mock spectrometer minimum integration times

The fft length and minimum allowable integration times are determined by:

the spectrometer can compute fft lengths of 4 through 8192 in powers of 2.
For each integrated spectra there must be at least 4 ffts averaged and <= 65536 integrated ffts. This is because:

the polyphase filter has an overlap by 4
The register that counts the number of accumulated ffts is only 16 bits. This sets the 65536 upper limit.

The spectrometer has a digital filter that can reduce the bandwidth to 172.032MHz/n where n is 1 to 1023 in steps of 1.

As the bandwidths narrow, the time for the fft gets longer (assuming the same number of channels).

The maximum i/o rate from the spectrometer box to the file server is about 70 Mbytes/sec. This i/o rate is determined by:

Each mock box has 2 separate frequency bands of 172 MHz bw (each with full stokes).

Single pixel receiver observing uses 1 freq band within each mock box (the second frequency band is ignored)

Alfa observing uses both frequency bands within each mock box (doubling the i/o rate from box to file server)

The tables below shows the minimum integration times and corresponding bandwidths for various configurations. The tables show:

Each table has the values for a single mock box. We have 7 x 2 sets of these boxes.
Sum PolA and B. 16 bit fast dump data (pulsar observing)

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Summed Pols, 16bit data Min dump Times
Bandwidth	fftlen	ResolutionBw KHz	tm 1fft Usecs	Min Time allowable (i/orate<=70Mb/sec) (sum >= 4 ffts) Usecs
				SinglePix(1band)	Alfa(2bands)
				avg 5 fft iorate:68.8 Mb/sec	avg 10 fft, iorate:68.8Mb/sec
172.032	8192	21.00	47.619	238.095	476.190
	4096	42.00	23.810	119.048	238.095
	2048	84.00	11.905	59.524	119.048
	1024	168.00	5.952	29.762	59.524
	512	336.00	2.976	14.881	29.762
				avg 4 fft iorate:43 Mb/sec	avg 5 fft iorate:68.8 Mb/sec
86.016	8192	10.50	95.238	380.952	476.190
	4096	21.00	47.619	190.476	238.095
	2048	42.00	23.810	95.238	119.04
	1024	84.00	11.905	47.619	59.524
	512	168.00	5.952	23.810	29.76
				avg 4 fft iorate:28.7 Mb/sec	avg 4 fft iorate:57.3 Mb/sec
57.344	8192	7.00	142.857	571.429	571.429
	4096	14.00	71.429	285.714	285.714
	2048	28.00	35.714	142.857	142.857
	1024	56.00	17.857	71.429	71.429
	512	112.00	8.929	35.714	35.714
				avg 4 fft iorate:21.5 Mb/sec	avg 4 fft iorate:43.0 Mb/sec
43.008	8192	5.25	190.476	761.905	761.905
	4096	10.50	95.238	380.952	380.952
	2048	21.00	47.619	190.476	190.476
	1024	42.00	23.810	95.238	95.238
	512	84.00	11.905	47.619	47.619

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PolA,B output separately, 16bit data, Min dump Times
Bandwidth	fftlen	ResolutionBw KHz	tm 1fft Usecs	Min Time allowable (i/orate<=70Mb/sec) (sum >= 4 ffts) Usecs
				SinglePix(1band)	Alfa(2bands)
				avg 10 fft iorate:68.8 Mb/sec	avg 20 fft, iorate:68.8Mb/sec
172.032	8192	21.00	47.619	476.190	952.381
	4096	42.00	23.810	238.095	476.190
	2048	84.00	11.905	119.048	238.095
	1024	168.00	5.952	59.524	119.048
	512	336.00	2.976	29.762	59.524
				avg 5 fft iorate:68.8 Mb/sec	avg 10 fft iorate:68.8 Mb/sec
86.016	8192	10.50	95.238	476.190	952.381
	4096	21.00	47.619	238.095	476.190
	2048	42.00	23.810	119.048	238.095
	1024	84.00	11.905	59.524	119.048
	512	168.00	5.952	29.762	59.524
				avg 4 fft iorate:57.34 Mb/sec	avg 7 fft iorate:65.54 Mb/sec
57.344	8192	7.00	142.857	571.429	1000.000
	4096	14.00	71.429	285.714	500.000
	2048	28.00	35.714	142.857	250.000
	1024	56.00	17.857	71.429	125.000
	512	112.00	8.929	35.714	62.500
				avg 4 fft iorate:43.0 Mb/sec	avg 5 fft iorate:68.8 Mb/sec
43.008	8192	5.25	190.476	761.905	952.381
	4096	10.50	95.238	380.952	476.190
	2048	21.00	47.619	190.476	238.095
	1024	42.00	23.810	95.238	119.048
	512	84.00	11.905	47.619	59.524

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Full stokes, 16bit data. Min dump Times
Bandwidth	fftlen	ResolutionBw KHz	tm 1fft Usecs	Min Time allowable (i/orate<=70Mb/sec) (sum >= 4 ffts) Usecs
				SinglePix(1band)	Alfa(2bands)
				avg 20 fft iorate:68.8 Mb/sec	avg 40 fft, iorate:68.8 Mb/sec
172.032	8192	21.00	47.619	952.38	1904.762
	4096	42.00	23.810	476.190	952.381
	2048	84.00	11.905	238.095	476.190
	1024	168.00	5.952	119.048	238.095
	512	336.00	2.976	59.524	119.048
				avg 10 fft iorate:68.8 Mb/sec	avg 20 fft iorate:68.8 Mb/sec
86.016	8192	10.50	95.238	952.381	1904.762
	4096	21.00	47.619	476.190	952.381
	2048	42.00	23.810	238.095	476.190
	1024	84.00	11.905	119.048	238.095
	512	168.00	5.952	59.524	119.048
				avg 7 fft iorate:65.5 Mb/sec	avg 14 fft iorate:65.5 Mb/sec
57.344	8192	7.00	142.857	1000.000	2000.000
	4096	14.00	71.429	500.000	1000.000
	2048	28.00	35.714	250.000	500.000
	1024	56.00	17.857	125.000	250.000
	512	112.00	8.929	62.500	125.000
				avg 5 fft iorate:68.8 Mb/sec	avg 10 fft iorate:68.8 Mb/sec
43.008	8192	5.25	190.476	952.381	1904.762
	4096	10.50	95.238	476.190	952.381
	2048	21.00	47.619	238.095	476.190
	1024	42.00	23.810	119.048	238.095
	512	84.00	11.905	59.524	119.048