Bye-bye duplexers?

This forum has been created to foster the discussion on future and cutting edge technology. This discussion is not limited or restricted to Motorola. Examples of allowed discussion are open source hardware (GNU Radio for example) and software (Open source P25, Asterisk, ROIP, etc). Discussion is also permitted where older technology could be applied to areas where it had previously not been used (Example: Trunking on amateur radio).

Moderator: Queue Moderator

Post Reply
User avatar
Wowbagger
Aeroflex
Posts: 1287
Joined: Tue Dec 10, 2002 10:46 am

Bye-bye duplexers?

Post by Wowbagger »

http://campustechnology.com/articles/20 ... garea=news

http://ieeexplore.ieee.org/xpl/login.js ... er=6887369

Summary:
Researchers have found a way to make a component that will allow RF to pass in one direction unchanged, but cause RF passing the other direction to be shifted in frequency. Thus, a system can transmit on one frequency while being able to listen on the same frequency over-the-air, by having the incoming frequency mixed to a new frequency in the device.

So, in theory you could transmit on 146.52 while somebody else is also transmitting on 146.52, and hear them by tuning to 10.7MHz.
This is my opinion, not Aeroflex's.

I WILL NOT give you proprietary information. I make too much money to jeopardize my job.

I AM NOT the Service department: You want official info, manuals, service info, parts, calibration, etc., contact Aeroflex directly, please.
User avatar
Bill_G
Posts: 3087
Joined: Thu Sep 17, 2009 5:00 am

Re: Bye-bye duplexers?

Post by Bill_G »

Interesting concept. It's difficult to conceive how a very low level signal on the same freq could pass without being swamped by the much stronger transmitter. But, apparently that is the promise of TVTL (time variable transmission line). Here is a link to Mr. Qin's paper where he states he achieved 13db of isolation between tx and rx with less than 5db insertion loss on the rx path.
Birken Vogt
Posts: 262
Joined: Thu Nov 10, 2005 7:53 pm

Re: Bye-bye duplexers?

Post by Birken Vogt »

How could such a device differentiate between the inevitable reflected signal, not only internal to the antenna but also reflections of the transmitted signal from other nearby objects which are many tens of db higher than the desired signal?

It looks to me like a more compact version of a circulator, but the shifting to a different frequency seemed to be accomplished by a mixer after the fact, which you could also do with a circulator.

I suspect that it is an over-enthusiastic appraisal of the device's capability, but a compact ciculator certainly has promise as well....
User avatar
Bill_G
Posts: 3087
Joined: Thu Sep 17, 2009 5:00 am

Re: Bye-bye duplexers?

Post by Bill_G »

Apparently, it's a race to the market with innovative ways to reduce the size of circulators. The brain trust at University of Texas Austin have developed a tunable circulator.

Image
Post Reply

Return to “Experimental and Next Generation LMR”