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HF Operation Guidelines

Australasian APRS HF Operations Guide.

As HF APRS is becoming more popular in Australasia, we have put together a set of guidelines that we should all adhere to. This will allow the successful long-term use of the ARPS HF network as it’s popularity continues to grow.

The Do’s and Don’ts for HF APRS.

Do’s

  • Do consider all other users of the HF network. Remember you are sharing this single frequency with hundreds of other operators.
  • Do use only a path of GATE,WIDE2-1
  • Do Net (set your frequency) to the Primary Net server for the band you are operating on. If you can not hear the Primary NET server, use a secondary NET server.
  • Do use a SSID of -4 if your station is a HF to VHF or HF to Internet Gate. (Refer to the SSID Guide)
  • Do use a SSID of -15 if your Mobile Station transmits on HF. (Refer to the SSID Guide)
  • Do keep your packet size to a minimum. Use the Mic-E or APRS compressed format and no or minimal information in your status text.
  • Do set your beacon time to 10 minutes or more. (The primary and secondary net stations are the Only station that will beacon at more frequent intervals)
  • Do use the path of ECHO or TUNE Only for tuning your radio into the Net.
  • Do use the following TNC settings for your success. TXDelay 400ms, PACket LENgth 128, SLOTtime 300ms PERsistance 64ms.

Don’ts

  • Don’t Digipeat any packets on HF (the only exception is for tuning your radio).
  • Don’t transmit Home station positions on HF. Only Gates and Mobile stations need to transmit position information.
  • Don’t feed VHF or IGate data to HF
  • Don’t allow your station to operate as a digipeater

NOTES:

Remember that an average length APRS Posit packet takes 3 to 4 seconds to transmit on HF. Assuming a channel efficiency of 30% for ax25 this results in a maximum of 7 stations being able to transmit per minute. At a transmission rate of one posit per 10 minutes the maximum number of stations that can be in a single APRS Gate’s coverage area is 70 stations. This will be less as the Net stations transmit frequently and messages and/or tuning may be under way on the channel. HF Propagation is also an important factor in limiting station numbers

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