My wife and I used a Radio Shack walkie-talkie with vox in the pre-FRS days. On the boat
we had then, a Nonsuch, it was a bit hard to communicate between helm and bow. It was
nice for a year or so as we worked out anchoring techniques, but after that we found
handsignals easier.

-jeff



"NavNut" wrote in message
...
Thanks Howard. I can't find full duplex radios at radioshack.com, and am a
bit leery of VOX. There's an interesting full duplex product at eartec.com.

Love to hear from more boaters who've actually used VOX headsets on board.


I'm confused. Is there a way to do truly "hands free" communications
around
a boat, or are those "hands free" headsets a bit of misnomer -- i.e. you
have to push a button to talk?

Yes (see other answers) it's called "VOX" (Voice Operated Transmit) not
"full duplex" but it's oft more PIA than not. Noise triggers it and you
can't hear while transmitting. True "full duplex" overcomes this by
using one frequency for transmit and another for recieve. It's
considered only a tad more discourtious than shouting.

73, Howard

The problem is that only a few of the VHF channels are full
duplex. Most are half-duplex (what you call simplex, but that's
not accurate -- simplex is one way only, like AM and FM broadcast
radio).

--
Chuck Tribolet

http://www.almaden.ibm.com/cs/people/triblet

Silicon Valley: STILL the best day job in the world.


"Peter" wrote in message ...

"Vito" wrote in message
...
NavNut wrote:

I'm confused. Is there a way to do truly "hands free" communications
around
a boat, or are those "hands free" headsets a bit of misnomer -- i.e. you
have to push a button to talk?

Yes (see other answers) it's called "VOX" (Voice Operated Transmit) not
"full duplex" but it's oft more PIA than not. Noise triggers it and you
can't hear while transmitting. True "full duplex" overcomes this by
using one frequency for transmit and another for recieve. It's
considered only a tad more discourtious than shouting.

73, Howard

I thought there was either Simplex or Duplex.
At least that's how they described the hands free car kits a few years back.

Not quite right. Half duplex channels are split frequencies (2
frequencies) like the marine operator channels. The base stations are
full duplex (can transmit and receive at the same time) but the ship
station is usually "half duplex", meaning it is operating on a duplex
channel but still requires push to talk. This mode allows the ship
station to interrupt the shore station at any time.

A half duplex channel is the same as a full duplex channel (pair).
They are really two frequencies capable of full duplex but may be used
only half duplex. Depending on the radio used. Each radio receives on
the oposite frequency it transmits on.

Being "half duplex" means that half of the circuit is duplex (base
station) and the other half (ship) is not duplex. The ship station
could operate a full duplex radio and then the circuit would be full
duplex. There are some full duplex ship station radios.

A "Simplex" channel means that only one frequency is involved. Both
stations transmit and receive on the same frequency. One must listen
while the other transmits. Like channel 16.

There are some full duplex headsets available. Meaning no vox
involved. You both can talk back and forth just like you are on the
telephone.
I don't know if there are any that are inexpensive though.

The ones with the vox in them are really "simplex" units. Meaning they
both operate on the same frequency and rather than push to talk, the
vox operates the push to talk for you.

These type of headsets mostly operate in unlicensed frequencies. They
are usually very low power and have short range.

Regards
Gary


On Thu, 3 Jul 2003 16:40:18 -0700, "Chuck Tribolet"
wrote:

The problem is that only a few of the VHF channels are full
duplex. Most are half-duplex (what you call simplex, but that's
not accurate -- simplex is one way only, like AM and FM broadcast
radio).

In literal definitions, Simplex means one way communication, Half Duplex
means two way communication but not simultaneously, and Full Duplex means
two way communication simultaneously. However, in radio, these terms are
typically used as follows:

Simplex: Transmit and Receive on the same frequency, not simultaneously.
Duplex: Transmit and Receive on split frequency pair simultaneously.
Half Duplex: Transmit and Receive on split frequency pair, not
simultaneously.
VOX: Voice Operated Transmit, has nothing to do with the mode of operation.

Most marine VHF channels are simplex (transmit and receive on the same
frequency). The Public Correspondence (marine operator) channels are duplex
(transmit and receive on different frequencies).

All FRS channels are simplex (transmit and receive on the same frequency).

For hands free operation, you want a radio with VOX. A decent radio with VOX
will have adjustments for VOX sensitivity and "hold" time.

Eric N3EF

"Peter" wrote in message
...
I thought there was either Simplex or Duplex.
At least that's how they described the hands free car kits a few years
back.

A quick "Google" search will give you plenty of sites to purchase FRS
radio's with VOX that have sensitivity adjustments as well as headsets/boom
mic with VOX for these radios.

Eric

"David Oswald" wrote in message
...
Yes, a decent radio will have VOX sensitivity settings and hold time
settings, but good luck finding that in an FRS radio.