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

From: Kai Ruottu (karuottu_miaauu_mbnet_point_fi_at_spam.tome.no)
Date: 07/19/04 

Date: Mon, 19 Jul 2004 15:21:42 +0300

On Mon, 19 Jul 2004 19:12:38 +1000, <Poniasahgsour Uryeghama> wrote:

>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

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