Viscous APRS Digipeater
Viscous APRS Digipeater is a modification of APRS Digipeater, which puts all packets heard from radio channel into a short term probation delay hold (4-8 seconds,) and checks to see, how many copies of that same packet (per APRS packet duplicate detection algorithm) will be heard during that interval.
If a packet is heard only once, it will then be processed like normal digipeater request. If a packet is heard more than once, it is silently forgotten.
At present (October 2009) only one software is able to do this: Aprx
With fresh Aprx v2, the necessary configuration is like follows:
mycall OH2MQK-1 <interface> serial-device /dev/ttyS0 19200 8n1 KISS callsign $mycall tx-ok true </interface> <digipeater> transmit $mycall <source> source $mycall relay-type digipeat viscous-delay 5 </source> </digipeater>
Graphs below show effect of enabling the viscous-delay 5 on digipeater configuration.
- Top graph is number of packets heard from radio.
- Mid graph is packets rejected by APRS Rx-iGate function (and unrelated to this topic)
- Bottom graph shows counts of packets transmitted by the digipeater subsystem.
- Most notable is that this added viscosity to digipeater does reduce transmissions by 80 to 95 percent.