i4jmy@iol.it wrote:
>Stated first that we can survive without accurate S meter readings and
>better we use something else to measure strenghts than communications
>receivers, the point that's difficult to use the modern receivers AGC
line in
>order to properly drive an S-meter divided into S-units is a
>bit pessimistic in the digital era.
>Whatsoever it is the actual AGC line response to the incoming signal
>amplitude, one of the several microprocessors inside a modern RX can
>perfectly be programmed to do (among many other stupid functions) the
>rough correction of the derived AGC voltage in order to drive a
>logaritmic metering circuit that follows the choosen dB/div and
>indicates an "S9" when 50uV are present on the antenna socket.
>
That is the kind of thing I meant by:
>>there are engineering solutions that could easily deliver the
>>full IARU specification
Also it should be possible to compensate for gain variations due to
switching in various preamps or attenuators, so that the S-meter
indicates the signal strength at the RX input socket.
But then there is another problem: an IARU-spec S-meter calibrated at
6dB/S-point all the way across the range will read very low compared
with most modern rigs. The manufacturers know that people don't like to
give "mean" signal strength reports, so they don't spend money on
something most of their customers would not like.
I believe it's called "marketing"...
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
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