[amsat-bb] PSAT PSK31 experimental software (Op ideas)

aflowers at frontiernet.net aflowers at frontiernet.net
Thu Jul 16 14:22:06 UTC 2015

What you are suggesting sounds like simply changing the idle signal to something with information in it.   I don't see any reason why that couldn't be done.  I'll give it some thought.  It's an experiment, after all....

Another way to do this is to just invent a mode that has two data streams interleaved with each other, source-coded for the data you want to send (a la JTx modes) but that breaks the universality of BPSK31 and varicode.  I really like the idea that someone can plug a handheld into a laptop or tablet running off-the-shelf software and see something meaningful.  

DopplerPSK already has a rudimentary "macro" format.  Have a look at the PDF on the download page and you'll get the gist of how it works.  It does not have any substitution functionality yet (like wildcards for the other stations' callsigns), but you could make a file with an arbitrary-length fixed message just fine.  I have planned a loop functionality (it's in the macro file format itself), but I didn't get around to implementing it yet....right now you can just press the button several times to stack the looped message in the buffer.  Just make sure there are spaces at the end of the text so that work don't run together between the boundaries.  One press of the macro button just dumps that text into the type-ahead buffer.
The "clear buffer" button will empty the buffer and you can start typing whatever you want.  You can use that to interrupt a macro message that is sending.  The ergonomics of having a conversation are not perfect (you can't copy paste into the text window and get it to send for example--which slow typists might want), but it's functional enough to be somewhat useful.

Also of note for those not aware, sending uppercase requires many more bits in the varicode table and is going to be more prone to bit errors due to burst noise (like, say a quick fade from a rotating satellite).  You can probably send your callsign a couple times in lowercase in the same amount of time it takes in all caps.  That's pretty poor FEC, and convolutional codes can address some of that, but for right now DopplerPSK is stuck with plain vanilla BPSK31 until someone implements a different scheme.  I'm not really sure this a big problem to be solved, though.

Andy K0SM/2

     On Thursday, July 16, 2015 9:29 AM, Robert Bruninga <bruninga at usna.edu> wrote:

 Full DUX PSK31 Operating ideas:

Can I assume the TX uplink software has the usual BRAG text and CQ
features, since the expectation is that users will continuously transmit
throughtout the entire pass and the operator has plenty to do other than
type continuously at the keyboard.  So I envision some continuously
running brag text including CQ's the call, the HF antenna, the power, the
grid, the location in DDN/DDDW whole degrees maybe (for APRS purposes),
the downlink antenna, and so forth.  And then maybe the looping uplink
will stop at the next item separator and allow the operator to inject
keyboard text.

In other words, the loop just runs.  But if the operator begins typing
(maybe he sees a buddy in the dowonlink) he just starts typing and the
LOOP stops at the next break in loop elements and inserts the typed text.
Im thinking that elements in the brag string would be separated by " - "
but then when ever the operator types text, then it is inserted in the
stream beginning with [ then text goes here and ends with a ] when he hits
the enter key?

By having a common system of continuous brag items and interjected live
text, then we all have consistent expectations as to what the PC is doing
versus the operator?

Bob, WB4aPR


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