Pshift levels vs fftlen

27jun08



Table of PSHIFT values vs fftlen .. over time
#

setup
A/D
rms

Relative noise power
vs fftlen
8192
1fff
4096
fff
2048
7ff
1024
3ff
512
1ff
256
ff
8k
4k
2k
1k
.5k
1
jun08 standard
9 shifts then 0,1...
30
1/2
1
1/2
1
1/2
0x1ff5
1 1111 1111 0101
shifts=11
0xffa
1111 1111 1010
shifts=10
0x7fd
111 1111 1101
shifts=10
0x3fe
11 1111 1110
shifts=9
0x1ff
shifts=9
0xff
shifts=8
2
9 shifts then 0,1
15
1/8
1/4
1/8
1/4
1/8
..
..
..
..
..
..
3
10 shifts then 0,1,0,1
30
1/2
1/4
1/2
1/4
1/2
0x1ffa
1 1111 1111 1010
shifts=11
0xffd
1111 1111 1101
shifts=11
0x7fe
111 1111 1110
shifts=10
0x3ff
11 1111 1111
shifts=10
0x1ff
shifts=9
0xff
shifts=8
4
butterfly 1, no shift then
9 shifts, then 0,1
15
1/2
1
1/2
1/4
2
0x0ffa
0 1111 1111 1010
shifts=10
0x7fd
0111 1111 1101
shifts=9
0x3fe
011 1111 1110
shifts=9
0x1ff
01 1111 1111
shifts=9
0x0ff
0 1111 1111
shifts=8
0x7f
0111 1111
shifts=7
5
butterfly 1, no shift then
10 shifts then 0,1
15
1/8
1/4
1/8
1/4
1/2
0x0ffd
0 1111 1111 1101
shifts=11
0x7fe
0111 1111 1110
shifts=10
0x3ff
011 1111 1111
shifts=10
0x1ff
01 1111 1111
shifts=9
0xff
0 1111 1111
shifts=8
0x7f
0111 1111
shifts=7
  

date
mode
8k
4k
2k
1k
.5k
02jul08(285,10)
1 rms=30
no pfb ovdrflows, 0x1ff5
pfb overflow, 0xffa



02jul08
2 rms=15
no pfb overflows, 0x1ff5
pfb overflow, 0xffa



02jul08
4 rms=15

pfb overflow, 0x7fd



02jul08
rms=30





03jul08(285,10)
1 rms=30
no pfb overflow, 0x1ff5
no pfb overflow, 0xffa

pfb&adc overflows,0x3fe

03jul08
2 rms=15



no pfb,noadc overflows,0x3fe

03jul08
3 rms=30
no pfb overflows,0x1ffa
no pfb overflows,0xffd

no pfb overflows, yes adcOver.0x3ff

03jul08
4






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