OpenTracker USB User’s Manual
15
Voltage
– Report input voltage in the comment field. The maximum value is 18.5
volts, and the minimum is the dropout voltage of the regulator – typically 6.7
volts.
Compressed
– Enables Base91 compressed position reporting. This mode is
widely, but not universally, supported. Packets in Base91 format are shorter
than their uncompressed equivalents and provide greater position resolution.
Telemetry every
n
– Sends a telemetry packet every
n
transmissions. See the
telemetry section for more details.
TX Interval
– How often the tracker should transmit. Allowable values are 0 to
65,535 seconds. This setting will depend on your intended use. One transmission
every two minutes is acceptable for most mobile stations. A fixed station (e.g., a
solar powered site reporting battery voltage and temperature) might choose an
interval in the range of 5 to 30 minutes. If you require transmissions more often
than every two minutes or so, consider using the SmartBeaconing™ options
detailed below. Special events with many trackers and short transmission
intervals should be operated on a separate frequency, not on the shared APRS
channel. An interval of zero will disable timed transmissions.
SmartBeaconing
– Originally developed for the HamHUD by Tony Arnerich,
KD7TA, and Steve Bragg, KA9MVA, the SmartBeaconing™ algorithm allows the
tracker to operate more efficiently by changing how often it transmits depending
on its speed and direction of travel.
When stopped or moving at a speed below the low speed setting, the tracker will
transmit at a fixed rate determined by the lower rate setting. Above the specified
high-speed threshold, the higher rate setting is used. Between these two
extremes, the interval varies between the low and high rates depending on the
speed. A turn angle can also be specified to cause the tracker to transmit when
turning. The final setting ensures that the tracker will never transmit more often
than the specified interval, regardless of speed and turn rate. This can be useful
to avoid transmitting more than once in a long, shallow turn.