[K3CAL] A Different Approach for Full Duplex

[Shawn Donley]

Here's an interesting item I ran across.  A professor at Cornell has developed a way to generate a transmit signal using multiple "mini-transmitters" and using the delay properties of a transmission line so that all the signals add at the antenna connection but all cancel where the receiver port is connected.


http://electronics360.globalspec.com/article/8240/developing-a-two-way-radio-on-a-single-chip?id=%2D1625855359&uh=eb49c0&email=sdonleybuy%40comcast%2Enet&md=170324&mh=d06200&Vol=Vol7Issue2&Pub=83&LinkId=1851867&keyword=link%5F1851867&et_rid=420542059&et_mid=83449462&frmtrk=newsletter&cid=nl http://electronics360.globalspec.com/article/8240/developing-a-two-way-radio-on-a-single-chip?id=%2D1625855359&uh=eb49c0&email=sdonleybuy%40comcast%2Enet&md=170324&mh=d06200&Vol=Vol7Issue2&Pub=83&LinkId=1851867&keyword=link%5F1851867&et_rid=420542059&et_mid=83449462&frmtrk=newsletter&cid=nl


Our repeater needs those very selective (and big) duplexer filters to provide sufficient filtering so that the receive input is not swamped by the transmitter output.  In the Cornell approach, it's all done by signal cancellation without big filters.


I guess in principle there's no reason this could not be done with higher power transmissions, but the prototype is obviously a low power device.


N3AE

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