[OZAPRS] HF APRS

[Robert]

So will this new idea be used on 6M as well.

Robert

-----Original Message-----
From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Glen English VK1XX
Sent: Monday, 18 December 2017 2:17 PM
To: ozaprs at aprs.net.au
Subject: Re: [OZAPRS] HF APRS

Yep

It's ready to go. But I have to get work done this week, got to go to sort a few things out at a few sites. I need to get some python code written before going to site tomorrow.

Over the weekend I remembered how it all works (it's a modem I wrote 4 years ago) , and modified a few blocks to reduce the CPU usage for this narrow band application, and also I added a block to generate IQ baseband signals from real input (radio output) , so it can use a standard radio.

Compilation targets are x86 and ARM+NEON... If compiling for ARM, it is HEAVILY NEON optimized as it had to run on a certain platform ... (oDroid) .

It searches through a specified bandwidth, throwing as many cores at it as you tell it to, each core gets a chunk of spectrum to work on. Roughly 50mS per second processing time per 2kHz of searching BW  on a
3.5 GHz i4670k single thread. Will run on a Odroid C1, C2, XU4 etc. 
might run on later Pis, never used them...

Sync can be acheived at about 9dB below what is required for a decode (~ 1dB SNR), the modem can decode multiple transissions simultaneously in the passband and used a 1/5 rate LDPC code. Modulation is D2BPSK (2nd order diff ).

g

On 18/12/2017 1:30 PM, Graeme wrote:
> Glen English has stated that he is working on something new for HF 
> APRS that should be a lot better than what’s currently available.
> Graeme 2HFG
> *From:* Gerard Hill
> *Sent:* Monday, December 18, 2017 11:25 AM
> *To:* Australian APRS Users
> *Subject:* Re: [OZAPRS] HF APRS
> PAs - as in Power Amplifiers, Andrew.
> In the past I've run an IGate using PSK63 and GFSK63 using software 
> called APRS Messenger 
> <http://www.crosscountrywireless.net/aprs_messenger.htm>.
> These modes have great performance even without Forward Error Correction.
> Availability for mobiles is limited although there is a standalone 
> modem for PSK63 available called FreeTrak63 
> <http://www.ringolake.com/pic_proj/FT63/ft63_page.html>.
> Some info on these modes from WA8LMF here 
> <http://wa8lmf.net/APRS_PSK63/index.htm>.
> Be interesting to know more about what Matthew is referring to.
> Cheers,
> Gerard - VK2IO
> On 18 December 2017 at 11:01, <vk4tec at tech-software.net> wrote:
>
>     What is “Pas”
>
>     Whats coming ?
>
>     *From:*OZAPRS [mailto:ozaprs-bounces at aprs.net.au] *On Behalf Of
>     *Matthew Cook
>     *Sent:* Monday, 18 December 2017 9:22 AM
>     *To:* Australian APRS Users <ozaprs at aprs.net.au>
>     *Subject:* Re: [OZAPRS] HF APRS
>
>     I'd wait until early next year and see what's coming in terms of
>     HF ARRS, plans are a foot.
>
>     73
>
>     Matthew
>
>     VK5ZM
>
>     On 18 December 2017 at 09:48, Robert <rbaker at bigpond.com> wrote:
>
>         Hi All.
>
>         Just a quick question on HF APRS.
>
>         I have seen people chatting about modified FSK modem used
>         directly onto Pas. My question is do I use these modified
>         modems when I directly use say IC-706 mk2, or will a TT4,
>         Opentracker do the job.
>
>         Thanks in advance.
>
>         Cheers
>
>         Robert
>
>
>         _______________________________________________
>         OZAPRS mailing list
>         OZAPRS at aprs.net.au
>         http://lists.aprs.net.au/mailman/listinfo/ozaprs
>         <http://lists.aprs.net.au/mailman/listinfo/ozaprs>
>
>
>     _______________________________________________
>     OZAPRS mailing list
>     OZAPRS at aprs.net.au
>     http://lists.aprs.net.au/mailman/listinfo/ozaprs
>     <http://lists.aprs.net.au/mailman/listinfo/ozaprs>
>
> ----------------------------------------------------------------------
> -- _______________________________________________
> OZAPRS mailing list
> OZAPRS at aprs.net.au
> http://lists.aprs.net.au/mailman/listinfo/ozaprs
>
>
> _______________________________________________
> OZAPRS mailing list
> OZAPRS at aprs.net.au
> http://lists.aprs.net.au/mailman/listinfo/ozaprs


_______________________________________________
OZAPRS mailing list
OZAPRS at aprs.net.au
http://lists.aprs.net.au/mailman/listinfo/ozaprs