Set up cost for 25 mile over water Microwave link.

[S2SRADIO]

I'm trying to get an estimate for the setup cost of a 25 mile over water microwave link. The signal needs to be clear enough to be processed into a VHF transmit 250 kW or at the receiving site. Please excuse my lack of technical knoweldge. If more information is needed to give an approximation please let me know. Thank you.

 

[robertjo24]

Yeah…going to need a lot more info

Are you trying to extend a voice circuit out 25 miles to connect to a 250Kw VHF radio? When you say 25 miles over water, is this a link between two terrestrial points separated by a body of water?

Basically what you would need to know to start designing the system…
1) Coordinates of each end of the link
2) Site info (power availability, building/tower availability & height, etc)
3) Microwave radios available for your area (licensed & unlicensed)
4) Frequencies available in your region/country/etc
5) Path obstructions between locations
6) Type of surrounding terrain (woodlands, desert, etc) and type of water (fresh/salt)
7) Is there any heavy traffic in the body of water (super tankers, cargo vessels, etc)

The best way to get started would be to check with system designers/integrators in your area (i.e. local Motorola shop) to have one of their systems engineers do a quick design for you. There are way too many variables to get any semblance of a useable answer in this forum.

 

[robertjo24]

You can get a pair of GE/MDS LEDR licensed 900Mhz radios for $12,000.
You could probably get a pair of 900 Mhz grid dishes for $2000.
The coax would depend upon system height, but fiogure another $1500 per side

You would also nee dsome sort of T1 mux on each end to handle the voice traffic. MDS has thoes as well.

This is all assuming you have adequaste height at each end (exsiting tower or structure) and no obstructions in the middle.

So, you are likely looking at anywhere from $22,000 to $25,000 for a licensed LEDR system.

 

[VEBill]

Who uses 250kW at "VHF", other than FM/TV broadcasters?

If this is for broadcast use (and even if it isn't...), then look up "studio transmitter link" (STL) systems.

 

[K7FE]

During the early 70's I was consulting at Hughes to develop an AML transmitter/receiver system. It used 5 watts of amplitude modulation on 12.7GHz powered by a Varian Klystron. One of the applications was to connected TV between Hawaiian islands. It did that very well. The system could be configured for a single channel or multiple channels.

One of those older AML transmitters just sold for $150.00

http://cgi.ebay.com/ws/eBayISAPI.dl...rt=nc&si=VagvgSd5ym%2FOWNaZNLF%2Bx%2BeqekM%3D

There are some inexpensive products today that will make the desired 25 mile path with ease. The link in the system below runs 5.7 to 5.8GHz and claims a range of 50 miles in that unlicensed area.

http://www.cableaml.com/ing_single_ch_video_links_lowcost_tvlink.html

Terry

 

[Higgler]

S2SRadio hasn't logged on since Jan. 4, 2011.
I think the question had a hiccup in it.

It's difficult to radiate one watt.

250,000 watts just to set up a 25 mile link is "interesting" to say the least.

Interesting note on communication across water, normally loss is expected as proportional to R^2 thru the air. A coworker said that across water, R^4 is closer to reality than is R^2. Still seems odd, but I believe him since he's alot smarter than me, and he described the info as coming from an expert doing a detailed talk at a communications conference, including measured data. Still seems a bit wacked, and should depend on the heights of the transmitter/rcvr above the water.

 

[MacGyverS2000]

I don't recall the "exact" figure, Higg, but from my comm days <chuckle> blasting across lakes always made the calc figures look poor by comparison.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

I interpreted the question as looking for a 25-mile link system *leading to* the very high power transmitter.

 

[Higgler]

maybe so.
I've been wrong before.