[sci.electronics] Communications Project

morganh@shazam.WV.TEK.COM (Morgan Hall) (10/16/89)

I have a need -- one that looks like it might make an interesting project for
the winter.  I'm tossing it out to the great minds on sci.electronics
because I tend to think just far enough to get an idea, then ZAP! the
blinders come down and I'm chasing the details of THAT project.  Hopefully,
someone else may think up a more elegant solution...

The need -- cheap, reliable, wireless communication for about 2 days a year.
I breed and show cats.  Our club puts on one two-day show every year.  The
format of a cat show consists of four independent judging rings who must 
communicate back to an announcer.  The announcer then uses a (rented)
PA system to call up cats to a particular judging ring.

We've tried hand-held CB's -- the local chatter makes them useless.  Phones
would work, but rental halls aren't necessarily good places to be stringing
the wires (and in some they're prohibited).  Whatever we use must be 
battery powered, as show halls normally don't have electrical outlets where
you want them.

The lo-tech solution is an alert announcer, hand signals, number cards,
a pair of opera glasses, and lots of mistakes.

Some thoughts are -- the cheap little FM mikes that snap on a 9-V battery
(would they hold frequency stability, and could we tune them to the same
frequency?) and a portable FM radio on an unused frequency.  "Toy" walkie-
talkies (isn't there a 40 Mhz version?).  Infra Red communications -- 
what about FM modulation an IR source at a fairly high frequency, then
decoding with a PLL?  Ultrasonics don't seem like a good idea, as cats can
hear quite high frequencies.

Off-the-shelf solutions generally are too expensive for a two-day show.
If I build something, I'll be concerned with ruggedness and reliablilty
as well as adequate range.

Suggestions?

arb2@uafhcx.uucp (Allan R Baker) (10/17/89)

In article <4979@orca.WV.TEK.COM>, morganh@shazam.WV.TEK.COM (Morgan Hall) writes:
> The need -- cheap, reliable, wireless communication for about 2 days a year.
> I breed and show cats.  Our club puts on one two-day show every year.  The
> format of a cat show consists of four independent judging rings who must 
> communicate back to an announcer.  The announcer then uses a (rented)
> PA system to call up cats to a particular judging ring.
 (deleted stuff)
> Some thoughts are -- the cheap little FM mikes that snap on a 9-V battery
> (would they hold frequency stability, and could we tune them to the same
> frequency?) and a portable FM radio on an unused frequency.  "Toy" walkie-
> talkies (isn't there a 40 Mhz version?).  Infra Red communications -- 

I don't know if this is what your looking for, but I recently bought a wireless microphone from Radio Shack that broadcasts on an unused FM radio station.
It is small (about  1 inch x 0.5 inch x 0.5 inch), and it has a clip on the
back as well. You tune it to the frequency you desire, and it costs $20.
If you haven't already, maybe you should consider it.

Allan R Baker
arb2@uafhcx.uark.edu

arb2@uafhcx.uucp (Allan R Baker) (10/17/89)

In article <4979@orca.WV.TEK.COM>, morganh@shazam.WV.TEK.COM (Morgan Hall) writes:
> The need -- cheap, reliable, wireless communication for about 2 days a year.
> I breed and show cats.  Our club puts on one two-day show every year.  The
> format of a cat show consists of four independent judging rings who must 
> communicate back to an announcer.  The announcer then uses a (rented)
> PA system to call up cats to a particular judging ring.
 (deleted stuff)
> Some thoughts are -- the cheap little FM mikes that snap on a 9-V battery
> (would they hold frequency stability, and could we tune them to the same
> frequency?) and a portable FM radio on an unused frequency.  "Toy" walkie-
> talkies (isn't there a 40 Mhz version?).  Infra Red communications -- 

I don't know if this is what your looking for, but I recently bought a wireless
microphone from Radio Shack that broadcasts on an unused FM radio station.
It is small (about  1 inch x 0.5 inch x 0.5 inch), and it has a clip on the
back as well. You tune it to the frequency you desire, and it costs $20.
If you haven't already, maybe you should consider it.

Allan R Baker
arb2@uafhcx.uark.edu

tom@hpdml93.HP.COM (Thomas Wheless) (10/18/89)

If you had four wireless mikes tuned to the same frequency and all operating
at the same time, they would interfere with each other. What you could do is 
add a pushbutton switch to each in series with the battery. When the person 
wanted to say something he would push the switch and power up the mike.

Otherwiset the concept of using multiple wireless mikes tuned to the same 
frequency is sound.

rcm@hpctdpa.HP.COM (Rick Myers) (10/18/89)

/ hpctdpa:sci.electronics / morganh@shazam.WV.TEK.COM (Morgan Hall) /  9:15 am  Oct 16, 1989 /
>
> The need -- cheap, reliable, wireless communication for about 2 days a year.
> I breed and show cats.  Our club puts on one two-day show every year.  The
> format of a cat show consists of four independent judging rings who must 
> communicate back to an announcer.  The announcer then uses a (rented)
> PA system to call up cats to a particular judging ring.
> 
[several lines deleted]
> 
> Suggestions?
----------

Contact your local ham radio club.  They are usually willing to provide
free communications to events/organizations as a community service.  They
use FM equipment which is relatively noise free.  The local club here
in Colorado Springs provides services for the Pikes Peak Hill Climb,
Pikes Peak Marathon, Motorcycle Enduro Races, and numerous other events.

Rick