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[TowerTalk] Noise and WANs

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Subject: [TowerTalk] Noise and WANs
From: (Steve Maki)
Date: Mon, 17 Sep 2001 01:02:16 -0400
N0FP wrote:

>Monday night I am sponsoring a picnic for the local ham radio club.  One of
>the members works for the WAN company (ISP) and is bringing his mobile 2.4
>GHz Wide Area Network setup in his pickup truck to demonstrate 500MB/Sec WWW
>interconnect from the vehicle.
>Deep Background:
>This WAN is operating in southern Minnesota.  It is apparently the largest
>RF based WAN in the world.  It goes from Central MN to the IA border (about
>125 miles square--just a guess).  This company has been suspected of causing
>unusual noises on the bands, including lots of falsing of repeaters near
>nodes (nodes are located on a 5-7 mile grid throughout the area).  It is an
>ethernet based structure.  A technician for the company has admitted that
>some of the equipment does not (and may not) meet FCC rules but I couldn't
>get him to elaborate as to how.
>The Plan:
>They don't know it but while they are demonstrating their blazing fast
>transfer rates right on my property, I am going to be in the shack taking
>notes off the screen of my spectrum analyser and radios (HF, VHF,
>UHF)--located only 150 feet from the demonstration.
>What tests should I (can I) perform to identify possible noise signatures
>eminating from their equipment?  Your thoughts would be greatly appreciated.

Most wireless ethernet gear runs on 2.4 gHz, while the wireless ISPs use a
2.4 gHz downlink and 900 mHz uplink system, though these systems are not
capable of 500mb. 500 mb sounds like it might be on a higher band, maybe
5.7 gHz. While not FCC type accepted, it's doubtful there is significant
interference to 144 mHz and 432 mHz repeaters, but not impossible I guess.

It's all spread spectrum, so a little hard to pick up on a spectrum analyzer
unless you are very close to the transmitter, like you will be. If you can
find the signals, it should be possible to pick up any correlation to
simultaneous interference to your radios.

Steve K8LX

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