This whole thread......

Some have touched on pieces of it but how about this summary..........

The Redline is a two piece radio. It does not send 5 Ghz up the cable. It sends an IF frequency which is lower and more forgiving as well as power to operate the outdoor unit. The Redline as pointed out does not have a spectrum analyzer (in the versions I have worked with). As such they probably just checked for RSL on any or all channels. This is not a spectrum analysis by any means. The Redline equipment is great equipment but it is not a spectrum analyzer.

A spectrum analysis is flawed in almost any case really because it is only good at the time of the testing and along the path of the test. You really will only see stronger signals with an omni. But you can still have your signal killed if someone is using directional antennas and looking down your path. There is a big difference from 8 dB to 29 dB.

The other case is a 5 Ghz. system in place that only is used at the end of the day or does "dumps' at certain times. Unlike a full duplex radio like a Proxim Tsunami that is talking all the time regardless of the received signal, you may only see a signal when the associated equipment is passing data. In my book you can't do "reliable spectrum analysis" with any radio or assocaited radio card. Yes, there are systems out there that work really well but I would not be willing to bet my reputation on most. Will they get you by in most cases??? Sure. But.......................................................

To answer your question......Yes, the spectrum analysis was flawed.

Personally...we never do spectrum analysis. It causes more headaches than what it is worth IMHO. Is it great for finding interference?? Sure.

I have installed links in lower Manhattan (nearly 70 to date on unlicensed 5 Ghz), Washington DC and Boston without ever needing a spectrum analysis. All these locations are RF hotbeds.

A few things to consider. Use a radio with a very good C/I value. Use 2' or larger antennas to keep the beamwidth tight. Use radios that are capable of 5 or 10 Mhz. channels. Use radios with high RF power output. If you need to run transmission line to the radio, use the right stuff for the job. LMR400 and 5 Ghz. are not my considered options unless the cable length is less than 24". We use LMR600 up to 100' and 5/8" heliax after that. make sure the radio has a good receiver threshold. Wherever possible we use 5.3 Ghz.

Last and not least consider your neighbors. If there is only one tall building in town and everyone is on it use 5 Ghz. you are probably in for some challenges. But if you do a spectrum analysis, find a clear channel, build on it and then smile and walk away only to have one of the existing operators change channels and rain on your parade.

Its a game of chance but with the proper engineering you can move the odds more in your favor.

Good Luck!


Bob Moldashel
Lakeland Communications, Inc.
Broadband Deployment Group
1350 Lincoln Avenue
Holbrook, New York 11741 USA
800-479-9195 Toll Free US & Canada
631-585-5558 Fax
516-551-1131 Cell

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