Ohh there should be SOME crosstalk - listen closely to your landline phone - you can hear yourself in the earpiece - this is called "side tone" and is pretty hard to get rid of without echo cancelling hardware. side tone happens because of the way that the coupling transformer extracts receive audio and impresses transmit audio on the DC "carrier" provided by the telephone company central office. besides the fact that a person using a repeater is still bound to the 10 minute ID rule, so some of the input must be mixed to the output or the user would never be heard to ID on the output while the patch was in operation.
Even an in band repeater with patch normally allows the radio user to interrupt. by giving the repeater input priority over the telco input. _____ From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Paul Plack Sent: Thursday, November 08, 2007 8:02 PM To: [email protected] Subject: [Repeater-Builder] "Full Duplex" Nate, The telephone industry standard definition for the term "duplex" means able to listen and talk simultaneously; the ability to have a channel in both directions at the same time, without the need for push-to-talk. In essence, if you can interrupt the other party without waiting for him to finish, you're in "full duplex." Any dual-bander which can receive on one band while it transmits on the other is capable of full duplex. At one time, this was the difference between a "duplexer" and a "diplexer." A duplexer was intended to allow simultaneous transmit and receive, as with an in-band repeater; the diplexer allowed two transceivers on different bands to function simultaneously into a common feedline and/or antenna. Both these terms have been mangled pretty badly over the years. The Scom controllers offer a duplex mode in their autopatches, but it would only be useful on a crossband repeater. Mobiles could listen on 2M to the caller while simultaneously transmitting on UHF, and the mobile station and landline party could interrupt each other at any time, just like a normal phone call. In practice, this would drive licensees and control ops nuts, because the mobile station's audio would not appear on the repeater output, and anyone monitoring the repeater would only hear the landline party, without the mobile station's side of the call. 73, Paul AE4KR ----- Original Message ----- From: Nate Duehr <mailto:[EMAIL PROTECTED]> To: Repeater-Builder@ <mailto:[email protected]> yahoogroups.com Sent: Thursday, November 08, 2007 5:37 PM Subject: Re: [Repeater-Builder] Part 97 question reference to Repeater control On Nov 8, 2007, at 2:34 PM, Paul Plack wrote: > Manufacturers sometimes market features on new radios without regard > to Part 97. I have an Alinco DR570T, one of the first, if not THE > first, dual-band mobile to feature full duplex crossband repeat. As > designed, it's crossband repeat function was clearly not legal. >From your description (and knowing the radio) you mean "bi- directional" (but not at the same time), not "full-duplex" (which means you can go both directions through it at the same time). I'm seeing the term "full-duplex" misused more and more in regards to dual-banders in cross-band repeat mode... did someone publish an article with this less-than-accurate terminology again somewhere? :-) -- Nate Duehr, WY0X [EMAIL PROTECTED] <mailto:nate%40natetech.com> com
