chorus digital remote control

zuzu

Howdo..

Question about chorus digital remote controls. Does chorus digital use standard IR signals or do they use IRDA specific?
I want to get one of them wireless video/tv senders but it says you can only use the controls if it uses standard IR signals like sky digital. I know that NTL and Telewest use IRDA but dont know about chorus?
Anyone help?

watty

I have never found any device that the video sender did not control if you used the original IR handset at the remote location. They feed EVERYTHING received over the link. A small electret microphone instead of the IR "eye" and the TX sends good quality FM audio at 433MHz!

I would think it would work.

Are you sure it doesn't work on NTL using the NTL remote? I'm surprised.

I'm surprised to hear that NTL & Telewest use IRDA (a high speed serial communications protocol). I have studied many many IR remotes and never heard that.

However you are correct that IRDA is unlikely to work on any remote Wireless IR extender product as it is high speed and bidirectional protocol.

REMOTE CONTROL THEORY
Old ones sometimes used Pulse Position or Pulse width modulation. These had usually no address field and only a limited number of codes.

RC5 family (and many similar schemes) use an Address header then a data field. One remote can control many devices / functions. Some devices use more than one Address. A form of manchester encoding modulates the 38KHz carrier.

Almost all remote controlled equipment is NOT IRDA for another reason. IRDA is very short range up to 60cm and typically less. It is relatively high speed.

Ordinary Remote controls are derived from Ultrasonic based designs which for various reasons ran using a 40KHz carrier. So IR remotes use a 30KHz to 50KHz carrier (often 38KHz or 40Khz) which allows interference rejection and a sensitive tuned pre-amp on the receiver. IRDA is higher speed (and also bidirectional) so is less immune.

Remote control data is sent quite slowly compared with IRDA, about 20 bps to 1200 bps as only equivalent of 2 to 4 bytes is sent on each keypress.


If a NTL remote really is IRDA there will be laptop / PDA control SW on internet. OTH simulating an ordinary remote on a Laptop IR port is nearly impossible. Connecting an IR LED and running special SW on the serial port handshake line is easy and how most IR gizmos for PCs work.

Some PDAs like Palm allow simple direct access to internals of IR port HW, so a Palm pilot can run IRDA or ordinary remote control SW. Several sites offer trial IR remote / learning/ macro/ custimisable SW for Palm with virtual touch keypads.

zuzu

thanks for the detailed reply. im just going by the info on maplin that the ntl/telewest uses IRDA so just wondering about chorus. i think ill get one anyway and check it out.