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Optimized configuration for an OT2 Digi (formerly Missing Telemetry Troubleshooting)

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  • Tony Komljanec
    A fixed position Opentracker 2 digi (firmware 55076) was erratically providing Telemetry and Posit beacons.  After extensive testing, I ve narrowed down a
    Message 1 of 1 , Sep 24, 2013
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      A fixed position Opentracker 2 digi (firmware 55076) was erratically providing Telemetry and Posit beacons.  After extensive testing, I've narrowed down a number of configuration parameters that contributed to the issue or caused unreliable operation.  Has anyone else observed this behavior?  

      1)  Use the "comment" feature instead of "status". Checking "comment" will append your comments to the posit for one packet that offers the best chance to be received successfully by other stations.  "Status" separates the posit from the comment into 2 concurrent packets.  If also using telemetry, this will result in 3 concurrent packets sent at once without any transmitter break. The likelihood of another digi repeating the first packet over top of your second or 3rd is high, resulting in packet collision and loss.  Comment + telemetry seems to work OK as 2 concurrent packets the way OT sends them.  Occasionally one of the two will be lost.  It would be better if OT firmware separated and sent packets as separate transmissions, rather than batching them into one transmit event.  

      2)  Do not enable power control for a Digipeater.  If power control is enabled, Telemetry and Posit beacons can suddenly stop being sent.  A power cycle or OT2 transition from one profile to another, can restart the Posit and telemetry beacons.  When exhibiting this issue, only scripted beacons were sent, while the posits or telemetry would cease.  However, it isn't immediately reproducible with a fresh configuration.  Needs to run a while as a digi before it acts up.  Could this be a bug in 55076?

      3)  If using software decoding, it is critical to use a quiet time > 80 (90 recommended) to ensure concurrent packets will be repeated without collision.   OT2 needs the long quiet time to wait for and decode all the concurrent packets sent by Argent OT products.  Once all concurrent packets are received, OT2 will re-transmit each packet as a separate transmitter event and add a fraction of a second transmitter break between them.  These seem to be successfully received by gateways.  If the default quiet time of 16 is utilized, OT2 digi will begin repeating packet 1 as soon as it is received, creating a collision and loss of packet 2 and 3.    

      Testing of the above was done on the bench with an OT2 connected to an exterior antenna, while OT and OT+ are working a transmitter with dummy load.  Only the OT2 could hear the OT / OT+ transmissions and repeat them to the outside world.  

      Which brings us to the OT+ (firmware 54908) which also seemed afflicted from the power control issue.  Programmed with fixed GPS coordinates, and power control enabled for instance to power up a radio for a short telemetry packet, only the very first packets at power up are sent.  After which the OT+ will remain silent.  No posit beacons at the specified intervals will occur.  This is a detriment for OT+ as it is well suited for a transmit only fixed telemetry applications.   The original OT (firmware 54555) was tested and didn't exhibit this power control bug.  

      If anyone can provide previous versions of firmware, I can test the above power control issues again.  The situation is puzzling.  I've verified my computer setup numerous times and haven't found anything I could identify as a fault on my part.  But I'm open to suggestion...   


      Tony K

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