Strange behavior of the Tracking Notch Filter (TNF) on the 6300

EA4GLI

I am used to PowerSDR with a Flex 1500, so my expectations of what TNF should do in SmartSDR might be skewed. Nonetheless I will post the Question and find out if you guys can replicate the behavior I am seeing in my 6300.

Basically, regardless of how wide my reception slice (blue) is, when I place a TNF to the right of the reception slice it will cut more from the signal that it is displayed on the screen.

To replicate this find a strong signal and make sure you listening wider that the signal is transmitting. 



In the example above the signal I am receiving on 14.283 is about 2700Hz wide. I created a very large Very Deep TNF on the right of the signal. Now, instead of moving the TNF towards the signal just widen the blue bar so you go inside the area of the TNF. Make sure you make the blue column wider than the end of the TNF so you can interact with it without having to move the TNF.



Right away the sound of the person on 14,283 changes (all the treble is gone) even though the TNF is not anywhere close to the actual 2700 Hz transmitted signal. If I do the same thing on the PowerSDR with the TNF the behavior is what you would expect, no change in the persons voice characteristics until the TNF reaches inside the 2700 Hz.

All you need to do is have the TNF touch the edge of your receiving column and it will alter the sound of the signal regardless of the location of the TNF.

The same cannot be replicated on the Flex 1500. On the 1500 it behaves as it should, only altering the receiving signal when the TNF is on top of the signal.



I will try to put together a video.
Does this behavior happen to your flex as well? Is this normal or just my specific radio?

EA4GLI

I added a video.


https://www.youtube.com/watch?v=-AAA1AYLas8

John

A similar problem in powersdr is that when one crated a TNF filter and drags it within the passband area, it shrinks in size, which is irritating because it can become a thin line almost invisible until its activated and the yellow colour is easier to see.

John

A similar problem in powersdr is that when one crated a TNF filter and drags it within the passband area, it shrinks in size, which is irritating because it can become a thin line almost invisible until its activated and the yellow colour is easier to see.

John

that blue bit peaking out bhind the filter looks like the 2nd receiver ?

RoyS

Hello Salvador,

In answer to your question "Is this normal or just my specific radio?"

Well, my 6300 does the same thing. However, I have never had use for the TNF outside the passband. In my opinion, this is just a quirk of the SSDR and does not really present itself as a problem.  

EA4GLI

It's all the same receiver John. What "peaks" on the other end of the TNF is the same receiver, I am just making it very wide intentionally.

The main reason I find it odd is that the TNF affects areas that visually are not being touch by the TNF. Any filtering done beyond the 2700 Hz of the received signal in my video shouldn't (in my opinion) be affected by the TNF and the correspondent should sound identical. All you are supposed to be eliminating, if the TNF is placed past the 2700 Hz mark, are any signals which are not a part of the actual transmission. 

It feels like visually I see one thing and then internally the TNF is doing another.

I really hope I am expressing this correctly. I don't want to be misunderstood, English is not my first language.

I see that Roy W5TKZ can replicate it (thanks OM!). So it is not just my flex.

I understand there is work to be done in the DSP portion of the SmartSDR software. Comparing it to the Flex 1500 and PowerSDR, I can see why.

I just wanted to point out this behavior, first to make sure it wasn't a specific issue of my radio, and second because it might help the FRS software developers in their quest to improve DSP in future revisions of the software.

Raf

Sal, I do not think you could have made this issue in anyway, shape or form more self explanatory.

This is an issue and yes IMO a problem. We cannot omit the fact that regardless if its a SSDR issue or not, that it remains a problem. Your post was well written and well illustrated with your screen grabs and video clip.

What you wrote and how you expressed the issue you are experiencing, does not lend in anyway to the realization that English is not your first language.

The TNF is supposed to do what is expected of it (for those who use it) and any adverse behavior is an issue which should be addressed.

Since this discovery is not unique to your radio, I think that there will be more raised hands asking for it to be resolved.

Take Care.



 

EA4GLI

@John

I am not able to replicate this behavior you are talking about on PowerSDR.

If I left-click on the created TNF on PowerSDR and I keep pressing down on to the left click mouse botton I can move the TNF left and right. And when I move up and down the mouse pointer while pressing the left boton down I can modify the width of the TNF. If you move the mouse down while pressing the TNF could get as narrow as 10Hz which makes the TNF almost "invisible" unless you zoom 2x or 4x.

You can also release the left botton on the mouse, move the pointer back down and press and hold it and move the pointer up to increase the width of the TNF even further.

What might be happening is that you are not moving completely horizontal and the vertical movement of the mouse is changing the width (as it is intended to do).

Is that the case... maybe I am not understanding the part about "drag within the passband"....

John

I will make a video clip qrx a bit.

John

ok, where I went wrong was not knowing about the up/down adjustment. All cleared up, but still would like to just click on the filter and drag it across the pass band without it shrinking in size.

EA4GLI

Actually John, once you get used to the 2 dimensional movement with the mouse you really appreciate how fast it is to set up a TNF as opposed to just moving on the horizontal axle and then having to find the edges to make it wider. In one motion I can select width and location. I really like it.

John

You are correct in that its a swift 360deg movement to resize the filter. I would also like to see them add more filter types such as a string of say 4 side by side or even 10, perhaps from a drop down box. Thanks for the put right about this. I have not used the filters in real anger as yet, but with a datong fl3 auto notch filter in the audio line, I am smiling.

Tim - W4TME

I changed this to a problem and added it to our bug tracker for additional investigation.  Thank you Salvador for a detailed explanation of the issue and how to reproduce it.