[hpsdr] Steady Waterfall

[Phil Harman]

I added a similar feature to the bandscope in KISS Konsole some time ago.
This is called "Waterfall AGC" and sets the minimum signal colour based on
the average band noise.

This works really well and you can change bands, antennas etc without the
need to adjust the waterfall settings.

Didn't see a need to set the Waterfall Dynamic Range but this would be
easy to code if needed.

73 Phil...VK6APH


> ***** High Performance Software Defined Radio Discussion List *****
>
> If you try the 'large FFT' variation of PowerSDR that I posted last
> year and again last month, it has a modified Linrad waterfall display
> color scale [in addition to the standard Linrad color scale display]
> that automatically adjusts the signal strength range over which the
> color scale is applied, based on the noise floor and the maximal
> signal strength detected.  It automatically compensates for changes in
> the noise floor.
>
> The code [both source and binaries] is at:
>
> http://www.nitehawk.com/w3sz/HPSDR-PowerSDR-Metis-W3SZ.zip
>
> The zipped file is large, approx 100 MB
>
> Unfortunately, I did not change the code to keep the center of the
> waterfall frequency scale at a fixed frequency, which I agree would be
> EXTREMELY desirable.
>
> 73,
>
> Roger Rehr
> W3SZ
> http://www.nitehawk.com/w3sz
>
>> On Wed, Apr 27, 2011 at 11:46 AM, Ben Witvliet <pa5bw at xs4all.nl> wrote:
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>>
>>> Hello all,
>>> (2) To get maximum sensitivity and best indication of weak signals, I
>>> set the (Setup - Display - Waterfall) LowLevel just below the noise
>>> level. I then set the HighLevel some 25 or 30 dB higher when the band
>>> is quiet. Weak signals are then showing up very clearly, and even short
>>> transmission are caught straight away.
>>>
>>> I found that adjusting the LowLevel is needed quite often, depending on
>>> the time of day, the band and the antenna used. And the HighLevel must
>>> be adjusted also to get best results. A band full of strong signals
>>> requires other settings than a very quiet band.
>>>
>>>
>>>
>>> Would it be an idea to set the Lowlevel automatically to the average
>>> noise level within the full receiver bandwidth (200 kHz)? The
>>> Waterfall-HighLevel could than be replaced by Waterfall-DR (Dynamic
>>> Range). Dr would be the present ´HighLevel´ minus ´LowLevel.  DR could
>>> be set automatically also, calculated from the strongest signals within
>>> full bandwidth or manually. Setting it manually to 30 dB would result
>>> in the DX setting I described above. If helpful I would be happy to
>>> devise a suitable formula for this.
>>>
>>>
>>>
>>> Kindest regards,
>>>
>>> Ben PA5BW
>>>
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