Signal compression from the faa radar


    Pulsar data was taken on 01aug04 (p1944) using the alfa receiver centered at 1420 Mhz with a 100 Mhz bandwidth. Data was sampled at 64 usecs for 67 seconds tracking a search position (p1944.G212.06-00.23.wapp1.53218.0052). The total power was used to look for any compression of the signals in Beam 0 and Beam 1 of the alfa receiver (wapp1). The plots show the results:     The measured data is being compressed by the FAA radar. This radar transmits at 1330 Mhz and 1350 Mhz using staggered 5 usec pulses (see measured lband radars for further info). The compression could be in the iflo system or in the wapp digitizers. The wapps have a 100 Mhz filter IF filter that was centered in this experiment at 1420 Mhz. There was probably not much roll off of the filter from 1370 to 1350 Mhz (so the culprit is most likely the sampling). One way to test this would be to move the cfr up to say 1450 or 1470 to see if this improves the situation.

    For people who are going to cover the 1330,1350 band they will be stuck with this compression until we get a back end with more bits (assuming the compression is not in the iflo).

processing: usr/p1944/