[OZAPRS] HF APRS

[Matthew Cook]

Andrew,

You're going to find that only Government agencies and the Military are
granted the luxury of such practice.  In the commercial world where time is
actually money, such practices are loosely followed largely by Graduates
until such time as they realise they can work with out it.  At which point
we make then senior.

73

Matthew
VK5ZM

On 18 December 2017 at 14:31, Andrew Rich <vk4tec at tech-software.net> wrote:

> Are we following any system engineering practices ?
>
> Sent from my iPhone
>
> > On 18 Dec 2017, at 1:17 pm, Glen English VK1XX <
> glenlist at pacificmedia.com.au> wrote:
> >
> > Yep
> >
> > It's ready to go. But I have to get work done this week, got to sgo 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
> >>
> >>
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> >>
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