Subject: [NEXTEL-1] Re: Advice on using spread spectrum link in critical communications]

From: [email-masked]
Date: Tue, 18 Nov 2003 17:23:18 -0500

-------- Original Message --------
From: "Dennis Kline" <[email-masked]>
Subject:  Re: Advice on using spread spectrum link in critical communications

Kevin:

I have used unlicensed spread spectrum for many microwave links.  I 
am a proponent of this technology as a quick and inexpensive means to 
establish a link.  I have installed "temporary" links that were kept 
in service for over 7 years with no issues.

Having said that, I have very strong opinions on using this 
technology for critical infrastructure.  The equipment vendors have 
come a long way in the last few years, and reliability has improved.  

But also, because it has become so popular, the potential for 
interference has increased dramatically.  Everything from garage door 
openers, microwave ovens, cordless phones, etc now occupy these bands.
And, at least from my perspective, the mitigation techniques, such as 
frequency hopping, OFDM, etc only provide false security.  In urban 
areas, it is not a question of 'IF' but "when" you have interference.

Your deployment plan needs to include a contingency plan for 
interference.  If you have a critical hop interfered with, what will 
you do?  Make sure you think about the options, and how quickly you 
will be able to restore a link.

Just my thoughts
Dennis

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