On 06/18/2012 11:25 AM, Jason Manley wrote:
FFT overflow is a latching flag. It probably overflowed before you set the
shift schedule? Try clearing the error and then reading it again. Or just run
rfi_spectrum.py which does a clear after every read (ie it will print FFT
overflows on the screen; if you don't see errors, all is well).
The plot shows a plausible looking spectrum but the error messages are
still there. I'll send you the spectrum separately.
Thanks,
Tom
p.s. Congratulations to you and all your colleagues.
kuiper@roachnest:/usr/local/projects/DSN_Obs/Firmware/KAT/rfi_sys/scripts$
./rfi_spectrum.py Connecting to ROACH... done.
Scaling back by 48828 accumulations.
Starting file 1340045390.spec.h5.
Plotting channels 0 ( 0.0MHz) to 16364 (799.0MHz).
[2550] Mon Jun 18 11:49:52 2012: input level: -44.73 dBm (ADC -25.23
dBm). FFT is overflowing!
Storing entry 0... done
Local max at chan 100 ( 4.88MHz): 32.94dBm
Local max at chan 15482 (755.96MHz): 15.77dBm
Local max at chan 15475 (755.62MHz): 15.75dBm
Local max at chan 15480 (755.86MHz): 15.79dBm
Local max at chan 15477 (755.71MHz): 15.78dBm
[2552] Mon Jun 18 11:49:54 2012: input level: -44.70 dBm (ADC -25.20
dBm). FFT is overflowing!
Storing entry 1... done
Local max at chan 100 ( 4.88MHz): 32.91dBm
Local max at chan 15465 (755.13MHz): 15.73dBm
Local max at chan 15475 (755.62MHz): 15.76dBm
Local max at chan 15479 (755.81MHz): 15.75dBm
Local max at chan 15477 (755.71MHz): 15.76dBm
[2553] Mon Jun 18 11:49:56 2012: input level: -44.63 dBm (ADC -25.13
dBm). FFT is overflowing!
Storing entry 2... done
Local max at chan 100 ( 4.88MHz): 32.92dBm
Local max at chan 15480 (755.86MHz): 15.77dBm
Local max at chan 15461 (754.93MHz): 15.75dBm
Local max at chan 15475 (755.62MHz): 15.77dBm
Local max at chan 15477 (755.71MHz): 15.76dBm
[2554] Mon Jun 18 11:49:57 2012: input level: -44.70 dBm (ADC -25.20
dBm). FFT is overflowing!
Jason
On 18 Jun 2012, at 20:10, Tom Kuiper wrote:
I'm trying to run the initialization script for the KAT 16K spectrometer. I
get FFT overflow even though all the shift bits are set. How is this possible?
Here's the transcript:
$ ./rfi_init.py
Connecting to ROACH... done.
------------------------
Programming FPGA... done
Checking clocks... ok, 200 MHz.
Auto-calibrating ADC... done
Attempting automatic RF gain adjustment...
Gain was -11.5dB, resulting in an ADC input level of -29.30dB. Trying
gain of -7.20dB...
Gain was -7.0dB, resulting in an ADC input level of -28.54dB. Trying
gain of -3.46dB...
Gain was -3.0dB, resulting in an ADC input level of -26.66dB. Trying
gain of -1.34dB...
Gain was -1.0dB, resulting in an ADC input level of -25.45dB. Trying
gain of -0.55dB...
done!
Setting FFT shift... set to 0xffff.
Configuring accumulation period to 1.00 seconds... done
Resetting counters... done
Current status: FFT is overflowing!
Thanks for your help.
Tom
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