Z-wave Home Automation.

[ericmark]

Link is for licence exempt I am not using licence exempt equipment so does not apply. It is a shared frequency and of course one should always ascertain the frequency is free before using but what chance do you really think there is of anyone hearing a 1mW transmission? Even if not on exactly that frequency the device would need some rather good rejection to stop a 400W transmission near by.

Radio Amateurs are not the only licensed users to use these frequencies it is a shared band so anything using the band must expect signals to get blocked from time to time. We had problems at one time with Traffic Master and I am sure there will be many others. It would seem anything under test uses the band then gets transferred.

Even my door bell uses this frequency band and uses a tone to identify transmitter but I am sure there is nothing on my door bell that monitors the frequency before transmitting. However if it fails then there is a back-up people knock my door.

 

[bernardgreen]

Link is for licence exempt I am not using licence exempt equipment so does not apply.

My understanding is that 433.92 MHz is a spot frequency allocated to short range equipment and is excluded from the amateur band. I recall there was a discussion about this a few years ago.

Even my door bell uses this frequency band and uses a tone to identify transmitter but I am sure there is nothing on my door bell that monitors the frequency before transmitting.

With a door bell almost certainly there is no channnel monitoring before transmit. Too expensive in both build cost and battery consumption. The person at the door can press the button again. Some better quality wireless alarm systems do use two way communications between sensors and panel with the sensor repeating alarm messages until it receives an acknowledgement from the panel.

 

[JohnW2]

You may be able to use 400 watts on adjacent channels which are assigned to amateur radio but not on 433.92MHz ... Look at page 17 of IR 2030 - Stakeholders - Ofcom ... 433.05- 434.79 MHz .....

Link is for licence exempt I am not using licence exempt equipment so does not apply.

My understanding is that 433.92 MHz is a spot frequency allocated to short range equipment and is excluded from the amateur band. I recall there was a discussion about this a few years ago.

As eric has implied, I'm doubtful about your facts. To the best of my knowledge, the only restriction on amateur radio usage of the '70cm' band in the UK is the one eric has already mentioned - namely the non-availability of 431-432 MhZ within 100km of Charing Cross (don't ask me ). I see nothing which prevents me using 433.92 MHz for amateur radio purposes.

In any event, as eric has also said, even if there were some prohibition of amateur usage of 433.92 MHz, there is no doubt that amateurs could be radiating dozens or hundreds of watts on frequencies very close to this one, and I would seriously doubt that the equipment we're talking about (particularly the cheaper variants) would have the selectivity to be 'immune' to the effects of that!

Kind Regards, John

 

[bernardgreen]

I accept that a licenced user of amateur radio may be permitted to transmit on 433.92 MHz with a considerable ERP. The impression I got was that they would avoid 433.92 MHz due to the prolification of licence exempt equipment that could legally use that frequency. Not a problem for the transmitter but at the receiver end having a nearby licence exempt system will interfere with reception on the channel.

 

[JohnW2]

I accept that a licenced user of amateur radio may be permitted to transmit on 433.92 MHz with a considerable ERP. The impression I got was that they would avoid 433.92 MHz due to the prolification of licence exempt equipment that could legally use that frequency. Not a problem for the transmitter but at the receiver end having a nearby licence exempt system will interfere with reception on the channel.

I don't disagree with any of that, but I think your previous assertions (twice) that licensed amateur usage of 433.92 MHz is not permitted were misleading (AFAIAA, just plain wrong ). As eric has said, it is a 'shared usage' part of the spectrum, and the fact that permitted licence-exempt usage is allowed on small parts within the '70cm amateur band' does not alter the fact that the whole band (apart from the 431-432 MHz business!) is available for licensed amateurs to use. As you imply, one might hope that amateurs would generally avoid 433.92 MHz and thereabouts, but that's a different matter from 'what is allowed'. In any event, as I said, I suspect that ('licensed') high erp radiation a long way away from that 'spot' frequency would be enough to 'disable' much of the sort of equipment we're talking about.

Kind Regards, John

 

[Patrick99]

Z-wave doesn't have the same problems as products which use the 433 Mhz frequency. Z-wave is very reliable and runs on the 868,42 MHz frequency. I am not marketing any products, on the other hand I just like the concept alot.