[lexridge]

I'm new at these long hops, but I may have a need to make an 18mi. (29km) hop to connect to a NTSC video transmitter, so that the transmitter may be remote controlled.

1. What would be the best radio/chipset to do this? Preferably PCI slot.
2. How much power output would be required?
3. What kind of throughput can I expect?

The signal path is already designated, as it is presently fed one way with a 2ghz video microwave (3 meter dish). I may even want to use the WIFI as a backup mpeg video feed, but that's for another discussion (BrianSlayer, this could be a whole new market for you).

thanks,

[indianboy]

what is the bandwidth requirement ?

what is the height of the tower to obtain fresnel clearance ?

what is the amount of RF noise in your deployment area ?

do you need to setup a box or a regular WRAP or Xscale Based unit ?

which band do you prefer 2.4 Ghz or 5 Ghz ?

what obstacles are there in the 28 kms LOS ?

These are important questions and after the answer it is a lot easy to recommend you any gear

[lexridge]

[0ldman]

5GHz has more loss over distance, but much smaller fresnel zone as well.
Parabolic grid antennas are smaller for high gain than the 2.4GHz, less wind loading, shipping costs, etc...

What country? FCC, you can run 1 watt tranmitted with a 27dBi grid legally at 5.7-5.8GHz.

[lexridge]

[0ldman]

If memory serves, 27dBi grid is 24 inches across, 22lbs wind load at 100mph. Thats the highest gain grid I've come across. Higher gain can be found, but I think most are solid dishes.

[lazerusrm]

i think i couple of Senao Wifi cards, some good LMR cable down the towers, some good antennas and you should be good to go!

I've done about 25Mi. point to point with this size antenna. We use $25 dollar verisions

of this antenna

http://www.alibaba.com/catalog/11687227/2_4_Ghz_24_Dbi_Antenna_Grid.html

Or maybe you could use an antenna this size: 5.5 Ft. around! 30 DB gain

http://www.radiolabs.com/products/antennas/2.4gig/stage5.php

This Card:

http://store.wifi-parts.com/enemwimica80.html

What do you guys think?

[indianboy]

My Best Bet

1. Any Good Machine.

2. Good LMR-400 Cable ( LMR-600 will be pretty good if you wish to setup an indoor unit )

3. Good Sensitivity and High Power Card (Wistron DCMA-82 or Ubiquiti XS5 - 600 mW )

4. 24 dbi Solid Dish or Grid Antenna in horizontal polarization.

5. And Some Wireless Calculators ..

[lexridge]

Thanks for all the replies, and thanks for the links lazerusrm. I believe I now have enough information to submit this to mgt for approval. I'll let ya know how everything goes.

[lazerusrm]

One thing to note here too, is if you're mounting on a 550' tower, and you're using LMR 900.. You are going to have a fair bit of signal loss through that much cabling.

About 2.8 DB/100 Ft. Signal loss would be present. on LMR 900

It would drop to about 1.7 Db/100Ft. On LMR-1700

So, at 550 Ft, you will be loosing 15.4 DB, and thats not including connectors on each end and pigtails, which could be another 1/2-1 1/2 db loss. LMR 1700 would drop that down to about 10-11 DB loss.

If its possible, it would be BEST to put your transmit equipment as close to the antenna as possible, and it would probably be cheaper. Since high guage LMR is very expensive in long runs :)

http://radiolabs.com/stations/wifi_calc.html

use this calculator!

[lexridge]

After conferring with the chief engineer, he tells me we would need to put the dish at approx. 250', as the 3 meter microwave dish is mounted at 227'. The batwings at the top make up the last 50', so the tower is actually 500' itself. That should help the cable loss considerably. I also plan on putting the PC at the base of the tower in a water tight box. Heat is really my only concern in regards to the weather tight box.

Downtown, the 250' tower is a free standing, with the microwave dish at approx 225' mounted between to legs. I'm hoping to mount this small mesh at the same height, but mount it directly to one of the legs. Our conduit to this tower is only about 25' away from the building, so I will put that PC inside, in the microwave equipment rack.

Next question: How big of a p/s unit should this PC contain in order to make 1 watt of RF power without starving the rest of the PC for power? I would think a 400 watt p/s should be sufficient, but I don't know the conversions from DC power in to RF power out.

[BrainSlayer]

justd 15 miles? mmh a 80 cm dish would be enough of not 60cm will work. i'm using 60 cm dishes (28 dbi) from antenna specialists (swedish company) for almost all long lange link. our longest link here is 15 km and has 30dbi snr in turbo mode (5ghz). the cards are just cm9 cards. so dont be afraid. a good quality dish has alot of power

[indianboy]

I am also convinced to BS statement. If you really want to make a powerful unit and pour your money in good stuff then go for Xscale 533 Mhz Board with CM9. Mount it on the tower itself inside a Metal Enclosure ( Less Interference if properly grounded ) with 2-3 feet LMR-400 cable. Metal Enclosures do keep a fair amount of heat outside.

The Antenna is the most expensive stuff . Get the best antenna and you can easily jump to 50's of Km with a standard CM9 card without creating a lot of noise with additional amps.

Good Luck with your setup and don't forget to post the result .

[lazerusrm]

only thing that may be bother him in a few years are those trees on that dang mountain

[elvicomte]

Hi,

I'm new on this forum but I've been playing with some WRAP boards and CM9 cards.
We set up a couple of 30 miles links with WRAP boards, CM9 radios, LMR-400 cable and cheap 24dBi antennas you can find here:

http://www.hyperlinktech.com/web/hg2424g.php

The result is full bandwidth in b mode (11MBps). Looks like the g mode is getting a little more picky after a certain distance. We couldn't get a higher thoughput than 11-12 Mbps.

We used some other firmware, but I see no reasons that DD-WRT wont work.

Have fun!