Intro

• Looked at the intermods in lband created by  a radar as it  went through its rotation period to see whether these signals were stable, or if they also jumped.

Setup

• Pulsar B1855+02
• period: 0.415823055263  dm 13.2992
• single pulses were seen
• wapp backend:
• 100MHz bw, 256 channels,
  
• 3 bands were taken
  
• i looked at the band centered at 1175MHz
• sample time:  512 useconds
• scan: 450 seconds total
• scan start: 10:15:18 utc
• after processing the pulsar jump occurred around pulsar period 600
• 600*pulsPeriod= 249.494 seconds into the scan
  

Looking at the data

The first plot shows the spectra and total power vs time for the intermods (.ps) (.pdf)

• top frame: 100 MHz spectra centered at 1172 MHz taken  at 16.3092 secs into the scan
• black is polA, red is polB
• the green lines show the freq channels used to compute the total power
• Bottom frame: total power vs time for the 1151 MHz power
• Black is polA
• Red is polB. I've added an offset for display
• the  spikes are spaced by the Ipp of the radar
• The spikes are when the radar is pointing at the observatory
• it took about 89 ms for the radar sweep throught the AO direction

• White is PolA
• red is PolB
• Each spike is when the radar points at AO.
• i took the 1st 12 spikes to compute the radar rotation period.
• rotation period 12.024 secs.
• this could be from the FAA radar (before carser)
• the punta borinquen 1270/1290 radar
• or the aerostat radar
• all of these have rotation periods of around 12 seconds.l
  
• more radar info

The 3rd set plots the data as 12.024 sec rotation periods of the radar (.ps) (.pdf)

• I took the 450 seconds of data and broke it up into 12.024 second sections.
• Using the 1151 MHz total power vs time, the radar ended up pointing at AO at 4.33 secs of its rotation period (using the scan start time as phase 0 of the 12 seconds).
• top frame: the first time the radar pointed at AO during the scan.
• The green lines are the edges of the beam as it sweeps by AO. these are for reference.
• Bottom frame: over plot the 37 12second rotations of the radar during the 450 second scan.
• I've offset each rotation for display.
• The black lines are the first 20 rotations. 0 to 240.48 seconds of the scan
• the red lines are rotations 21 to 37  252.504 to 444.888 seconds
• the pulsar jump occurred around pulsar period of 600. 600*0.41582305526d = 249.494 seconds
• so the jump occurred between the black and red radar rotations.
• The green lines show the start, end of the first time the radar pointed at AO
• You can see that the red rotations are starting to drift to the left
• at the end of the scan, the radar pulses had drifted by about 76 milliseconds.

Summary

• pulsar search data taken on 10apr2003 on B1855+02 showed a jump in the main pulse after pulsar period 600.
• Using one of the 12 second radar intermods we could see that the radar mods  also started to drift  after pulsar period 600.
• the total drift ended up being about 76 millisecs
• Looks like the jump was instrumental.

processing: x101/230729/rankinmode.pr0

home_~phil