[amsat-bb] NO-84, what is the secret?

Jerry Pixton jpixton at shentel.net
Tue Dec 8 01:34:53 UTC 2015


I might add that most of the psk31 decoderS seem to work. I have been 
using DigiPan, Fldigi and my lash up of some of the WinPSK technology. 
If you use DopplerPSK you don't have to worry about a full duplex psk 
program - one app is your receiver and one app is your transmitter.

Most days I find I am the only one on the bird while it is visible here 
in VA. But I have been able to make 4 unique contacts so far. KC4LE and 
I have several repeat contacts in the past week.

What Bob says about transmitting continuously is so true - your 
transmitter has to be able to stand the 10 minutes or so. But it is 
bothersome to see a signal, click on it to start decode (which is not 
instantaneous) and the station stops transmitting.

You can tell the stations that are using doppler control on the uplink 
as their psk31 traces are more or less a vertical line as apposed to the 
traces that move rapidly down in frequency (high tone to low tone). 
There is a lot of 10m ground activity as well as some robot that tells 
me I am being received at some ground station, hi

The 70cm signal seems to be hard to decode with a lot of errors from 
noise or whatever so you want to put a lot of redundancy in your 
messages and keep the message short but repeat them often so other 
stations might decode the pieces eventually.

I am finding a protocol similar to JT65 etc where you call cq, you 
acknowledge a station answering your cq with your grid, they acknowledge 
your grid and send their grid, when you decode their grid you can send 
73s. So the 5 messages like DppplerPSK has works very well and that is 
all the time there is on a pass.

Give it a try. Remember the downlink doppler on 70cm is going to shift 
the signal up by 10 KHz at AOS, to zero at TCA and down 10 KHz by the 
end. Your can program 5 memories in your radio, hand tune the downlink 
or use one of the doppler control programs for the downlink.

I have found that the idea of shifting the audio tone instead of the RF 
carrier (that is keep the USB transmitter right on 28.120) works much 
better for decoding the signal.

Probably too much info at the moment, but come back to it after getting 
your feet wet.

73 and see you on NO-84 psk31

Jerry, W6IHG

On 12/7/2015 3:09 AM, KO6TZ Bob wrote:
> Mark,
> The FM transmitter does not turn on unless the SSB receiver hears a
> PSK-31 signal.
> Once you start transmitting on 28.120 USB, never stop for the duration
> of the pass.  Keep the transmitter turned on.   Just change the Macro
> Text as needed for the contact.  If you see the FM transmitter turning
> off and on, increase your power.  I usually need 40-80 watts.  As with
> anything on HF, band conditions are important.
> The reference to 28.120 +2kHz means set the radio dial on 28.120 USB and
> transmit at 2KHz on the waterfall. (This is +/- for other station
> signals as you would expect.)
> If your signal is too high on the waterfall to copy well, just turn the
> VFO to bring it down where you can copy yourself.  For the decoder, I
> suggest using anything that displays two or more signals.  For the
> transmitter, use DopplerPSK_ V:0.2.
> Hope this helped.
> KO6TZ   Bob
> --------------------------------
> I heard APRS on the 144 MHz band.  But I did not hear any PSK31 on the
> downlink.  I did not try to transmit.
> 1.    What's the secret to receiving PSK31 on FM?  I never tried that
> before.
> 2.    Transmit says 28.120 kHz +2 kHz SSB uplink.  Can someone please
> translate that into USB DIAL and software tone?  If it is 28120 USB and 2
> kHz tone, most SSB rigs attenuate the audio at that level.
> Mark Lunday, WD4ELG
> Greensboro, NC  FM06be
> wd4elg at arrl.net
> http://wd4elg.blogspot.com
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Dr. Jerry R. Pixton, PIXOS Designs
jpixton at shentel.net

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