[amsat-bb] PSAT2 downlink for DTMF grids and messages

[Scott]

Well, at the last minute before tonight's PSAT-2 passes, I finally figured
out the correct format for the DTMF QSL messages & answered my own question.

Here's a tweet w/ screen shots & audio URLs from tonight's successful DTMF
connections:

https://twitter.com/scott23192/status/1161174309328621573

I found the following page particularly helpful:

http://aprs.org/QIKcom/Q2-DTMF-messages.txt

... in particular, the instruction:

---------------------------------------------

DTMF messages are sent in a 16 key string starting with the "C", ending in #

  //

    CMMxxCCCCCCkkkk#  Where CCCCCCkkkk are your callsign keys and key code
                      and MM is the message number below

---------------------------------------------

.. so, here is how it breaks down if anyone else could use the extra
help that I did.

Get your call/grid DTMF from http://aprs.org/PSAT2Translator.html

(important note:  if your callsign is less than 6 characters, put a
space or 2 at the end to bring your character count to -6- before
clicking "Translate")

... so for a CQ, I use that string exactly:

*18175453702201#

However, if I want to QSL someone else's CQ, I only use the call sign
portion of that DTMF string.  The string that gave me the QSL success
was:

C40455453702201#

... let's break that in its parts:

>C :  message follows
>40 :  message #40 is a QSL
>45 :   I am QSL-ing CQ #45   (from KC9ELU as seen on http://www.aprsat.com/dtmf ) [... or heard directly over-the-air!! ]
>545370 :  the call sign portion of my original DTMF translation
>2201 : also from the original DTMF translation - simply put, a converted 'key code' that goes with the previous numbers representing my call sign
># :   END of message

I won't go into the creation of the DTMF audio file here (I use
Audacity); please feel free to contact me if you need help on that.  I
used audio files transmitted via Signalink at my location, but of
course if you have a radio with DTMF memory capability, that's an
option, too.

Hope that is helpful to someone else since I was so slow on the
pick-up on how to format the QSL type of message.

-Scott,  K4KDR

======================


On Mon, Aug 12, 2019 at 11:46 PM Scott <scott23192 at gmail.com> wrote:

> Many thanks to Robert for the time he's put into creating these very
> informative web pages!
>
> Bob, I have read and re-read the DTMF instructions but even though it
> reflects poorly on me, I'm not sure what exact string to transmit to QSL
> someone's previous CQ.
>
> So here is my best guess - please correct as required.
>
> My callsign/grid DTMF (that has worked once) is:  *18175453702201#
>
> For me to QSL CQ #45 from KC9ELU, do I transmit the following?:
>
> C4045*18175453702201#
>
>
> Thanks in advance!
>
> -Scott,  K4KDR
>
> ==========================
>
> On Mon, Aug 12, 2019 at 9:55 PM Robert Bruninga via AMSAT-BB <
> amsat-bb at amsat.org> wrote:
>
>> Thanks to Robert, KE6BLR, we can now capture the DTMF Grids and Messages
>> data coming down from PSAT2.  I have added the DTMF page to the list of
>> links for PSAT2:
>>
>> http://aprs.org/sats.html
>>
>> Summary:  You encode your Grid and callsign into a 16 digit DTMF memory on
>> your radio.  Using narrow band FM, send it on 145.98 withi doppler
>> compensation or at the middle of a pass.
>>
>> PSAT2 assigns a CQ number and acknowledges it by voice and then sends an
>> APRS packet that contains the grid.  Robert's web page will capture that
>> packet.
>>
>> A second station can send their DTMF grid and get the same process but
>> with
>> a new CQ number.
>>
>> Now, either station can send a DTMF QSL Message for the other guy's CQ
>> number which will also be spoken and recorded on the APRS downlink.
>>
>> Details on the psat2 page on the above web page.
>> PSAT2 is entering a phase of Apogee in the northern hemisphere for a week
>> or so and so is more workable in the USA and southern Europe.
>>
>> Bob, WB4APR
>>
>