[Asterisk-Users] FRS & *: an actual business use

[Rich Adamson]

> > I've noticed a growing number of stores using FRS radios. It would make
> > sense to interface (via soundcard/console driver, with the nessacary
> > electrical conversion) a VOX FRS radio to asterisk to allow someone in
> > the office to page/talk with people on the floor or warehouse. You could
> > throw that call (ie, all the radios) into a meetme conference. Then, you
> > could have people in the office either dial that extension and/or have
> > some of them always in that conference on a speaker phone (muted usually).
> Yah I started this thread with this basic requirement &
> have been trying to track down if this is feasible. So I have been
> talking with local radio hams. They have brought to my attention some
> limitations
> with using a low end FRS/gmrs handset as the base station
> 1) battery , since this would be in used more than the individual handset
>     but you could rig a direct power supply to it
> 2) talk time, these low end handset are designed to cut out after a
> configured period
>     apparently 30-60 secs
> 3) the actual radio, under continuos use most experts here believe the
> radios would over heat
>     and die a quick and certain death :)
> 
> BUT the best suggestion I found was to use a real uhf radio & tune it to the
> gmrs/FRS frequency
> and drop its power to the 2 watts like the GMFRS/FRS radios
> a Motorola cm200/cm300 http://www.motorola.com/cgiss/mobiles/cm300.shtml
> might work
> 
> Then I believe you can use the zapata analog telephony adapter to interface
> to cm200/cm300
> via the 9pin adpater and the cm200/300 mic jack and asterisk will interface
> via app_rpt...
> 
> I would appreciate anybody more familiar with this technology to vet this
> config
> and raise any flag if they see any issues with this
> ...from a tech pov the legal issue has been raised & I don't really want
> hear any more about that :(

I've not played with those Motorolas, but the older ones required a special
box to program the frequencies, etc. Doubtful that can be done from the
front panel as service tech's would have a major problem chasing commercial
users/employees who were playing around with the radio accidently changing
frequencies and other programmable features.

Also, Motorola has been rather careful with their designs in the past, not
allowing a radio to be programmed in such a way as to allow it to be used
in bands that would make it illegal. Best ensure exactly what frequencies
it truly can be programmed to use; best guess is the FRS frequencies are
restricted for obvious reasons.

Ham radio phone patches are basically a 2-wire to 4-wire hybrid (not unlike
pstn fxo interfaces), and require a fair amount of tweeking to minimize
crosstalk/feedback, etc. They also are impedance matching devices intended
to interconnect 600-ohm pstn lines with high-impendance radio inputs, etc.
Therefore, proper impedance matching to whatever radio is selected will
be required in any case. (Use of sound board mic and speaker jacks will
still require impedance matching and level adjustments that should be
well researched.)

After all of the above is addressed, you'll still run into issues with
the lack of control from *. E.g., who controls dropping the call? What
happens when the call is not dropped and busy signal is constantly
transmitted to all radios? etc, etc.