Motorola Quiet Talk - looking for technical info

[kcbooboo]

Some two-way radios (FRS, etc) have a technology called Quiet Talk (QT, trademarked by M) which claims to reduce noise and eliminate other manufacturer's equipment from being heard on QT-equipped Motorola radios.

Does anyone have technical data as to how they accomplish this? It could be similar to HearClear or companding, but that wouldn't necessarily eliminate other mfgr's signals. They could use some non-standard PL tones too. Maybe it's a special tone burst at the start of transmissions. I just don't know and am looking for any info. Lots of hits on google, but mostly sales talk where they mention that the radio has QT.

Thanks.

Bob M.

[n9upc]

My understanding of QT was that it was voice inversion scrambling and I think in Narrowband.

Regardless I was under the information that it was voice inversion.

[Al]

I've always thought that QT was a Kenwood trademark, like PL or private line was to Motorola. Are you certain we aren't talking about Kenwood equipment here, Bob?

[kcbooboo]

Well, if you google for

quiet talk motorola

you'll get a ton of hits for Talkabout radios, and many of the data sheets indicate this is a trademarked term.

Voice inversion would not keep you from hearing other mfgr's radio signals, unless they included PL tone in that and inverted it as well.

Part of the technology could be companding, but that would improve the S/N ratio, not eliminate other mfgr's radio signals, which is what QT is claiming it can do.

Bob M.

[n5tbu]

Typical Moto Bull to make you think their product is un hearable and private.
QT is Pl or CTCSS nothing more.
mod

[Josh]

Wrong!

When using Quiet Talk, or on the T6xxx series, it's called QuietT6x or something like that..

Anyhow, when enabled on all radios in your group (all must be the same or similar model featuring Quiet Talk.

It makes use of a QC type feature wheras the initiating radio transmits a single-tone for about a second that gets decoded by the other radios and opens up the squelch. from then on and radio transmitting on that frequency, and/or pl can break the squelch and talk to the other units. After like 30 seconds or so of inactivity it goes back into the semi-dormant state, the radio will not unmute for any traffic regardless of PL unless it hears the certain tone again... Come to think of it, I think the call tone sets it off, hence why your call-tone features a ''tone'' before the annoying whistles etc... it works with the QuieT feature. Never made use of it... in fact, I think I even got rid of any radios I had like that b/c the audio and reception both sucked. I still have and sometimes use Motorola Sport 7x FRS HTs.... look like actual radios and have pretty decent audio, 7 channels, 7 pls... not fancy at all.

-Josh

[transistor747]

Speaking from many years of working on 2-way systems.

Motorola = Private Line
GE = Channel Guard
RCA = Quiet Talk

They were all labels for tone coded squelch, CTCSS.

[wa2zdy]

RCA was QC = quiet channel. We had RCA Carfone rigs in our radio cars into the mid 80s - I remember them well and I had a Carfone head somewhere around here too not all that long ago. Made a nice speaker.[/img]

[transistor747]

Quiet Channel!
Damn, you're right.
Sorry about that.

Speaking of RCA carphones, was that the one that had only white wire in it?

[kcbooboo]

My brother, who originally asked me the question, has a pair of radios with QT. He tells me that the QT signal is a 55 Hz tone for about 0.4 secs that's broadcast at the beginning of one transmission. It will come out again at the beginning of a transmission once 30 seconds have passed, if the radio is still being used. The receiver, upon hearing this tone, will open up, allowing the conversation to be heard, but it will close up again in 30 seconds unless it hears another QT tone. The manual alludes to this 30 second "open" period but doesn't fully explain the significance.

Tha manual also says you should select your channel and PL tone, and with QT enabled, press PTT or the CALL button, release it, then press PTT again and start talking. I guess this gives the QT tone a chance to get out and prevent the first syllable or word from getting lost. Also, the PL and voice are muted until the QT tone has been sent out.

Since other manufacturers wouldn't transmit this 55 Hz tone, this allows the Motorola radios to ignore signals from other brands of equipment. They could still interfere with any conversation, but the QT-equipped radio wouldn't unsquelch, so the user would not be bothered hearing stuff until the radios are used again.

Thanks, Chris, for straightening out RCA's QuietChannel vs QuietTalk. I thought that's what it was too but didn't want to say anything until I was absolutely sure.

Bob M.

[wa2zdy]

Speaking of RCA carphones, was that the one that had only white wire in it?

Not sure about the drawer but the control head yes, now that you remind me, that was it - all white wire. Fun to follow the wiring in there. NOT!

Edit: I guess it was a while ago I had that Carfone control head as a speaker. I didn't think it was quite so far back but the pic this link is to is from about 1986. Not the old 2m rig and the . .. gasp . . ..CB.

http://www.geocities.com/wa2zdy/ke2p-mobile-1986.jpg

[nmfire10]

So basicly it is a bastardized Singletone with no useful purpose. Wonderful.

[Josh]

Shoot, it's been out for years, and probably no longer even offered as an option in their product line-up.

-Josh

[CAPTLPOL]

I have one with that option. I one have the one so I never have used it. QT is not CTCSS.

[nmfire10]

How many joules did it take to bring this one back?