[amsat-bb] Re: FM receiver filters

Bob Bruninga bruninga at usna.edu
Wed Dec 31 07:42:35 PST 2008

> I suggest you consider AFC. 
> Not enough demand for that wide a filter.

Won't work for packets, or at least would require a long TXD making packet communicatiosn inefficient. 

As to rarity, only one filter in the whole world is needed and that is on the uplink receiver.  This lets eveyrone on the ground use conventional rigs without mods, and with minimal doppler uplink tracking.

Too many simple satellites are being built without considering the need for a wider bandwidth receiver on the uplink.  The difficulties of such an approach for users is very obvious on the ISS cross band repeater, which is using a stock amateur transceiver with a 12 KHz wide receiver on the uplink, which makes even 5 KHz step tuning on the uplink be out-of-bandwidth splatter half the time.

This is not a complaint at all.  The ISS team is to be congratulated for making the most of what they were able to get up there.  It just takes more skill by users on the ground...

It is good to see this new UK project planning on a wider uplink RX filter.

Bob, Wb4APR

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