LF: SlowJT9 v0.9.02: Decode simultaneous

[James Hollander <mrsocion@aol.com>]

Rik, all,        So, as I understand it, on some ordinary night a MF station would/could run at least two software instances of JT9—one instance set to decode 2 minute slow JT9, and the other instance decoding 1 minute JT9 concurrently. 

 

The 1^st  s/w instance is set for slow JT9.   If the station you want to call or have respond to a CQ is low-SNR like a QRP, transcontinental, or transoceanic station, then you activate your transmission using the slow JT9 software instance.   If low-SNR stations comprise the only intended reception, then slow JT9 is all you use and forget the 2^nd s/w instance.   You get deep-SNR receptions and QSOs that regular JT9 can’t deliver.

 

The 2^nd s/w instance is set for regular JT9. Suppose the station you want to call or have respond to a CQ is likely above, say, the 50% decode probability, at least SNR -27 dB most of the time. Then you activate your transmission on-the-fly instead with regular JT9 using that 2^nd s/w instance.  That way, you either get a reply after 1 minute or have the chance to repeat your transmission.

 

The nimble operator uses the 1^st  or 2^nd  s/w instance that’s simultaneously running as conditions and as sought-after stations warrant.  No need to change TX frequency.  The DX may be on some other frequency than you, but that’s fine.  You call them with slow JT9 or regular JT9 as you decide on-the-fly without changing your frequency and they will see you on their PC display if they can. 

 

Other stations may be running either slow JT9 or regular JT9 at any given time, and that’s fine too because you can receive them either way.  You’ll see stations TXing slow JT9 on one decoder window and stations TXing regular JT9 on the other decoder window. If a station sends slow JT9 for a while and then regular JT9 for a while, you’ll see that station go from one decoder window to the other.

 

If a station is already running regular JT9 diversity with two RX antennas and two regular JT9 decoders connected to SDR sub-RXs, you just add two more decoders for slow JT9 diversity as well. Depending on your PC, use a PC powerful enough to run the s/w instances concurrently. 

 

Feel free to clarify if I’m missing anything important.  Very interesting!  73, Jim H  W5EST

 

 

-----Original Message-----
From: Rik Strobbe <rik.strobbe@kuleuven.be>
To: rsgb_lf_group <rsgb_lf_group@blacksheep.org>; rsgb_lf_group <rsgb_lf_group@yahoogroups.co.uk>
Sent: Mon, Nov 12, 2018 4:05 pm
Subject: Re: LF: SlowJT9 v0.9.02

Hi Paul, it seems that we will have to make a choice: - either the old JT9-2 and JT9-5 standard and only decoding one mode at a time - or keeping the current JT9-2 and JT9-5 parameters and keep the option open to decode all JT9 submodes simultanious. I tend to go for the second option, but everyone is welcome to convince me otherwise. 73, Rik ON7YD - OR7T ________________________________________ Van: owner-rsgb_lf_group@blacksheep.org <owner-rsgb_lf_group@blacksheep.org> namens N1BUG <paul@n1bug.com> Verzonden: maandag 12 november 2018 22:43 Aan: rsgb_lf_group@blacksheep.org; rsgb_lf_group@yahoogroups.co.uk Onderwerp: Re: LF: SlowJT9 v0.9.02 I can confirm something similar. My CPU is running around 30% (it's a VERY busy system with many apps running). When SlowJT9 invokes the decoder I see a short spike to 50%, sometimes as high as 55%. 73, Paul N1BUG On 11/12/18 4:13 PM, Rik Strobbe wrote: > I just had a look at the CPU usage of my computer: > it is wobbeling between 2% and 5% but peaks to 40% if the JT9 decoder is invoked. > I am afraid that invoking 3 instances of the JT9 decoder at (almost) the same time is not a good idea. > > 73, Rik ON7YD - OR7T