[600MRG] LF: SlowJT9 v0.9.02: Decode simultaneous

[James Hollander]

Rik, all,        So, as I understand it, on someordinary night a MF station would/could run at least two software instances ofJT9—one instance set to decode 2 minute slow JT9, and the other instancedecoding 1 minute JT9 concurrently.  
 
The 1st  s/w instance is set for slow JT9.   If the station you want to call or haverespond to a CQ is low-SNR like a QRP, transcontinental, or transoceanicstation, then you activate your transmission using the slow JT9 softwareinstance.   If low-SNR stations comprisethe only intended reception, then slow JT9 is all you use and forget the 2nds/w instance.   You get deep-SNR receptions and QSOs thatregular JT9 can’t deliver.
 
The 2nd s/w instanceis set for regular JT9. Suppose the station you want to call or have respond toa CQ is likely above, say, the 50% decode probability, at least SNR -27 dB mostof the time. Then you activate your transmission on-the-fly instead with regular JT9 usingthat 2nd s/w instance.  Thatway, you either get a reply after 1 minute or have the chance to repeat yourtransmission.
 
The nimble operator usesthe 1st  or 2nd  s/w instance that’s simultaneously running asconditions and as sought-after stations warrant.  No need to change TX frequency.  The DX may be on some other frequency thanyou, but that’s fine.  You call them with slow JT9 or regular JT9 as you decide on-the-fly withoutchanging your frequency and they will see you on their PC display if they can.  
 
Other stations may berunning either slow JT9 or regular JT9 at any given time, and that’s fine toobecause you can receive them either way. You’ll see stations TXing slow JT9 on one decoder window and stations TXingregular JT9 on the other decoder window. If a station sends slow JT9 for awhile and then regular JT9 for a while, you’ll see that station go from onedecoder window to the other. 
 
If a station is alreadyrunning regular JT9 diversity with two RX antennas and two regular JT9 decodersconnected to SDR sub-RXs, you just add two more decoders for slow JT9 diversityas well. Depending on your PC, use a PC powerful enough to run the s/winstances concurrently.  
 
Feel free to clarify ifI’m missing anything important.  Very interesting!  73, Jim H W5EST


 
-----Original Message-----
From: Rik Strobbe <rik.strobbe at kuleuven.be>
To: rsgb_lf_group <rsgb_lf_group at blacksheep.org>; rsgb_lf_group <rsgb_lf_group at 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 at blacksheep.org <owner-rsgb_lf_group at blacksheep.org> namens N1BUG <paul at n1bug.com>Verzonden: maandag 12 november 2018 22:43Aan: rsgb_lf_group at blacksheep.org; rsgb_lf_group at yahoogroups.co.ukOnderwerp: Re: LF: SlowJT9 v0.9.02I can confirm something similar. My CPU is running around 30% (it'sa VERY busy system with many apps running). When SlowJT9 invokes thedecoder I see a short spike to 50%, sometimes as high as 55%.73,Paul N1BUGOn 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


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