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SPECTRAN V6 FFT rates

The SPECTRAN V6 FPGA offers around 930GMACs so in theory we could implement a 64k FFT but since we also need to add some other features we limited it to 8k (16k might be possible later on with a firmware upgrade), which still is quite an impressive number for such a small unit. The minimum FFT size thow was limited to 8.

The SPECTRAN V6 uses an 2GSPS ADC offering 245MHz IQ rate, a high speed 50% overlaping dual FFT engine and can use two Rx at the same time. So a FFT size of 8 can generate up to 2 x 2 x (245Mio/8) = 120Mio FFT/s or 960Mio FFT points/s. The following table shows the used FFT size vs the resulting FFT rate/s:

  • FFT of 8 = 2 x 2 x (245Mio/8) = 120Mio FFT/s
  • FFT of 16 = 2 x 2 x (245Mio/16) = 60Mio FFT/s
  • FFT of 32 = 2 x 2 x (245Mio/32) = 30Mio FFT/s
  • FFT of 64 = 2 x 2 x (245Mio/64) = 15Mio FFT/s
  • FFT of 128 = 2 x 2 x (245Mio/128) = 7,5Mio FFT/s
  • FFT of 256 = 2 x 2 x (245Mio/256) = 3,75Mio FFT/s
  • FFT of 512 = 2 x 2 x (245Mio/512) = 1,875Mio FFT/s
  • FFT of 1024 = 2 x 2 x (245Mio/1024) = 0,9375Mio FFT/s
  • FFT of 2048 = 2 x 2 x (245Mio/2048) = 0,46875Mio FFT/s
  • FFT of 4096 = 2 x 2 x (245Mio/4096) = 0,234375Mio FFT/s

At all FFT rates the number of FFT points will stay stable at 960Mio FFT points/s.

 

Please note that all mentioned FFT rates are only for the internal FPGA based FFT engine. Smaller or much high FFT rates can be  achieved by using the V6 in raw IQ streaming mode together with our RTSA Suite PRO software.