[amsat-bb] Tutorial on Working APRS Contacts on Kenwood TM-D710

[Clayton Coleman W5PFG]

Like many topics in the amateur radio world, there is a mix of what is 
prescribed in protocol versus how it's applied in the real world.

Bob's right here. There are excess packets created by using APRS 
messaging vs a simple "one time" packet being sent as a UI.

The weakness in using the built-in APRS functions of Kenwood, Yaesu, or 
other traditionally-terrestrial messaging systems is the load of 'waste' 
packets generated vs using a simple UI packet. The APRS messaging 
functions will often continue to transmit until they receive an 
acknowledgement. This can be problematic in a short-duration LEO 
satellite pass, especially when one station tries to message everyone in 
their HEARD list!

Many people who operate solely with a radio such a Kenwood are oblivious 
to 'waste' packets being digipeated (repeat ACK's, REJ's, etc.)  Unless 
you're sitting at a terminal and viewing all the packets, your view of 
what is passing by is extremely limited; not just by the tiny display of 
your radio. For fun, I suggest running a terminal attached to your radio 
and monitor all packets at Field Day.

I've observed passes when 10-15 stations were able to exchange packets 
and I've observed other passes when 2-3 struggled because one or two 
other stations were over-beaconing and sending messages repeatedly.

It's like the many new stations incorrectly assuming the best way to be 
digipeated is to keep pressing BCON on their Kenwood radio until the 
glorious "MY POS" flashes and they hear a beep! OUCH. Those are 
typically people on omni antennas or in their car that have no idea 
they've been digipeated every time but their station is not hearing.

Not everyone has the luxury of sitting in their shack to operate a 
packet/APRS-capable satellite. At home, I use UISS. By default UISS does 
not request acknowledgement or require it. It will only transmit a 
message or position packet upon pressing the appropriate function key. 
This helps limit the amount of "rapid-firing" typically employed by many 
of the folks using transceivers with built-in packet/APRS capabilities.

Occasionally I like to make contacts via ISS or other satellites with 
packet digipeaters using either one of my Kenwood mobile or HT 
transceivers. Do I use the status text method? No. I use the MSG 
function like others on this thread have described. I keep it short and 
sweet.

Do you want to strictly adhere to terrestrial protocol rules for 
acknowledging messages, often resulting in the logjam of packets, or do 
you want to increase efficiency and send the minimal frames necessary to 
get a clean exchange via satellite with another station? I leave that up 
to the operator.

Have fun.

73
Clayton
W5PFG


P.S. I think the unattended beacons remain my favorite nit-pick of 
packet/APRS satellites' use. :-)