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<div class="moz-cite-prefix">According to the author of APRS
Messenger, MFSK16 can work down to a signal to noise level of
-13.5 dB in a 3 kHz bandwidth. That's 2 dB better than PSK-31 or 6
dB better than PSK-63. It also has forward error correction and an
interleaver so that noise spikes and lightning crashes don't lose
data.<br>
<br>
MFSK16 can be transmitted at full power like the GMSK modes so
that adds an extra 3 dB to the link budget as the transmitter
doesn't have to be run at half power as with PSK modes. There are
multiple software receivers on MFSK16 giving a maximum tuning
range of ± 75 Hz.
<br>
<br>
Switching to MFSK16 here the beacons became almost twice as long
as for PSK63. The reward was immediate as the <a
href="http://aprs.fi/info/WA8LMF-13">WA8LMF</a> iGate in
Michigan started receiving these transmissions on 30m. I'm using
50W into a low dipole and WA8LMF uses a magnetic loop. 5W would
certainly give Australia-wide coverage. Transmission length can be
reduced by using the compressed APRS format though can never be as
short as for FSK300. Where the power budget is low like on a
balloon, MFSK16 would be ideal.<br>
<br>
Cheers,<br>
Gerard - VK2IO<br>
<br>
<br>
On 8/04/2014 12:49 PM, Mark Jessop wrote:<br>
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<div class="moz-cite-prefix">Going from experience, and a lot of
simulation and on-air testing, I'd say MFSK16 will be a far more
reliable system than PSK63, mainly due to it's r=1/2 forward
error correction. You probably wouldn't need much more than 5W
for australia-wide coverage.<br>
<br>
It's also fairly easy to generate (with a DDS anyway), and is
constant amplitude (no linear amp required!), so you could make
a 5W MFSK beacon using a Class E PA running at >95%
efficiency.<br>
<br>
The main downside is it is slow, so channel congestion becomes
more of an issue.<br>
<br>
Cheers,<br>
Mark<br>
<br>
<br>
On 8/04/14 11:54 AM, Gerard Hill wrote:<br>
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<div class="moz-cite-prefix">About 4 years ago a bunch of us
started experimenting with <a moz-do-not-send="true"
href="http://wa8lmf.net/APRS_PSK63">PSK</a> for APRS on HF.
We used the <a moz-do-not-send="true"
href="http://www.crosscountrywireless.net/aprs_messenger.htm">APRS
Messenger</a> software which supported a variety of speeds
from 31 to 250 bps. It proved far superior to FSK300 packet. I
ended up running an IGate on 7034.7 kHz and a receive-only
IGate on 10149.7 kHz. These PSK ports closed 2 years ago.<br>
<br>
APRS Messenger requires a PC running Windows and continues to
be developed so now supports <a moz-do-not-send="true"
href="http://www.radio-electronics.com/info/rf-technology-design/pm-phase-modulation/what-is-gmsk-gaussian-minimum-shift-keying-tutorial.php">GMSK250</a>
and MFSK16 modes as well as PSK63 and PSK250. APRS messages
contain a checksum allowing posits to be verified before
injection into the APRS-IS. It is great software for the
shack, not so convenient in the mobile where a compact tracker
is needed.<br>
<br>
Last year, the <a moz-do-not-send="true"
href="http://www.ringolake.com/pic_proj/FT63/ft63_page.html">FreeTrak63</a>
was developed for mobile use. It can generate PSK63 and
MFSK16. Blank PCBs are available.<br>
<br>
Anyone interested in trying PSK63 for APRS?<br>
I'm running it on 10149.7 at the moment using VK2IO-63.<br>
<br>
Cheers,<br>
Gerard - VK2IO<br>
<br>
On 4/04/2014 8:00 AM, Andrew Rich wrote:<br>
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<blockquote
cite="mid:8120BB83-23CE-4026-AF48-FD992903532B@tech-software.net"
type="cite">
<pre wrap="">Psk had very good noise performance
Psk63 is faster than psk31
No error check tho
Sent from my iPhone
</pre>
<blockquote type="cite">
<pre wrap="">On 4 Apr 2014, at 6:58 am, Matt VK2RQ <a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:matt.vk2rq@gmail.com"><matt.vk2rq@gmail.com></a> wrote:
This is an interesting article on that topic:
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://wa8lmf.net/APRS_PSK63/">http://wa8lmf.net/APRS_PSK63/</a>
73,
Matt VK2RQ
</pre>
<blockquote type="cite">
<pre wrap="">On 4 Apr 2014, at 7:37 am, Shaun <a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:vk2xpp@optusnet.com.au"><vk2xpp@optusnet.com.au></a> wrote:
What is the advantage of psk63?
Brief reply only from my iPhone
</pre>
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<pre wrap="">On 3 Apr 2014, at 17:56, Andrew Rich <a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:vk4tec@tech-software.net"><vk4tec@tech-software.net></a> wrote:
Just got a icom 7000 and scs packet modem will see if it does psk63
Sent from my iPhone
</pre>
<blockquote type="cite">
<pre wrap="">On 3 Apr 2014, at 2:49 pm, Andy Nguyen <a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:an@comms.net.au"><an@comms.net.au></a> wrote:
Thanks Mark,
Just checking :)
Regards
Andy VK3YT
</pre>
<blockquote type="cite">
<pre wrap="">On 3 Apr 2014, at 3:35 pm, Mark Jessop <a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:lenniethelemming@gmail.com"><lenniethelemming@gmail.com></a> wrote:
Planning on a HF balloon payload there Andy?
And AFAIK there's no PSK capable iGates in Australia.
- Mark VK5QI
</pre>
<blockquote type="cite">
<pre wrap="">On 3/04/14 3:04 PM, Andy Nguyen wrote:
Hi all,
Do we have any iGate on HF (30m) in Australia that supports PSK63 ?
Regards
Andy
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