RE: TI-H: RF Linking

To: "'ti-hardware@lists.ticalc.org'" <ti-hardware@lists.ticalc.org>
Subject: RE: TI-H: RF Linking
From: Christopher Kalos <raptorone@geocities.com>
Date: Sun, 5 Oct 1997 22:38:23 -0400
Reply-To: ti-hardware@lists.ticalc.org

I'm not sure it's full duplex, as that is physically impossible.  After all, how do you send two opposing direction signals over one wire?  I could be dead wrong, but that seems impossible.  I think what it does is switch over after a number of bits in order to run checksums or something, as if I disrupt communication for a brief period of time (using an FM transmitter at close range, 100 MHz range does the trick), it still sends the data out, albeit a bit slower.  There is some sort of correction and retransmission built in, I'm just not 100% sure as to how it works.  However, the basic mechanism is to switch between Rx and Tx.
Christopher Kalos
raptorone@geocities.com
raptor_one@hotmail.com
Executive Director/Administrator
Virtual Technologies Developer's Group


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From: 	Matthew R Price[SMTP:pricem@juno.com]
Sent: 	Sunday, October 05, 1997 9:15 PM
To: 	ti-hardware@lists.ticalc.org
Subject: 	TI-H: RF Linking



So far all the discussions have been assuming that we use two frequencies
to transmit.  Why don't we instead multiplex our RX and TX lines onto the
same carrier freq.  That way we wouldn't have to deal with the self
induced interference of having a transmitter right next to a receiver. 
This would also simplify full-duplex transmition and lighten the power
load for the device.  I'm not an electrical engineer but I do have some
basic knowledge; I'm not sure exactly what the relationship between the
two freqs. should be.  Doing this would also provide us with a much
cleaner channel.
Does anyone know if the calcs are capable of full-duplex, or would we
need to include some sort of buffer inside the RF link module?

Matthew


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