Looking at the ALFA IF using lband wide..


     The ALFA IF was hooked up to the lband wide receiver on 15may03 and tested. The setup was: The first set of measurements used a 2 usec time constant and sampled the system at 1 Mhz. The data was then smoothed to 15 useconds. The  plot shows the 1415 Mhz band when the san Juan radar was pointed at the observatory (about once every 12 seconds). You can see the downward going spikes when the radar at 1350 drove the system into saturation. This is probably happening in the alfa IF or the lbw dewar. The downstairs amplification was after the 5 Mhz filter that cut out the radar. The radar pulses are 2*5usecs long. The data has been smoothed to 15 usecs and the compression last for just 1 sample (15 usecs). The telescope was sitting at az=406.37 and za=7.0544. This spot gives a strong response to the radar.

    The second set of data was tracking blank sky. A 2 millisecond time constant was  sampled at 1 millisecond. The plot shows the total power in a 5 Mhz band around 1415 Mhz for 3000 seconds.

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