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Date: Sun, 10 Apr 2011 14:16:42 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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Subject: LF: Re: GPS Sync
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Wolf,

Does the Rockwell Jupiter TU30 GPS module (used by DF6NM, OE3GHB and me 
and others) provide this NMEA informations too? And how will we feed the 
informations to SpecLab? You mentioned the soundcard, but how is this 
possible? We would at least need a stereo soundcard, right?

73, Stefan

Am 10.04.2011 13:39, schrieb wolf_dl4yhf:
> Hello Stefan,
>
> Yes, the charm of the GPS-sync'd sampling is that it allows truly 
> coherent transmission - even after the program was shortly stopped, PC 
> rebooted, generator re-fuelled, or whatever strange things may happen. 
> The sine wave generator will (optionally) not calculate the argument 
> based on the number of soundcard samples, but derived from the 
> GPS-derived time of day. Which, with the GPS 18x LVC mentioned before, 
> seems to have a resolution (not neccessarily a precision) in the 
> sub-microsecond range (192 kHz SR -> 5.x microsecond samples, but 
> internally interpolated to a higher sample rate near the slope of the 
> sync pulse).
>
> At 192 kHz sampling rate, I get a standard deviation in the measured 
> pulse position of only 30 to 60 nanoseconds (per one-second-interval) 
> measured over one minute, which almost sounds too good to be true. 
> Thus i'm a bit sceptic, this needs more testing.
>
> Some preliminary info about the GPS-based calibration is already 
> available here:
> http://www.qsl.net/dl4yhf/speclab/frqcalib.htm#gps_pps_output
>
> Note: The NMEA decoder for the soundcard is not implemented in the SL 
> version on my website. It will be implemented when the weather(!) 
> permits ;-)
>
> 73,  Wolf DL4YHF
> (off for a walk now..)
>