[mythtv-users] Why do I need an IR blaster?

[Ray Olszewski]

At 03:03 PM 6/19/2003 +0000, Desmond Rivet wrote:
>Hi all,
>
>I have a Scientific Atlanta 2200 Explorer box for my digital cable. I 
>would like to get a remote working for both MythTV and this box.
>
>The (brief) reserach I have indicates that I will need to build an IR 
>blaster to do this. This involves setting up a receiver which will then 
>re-trasmit the signal to the cable box. Yes?
>
>Why do I need to do this? If the cable box is close to the mythtv box, 
>then would i just need a reciever (no need to re-trasmit). I mean, the IR 
>signal from the remote can go to two places, right?


You are almost right as far as your thinking goes, but you are not thinking 
this through all the way.

If ALL you want to do with Myth is watch "live" TV, -AND- if you have a 
combined backend-frontend (so everything is close together, as your 
question postulates), -AND- if you can set up Myth so it will respond to 
the same remote codes as your digital-cable box does (I don't know how hard 
this is), then this approach *might* work.

But if you want to schedule recordings to happen in your absence, on a 
timed basis, then the Myth host needs to be able to control the 
digital-cable box in your absence, so it needs a way other then your 
handheld remote to set the channel on the digital-cable box. That is the 
capability that a working IR-Blaster setup provides.

That's why the usual solution to this problem is in two parts:

A. Use some sort of device to control the Myth host remotely. (Ideally a 
remote, but running LIRC to both send and receive signals is a demanding 
configuration., so a wireless keyboard/mouse combo is an alternative.)

B. Use some sort of device that lets the Myth host control the 
digital-cable device. Depending on the digital-cable box (I am unfamiliar 
with the one you have), this might be an IR Blaster or a serial-cable 
connection, probably controlled by LIRC.

Because running LIRC to both send and receive is tricky ... I don't 
actually recall ever seeing a working setup described, either here or on 
the LIRC list, in the sort of detail needed to allow someone to replicate 
it ... this sort of setup is easier to construct if you have separate 
backend and frontend hosts.

BTW, an IR Blaster doesn't just "re-transmit" the signal. In principle, it 
sends its own set of codes, allowing  the possibility  for the code set 
used by the Myth host to be different from the one used by the 
digital-cable box.