Request for NR and NTCH inside AGC loop

[Ignacy]

NR seems to be quite effective but especially for weak signals it drops the signal strength by up to 20db.

NTCH is also outside the AGC loop. I also suggest the following refinements to NTCH:

 - faster or adjustable notch time in automatic mode. Now it takes a second and does not work if the carrier is slowly drifting.
 
- adjustable width in manual mode; e.g., can be adjusted by buttons 1-4
For instance 1=20Hz, 2=50 Hz, 3=..... The current one is 250HZ and is wide.


It may be the same code to put both NR and NTCH into the AGC loop.

Would anyone agree that these features will be worthwhile? For me several times NR 3-3 made a difference between a copy and no copy for weak signals but the volume was too low.

Ignacy, NO9E

[John Lemay]

Ignacy

Maybe your rig has a problem. NR does not affect the signal strength at all.
It does however reduce the audio level, depending on how aggressive the
setting is.

Regards

John G4ZTR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Ignacy
Sent: 15 January 2009 00:49
To: [hidden email]
Subject: [Elecraft] Request for NR and NTCH inside AGC loop


NR seems to be quite effective but especially for weak signals it drops the
signal strength by up to 20db.

NTCH is also outside the AGC loop. I also suggest the following refinements
to NTCH:

 - faster or adjustable notch time in automatic mode. Now it takes a second
and does not work if the carrier is slowly drifting.
 
- adjustable width in manual mode; e.g., can be adjusted by buttons 1-4
For instance 1=20Hz, 2=50 Hz, 3=..... The current one is 250HZ and is wide.


It may be the same code to put both NR and NTCH into the AGC loop.

Would anyone agree that these features will be worthwhile? For me several
times NR 3-3 made a difference between a copy and no copy for weak signals
but the volume was too low.

Ignacy, NO9E




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[Ignacy]

I am not the first one writing that NTCH is outside the AGC loop and that NR reduces the signal strength. With NR, less on strong signals but much on weak signals. For example, signals that are buried in noise seem to be brought to life with NR 3-3 but the AF gain needs to be all the way up, or more.
Ignacy  

<quote author="John Lemay">
Ignacy

Maybe your rig has a problem. NR does not affect the signal strength at all.
It does however reduce the audio level, depending on how aggressive the
setting is.

Regards

John G4ZTR

[Gary, W7TEA]

I've found that adjusting AGC THR makes quite a difference.  I normally have THR at 4 but when I need the NR, I adjust THR to 6 or even 7.  I set NR at 2-1 or 2-2.  With this setting, I normally do not have to turn AF gain up.  

73,  Gary W7TEA



<quote author="Ignacy">
I am not the first one writing that NTCH is outside the AGC loop and that NR reduces the signal strength. With NR, less on strong signals but much on weak signals. For example, signals that are buried in noise seem to be brought to life with NR 3-3 but the AF gain needs to be all the way up, or more.
Ignacy  

John Lemay wrote

Ignacy

Maybe your rig has a problem. NR does not affect the signal strength at all.
It does however reduce the audio level, depending on how aggressive the
setting is.

Regards

John G4ZTR

[Ignacy]

It reminds me of methods to receive weak signals with other radios. Adjust crystal filters for a single peak, reduce RF gain, play with ATT.... K3 makes these steps unnecessary.

All what K3 needs for NR (and NTCH) is to put them inside the AGC loop, like for instance in IC7000.

NR at level 1 or 2 does not reduce the signal strength too much but also does not bring signals out of the mud.

Ignacy

 

<quote author="W7TEA">
I've found that adjusting AGC THR makes quite a difference.  I normally have THR at 4 but when I need the NR, I adjust THR to 6 or even 7.  I set NR at 2-1 or 2-2.  With this setting, I normally do not have to turn AF gain up.  

73,  Gary W7TEA

Ignacy wrote

I am not the first one writing that NTCH is outside the AGC loop and that NR reduces the signal strength. With NR, less on strong signals but much on weak signals. For example, signals that are buried in noise seem to be brought to life with NR 3-3 but the AF gain needs to be all the way up, or more.
Ignacy  

John Lemay wrote

Ignacy

Maybe your rig has a problem. NR does not affect the signal strength at all.
It does however reduce the audio level, depending on how aggressive the
setting is.

Regards

John G4ZTR