Friday 27 September 2019

Better late than never. Better never late...

RadCom, the RSGB's monthly magazine (not available in any shops), is, by any standard, a pretty poor offering.

As such, the magazine gets put in the bathroom, where I pick it up and put it down until the next month's pointless text arrives.

This month (October 2019), I was interested to see the EMC section dealing with the 'novel' RFI source that are CCTV camera systems.

Novel, that is, to the RSGB.  I first noticed RFI from a wireless image transmission system around 2009.  I wrote about a later, entirely wired system, in 2014.

So, congratulations to the RSGB for catching up - eventually.

There is something else that struck me as very, very odd in this month's EMC section.  In relation to some work by one operator to minimise RFI, it's implied that a reduction to the point where the 'S' meter does not register a signal is an indication of success.

Well, this would certainly not be acceptable for my WSPR reception.

I can switch on a number of poorer SMPSUs around the house, and they will produce copious amounts of RFI.  The CCTV system I reported on in 2014 is the only one I've seen trigger the 'S' meter.  Typically, SMPSUs will raise the noise floor by several dB without triggering the 'S' meter at all. So use something like an SDR receiver or spectrum analyser to determine the success or otherwise of EMC efforts, so that you get an objective, numerical assessment.


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