Hi
I would like some help for creating wireless ethernet network using
VHF radio with frequency range of 130MHz-18MHz. The distance supported
shall be upto 100km LOS. Kindly advise on industry products available
for such option.
Regards
Khan
look at a product called the TNC-X -- 1200 baud packet modem -- with
appropriate software on your PC to act as a gateway, you can do TCP/IP over
packet.... the interface to the radio is audio, so just about any voice
radio will work with an appropriate cable to hook up the earphone,
microphone, and transmit switch.
Keep the frequency up as high as possible... in fact, you can basically
scrap the 18-100 mhz range, atmospheric conditions can make so you cannot
talk 10km with 100 watts under some conditions. and at the lower
frequencies, there is every chance your signal will go MUCH further due to
those same atmospheric conditions.
I also strongly suggest beam antennas at both ends, up as high as your local
laws permit.
TNC-X packet modem
http://www.tnc-x.com/
AGW Packet Engine
http://www.elcom.gr/sv2agw/
I hope you have an FCC license (or the equivalent in your area) because for
100km range, you will have to use higher power than is allowed for
unlicensed operation in most jurisdictions. If your purpose is
non-commercial, get an amateur radio technician class license, which will
allow you to operate in the 144-148mhz "2 meter" band.... 50-100 watts will
cover 100km quite nicely with a couple of 3 or 4 element yagi antennas..
Getting the technician class license is pretty simple... most countries have
dropped all morse code requirements, so its just a test you have to take to
get licensed..
And finally -- for 100km, you could most likely get away with a couple of
2.4ghz parabolic antennas and run 802.11b wifi, which takes no licensing,
uses off the shelf hardware, and has much higher data rates than 1200 baud
packet. The only issue is getting your wireless access point as close to the
antenna as possible... in a weatherproof enclosure mounted on the antenna
mast. There are linksys routers that have open source firmware, and there
are plenty of very reliable hacked firmwares that have features
specifically for setting up point to point links. You put the parabolic on
one of the antenna ports, and a small omni antenna on the other for people
around the antenna to access.