Noise reductor adjustment

[glovisol]

The Noise Reductor switch (NR) is very effective in removing not only white noise, but even interference tones, etc. when turned ON. However the slide type NR green colour adjustment does not seem to have any effect in whatever position from 0 to 200. In other words the NR noise cancellation effect starts operating as soon as the NR pushbutton is acted upon, but its control level does not seem to be operative.

What am I doing wrong?

[glovisol]

I omitted to mention I am using the RSPduo with SDRuno.

[Mike2459]

It works on my RSP2 with Uno 1.23, although when the slider is moved the change is not instantaneous. It seems to take a few seconds to stabilize.

[glovisol]

With my RSPduo and RDSuno 1.23 the slider does not seem to work, even if I wait a few seconds. However the noise reduction is very good, as shown in the enclosed PC screens with oscilloscope. Noise is reduced by 12 dB from 80 to 20 mVp.

[glovisol]

Hi Mike 2459, apologies, you are quite right. It takes 10 seconds approx., but then the action of the slider at 200 is quite noiceable! Thanks.

Amended 20/10/18: The NR device has two response times: there is an immediate and very noticeable partial reduction effect, followed by a final adjustment with a response time of 30 seconds approx., when moving the cursor from 2 to 200. Once set, NR can be switched ON and OFF and noise cancellation is immediate, with no further delay.

In effect the noise reduction, with slider at 200, is much higher that 12 dB, while not altering the weak received signal, apart from a slight cut of the highs, which does not impair readability. Tomorrow I shall post much more accurate and up to the point measurements.

glovisol

[glovisol]

I suspect that the time lag shown by the NR to reach full action depends on the speed of the PC processor: e.g. the faster the PC, the shorter the time lag. This device is extremely good in suppressing noise: on 14 MHz, with a noise floor of -125 dBm an SSB signal at - 119/120 dBm (1.0 uV) on the HI Z input is fully and easily readable, while it is not intelligible with NR OFF.

[mikeladd]

Very interesting. Following this.

[glovisol]

Here below NR action documented at 1.8 MHz. Noise attenuation with cursor @ 200 is in excess of 14 dB. Lest someone notices an unbelivable noise floor @ 1.8 MHz, PC screens taken with RSPduo in operation with an antenna attenuation of 20 dB. The NR facility is of course useful with weak signals. With average to strong signals (e.g. 10/12 dB above noise floor) NR is best kept OFF.

[glovisol]

Hi Tech_Support,

The Noise Reductor works so well it made me curious on its operating principles....perhaps you could give us some idea on how it works.

glovisol