VHF Ethernet

On a sunny day (25 Feb 2007 04:20:49 -0800) it happened snipped-for-privacy@gmail.com wrote in :

You need a license to transmit.

130MHz (18MHz bandwidh?) are you crazy? You would be arrested the same day.

perhaps - perhaps not. Depends on the country.

R

On a sunny day (Sun, 25 Feb 2007 15:09:41 +0100) it happened Rene Tschaggelar wrote in :

Somalia?

With this bandwidth it covers aircraft bands, pretty much guarantees you to be arrested probably in 99% of countries.

SioL

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

AGW Packet Engine

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.

If he meant 18mhz bandwidth -- there is nothing out there except wifi off the shelf for that bandwidth -- and you wont be running that at 130mhz !!

I've got some 900mhz gear that will do 24khz bandwidth and thats clunky enough !! You can get amateur television hardware that will do 6mhz bandwith on a 1.2ghz carrier pertty easily, but then you are stuck with some pretty intense work to modulate and demodulate the data at that rate -- whip out your DSPs, boys !!

messagenews:45e198b4$1 snipped-for-privacy@news.bluew>

wrote

We have a licence for a particular frquency in range specified. No chance of geting arrested we are doing it all by legal means. Thanks to people all for the answers. Looking for right solution. thanks

On a sunny day (Sun, 25 Feb 2007 16:44:27 GMT) it happened "John Barrett" wrote in :

Well it is not that hard, TV at 67MHz with 6 MHz bandwidth is normal. I have build some small VHF TV modulators in the old analog days, to display output of stuff on the screen around ch4. The problem is limiting the bandwidth....

The other problem he has is line of sight. At 130MHz the TV broadcast transmitter is on a > 100 meter high tower, and radiating many kW, and 100km is at the edge of range really... Analog TV is good old AM, and FM carrier for the sound here.

Bit egoistic approach to grab 18MHz just for your personal Ethernet and pollute the whole area with it.

The correct approach for that distance, if wireless, is to hire an up/downlink from a statellite provider, that comes actually cheap. Maybe there is no satellite service like that where the OP is.

On a sunny day (Sun, 25 Feb 2007 16:37:34 GMT) it happened "John Barrett" wrote in :

Ah, I have 1200Bd packet over 27MHz, do you have any idea how long a 1 MB download takes? LOL

I think the OP meant a freq range of 130MHz-180MHz (left out the '0')

Covers TV broadcast and stolen vehicle trackers worldwide. Should get the cops on his ass real quick.

I was being facetious -- the best solution for high data rates at that distance is wifi over parabolics -- though he will problably need 50ft high towers or better to pull it off -- and they aint cheap !!

a slow speed (1200 baud) it can be done easily at 144mhz with off the shelf hardware and a ham radio license (non-commecial only)

I know exactly how long it takes :)

can you confirm the frequency range and desired data rate ?? would help with specifing a solution :)

18 MHz @130 MHz bandwidth is easily done with spread spectrum. Lowers detectability and interference.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

range is 130MHz to 180MHz ...sorry for the stupid typo mistake

Another homework problem?

--
James T. White

would have the power.

Frequencies will be a tad lower.

--
.

On a sunny day (Sun, 25 Feb 2007 18:56:52 GMT) it happened "John Barrett" wrote in :

Sometimes it did not finish at all.... :-) It is not simply 1200 bits / second, but the packets are send as a frame, sync pattern first, CRC is added, then the transmitter waits for a reply (ack or reject if received CRC was wrong, because of for example interference), and then and only then (if the band is free from other transmitters, some wait time the transmitter listens) the next packet is send again. Hours.

Is "130MHz-18MHz" a typo? Do you actually mean "130MHz-180MHz"?

Or are you just another googler that we'll never hear from again? The answers don't just show up on your desk - you have to come back to the NG to read them.

Good Luck! Rich