LF: Re[2]: LF: opera coding demistified

[Alex K <rn3aus@mail.ru>]

Hello LF!
Please see also: http://136.su/forum/index.php?topic=117.0
http://rn3aus.narod.ru/dds_tx/
and in attachment is C coding routine for OPERA
73 de Alex/rn3aus

Opera      1: 0.256 s
Opera      2: 0.512 s
Opera      4: 1.024 s
Opera      8: 2.048 s
Opera    32: 8.192 s

To:rsgb_lf_group@blacksheep.org

Subject: Re: LF: opera coding demistified

Stefan Schaefer wrote

> G.., i have done it. Downloaded ... to my LF PC. Still can't belive it...

... well, I haven't ;-) Out of curiosity, I have instead implemented Guido's excellent guide on Opera encoding 

http://rn3aus.narod.ru/opera_protocol.pdf

in a little Basic program, which outputs the 110... keying sequence for any given callsign.

And it works! For a quick on air test, I decided to use SpecLab's test signal generator, modulated by an arbitrary waveform which can be loaded from a text file. To fit to the required data format, I edited the sequence by zero-padding from 239 to 256 symbols, then replacing every "1" by two lines of "32767", and every "0" by two lines of "0", giving 512 samples total. For "Op4" speed, the AM modulator period was set to 0.256*4*256 = 262.144 seconds. Audio output was used to key my TX on 478.63 kHz. I sent for strings on Saturday night 21:30 to 21:47, and within a few minutes, pskreporter.de showed spots from DF2JP, G8HUH, ON6EO and DD7PC.

In case you would also like to send Opera without "his master's software", or associate obscure received sequences with possible candidates, the little program and sourcecode is at

http://df6nm.bplaced.net/opera/opera_generator.zip (24 kB)

Best 73,

Markus (DF6NM)

From: Rik Strobbe

Sent: Friday, February 17, 2012 11:48 AM

To: rsgb_lf_group@blacksheep.org

Subject: LF: opera coding demistified

PE1NNZ seems to have demistified the opera coding, those interested can read the attached file.

73, Rik  ON7YD - OR7T

opera-code.txt
Description: Text document