IP over Microwave

IP over Microwave

Postby criten » Mon Oct 03, 2011 8:23 pm

Just wondering if anyone has any comments and suggestions cause I'm a total newb to this kind of thing.

Working as a volunteer technician at a community radio station.

We've received advice that a commercial broadcaster will be installing a DAB+ transmitter a few years away. As DAB+ is "multiplexed" which makes it similar to trunked radio, and the law is that commercial DAB+ transmitters must allocate two ninths of their capacity to community broadcasters, we'll get access to use it once its up. The backhaul (or what the industry calls STL (studio to transmitter link)) should be the standardized STL-IP. We will have to provide our own microwave link to the transmitter site.

So we're looking to migrate our current FM transmitters analogue STL to STL-IP.

The STL equipment is fine but its the IP equipment I need a hand with. I'm told we use "microwave" at the moment but the actual frequency is in the 800mhz band. We'll need some kind of IP based radio system - only has to work for about 300m. Once the DAB+ transmitter is installed, we'll need to do it for about 10km. The bandwidth requirements for STL-IP are actually quite minimal - the encoded stream would have plenty of overhead at 256kbit.

There is no option for multiple pathways with the DAB+ transmitter, but with our own FM transmitter, there is already ADSL2+ at one end and fibre optic at the other - would serve as a good alternate pathway.

Does anyone have advise on what IP to radio equipment we should use? What kind of compliance we'd need to get licensed? And how we can do this at minimal cost cause they have absolutely no funding?
criten
 
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Re: IP over Microwave

Postby col05_au » Tue Oct 04, 2011 6:53 pm

Criten,

Unfortunately playing with radio is never cheap, and often a struggle for a community groups.

To avoid ongoing license costs you could look at a class licensed ISM (often referred to as unlicensed). There are several area's of spectrum allocated for such devices 900MHz, 2.4GHz and 5.8GHz all with the respective pro's and cons. The most common being all of which will require a good clean path.

Several vendors do Ethernet based radio's for the ISM bands RAD AirMux, Aviat, Trio (now Schneider Electric) to name a few.

However when looking at the specs keep in mind they are for a correctly designed system, any compromises may have a significant impact on performance.

I have used 5.8GHz RAD products over 5 odd kilometers with good reliable throughput around the 16MB/S mark, Trio J series over distances of 40-50KM but throughput is low 256KB/S so may not be sufficient for your application.

The other alternative is to use a licensed product however you will face the issues of license fees and applications, you will however gain the protection of being protected from interference and other users.

Hardware here is more expensive, however reliability of a correctly designed system will pay benefits.

You could take the traditional microwave option very expensive and much more bandwidth than you will require vendors like NEC, Avait, SAGEM, Alcatel to name a few.

What could be a better option is to use a UHF type product still providing the IP interface like a 4RF / Aprisa product more pricy than your ISM radio's but a hell of a lot cheaper than a microwave solution.

Several options, personally I like the 4RF option but cost will /could be a factor.

My 2c based on personal experience on having worked with all the above gear, I'm sure there is other equipment others have used as well.


Col
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Re: IP over Microwave

Postby ivahri » Tue Oct 04, 2011 7:54 pm

We use 4RF- I love the gear & it is extremely reliable (like nearly 100% availability for the past 3 years on 5 of these links). You would be looking at about $10K an end (in other words $20k plus antennas etc) but in terms of licenced gear that is pretty cheap.

And it is K1W1 made, and after the weekend we need to show pity on them...

Cheers,

Richard
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Re: IP over Microwave

Postby criten » Tue Oct 11, 2011 12:15 pm

I was of the understanding that a 2.4GHz class license, such as a 802.11n WiFi router, shouldn't have its primary intentions of being used off your premises. Am I wrong?
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Re: IP over Microwave

Postby col05_au » Tue Oct 11, 2011 2:56 pm

Not to my knowledge.

I am not aware of any requirments to adhere to a property boundary.

Col
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Re: IP over Microwave

Postby ivahri » Tue Oct 11, 2011 3:42 pm

Criten,

I've seen these licence free links used particularly by Councils at various base sites in the bush.

Cheers,

Richard
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Re: IP over Microwave

Postby criten » Tue Oct 11, 2011 7:39 pm

Ahh thats why I posted.

Interesting because the FM transmitter is literally 200m from the studio and we have an alternate IP pathway anyway. So low cost 802.11 gear it sounds like...
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