LF: Re: Re: Op-32 correlation results online

[<jrusgrove@comcast.net>]



Markus

 

Thanks for the information and your work on 'deep search' OP-32. It's nice to know that the time and $ spent on frequency stability / phase coherence is worth it.

 

After not getting any OP-32 spots from EU last night (at least by the stations using the conventional program) I switched over to QRSS45 at 0400Z for a couple sequences of 'XNS' on 137781. The signal was displayed immediately at the F1AFJ and YV7MAE grabbers with good signal levels  ... signal levels that one would expect to have have been decoded by OP-32. Hartmut reports seeing 'XNS' QRSS but no OP-32 decodes either. As time goes on, I'm becoming more convinced that QRSS trumps even the very weak signal digital modes. Think folks are being ' wowed ' by the impressive s/n abilities quoted by the programs ... without comparing them to something as simple as QRSS which may turn out to be a better weak signal performer.

 

Jay W1VD  WD2XNS  WE2XGR/2

 

  

----- Original Message -----

From: Markus Vester

To: rsgb_lf_group@blacksheep.org ; rsgb_lf_group@yahoogroups.co.uk

Sent: Friday, February 22, 2013 5:07 AM

Subject: LF: Re: Op-32 correlation results online

The Op-32 detections from last night are on

http://www.df6nm.bplaced.net/opera/detected_130221-22.txt 

which are basically the correlation hits which were marked by *. The current list of templates is

http://www.df6nm.bplaced.net/opera/callsigs.txt

 

Jay appeared again here three times. RN3TTS was detected for the first time, once at the beginning. WE2XEB was not copied (yet) - Bob if you could tell your actual transmit frequency I would try to inspect the spectrogram more closely.

 

I have collated a gallery of zoomed spectra and spectrograms

http://www.df6nm.bplaced.net/opera/Op-32_spectra_130221-22.png

UA4WPF and WD2XNS both have a very well defined central peak, which proves that their signals are phasecoherent between dashes and also very stable. RA3YO seems to be phase-coherent as well but with some frequency variation. The others seem to be sending incoherently, possibly because their oscillators or dividers are being restarted with every dash. Experiments with simulated signals have indicated that my detection threshold seems to be about 6 dB lower for coherent signals.

 

BTW Blacksheep still seems to be sick for me. Like Alan, the last message I got was yesterday 16:38 from Jay.

 

Best 73,

Markus

 

www.df6nm.de

 

 

----- Original Message -----

From: Markus Vester

To: rsgb_lf_group@blacksheep.org ; rsgb_lf_group@yahoogroups.co.uk

Sent: Thursday, February 21, 2013 11:09 PM

Subject: Re: Op-32 correlation results online

To produce some kind of realtime feedback to transmitting stations, I will upload screenshots from the experimental Opera deep-search utility in ten-minute intervals to

 

https://dl.dropbox.com/u/26404526/df6nm_opds.png

 

This is unfiltered output, so repeating partial correlations will often appear in several consecutive time slots. The "proper" ones with most overlap are marked by an asterisk.

 

The "mHz" column shows the apparent bandwidth of the central peak: Coherent stable transmissions will often remain within 1 or 2 mHz, whereas spreading by non-continuous phase will typically result in 60 to 150 mHz. There are actually two separate carrier searches, which can lead to the same signal being picked up twice within the same slot. Peaks on Loran line frequencies are being excluded from processing.

 

 

BTW Again I haven't received anything from Blacksheep since 17 UT, so I'm currently pretty much blind to email from the group.

 

Best 73,

Markus

 

www.df6nm.de