[OZAPRS] (no subject)

[Matthew Cook]

Hi Glen ,

I've been fortunate to have played with these systems and for what is old
tech (FEC, block encoding & Turbo modems) they still work well.   I've seen
STANAG 4539 modems hanging onto 600 bps connections at -2dB SNR dropping
back to 75 baud at -18dB SNR.  Some times it is not about the speed over
the forward path.   Doing 64QAM in 2.7kHz of BW is still impressive with
good channel SNR.

Anyway one day we'll get some of the more funky modem topologies to play
with. David DGR has been doing some good work with n-ary PSK modems of
late, which has been interesting.

73

/M.



On 18 October 2017 at 07:50, Glen English VK1XX <
glenlist at pacificmedia.com.au> wrote:

> thanks for the link Matthew. yeah most of those HF modems are a POS
> compared to modern OFDM based modems at any sort of decent data rate
> (although they are alot less demanding on th transmitter due to being
> constant envelope ) . IIRC the STANAG modem heavily used compression to
> achieve the reasonable speeds (of plain text transfer)- I think it slows
> down alot for black comms as it doesn't readily compress as well.
>
>
> g
>
>
> On 17/10/2017 5:26 PM, Matthew Cook wrote:
> > STANAG 4539
>
>
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