[SOLVED] Star topology chipset for long range (high power) comms

Hi everyone,

For a project involving multiple drones communicating to a single base station, I'm looking for a chipset (or alternatively a module) that supports a star topology network (i.e. multiple transmitters sending data to a single receiver). I need quite a bit of range (about > 2 km) with antennas that aren't ridiculously large since they need to be mounted on drones. For throughput I'm looking for about 100 kb/s.

I'm flexible regarding frequency and transmission power, as long as it's in an ISM band.

It's the first time I'll be designing something like this, so any tips and suggestions are much appreciated!

Many thanks,

AC

As it can help others, I've settled for the combination of a Nordic Semi nRF905 front-end chip and a RF5110G amplifier.

ArticCynda said:

As it can help others, I've settled for the combination of a Nordic Semi nRF905 front-end chip and a RF5110G amplifier.

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Just asking out of curiosity, isn't that power level is above ISM allowed power levels?

ktr said:

Just asking out of curiosity, isn't that power level is above ISM allowed power levels?

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That's a good question. I'm not an expert in the matter, but the way I interpret the rules, there are no power level limitations in ISM bands. They are designed for industrial, scientific and medical applications which use very strong RF transmitters such as for example microwave ovens. Your microwave oven emits about 800W at 2.45 GHz, so any limitation of power levels in ISM bands would de facto make microwave ovens unusable.

The downside is that devices operating in ISM bands need to be interference tolerant for the same reason.

Hopefully your microwave oven doesn't radiate 'outside the box' though!

Brian.

the way I interpret the rules, there are no power level limitations in ISM bands.

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Completely wong. There are limits for specific bands and applications, according to national (e.g FCC in the US) or regional (e.g. ETSI in Western Europe) regulations.

ArticCynda said:

That's a good question. I'm not an expert in the matter, but the way I interpret the rules, there are no power level limitations in ISM bands. They are designed for industrial, scientific and medical applications which use very strong RF transmitters such as for example microwave ovens. Your microwave oven emits about 800W at 2.45 GHz, so any limitation of power levels in ISM bands would de facto make microwave ovens unusable.

The downside is that devices operating in ISM bands need to be interference tolerant for the same reason.

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Well, as a matter of fact I design MW products in ISM bands; and as far as I know +20 dbm is the commercial limit for most of the ISM bands; and there is also a limit on ACPR and EIRP. You should take a look at the regulations before continuing your design.

Thanks for the feedback everyone, it appears I missed a part of the regulation concerning specific ISM applications designed as RF transmitters. ktr, thanks for the referral. Indeed in the 433 MHz band, the limit is apparently 10 dbm (= 10 mW). I'm exceeding this by a factor 150 now so will have to look for a more sensitive receiver instead.

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betwixt said:

Hopefully your microwave oven doesn't radiate 'outside the box' though!

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Mine definitely does, as evidenced by the fact that wifi in the entire house goes down while it's running. It's an older model though so perhaps not very well shielded.

ETSI regulations applies for entire Europe (and many other countries from all over the world as associates or observers), not only Western Europe.

https://en.wikipedia.org/wiki/ETSI#...unications_Standards_Institute_membership.png