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Re: This Weekend in Minneapolis: Central States VHF S ociety Meeting



I think the main problem is going to be the recovery time of the AGC  
in the radio.  If the pulses are about once a second, it's pretty  
likely that the AGC is ramping back up slightly after each pulse but  
not high enough to get any usable weak signals through.  They're at  
*least* 10-20dB above the signals you're looking for, so it's not  
going to be possible to hear them with most radios.

If everyone using an 802.11 wireless network were to move to channels  
outside the amateur band (which I think is possible in most  
countries), it might help quite a bit, but persuading people to move  
is probably a monumental challenge.  I've noticed some WAP  
manufacturers are now putting higher numbered default channels in  
their firmware, which does seem to help (seeing as how most people  
just leave their WAP's on the default channel and never change that),  
but it will take some time before that has a major impact ..

On Jul 29, 2006, at 1:44 PM, Douglas Quagliana wrote:

> I made some recordings of the popping hoping to be
> able to make a model the pop waveform and remove it
> with some digital signal processing. This won't work.
> As Bob and others have noted, the local signals are
> tens of decibels stronger than the signals you
> are trying to receive from the satellite. The local
> "pop" signals completely swamp the receiver while
> they are present.
>
> But...the pops are only there for a fraction of a
> second albeit a fraction of every second. Much
> (most?) of every second *appears* to be clear --
> at least in the unscientific limited survey that
> I made at my locations. Is this typical?
>
> Has anyone done any measurements to see just
> how much we lose to the noises and how much signal
> we could still get through in between -- especially
> if we go digital and apply some DSP and some
> forward error correction (FEC) to this? In the
> absence of data showing that this is totally
> impossible (or just some data showing that this
> is totally not worth the effort!) I would think
> of this as a challenge.
----
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