Re: Choice of frequency and protocol on RF links?


ElderUberGeek wrote:
Hey, sorry, I didn't think it matterd that much...

It matters immensely. In the US, it's forbidden to use encryption in
the unlicensed bands, for instance. One of my assigned tasks (in
theory) is to create a harmonized list of design requirements for ERP,
duty cycle, etc. etc. across all the markets my employer services, and
every time I pick up this particular to-do, I get daunted and go back
to some easier job, like (say) convincing Palestine and Israel to just
get along.

Firstly the country it Norway.

Then you have at least one other SRD [non-ISM] band to play with, I
believe (I'd have to check to be certain) you have the 868MHz region
available. But I agree with you that 433 is probably the right choice
here.

For the range you're talking about, ERP requirements would be real low.
And I believe Norway in common with many other Euro countries has the
nice rule that you get a certain amount of on-time per hour (based on
band and ERP) and you can split that up however you want; spend it all
at the start of the hour, or spread it across the whole hour. Managing
collision is an interesting problem though.

My way of thinking, at the moment, is that probably a Zigbee
chip/module would be a good way to go since they are (supposed to be?)
robust, prices are coming down, and there are plenty of

_Maybe_. I'm yet to be convinced that Zigbee will survive
industrial/commercial applications of the type we do.

.