This program is used to analyse pulsars of known parameters.  It contains
  both a post-detector spectral display, and a "pulse profile" display.
  It has a built-in de-dispersion filter that will work up to DM=100 for
  21cm observing, and up to DM=5 for 327Mhz observing.

The program takes the following options:

  --rx-subdev-spec     which USRP Rx side?  A or B

  --decim              USRP decimation rate use either 64 or 128

  --freq               USRP daughtercard frequency

  --observing          Actual observing frequency (default is to use the
                       setting for --freq)

  --avg                Averaging setting for spectral display--higher numbers
                       equal more averaging.  25 to 40 is typical.

  --favg               Pulse folding averaging.  2 to 5 is typical.

  --gain               USRP daughtercard gain control

  --reflevel           Reference level on pulse profile display

  --lowest             Lowest spectral bin that is considered valid, in Hz

  --longitude          Observer longitude: West is negative

  --latitude           Observer latitude:  South is negative

  --fft_size           Size of FFT for post-detector spectrum: default is 1024

  --threshold          Threshold (dB) to be considered a spectral "peak"
                       This is relative to the average spectral level

  --lowpass            Low pass frequency for post-detector spectral display
                       20-100 is typical

  --prefix             Filename prefix to use for recording files
                       Default is ./

  --pulsefreq          The frequency of the expected pulses
                       For sentimental reasons, this defaults to 0.748Hz

  --dm                 The DM

  --doppler            The doppler shift, as a ratio

  --divbase            The base of the Y/Div menu in pulsar display

  --division           The initial Y/Div in pulsar display

DM, Doppler, Gain, Frequency, and the averaging parameters can all be
  changed using the GUI at runtime.

If latitude and longitude are set correctly, and the system time is
  correct, then the current LMST is displayed below the frequency
  input, updated once per second.

Moving the mouse in the post-detector spectrum display shows you that
  point in the post-detector spectrum, both frequency and signal level.

The post-detector spectrum is analysed, with results shown below
  "Best freq".  It shows the spectral peaks, and computes their relationship.
  It shows the harmonic compliance among the peaks, as well as the average
  peak-to-peak distance.


Here's a complete example for observing a pulsar with a frequency of
  1.35Hz, at 431.5Mhz, using an IF of 10.7Mhz, and a DM of 12.431, using
  1Mhz observing bandwidth:

./usrp_psr_receiver.py --freq 10.7e6 --decim 64 --dm 12.431 --avg 35 \
  --pulsefreq 1.35 --fft_size 2048 --lowest 1.00 --gain 75 --threshold 11.5 \
  --observing 431.5e6 --reflevel 200 --division 100 --divbase 10 --favg 3 \
  --lowpass 20 --longitude -76.02 --latitude 44.95

Since the observed pulsar is at 1.35Hz, a lowpass cutoff for the
  post-detector spectral display of 20Hz will be adequate.  We
  tell the spectral analyser to use a threshold of 11.5dB above
  average when analysing spectral data, and set the epoch folder
  averager (pulse profile display) to use an average from 3 samples.
  Notice that our actual USRP/Daughtercard frequency is 10.7Mhz, while
  our observing frequency is 431.5Mhz--this is important in order for
  the DM de-dispersion calculations to be correct. We also set our
  latitude and longitude, so that logfiles and the LMST display
  will have the correct LMST in them.

The entire complex baseband can be recorded, if the "Recording baseband"
  button is pressed.  Filenames are generated dynamically, and a header
  file is produced giving observation parameters.  The baseband data are
  recorded as octet pairs: one for I and one for Q.  Pressing the button again
  turns off baseband recording.  This baseband is "raw", so it will
  not have been de-dispersed.  The data rate will be whatever the
  USRP was programmed to at the time (based on --decim).

  The files are:  YYYYMMDDHHMM.pdat  and YYYYMMDDHHMM.phdr

  The .phdr file contains ASCII header information describing the
  contents of the .pdat file.

Similarly the raw, pre-folded, band-limited post-detector "audio" data can be
  recorded using the "Record Pulses" button.  The data rate for these is
  currently 20Khz, recorded as short integers.  Just like baseband recording,
  pressing the button again turns off pulse recording.

  The files are: YYYYMMDDHHMM.padat  and YYMMDDHHMM.pahdr

  The .pahdr file is ascii text providing information about the contents
  of the corresponding .padat file.