From: "Paul Keinanen" <keinanen@sci.fi>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: S-meter standard
Date: Thu, 01 Feb 2001 00:01:05 +0200
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On Tue, 30 Jan 2001 23:36:06 +0000, Stewart Bryant
<stewart.bryant@virgin.net> wrote:


>Why do the manufacturers still bother with S units. 
>Why don't receivers just measure dBuV or dBm at the antenna?

While it certainly would be nice to have a dependable dB scale on the
meter, I do not see the point of calibrating the scale to some antenna
terminal reference level on LF. On UHF/microwave, dbuV or dBm scales
make some sence, since these values could be related to the internal
noise temperature of the receiver. 

In order to give some usable information (e.g. in the report
exchange), the reported value should be derived from the actual field
strength [V/m] or power density [W/m淫 around the receiving antenna.
If this is not possible, I do not see much advantage of promoting dBuV
over S-units, provided that the S unit scale is linear (e.g. 6 dB / S-
unit).

Paul OH3LWR
    
>
>73
>
>Strewart
>
>Dick Rollema wrote:
>
>>      To All from PA0SE Walter, DJ2LF, wrote:  But nevertheless -
>>      what about S9 on LF is 500uV? I would prefer to stick to S9
>>      is 50猩 over 50 ohms (or better S9 means -73dBm, to make it
>>      independent of  receiver input impedance) and  one S-point
>>      is 6dB. These are values recommended by IARU and therefore
>>      can be considered as a  "standard" that has been accepted
>>      internationally (except by the receiver manufacturers). I
>>      don't think IARU has  stated a lower frequency limit, only
>>      that it should be used below 30MHz. Using a new "standard"
>>      for LF would add to the confusion which is already big
>>      enough. If it is nevertheless felt that S9 is 500猩 would be
>>      better for LF then this should be made a proposal to be
>>      presented at the next IARU conferences in the three
>>      regions. 73, Dick, PA0SE
>>