RF tx/rx

[Dr_Doggy]

I have a device that passively relays RF data, for tv signals that works for the following signal range:

Downstream bandwidth: 54/85/105 MHz to 1002 MHz
Upstream bandwidth: 5MHz to 42/65/85 MHz

One thing i dont really get is bi-direction on a coax cable.... but really my question is:

what circuits could i use to modulate & demod some serial port tx/rx data in to a RF signal capable of passing through this device?

 

[Nigel Goodwin]

I have a device that passively relays RF data, for tv signals that works for the following signal range:

Downstream bandwidth: 54/85/105 MHz to 1002 MHz
Upstream bandwidth: 5MHz to 42/65/85 MHz

One thing i dont really get is bi-direction on a coax cable.... but really my question is:

It's simply a di-plexer at each end, effectively a combined hi-pass and lo-pass filter.

what circuits could i use to modulate & demod some serial port tx/rx data in to a RF signal capable of passing through this device?

Just modulate an RF carrier at one end, send it up the cable, and demodulate at the other end - essentially you need a wireless serial link, but without the radio part.

 

[dr pepper]

Its the same as havong 4 radios on diffo frequencies on the bench all communicating to 4 receivers outside somewhere using aerials on each, only instead of transmitting through the air your doing it through a coax.
One thing to consider esp with a diplexer is that your modulated signal will have to have its impedance matched to the diplexer and coax.