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

Wed Aug 14 12:59:57 UTC 2019

That is so cool! I am beginning to TX with DTMF; I hope to get it working soon from my Yeasu FT2DR without doppler shifting.
73
Robert MacHale. KE6BLR Ham Radio License. http://spaceCommunicator.club/aprs 
. Supporting Boy Scout Merit Badges in Radio, Robotics, and Space Exploration

    On Tuesday, August 13, 2019, 10:29:59 PM PDT, Scott via AMSAT-BB <amsat-bb at amsat.org> wrote:  

 Well, more great news on the PSAT-2 DTMF front.

In my previous post I had mentioned that the satellite accepted a "QSL"
from me against KC9ELU's CQ message.  Here's the downlink from that:

--------------------------------------------
}K4KDR >APS,TT,PS2*::ALL      : Q S L, your number 45, My number is 53.
--------------------------------------------

Well, on tonight's 0445 UTC pass, even though PSAT-2 was well past me and
losing elevation, KC9ELU got through to it with a QSL of my #53!

The downlink audio was something like "KC9ELU QSL your CQ #53 - Thanks for
the Contact".  I can only paraphrase because like a total idiot with the
satellite so far past me, I had stopped recording.  Yes... I should know
better and am usually more careful.

Anyway, great fun to see the full contact sequence completed, even if it
took multiple passes on different days.

***UPDATE:  Just got an email from KC9ELU - he didn't have audio but did
decode the downlink packet!  Makes me feel better to actually see it:

---------------------------------------------
}KC9ELU>APS,TT,PS2*::ALL      : Q S L, your C Q number 53 and thanks for
the contact.
---------------------------------------------

Earlier in the pass I was able to get another QSL accepted against PY5LF's
CQ #59, too:

--------------------------------------------
PSAT2-1>APOFF,ARISS:}K4KDR >APS,TT,PS2*::ALL      : Q S L, your number
59,  My number is 62.
--------------------------------------------

... but Direwolf decoded that downlink packet with a bit error, so it was
not iGated onto the greater APRS network.  But that's going to happen
sometimes, especially with a sat at low elevation.  At least I got to hear
and see the feedback that I was heard by the DTMF engine.  Here is the
downlink audio from that one:

https://www.qsl.net/k/k4kdr//files/2019-08-14--0445--psat2.mp3

So Luciano, if you'd like to QSL my #62, the satellite should respond with
that "Thanks for the Contact" message to complete that full exchange.

-Scott,  K4KDR

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

On the 0448 UTC pass tonight, even though the satellite was well past me

On Tue, Aug 13, 2019 at 3:38 AM Scott <scott23192 at gmail.com> wrote:

> 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
>>>
>>
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