Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud

looking for.

One should be very careful when reading these range claims. This company stated up to 32 km for their EU compatible 500 mW EiRP module. Although they use a disclaimer "typical, depends on antenna and environment", but this is not a _typical_ value, it is the _maximum_ theoretical range calculated from the EiRP, path loss and receiver sensitivity. This might be possible between two such devices mounted on top of two 300 m masts and with a nation wide power failure to reduce the background noise level :-). So clearly, such distances have not been measured in practice.

It should also be noted that in EU, the maximum duty cycle for the 500 mW class is 10 %, thus the effective throughput would be comparable to

9k6 full duplex.

Apparently the 914 m range specified for the 5 mW module (100 % duty cycle) has actually been measured in practice on some actual line of sight path with realistic noise levels, since calculating with the theoretical free space losses only, the range should be more than 3 km.

With obstructed paths, the range is still much smaller.

Paul

With that kind of size, it's difficult to fit into a model plane...

Kelvin

I'm not interested in model plane. I do not have size limitation, my mobile platfrom is car (not a model one).

First I must say that I really don't know anything about these things in technical sense, but with the following there could be some possibilities... (Ok, my soldier passport tells "Suitable for working as a group leader in a link station", but it has passed 25 years since I installed those radio links in the Finnish army :-)

When the familiar available radio systems for that 3 - 11 km range are those PMR446 (446 MHz) in Europe and FRS/GMRS (462 and

467 MHz) in U.S.A. and receiver/transmitters are in the tens of bucks/euros price area per a pair of mobile phones, there shouldn't be any kind of lack of available cheap hardware for these purposes. However those GSM etc. cellphones needing their base stations are much more known among people than these 'ad hoc' radio networks with mobile stations communicating directly with each others...

But using the PMR446/FRS/GMRS channels for something else than voice communication can be strictly forbidden... Searching via Google for FRS/GMRS and PMR446 should give quite a lot hits and places where to buy...

For FRS there however seem to be some data transfer possibilities like for the Bellsouth's 'toy for children' :

"The innovative FRS (Family Radio Service)/GMRS (General Mobile Radio Service) device - model #2176 - operates up to a ten-mile range offering crisp, clear voice communication and, for the first time ever, text messaging capability. The compact unit comes complete with a belt clip for maximum mobility and is perfect for connecting parents with their children, tweens and teenagers with their friends, and thrill-seekers with each other on the slopes or on the trail."

Or for the Garmin Rino:

"The Rino 120 is state-of-the-art GPS navigation and two-way communications combined, with enough memory to download detailed mapping for driving, hiking, hunting, fishing or just about anything else you can dream up. It's waterproof and can "beam" your exact location to another Rino user within a two-mile range (on the FRS spectrum) using "Position Reporting". "

What one can (legally) do with the existing PMR446 and FRS/GMRS "Family Radio"s is though a little unclear. How quickly the location info will be transferred for instance is not told... Then there are those not-in-use-any-more bands like the North-European NMT-450 with its bands:

453,000-457,475 MHz and 463,000-467,475 MHz

being freed for other use. In Germany was something like C-Net in that near 450 MHz area...

Anyway the current European frequency table tells that for all kind of analog/digital use there are/will be the bands:

450-455 MHz paired with 460-465 MHz (5+5 MHz) 455-456 MHz paired with 465-466 MHz (1+1 MHz) 456-459 MHz paired with 466-469 MHz (3+3 MHz) 459-460 MHz paired with 469-470 MHz (1+1 MHz)

marked as for "Analogue and digital land mobile PMR/PAMR" use (PMR = Professional&Private Mobile Radio, PAMR = Public Access Mobile Radio)

I would expect to see something like that WiFi for these bands, but with much less transfer capability. A typical ADSL-speed like 256 kilobits per second could be reasonable.... In areas like the Finnish Lapland where distances like 30 km from the nearest 'village' with optic cable are not rare, implementing net connections via radio links would sound reasonable. However no supply for these demands seem to exist yet... The common opinion seems to be that us stupid "reindeer-biter-ashamans" living in our forests and mountains, will never need any quick net connections. If needing a connection, people can use the old POT lines with modems or GPRS/Edge or something. The time when PCs were always connected only to those big computers and there was no sanity to connect PCs with each others, easily comes into ones mind from the current cellphones...

Ok, from that 'NMT450' time there are still in sell all kind of tuned antennas etc. for the 450 MHz band. When here in Finland we only have those PMR446's allowed with their 0.5 W power, not

2-3 W as the American GMRS allows, it has sometimes came into mind to try to use some full wave 450 MHz antenna in the roof when the 'mobile' radio is solidly installed into a house. The 1/4 wave 'march antenna' isn't that good in 'base stations'... There are areas where no GSM field can be found but people still live and walk there and all kind of 'ad hoc' networks could be very useful.

Let's hope this could help...

Cheers, Kai

Have a look at

900MHz transceivers, half-duplex, up to 115.2 Kbps, Up to 20 miles (32 km), approved in the U.S., Canada and Australia for mobile applications;

Stefan