[aprssig] [aprsisce] Dual iGate: Terrestrial and ISS
bruninga at usna.edu
Wed May 8 09:19:27 EDT 2013
> We've got a 30M gateway in the area,
> seems silly to have 2 within 20 miles of each other.
Not at all. That is called spatial diversity and is a vast benefit for any
HF net. Even if they were a few hundred meters a part, they would still
show diversity. When one is in a fade, the other would not be. Diversity
whether in the spatial, or time domain or any other domain is a great way to
improve link reliability.
> I want at some point to run HF VHF cross band,
> I have a fair amount of traffic going down the English Channel...
> Obviously there needs to be a fair amount of filtering on VHF to HF and IS
> to HF
Red flags going up here (though I have not followed the thread closely).
But here are the "rules" for HF/VHF gating established back in 1994 or 5 or
1) Gating every packet from HF to local VHF is fine... but ONLY if we assume
everyone on HF is using a path no longer than GATE,WIDE1-1. The idea being
that the packet is heard in the SAME local area as the HF=>VHF gate. Thus
locals who know the GATer can work out if the load is a problem
2) Gating VHF to HF is strictly not desired under any circumstances *other*
than messages. Messages are CALL-A to CALL-B and should go
anywhere/everywhere there is a path available.
3) There should be no DIGIPEATING on HF except for emergency messages or
live one-on-one testing for short periods. The APRS HF network is the
worlds largest spatial diversity receiver. Some gate, somewhere will hear a
packet if it is to be heard. No sense doubling the QRM all the time by
Hope that helps.
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