#### Locked dB indicators

David Herring

Hello All…

I just want to make sure I correctly understand the dB column in the Band Activity window. As I read the manual, it says that this column is the “measured signal-to-noise ratio.”

I take that to mean the difference between the band noise at the moment and the signal of this specific station, yes?

So then, would it be safe to say that, in a single given period, if there are two stations decoding, one is listed as 7 dB and the other as 1 db, that that is a difference of 6 dB and so the 7 dB station’s signal is double the strength of the 1 dB station?

73,
Dave - N5DCH

Reino Talarmo

So then, would it be safe to say that, in a single given period, if there are two stations decoding, one is listed as 7 dB and the other as 1 db, that that is a difference of 6 dB and so the 7 dB station’s signal is double the strength of the 1 dB station?
Hi Dave

Yes, signal strength e.g. in mV/m and four times in power.
Of course this is just a single instance and especially on longer distances much more "measurements" are needed for a reliable difference value.

The S/N calculation seems to be quite stable and some antenna comparation measurements have given sensible results, when using the same message instances for comparation.

73, Reino OH3mA

David Herring

Thank you, Reino! Much appreciated.

73,
Dave - N5DCH

On Dec 3, 2022, at 2:03 AM, Reino Talarmo <reino.talarmo@...> wrote:

So then, would it be safe to say that, in a single given period, if there are two stations decoding, one is listed as 7 dB and the other as 1 db, that that is a difference of 6 dB and so the 7 dB station’s signal is double the strength of the 1 dB station?
Hi Dave

Yes, signal strength e.g. in mV/m and four times in power.
Of course this is just a single instance and especially on longer distances much more "measurements" are needed for a reliable difference value.

The S/N calculation seems to be quite stable and some antenna comparation measurements have given sensible results, when using the same message instances for comparation.

73, Reino OH3mA Geza Szabados-Hann

Please note, that the dB value is the ratio of the signal comparing the noise, whereby the calculation is based on a bandwith of 2500 kHz. A signal with -17 dB received with a bandwith of 50Hz would result a signal equal to the noise (2500/50 = 50 = 17dB). If you decrease the bandwith of your receiver, the dB values will increase, as less noise is received, but the calculation is baded on 2500 Hz bandwith.

73,
Geza, DG5LP

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