Data Rates

Data Rates and Files Sizes.  Here are some guidelines for estimating the size of data files generated in various common observing modes.

  • Real time beamforming mode (a.k.a. DRX mode), 19.6 MSPS (the maximum sample rate), Two “tunings” (center frequencies), each Nyquist sampled 4-bits “I” + 4-bits “Q”: 264.91 GB/h.
  • Real time beamforming mode, 19.6 MSPS, two tunings, 32-channel FFT, 6144 FFTs averaged (Thus, 612.5 kHz x 10.03 ms): 192.69 MB/h.
  • Real time beamforming mode, other sample rates: can be extrapolated from the above numbers.  Rates available range from 0.250 to 19.6 MSPS in 7 steps.
  • TBN, 100 kSPS (maximum rate): 356.86 GB/h.

Above, 1 GB is defined as 1024^3 bytes, and 1 MB is defined as 1024^2 bytes. For a number of reasons, we ask users to avoid contiguous observations longer than 4 hours, so the largest data files that are commonly generated are 1060 GB.  This is about 1/10th of the capacity of a DRSU.

Also worth remembering is that a common “2TB” USB hard drive can hold about 1.7TB, which is about 6.5 h at the maximum DRX rate.  If you intend to receive/store data on this type of media, you would do well to consider planning your observations so as to make most efficient use of the available space. For example: 1 x 6 h observation or 2 x 3 h observations are good; 4 h is bad (unless the next observation is ~2.5 h ).

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