On 5/10/2022 4:46 PM, Tony wrote:
In some cases, the beacons signals came within 1 S-unit of other Yagi
equipped stations here in New York and New Jersey including my own. It
most cases it was within 2 S-units. I believe the remote SDR receivers
have calibrated 6db per S-unit S-meters so the readings should be fairly
accurate.
This discussion is missing multiple factors. S-meter readings are based
on the voltage at the input terminal of a receiver, and one s-unit is
defined as 6 dB, which corresponds to a 4:1 power difference. That's a
VERY rough indicator. Two S-units is a 16:1 power ratio -- the
difference between 1.6kW and 100W, or between 5W and 80W.
S-meter readings depend on its calibration and linearity, which has been
notoriously bad as long as there have been S-meters.
S-meter readings also depend strongly on the antenna feeding the
receiver, as well as vertical directivity, which is strongly dependent
on its height AND terrain.
The post IS correct to the extent that Elecraft rigs and SDR receivers
in general CAN be accurately calibrated and have good linearity. I've
done that calibration for my two K3s and their attached P3s, using an HP
generator as a signal source, and set the P3 display in dBm.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|