Thanks all for the great advice.

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Hello Timothy,

?

I was hoping to use TBEACON with embedded telemetry in the same way that telem-balloon.conf uses PBEACON (see lines 38-40). If I understood your reply correctly it just isn't supported, and would be better implemented as separate TBEACON for position only and CBEACONs for the telemetry data.

It's more a matter of not having enough space in the APRS packet payload.? With that said, you can do anything with the CBEACON payload you want.? As long as your software can decode it, then more power to you!? This is the power of being a HAM!

With the rate that car club wants to see this data my plan was to stay far away from 144.390 . I know I will end up monopolizing whatever frequency I end up on, but it will only be for an hour or so on only a few days out of the entire year. I am working with local hams that are more experienced than I to find the best frequencies, and goal is always to use the lowest power possible. No one wants to be that guy.

You're saying all the right things an I fully imagine there are available experimental frequencies in the digital portion of your local bandplan that will work.

If placing a Tracker w/ telemetry unit on each of 6-8 cars with the goal of being able to receive data from these cars in? as close to real-time as possible.

What would be the better design:
Option 1: All cars on the same frequency (not 144.39)
Option 2: Each car on it's own frequency.

That depends on several factors but for #1, assuming that each transmitter has a GPS signal with the PPS signal to ensure very accurate time AND you can come up with a schedule to have each of these eight stations interleaving their packets in a given minute, it might work.? Now, since you're also using SMARTBEACON, I don't think you'll have very consistent and deterministic beacon timing.? As some point, I bet you'll start to see packet collisions.? APRS, using unacknowledged AX.25 UI frames, will just "loose" those packets.? I'm assuming that you plan on also recording all of these packets to an onboard storage device so after the race, you can fill in any possible gaps.? For #2, this reduces the collision risk but then you also need another dedicated receiver for that frequency.? That does make things a bit more complicated though sometimes maybe using an SDR can keep at least the hardware complexity down.

Ultimately, you need to review why you really need "near real time".? For a race that takes almost an hour, I would think that getting data from the car every minute or even half-minute would be perfectly fine.

--David
KI6ZHD

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Hello Timothy,

?

2. Send telemetry data (battery voltage and current draw) from the car's on-board cycle analyst via a serial connection to the raspberry pi. -- Here is where our questions really lie.

Ok...

Does the TBEACON support the COMMENTCMD?

No.. it only sends fixed telemetry but I think you're overlooking a key point.? Different Direwolf beacons run all independently.? This means that you can have PBEACONS, OBEACONS, TBEACONS, and CBEACONS all running at the same time at different intervals sending different data.? Per the APRS_Telemetry doc, it's example sends:


The command "direwolf -c telem-volts.conf" would send out the following beacons on their specific schedule:
--
MYCALL-9>APDW13,WIDE2-1::MYCALL-9 :PARM.Supply
MYCALL-9>APDW13,WIDE2-1::MYCALL-9 :UNIT.Volts
MYCALL-9>APDW13,WIDE2-1:T#1,4.808
MYCALL-9>APDW13,WIDE2-1:T#2,4.797
MYCALL-9>APDW13,WIDE2-1:T#3,4.808
MYCALL-9>APDW13,WIDE2-1:T#4,4.802
MYCALL-9>APDW13,WIDE2-1:T#5,4.807
--

If you look in that conf file, you'll see the various beacons.? The first two lines are the EQNS lines to define what the future telemetry data represents.? These simple text lines are sent every minute (an extremely fast rate for APRS so that should be on one of the alternative APRS frequencies in your area to not clog up the national 144.390 frequency.
--
CBEACON delay=0:10 every=1:00 via=WIDE2-1 infocmd="telem-parm.pl MYCALL-9 Supply"
CBEACON delay=0:11 every=1:00 via=WIDE2-1 infocmd="telem-unit.pl MYCALL-9 Volts"
--


The next CBEACON is actually getting the A2D data via the Python script.. then running that output through Perl script to put it into the required APRS Telemetry format.? It does this every 10 seconds.? For your application, you might do this every second or so.
--
CBEACON delay=0:15 every=0:10 via=WIDE2-1 infocmd="telem-data.pl `telem-seq.sh` `PYTHONPATH=~/Adafruit-Raspberry-Pi-Python-Code/Adafruit_ADS1x15 telem-volts.py`"
--

Does this still all work with SMARTBEACONING?

? The only slight difference here is that the "SMARTBEACON" parameter changes the transmission rate of the TBEACONS (tracker beacons) which shows your location.? Again, the TBEACONS (which has the modified transmission times per the SMARTBEACON parameter), CBEACONS, etc. all run in parallel!

The parameter examples show perl, python, and bash script but doesn't really give clear guidance on what each does

It seems you're not the familiar with Linux.? Let me translate for you:?? infocmd="telem-data.pl `telem-seq.sh` `PYTHONPATH=~/Adafruit-Raspberry-Pi-Python-Code/Adafruit_ADS1x15 telem-volts.py`"

Run the program "telem-data.pl" perl script but as part of it's TWO command line arguments:

?? Argument #1 - run the telem-seq.sh script and use it's output as the argument

?? Argument #2 - Giving a Python path for various Python libraries first, now run the telem-volts.py" script and use it's output as the second argument


In this example, this CBEACON runs four times and it creates the output:

??? T#1,4.808
??? T#2,4.797
??? T#3,4.808
??? T#4,4.802
??? T#5,4.807

Which stands for:

?? Telemetry packet : sequence #1 : voltage: 4.808v
?? Telemetry packet : sequence #2 : voltage: 4.797v
?? Telemetry packet : sequence #3 : voltage: 4.808v
?? Telemetry packet : sequence #4 : voltage: 4.802v
?? Telemetry packet : sequence #5 : voltage: 4.807v

Make sense?

Could calling three different systems be made more efficient by using just one script that ends up echoing what the combination of all of them do?

Sure.. go ahead and write it and submit it to John WB2OSZ for inclusion in Direwolf.? That's what OpenSource is all about.? I think why this was done this way is that John didn't write the Python A2D code.. the people at Adafruit did.? He's simply demonstrating the power of Linux being able to mix and mash different programs together to make it work.


--David
KI6ZHD

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It's worth mentioning that getting the N7NIX DanTracker going is a bit a of a bear.? I need to update my docs (from Rasbian Wheezy) to try and see if the the newest versions of the Node.JS plugins are compatible (they weren't in the past) but here they are:

??

--David
KI6ZHD

Gents, as always very helpful. Dantracker looks perfect. All I need now is to sneak a few things into the Christmas shopping basket without the station manager finding out ;-)

David and others ...

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Hello Timothy,

?

Name here is Timothy (KD9DBG) and the high school radio club that I advise (KD9DCS) is trying to build GPS and telemetry beacons for our school's super mileage vehicles.

Cool project!

Have come to the conclusion that we need to use CBEACON and INFOCMD or COMMENTCMD (if embedding the data in a position report)

The GPS data is correctly coming in through GPSD (does the COMMENTCMD work with TBEACON?)

You're a bit all over the place here.? Can you tell us what you're trying to do?? I would think that the TBEACON examples in the Raspberry-Pi-APRS-Tracker.pdf document would be sufficient.? No?

I guess the question comes down to could we just use one perl or python or other language script to grab the serial data, put it in the right order/format?

CBEACON delay=0:15 every=0:05 via=WIDE2-1 infocmd=""

What would be in this CBEACON that isn't covered in say the TBEACON?

If CBEACON is what you want, have you reviewed the telemetry-toolkit/telem-volts.conf example configuration file?


--David
KI6ZHD

I have a dry sense of humor too. Love the Watts comment :)

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Hello John,

Curious, what device are you using?? Even with Echolink, a keydown delay of 1.5sec is really way to slow.

--David
KI6ZHD

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?

Yeah... after I replied, I realized that. I stayed silent to avoid my
face turning a deeper shade of red.

I apologize - it was meant as a dry bit of humor, perhaps it was a bit too dry.
A bit like the time I drily asked someone on Usenet if they were measuring metric
or Imperial Watts.

73,
Dana? K6JQ

The device was designed specifically for Echolink. This lack of an
adjustable T/R delay was intentional. They sell another device that is
identical, except the T/R delay is adjustable. Of course, I read this
later.

My Rigblaster should have no issue with DW. I need to get all set up
again. My move to Windows 10 and other stuff has me rebuilding. I was
mostly just tinkering with that HT adapter on applications other than
Echolink, that it was designed for.

Yeah... after I replied, I realized that. I stayed silent to avoid my
face turning a deeper shade of red.

Very good ... thank you.

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I would agree.... 1500ms is terrible and I can't think of a reason why someone would design in such a huge delay into their product!

--David
KI6ZHD

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?

Hmmm... never tried... It's an idea.

I was being facetious :-)

73,
Dana? K6JQ

Hmmm... never tried... It's an idea.

Thanks.. I'll give that a shot and see.... my adapter, though, looks
like it has a TX to RX delay that's set to 1.5 seconds. The RX to TX
time is good.

I *can* also use my Rigblaster Nomic with my IC-2200H, (which I actually
do all the rest of the time) so there is a definite way for me to be on
packet. I'm just playing with HTs.