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Дата изменения: Unknown Дата индексирования: Sun Apr 10 21:25:07 2016 Кодировка: IBM-866 Поисковые слова: п п п п п п п п п п п п |
DiFX can support a wide range of spectral resolutions. Achieving the highest resolutions can be tricky for a number of reasons, many with adverse performance side effects:
Some general tips to consider:
Some example .v2d file content leading to 0.5 Hz resolution:
# Might need to increase the largest read size to accomodate long FFTs maxReadSize = 40000000 # Correlate a 1 kHz portion of the input band centered on 4101.3 MHz ANTENNA FD { toneSelection=none filelist=fd.filelist addZoomFreq=freq@4101.2995/bw@0.001 } ANTENNA KP { toneSelection=none filelist=kp.filelist addZoomFreq=freq@4101.2995/bw@0.001 } ANTENNA NL { toneSelection=none filelist=nl.filelist addZoomFreq=freq@4101.2995/bw@0.001 } ANTENNA OV { toneSelection=none filelist=ov.filelist addZoomFreq=freq@4101.2995/bw@0.001 } ANTENNA PT { toneSelection=none filelist=pt.filelist addZoomFreq=freq@4101.2995/bw@0.001 } SETUP default { tInt = 2 # this is the shortest integration allowed for half Hz fftSpecRes = 0.0000005 specRes = 0.0000005 doPolar = False numBufferedFFTs = 1 # When 1 FFT per integration, this is the only legal value maxNSBetweenACAvg = 2000000000 # change to be integration time; avoid warnings }
Note that the above 5 station correlation of a pair of 4 MHz channels requires 12 GB of RAM for each core process.