Re: SDRC & SDRPlay RSPdx S-Meter Study


Siegfried Jackstien
 

i have seen the video

summarize ... set rf gain to 27db (max sensitivity), if gain to - 35db (not overdrive next stages) , visual gain to -40 db (calibrate s-meter)... and your readout should be good to plusminus 1 db or so ... between -130dbm and -50dbm!!

base noise then is at around -145dbm (from what i could see in the video) ... so a -140dbm signal is still clearly 5 db over the base noise

.....

what i do on any sdr... i set the gain (rf gain and if gain)  that the base noise just BARELY lifts up ... to have the max sensitivity ... and then with visual gain i set it that the s meter readings are ok (do match the real level) ...

most sdr are quite accurate in readings (as you found out with your signal generator)

why the rspdx needs a minus 75 db correction downwards (if gain and visual gain summed up) ... ok that how it is done in THIS sdr (others sure need different settings)

gedas ... a question ... can you try to set visual gain lower and increase if gain .. or set if gain lower and increase visual gain ... and have the same results??

does the rspdx overdrive on a setting?? (sure it does depending what level you throw at it) ... at what level with what settings??

means try to find a setup with max sensitivity and high dynamic range before overdriving ... try different combinations of visual gain and rf gain to find the best compromize and then let it there

plus ... you can do that also on vhf and uhf (and maybe find complete different numbers)

next is ... if you set your receiving a  bit sideways from centre ... do you see "ghost" signals?? (a mirror of the main signal or mixing products)??

pull the "high" slider in spectrum a bit upwards (to see those high peaks also with -50dbm or higher without going "out of sight" at the top)

greetz sigi dg9bfc


Am 04.07.2021 um 19:07 schrieb Gedas:

Have you watched the video Simon? I ask because the video sorta shows clearly what happens. I guess if you saw it and still wanted me to summarize the data I would do that (it is the least I could do for you after everything you have done for us). 73

Gedas, W8BYA EN70JT

Gallery at http://w8bya.com (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 7/4/2021 12:55 PM, Simon Brown wrote:

Any chance you could write the details here?

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Gedas
Sent: 04 July 2021 16:49
To: main@SDR-Radio.groups.io
Subject: [SDR-Radio] SDRC & SDRPlay RSPdx S-Meter Study

 

So just for the fun of it yesterday I input different RF level carriers into my RSPdx while changing some of the RF gain, IF gain, and Visual Gain settings.

No conclusions are being drawn here, simply noting some observations. I was always curious to see what different levels looked like on the s-meter of my receiver. I hope it is of some value to others.

https://www.youtube.com/watch?v=qHJE6wa9dVw

Gedas, W8BYA EN70JT
 
Gallery at http://w8bya.com (under repair)
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

 


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