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[Linrad] Re: Notes on Linrad/MAP65-IQ/SDR-IQ

Hi Joe and all,

Thanks for posting a detailed list of how you've configured your 
K3->SDR-IQ->Linrad->MAP65-IQ system.  You did a great job of figuring 
out the necessary entries for Fadd, Fmin, Fmax, to get everything into a 
usable state.

I am aware that the displayed time on decoded text lines is local, 
rather that UTC.  This will be fixed ... and I'll certainly look for a 
more convenient way to specify some of the frequency-setting options.

Thanks again for posting your results and experiences.  I'm sure they 
will be useful to others.

	-- 73, Joe, K1JT

N6KK wrote:
> Notes on Linrad/MAP65-IQ/SDR-IQ:
> Equipment:
> 2x5MWL, preamp, XV144, K3, 1.5KW amp, SDR-IQ
> 2.8 GHz P4, 1.5 GB RAM, D44 soundcard
> XP Pro (SP 3), MAP65-IQ, Linrad (3.02)
> Issues and solutions:
> 1)  I use the IF output (8.21 MHz) from the K3 to feed the SDR-IQ.
> The passband at that point is inverted, so I had to rediscover (since
> I've been down this path before) the parameters in Linrad that needed
> to be changed and recompile.  No big deal.
> 2)  The (much reported) loop-back address in the par_netsend_ip file
> requires a carriage return after the ip address. Otherwise it appends
> *.100, so you end up with a bad ip.
> 3)  Setting Linrad's priority to High resulted in Linrad freezing
> immediately.  So far priority of Normal seems to be working OK.
> 4)  Linrad would run for a few minutes, then freeze.  Just before each
> freeze, there was a spike in CPU utilization (from ~30% to 100%).  In
> addition, after a click in the wide waterfall to select a signal of
> interest, any click on the high resolution spectrum or baseband
> spectrum would intermittently cause a black screen with an
> unrecognized error code (which I didn't write down, duh!) and request
> to quit the program.  After investigating, it seems something in the
> Zone Labs firewall wasn't happy.  After removing the firewall and a
> reboot Linrad has run with no problem for 12 hours so far.
> 5)  Another potential issue was that I had the power saving feature
> configured to turn the hard drives off after 4 hours.  Normally that’s
> not a problem as everything runs out of RAM, but if a program
> (Linrad?) requires a quick disk access and the drives have been
> powered down and take a few seconds to spin up, the resulting delay
> could cause a problem.  The hard drives are now powered all the time.
> 6)  For the K3 IF of 8.215 MHz and a center frequency of 144130, I
> needed to change the MAP65-IQ parameter Fadd to (144130-8215) 135915
> based on some of Joe's comments and the code (which I took a peak
> at).  For an 80 KHz display range, I changed Fmin to 90 and Fmax to
> 170 (130 +/- 40), and the top of the MAP65-IQ waterfall displays 215
> +/- 40, as expected.  Moving the cursor in the waterfall shows (after
> adjusting Fadd a bit) the last three digits of the received frequency
> at the top of the display.  That number is also reported as the
> frequency in the decoded outputs.  Cool …
> 7)  My noise environment is very bad and I'd like to get the Linrad
> smart noise blanker running, but it needs a calibration file for this
> particular sample frequency.  Since the SDRs don't require individual
> calibration like the WSE units do, can you make one up and put it on
> your website Leif?
> 8)  The MAP65-IQ displayed time for decodes is the local computer
> time, not UTC, although the moon az and el computations are correct
> and the time in the lower left block is in UTC.
> 9)  The power out from the XV144 goes from about 7 watts for the
> lowest MAP65 tone to 3 watts for the highest tone.  I think this has
> something to do with the K3 setup, but I'm working on it.
> I still have lots of tweaking to do, but yesterday and today I copied
> numerous stations across the band (even with extremely high noise).
> The narrow band decoder does seem to be more sensitive than the
> wideband, but that's just a first impression.  This is definitely a
> large step forward for EME with the SDR-IQ!
> Thanks Joe and Leif for making this happen!
> Joe N6KK
> > 

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