Re: LF: Idiot's guide to receiving Ebnaut? - Tutorial part2

[Wolfgang Büscher <dl4yhf@freenet.de>]

It will possibly work if the software (SL) would not expect a 'normal' rectangular pulse, look for the "valid" low->high transition (because some cards have the bad habit of inverting the polarity), expect a minium amplitude (to tell the PPS- from the NMEA signal that is optionally fed into the soundcard on the *same wire*), etc.

http://www.qsl.net/dl4yhf/speclab/GPS_pps_nmea_combiner.png

But out of curiosity, I will experiment with such an "almost-Dirac" pulse myself, and see what arrives after the signal passed through the soundcard's sigm-delta converter.

Cheers,
   Wolf .

Am 24.10.2016 um 22:22 schrieb Andy Talbot:

Won't the sound card's input filter, the anti-alias filter, extend this pulse, however short it is, into something the sampling rate will always see?  So there is no need to deliberately lenghen it.  

The only real advantage to doing so, perhaps, would be to increase the pulse energy within a one sample period leading to a hight amplitude in the capture.

The 1 PPS from my HP-5061 is only 1us in width, but can still be detected on a soundcard stream at any sampling rate chosen.

Andy  G4JNT

On 24 October 2016 at 21:07, Wolfgang Büscher <dl4yhf@freenet.de> wrote:

Hello Jim,

I still wonder why the sync pulses from the Thunderbolt E are so short - you mentioned 10 us in your email, but what is the exact pulse length ? With a slightly modified software (SL) it may be possible to use them as they are.. if they are longer than a sample from the soundcard.

73,
   Wolf DL4YHF
  (not QRV on LF+MF unfortunately..)