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

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I'm looking for "Low Cost" radio tranceiver with 5Km range and  full-dublex
19200-115200 baud rate. Would you suggest one?





Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
<Poniasahgsour Uryeghama> wrote in message
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full-dublex
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Could you tell us what you want it for?

If low cost is a prime consideration, you may be better off looking at half
duplex systems. If you don't especially want a serial port connection, you
may like to consider 2.4GHz Wireless LAN cards with a good antenna system.

Mark



Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
What about the range of 5Km? Do you thik wireless LAN (802.11) would reach
that far?

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

<Poniasahgsour Uryeghama> wrote in message
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Yes, but you have to have decent antennas. Have a look at
http://www.nodedb.com/australia/ or http://www.air-stream.org and see what
people are up to.

Mark



Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
with the right rx/tx aerials you can expect considerably more , and
quite cheaply

"Poniasahgsour Uryeghama" wrote:
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Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
On Tue, 13 Jul 2004 20:20:45 +1000, atec

<WLAN cards>

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While a WLAN link can be longer than 5 km, you need quite high towers
to have a clean line of sight path between the stations, with
preferably no obstacles within the first Fresnel zone :-).

In most countries the WLAN is limited to 100 mW ERP (+20 dBm) and when
the path loss for 5 km and 2450 MHz is 114 dB, the received power with
an omnidirectional antenna would be -94 dBm. After the feeder losses
at the receiving end the power level entering the WLAN card can be
calculated. Compare this figure to the nominal sensitivity of the WLAN
card at various speeds and you know how much receiver antenna gain you
are going to need. This calculation assumes a clean path with
unobstructed Fresnel zone.

You must also consider the local noise level near the receiver from
other sources.

Paul
 

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

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A full duplex system requires two separate radio links, one for each
direction. To avoid the problem with duplex filters, use two complete
separate unidirectional radio links operating at different frequency
bands.

A 5 km range is easy, if you have a _guaranteed_ line of sight, but if
not, it becomes quite tricky to get a decent reliability, requiring a
lot of power (several watts), special modulation and coding systems to
avoid selective fading etc.

Then you have to consider in which countries this system should be
operated and check separately for each country which frequency bands
can be used for this kind of operation. Remember, you need two
separate bands, if you insist on full-duplex operation.

It would be easiest if some license exempt bands could be used, but
these are usually limited to 10-100 mW, which would not be sufficient
for reliable 5 km non-light of sight paths at those speeds. Also note
that there are usually a lot of all kinds of other activities on
license exempt bands that could block your link at much shorter
distances, thus, you may need some frequency hopping or spread
spectrum system to avoid the other users.

For reliable systems, most likely a licensed radio system would have
to be used, with type accepted devices and separate licenses for each
installed transmitter. Depending on your definition of "Low Cost" this
may or may not be acceptable :-).

Paul


Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
One of the unit in my implementation will be mobile and therefore wireless
LAN seems to be out of question (no tower, no directional antenna).  Any
other recommendation?

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full-dublex
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Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
<Poniasahgsour Uryeghama> wrote in message
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COuld you define "low cost"? - it such a relative term.

Mark




Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
< US$300


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Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
<Poniasahgsour Uryeghama> wrote in message
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Have a look at this unit. It is US$269. It will have the same problems as
the Wireless LAN as it operates in the 2.4GHz band as well.
http://www.microdaq.com/wireless/aerocomm/index.php

If this is for import to Australia, you will need to add freight and GST
(depending on application). You may get a tax reduction as an export from
the country of origin.

If you are looking for a unit with a that will handle 5km all terrain, you
will need to up your budget. Using something outside of bands like the
2.4GHZ band, you may require a licence which will add to your costs.

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Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
With that kind of size, it's difficult to fit into a model plane...

Kelvin





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Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
I'm not interested in model plane. I do not have size limitation, my mobile
platfrom is car (not a model one).


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

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 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


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


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Completely unrealistic with those requirements.

Drop the full duplex and data requirements and provide at least nearly
line of sight paths (with the other station up in a high tower or
balloon) may make the situation more realistic.
 
Paul


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

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Hmm, sounds like an EER application to me.




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

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GSM? Cellular technology is cheap enough these days.

Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
GSM  device itself is not expensive but call charges are not.

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wireless



Re: Low cost Radio tranceiver Range :5Km Baud Rate : 19200-115200baud
GPRS, then?
< $200 US.  Call charges negligible for smallish amounts of data in
Australia.

Alf.



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

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In the Netherlands you can get a rate of Eur 1.5 / megabyte for GPRS.
For sending and receiving, so for GSM-to-GSM cost you have to double it.
But if the amount of data is limited this is very acceptable.


Thomas

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