/110309/327azswing.pro


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