Hi Michael,
The most useful tool for you to use in diagnosing your wireless fault is a graph of RSSI - received signal strength indication. This is the quickest way to find out whether your problem is RF design related or interference related.

If you find your packet loss doesn't correspond to dips in RSSI, you likely have an interference problem.
If you find your packet loss does correspond to low RSSI, and it also corresponds to sunny days, you might have a thermal issue. The solution to your problem is most likely just moving the Trango unit (maybe a few meters off a metal roof, instead of right on top of it) or attaching a bigger dish to it. If it's a critical link, move to an OFDM based radio with the ability for space diverse antennas (like an Orthogon Spectra unit).
Someone smart at BCL gave a paper last year called "BCL's experience with designing and implementing low and high capacity wireless networks" I can't find it online, but remember a case study about their path from Blue Duck to Beltana (Kaikoura area, South Island) and how they diagnosed and remedied a thermal ducting issue. It's worth a read if you can get your hands on it.


From: Michael Davies [mailto:michael@hereisasite.co.nz]
Sent: Tuesday, 1 August 2006 3:48 p.m.
To: nznog@list.waikato.ac.nz
Subject: [nznog] Wireless link adversly affected by the sun?

Hi there,


As the subject suggests, I’ve been noticing an interesting problem with our internet. We’re lucky enough to be on the receiving end of a wireless net connection running through Trango broadband hardware, fairly conventional wireless tech. However I’ve noticed through monitoring the connection with smokeping to various places around the country that the connection quality seems to decrease dramatically through the middle of the day, but not every day. At first I thought that this was simply related to congestion somewhere, but from following the weather a bit I’ve started noticing that it gets worse on the nice sunny days.


For example: Today, a balmy 17 degrees in Dunedin and beautifully sunny all day. Packet loss and jitter begins to increase at about 9am and peaks about 1pm with 60% loss, then at 2pm as if flicking a switch it returns to nearly 0% loss. From looking at the graphs over time, this does happen quite often but not every day and the loss today is definitely the worst I’ve seen it (but also the warmest/sunniest day we’ve had in Dunedin for quite a while).


Has anyone seen or heard of this happening before? Would there be any way to prevent this – supposing that the sun is the culprit – short of installing a Mr. Burns type sun shield?