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[aprssig] Homebrew transmitter

Stephen Brown Jr stephen.brown75 at gmail.com
Tue Aug 29 16:04:14 UTC 2006


Ok on the channel busy thing, makes perfect sense now that I think about it.
But in the case of an open tracker, which is encode only, does it know when
or when not to transmit, in the case of the channel being busy for example?

On 8/29/06, Tim Smith <rt_smith at yahoo.com> wrote:
>
> The channel-busy debate is indeed a sticky one.  The question to buy or
> build is really a no-brainer in my opinion.  There are plentiful
> sources of surplus HT's, amateur mobiles, convertable commercial rigs
> that are well suited for tracker or fixed operations.  I bought several
> IC2A's on ebay for very low prices which can give you up to a couple of
> watts with a good receiver (and is frequency agile).  Even the higher
> power mobile rigs (relatively small too) go for relatively short money.
> The best part is, they all do their part in channel management by
> observing the golden rule of "listen before you transmit".
>
> Not having a channel busy indicator serves really only two negatives.
> One is that you may trash another posit as well as your own not being
> successful.  In a busy metro area, you're doomed for failure.
>
> 73,
>
> Tim - N1TI
>
> --- "Curt, WE7U" <archer at eskimo.com> wrote:
>
> > On Tue, 29 Aug 2006, Josh Freeman wrote:
> >
> > > Wouldn't you need some sort of receiver, if only to be able to
> > detect
> > > when the channel is busy?
> >
> > This is a tricky one:
> >
> > Stephen mentioned that he wanted to home-brew a tracker for a car.
> > I'd think he'd want 10W or more in that case.  I'd prefer 20W for a
> > vehicle.
> >
> > The channel-busy thing has been discussed on this list many times.
> > I _think_ that the general concensus was that it's ok sometimes to
> > not have a channel-busy, if it's a low-power tracker, probably 1W or
> > less.  I'm sure some will violently disagree that even the
> > low-powered ones should be allowed to be transmit-only (witness the
> > hoopla about the PocketTracker).
> >
> > I think the requirements conflict here.  He needs higher power for
> > the car, so needs channel-busy detect of some sort.  If he goes to
> > lower power and a transmit-only setup, he won't get many posits
> > received by anyone.
> >
> > --
> > Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
> > "Lotto:    A tax on people who are bad at math." -- unknown
> > "Windows:  Microsoft's tax on computer illiterates." -- WE7U
> > "The world DOES revolve around me:  I picked the coordinate system!"
> >
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> >
>
>
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