11apr05 p2030 compression with new rf amps and the wapps are not starting together.


        P2030 is the pulsar consortium search project. They are using 100 Mhz (3 level sampling) centered at 1420 Mhz. They sample 256 lags every 64 useconds and then the polarizations are added before writing to disc.
    On 09apr05 extra amplifiers were added to alfa before the first mixer. Data taken on 11apr05 was used to see how the compression of the system was being affected by these amps. Total power was computed for the first 12 seconds of the first few  scans done on 11apr05. The data was averaged by 10 (down to 640 usecond sampling) and then normalized to the median value over the 12 seconds. The data is plotted vs time with each pixel offset for display purposes. The units are Tsys.
The plots for 6 scans are (you'll have to rotate by -90 deg in acroread to straighten them out.. sorry..):     The negative going power is compression in the system. After smoothing by 10 samples the signal is still compressing by 10% of tsys.  You can see the compression dissappear for 1.2 second and then come back strong. This is caused when the aerostat blanks its transmitter in our direction. The compression is lasting for a large fraction of the 12 second radar rotation period.

    A blowup of 30 millisecs of data (at 64 usecs resolution) shows the individual radar pulses match the spacing of the 7 aerostat ipps:

    The strucuture caused by the compression gives you a reference for aligning the 7 alfa pixels in time. The plots 2,3, and 4 show that the data in the 7 pixels can be off by 1 second. All of the wapps are not starting at the same time. The headers for the  individual wapps have start times that correspond to these differences (so the timing has no been lost).  Of the 31 search scans taken on this day, 12 of them had these offsets.
processing:usr/p2030/apr05_10dbamp/ apr05_10dbamp.pro