Subject: [NEXTEL-1] Interference from Strobe Light

From: "Bender, Klaus" <[email-masked]>
Date: Wed, 15 Jan 2003 14:40:59 -0500

We have a client who is claiming that they are getting interference from a
strobe light on a tower. The strobe is used for FAA and flashes red. Has
anyone had any experience with this?
 
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Klaus Bender - Spectrum Management & RF Engineering
V:  (703) 558-2204 F: (703) 276-1169 M: (703) 887-1474
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From: "Bill Smith" <[email-masked]>
Date: Wed, 15 Jan 2003 15:05:20 -0500

Yes, it has been discussed several times on the tower-pro list. It's a
result of the restriking of the strobe tube to give the longer light needed
at night.  We installed cages and inline filters on our Flashguard 3000
strobes due to interference to our 451 MHz system. The single pulse for the
day strobe isn't enough to cause noticeable problems. If you look at the RX
signal with a spectrum analyzer, you will see the problem extends from
around 50 MHz up to nearly 1 GHz depending on the type of strobe and the
proximity of the antenna to the strobe head.

Solutions are to either go incandescent at night, install an RFI cage and
inline filtering or move the RX antenna and strobe head further apart.  We
had 6 feet of separation from the head and main RX antenna and still had
nearly 20 dB of RX desense at 456 MHz.