Infrared controllers for lighting

You can say that  if you are the only user of the radio channel in the vicinity and you are comparing it with a simple on-off keyed wire link. more generally it is certainly not really true.

There are some very fast (hundred megabit) protocols for communicating over mains wiring. Personally I do not like the really fast systems  as the signal speeds involved are really radio frequencies , and certain wiring layouts act as accidental aerials so there can be  a problem, of interference, both getting out and in, often in ways that means it will work really well in one house and cause huge grief in another, despite the wring being superficially similar. But for a few hundred kilobits per second, a bit of wire is just fine.

Any radio system has to stay in it s permitted channelisation, and cope with the channel being blocked for some fraction of the time, and the more nodes and users there are within range of the system  the more time it spends saying "'excuse me, hello "  "ouch - say that again" and "sorry?" and the less actual data is transmitted.


A wired smoke alarm  is less likely to be jammed when another one of the same model is installed in the neighbouring flats. Unlike wires, radio waves do not really stop at property boundaries.


I'd take the salesman's pitch with a pinch of salt - and ask why they really need a high speed link anyway  you could sent the full text of the song " London's burning" over the wire in 100 milliseconds at a few hundred kbits/sec, well within reach of 3 core and earth over half a km or so and in this case surely a simple "fire at node 1234"  or "button pressed at node 4567" is nearer the level of message complexity required.


Mike.

You can say that  if you are the only user of the radio channel in the vicinity and you are comparing it with a simple on-off keyed wire link. more generally it is certainly not really true.

There are some very fast (hundred megabit) protocols for communicating over mains wiring. Personally I do not like the really fast systems  as the signal speeds involved are really radio frequencies , and certain wiring layouts act as accidental aerials so there can be  a problem, of interference, both getting out and in, often in ways that means it will work really well in one house and cause huge grief in another, despite the wring being superficially similar. But for a few hundred kilobits per second, a bit of wire is just fine.

Any radio system has to stay in it s permitted channelisation, and cope with the channel being blocked for some fraction of the time, and the more nodes and users there are within range of the system  the more time it spends saying "'excuse me, hello "  "ouch - say that again" and "sorry?" and the less actual data is transmitted.


A wired smoke alarm  is less likely to be jammed when another one of the same model is installed in the neighbouring flats. Unlike wires, radio waves do not really stop at property boundaries.


I'd take the salesman's pitch with a pinch of salt - and ask why they really need a high speed link anyway  you could sent the full text of the song " London's burning" over the wire in 100 milliseconds at a few hundred kbits/sec, well within reach of 3 core and earth over half a km or so and in this case surely a simple "fire at node 1234"  or "button pressed at node 4567" is nearer the level of message complexity required.


Mike.