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Telemetry Reporting

All tracker models have the ability to send telemetry information from onboard sensors, as well as external input sources.

Reporting options section from OTWINCFG

Some of the telemetry information can be embedded into the comment section of a packet, or you can configure the tracker to send separate packets in the APRS telemetry defined format.

T#sss,aaa,bbb,ccc,ddd,eee,76543210
  • sss: Sequence number, wraps at 999
  • aaa, bbb, ...: Analog values (0-255)
  • 76543210: Binary bits; profile status can be reported as a bit

A digital counter input is available on some tracker models and can be reported. Commands ANALOG and GPIO may be used to access telemetry values.

Pin Assignments by Device

OT3m

Pin Function Value
Supply Voltage Telemetry aaa, ANALOG 0 Volts * 10 (Max 20v)
Terminal Block A1 Telemetry bbb, ANALOG 1 Volts * 10 (Max 20v)
Terminal Block A2 Telemetry ccc, ANALOG 2 Volts * 10 (Max 20v)
Terminal Block A3 Telemetry ddd, ANALOG 3 Volts * 10 (Max 20v)
Terminal Block A4 Telemetry eee, ANALOG 4 Volts * 10 (Max 20v)
Radio Pin 9 (AUX_IO) GPIO 0 ON = High, OFF = Low
Terminal Block IO Telemetry bit 1, GPIO 1, Profile Jumper ON = High, OFF = Low
Terminal Block CT Counter Input / Beacon Trigger Pull to ground
Active Profile Telemetry bit 0 ON = Profile 2, OFF = Profile 1

OpenTracker USB

Pin Function Value
Supply Voltage Telemetry aaa, ANALOG 0 Volts * 10 (Max 20v)
CN4 Pin 3 Telemetry bbb, ANALOG 1 Volts * 10 (Max 20v)
CN4 Pin 4 Telemetry ccc, ANALOG 2 Volts * 10 (Max 20v)
CN4 Pin 5 Telemetry ddd, ANALOG 3 Volts * 10 (Max 20v)
CN4 Pin 6 Telemetry eee, ANALOG 4 Volts * 10 (Max 20v)
Radio Pin 9 (AUX_IO) GPIO 0, Power Relay ON = High, OFF = Low
CN4 Pin 7 Telemetry bit 1, GPIO 1, Profile Jumper ON = High, OFF = Low
Active Profile Telemetry bit 0 ON = Profile 2, OFF = Profile 1

OT2m Telemetry Elements

Entry Description Sensor input
aaa Temperature from LM335D sensor (U5) LM335D
bbb Source voltage (R16 / R17) Voltage Divider
ccc Pin 10 (PTA0/ADC0) on MON08 header MON08 header
ddd Counter input: Pin 1 (IRQ1) accessory port or Pin 6 MON08 header Accessory Port
eee HDOP from GPS
bits Bit 7 = jumper state (Pin 6 CFG), Bit 8 = profile in use

T3-301 Telemetry Elements (UNDER CONSTRUCTION)

Entry Description Sensor input
aaa
bbb
ccc
ddd
eee
bits

MON08 Pinout

 1 - PTB7/T2CH1
 2 - GND
 3 - PTB5/T1CH1
 4 - Reset
 5 - NC
 6 - IRQ
 7 - NC
 8 - PTA3/ADC3
 9 - NC
10 - PTA0/ADC0
11 - NC
12 - PTA2/ADC2
13 - Clock Oscillator
14 - PTA1/ADC1
15 - +5V
16 - PTB0

MON08 Header

Telemetry Equations, Units, Parameters, and Labels

APRS telemetry reports are raw values. Software must apply conversions using defined sentences:

  • PARM: parameter names PARM.Temp.,Bat.,Extrn,Count,HDOP,NA,NA,NA,NA,NA,NA,JU,CF

  • UNIT: units UNIT.Deg.,Volts,Volts,NUM,HDOP,,,,,,,ON,NUM

  • EQNS: conversion coefficients EQNS.0,1.9608,-273,0,0.07843,0,0,0.07843,0,0,1,0,0,0,0

Conversion formula: FINAL = a*x^2 + b*x + c

  • BITS: digital label states and project name BITS.11111111,Your Telemetry Name

These must be sent to the tracker as APRS messages to the target callsign.