Elecraft

A very desirable capability

Classic

List

Threaded

7 messages Options

Peter Alterman

A very desirable capability

Reading Drew's (AF2Z's) comment,

"The single most important feature that would get me to spring for a K4
would be advanced noise abatement controls. I have little idea how the
NR & NB work, but strictly from the user standpoint instead of scrolling
through a small assortment of fixed presets I envision several
continuously variable controls that would allow us to adjust the several
noise limiting parameters. Perhaps having some kind of graphical display
showing a dimensional representation of the noise parameter space and
the noise itself would help in zeroing in on the best noise reduction..."

I wondered if such a graphical capability couldn't be created in software for the current set of Elecraft radios?
That would be a great way to make the NB/NR capabilities of the current radios much more user friendly.

regards,

Peter W2CDO

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

efortner

Re: A very desirable capability

I agree 100%

Earl, K4KAY

To: [hidden email]
Subject: [Elecraft] A very desirable capability

Reading Drew's (AF2Z's) comment,

"The single most important feature that would get me to spring for a K4
would be advanced noise abatement controls. I have little idea how the
NR & NB work, but strictly from the user standpoint instead of scrolling
through a small assortment of fixed presets I envision several
continuously variable controls that would allow us to adjust the several
noise limiting parameters. Perhaps having some kind of graphical display
showing a dimensional representation of the noise parameter space and
the noise itself would help in zeroing in on the best noise reduction..."

I wondered if such a graphical capability couldn't be created in software
for the current set of Elecraft radios?
That would be a great way to make the NB/NR capabilities of the current
radios much more user friendly.

regards,

Peter W2CDO

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Don Wilhelm

Re: A very desirable capability

In reply to this post by Peter Alterman

Peter,

Since "one size" does not fit all noise sources, I believe that what you
suggest is not practical.
It may be that something could be done to provide the most useful noise
reduction for "average noise", but the closest to that right now would
be the default settings in the K3/K3S.

If you do not know what the default settings are, save your K3/K3S
configuration, then do an EEINIT (Reset to Factory Defaults), then look
at the NB and NR settings. Finally load the saved configuration file
and then set the NB and NR settings to the defaults that you recorded.
Be aware that some of the settings are per band, so you will have to
check them on each band.

That will give you a "one button" NB and NR as you might find in many
other amateur transceivers.

I am glad that the K3/K3S offers adjustability for the NB and NR
parameters. It does take some study to learn how to use the parameters
provided, but if you do that study, you will be rewarded with good noise
reduction for most any type of noise.

73,
Don W3FPR

On 8/22/2017 4:07 PM, Peter Alterman wrote:

> Reading Drew's (AF2Z's) comment,
>
> "The single most important feature that would get me to spring for a K4
> would be advanced noise abatement controls. I have little idea how the
> NR & NB work, but strictly from the user standpoint instead of scrolling
> through a small assortment of fixed presets I envision several
> continuously variable controls that would allow us to adjust the several
> noise limiting parameters. Perhaps having some kind of graphical display
> showing a dimensional representation of the noise parameter space and
> the noise itself would help in zeroing in on the best noise reduction..."

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Bob McGraw - K4TAX

Re: A very desirable capability

One point I've observed is the fact the noise on a given band may not be
the same from day to day, or week to week. Thus I find it necessary to
tweak the values of NR and NB for best performance. Same issues with
band to band, i.e. what I need on 80M is no where close to what I need
on 6M in terms of NR and NB. And, the NR and NB are very different in
their performance character in terms of handling noise artifacts.

One thing that also helps is to use minimum necessary RF gain and
correct utilization of Attenuation. Thus on 160M and 80M and to some
extent 40M, I use 15 dB Attenuation and reduce the RF gain a wee bit.
In doing so, the signals pop out of the noise.

A point to consider is optimum receiver performance occurs when the band
noise floor is 10 dB to 15 dB above the receiver noise floor. Since we
can't really change the receiver noise floor, we must change what is
arriving at the front end. This means some degree of attenuation and RF
Gain reduction is required. For the math.......if no signal band noise
is -97 dBm or S-5 and the receiver noise floor is - 125 dBm, a
difference of 28 dB, the receiver should have 15 dB of attenuation
activated. You can do the same with the RF Gain by reducing it about 3
or 4 S units. Too much RF gain being utilized in an attempt to hear weak
signals is not necessarily a good thing. As one goes higher in
frequency, usually band noise decreases and finally to a point where the
PRE should be used. In many cases I've heard hams describe the use of
ATTN is to prevent receiver overload. While true under some cases, most
residential QTH locations and antennas won't encounter enough signal to
overload the receiver. Thus the ATTN function is more beneficial when
used in correct receiving gain structure.

73

Bob, K4TAX

On 8/22/2017 4:11 PM, Don Wilhelm wrote:

> Peter,
>
> Since "one size" does not fit all noise sources, I believe that what
> you suggest is not practical.
> It may be that something could be done to provide the most useful
> noise reduction for "average noise", but the closest to that right now
> would be the default settings in the K3/K3S.
>
> If you do not know what the default settings are, save your K3/K3S
> configuration, then do an EEINIT (Reset to Factory Defaults), then
> look at the NB and NR settings. Finally load the saved configuration
> file and then set the NB and NR settings to the defaults that you
> recorded. Be aware that some of the settings are per band, so you will
> have to check them on each band.
>
> That will give you a "one button" NB and NR as you might find in many
> other amateur transceivers.
>
> I am glad that the K3/K3S offers adjustability for the NB and NR
> parameters. It does take some study to learn how to use the
> parameters provided, but if you do that study, you will be rewarded
> with good noise reduction for most any type of noise.
>
> 73,
> Don W3FPR

alorona

Re: A very desirable capability

Once again, a beautiful post by Bob. His description suggests a feature that could be put into any new transceiver.
Imagine a graphical depiction of Bob's scenario below on the color screen of the radio which would help you optimize the placement of the dynamic range of the radio with respect to the band noise. A simple vertical graph, showing measured band noise floor at the bottom and a vertical axis calibrated in dBm, with a movable rectangular "window" shaded with a color that moves up and down according to the setting of the RF Gain, Atten, and Preamp of the radio.
Maybe this already exists in one of the fancy SDR radios and I don't know about it? But it seems to me that this would be a great aid to visualizing where the dynamic range of the radio is set. If too much of the colored window I'm talking about is below the band noise, it would be obvious that reducing gain or adding attenuation would optimize the dynamic range without sacrificing sensitivity -- a concept that many hams have difficulty understanding.

In the K3, for example, the shaded rectangle would have a fixed height of about 104 dB, the dynamic range of the receiver. As you decreased the RF Gain, that window would move up, and as you increased RF Gain it would move down. Turn on the ATT and the window jumps up by 10 dB. Turn on the preamp and the window jumps down by whatever the gain of the preamp is. According to Bob's excellent description you want the bottom of the window to be about 10 dB below the noise floor, but no lower. Think of how easy it would be to adjust your controls if you could *see* what's happening on the screen of the P3. Those of us with "preampitis" would finally realize that the preamp is unnecessary in many situations.

The key to this would be to give the receiver the ability to measure the current noise floor in dBm so it could be plotted on the screen, showing the operator the noise floor in real time, and for the receiver to know at all times what its maximum signal level handling point is. The P3, of course, already measures noise floor; maybe each receiver would need a pre-measured dynamic range burned into a ROM at the factory. But I don't even think that's necessary... some nominal window height as I mentioned earlier would probably be good enough, plus or minus a couple of dB.

R,
Al W6LX
___________________________________________________________________

One thing that also helps is to use minimum necessary RF gain and
correct utilization of Attenuation. Thus on 160M and 80M and to some
extent 40M, I use 15 dB Attenuation and reduce the RF gain a wee bit.
In doing so, the signals pop out of the noise.

A point to consider is optimum receiver performance occurs when the band
noise floor is 10 dB to 15 dB above the receiver noise floor. Since we
can't really change the receiver noise floor, we must change what is
arriving at the front end. This means some degree of attenuation and RF
Gain reduction is required. For the math.......if no signal band noise
is -97 dBm or S-5 and the receiver noise floor is - 125 dBm, a
difference of 28 dB, the receiver should have 15 dB of attenuation
activated. You can do the same with the RF Gain by reducing it about 3
or 4 S units. Too much RF gain being utilized in an attempt to hear weak
signals is not necessarily a good thing. As one goes higher in
frequency, usually band noise decreases and finally to a point where the
PRE should be used. In many cases I've heard hams describe the use of
ATTN is to prevent receiver overload. While true under some cases, most
residential QTH locations and antennas won't encounter enough signal to
overload the receiver. Thus the ATTN function is more beneficial when
used in correct receiving gain structure.

73

Bob, K4TAX

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Mike Markowski-2

Re: A very desirable capability

Bob K4TAX,

Why 10 to 15 dB above - is your idea to have some margin for band noise
floor changes? It seems you'd maximize dynamic range by making the two
equal.

Tnx es 73,
Mike ab3ap

On 08/26/2017 03:36 PM, Al Lorona wrote:

> Once again, a beautiful post by Bob. [...]
>
> R, Al W6LX
> ___________________________________________________________________
>
> [...] A point to consider is optimum receiver performance occurs when the
> band noise floor is 10 dB to 15 dB above the receiver noise floor. [...]
>
> 73
> Bob, K4TAX

Bob McGraw - K4TAX

Re: A very desirable capability

Most legacy receivers are designed for 10 meters. Within this point,
this generally says the receiver gain on lower frequencies is somewhat
excessive. Plus typical of most environments, the band noise increases
as frequency decreases. Additionally, the ear has the ability to easily
discern two signals, one being noise, with a 10 dB differential. With
hearing, if two signals are of equal level, the signal of the higher
frequency component will sound louder. Usually this is the noise
component. Thus we desire to make a difference for ease of hearing.
As to the physics of the receiver, anytime gain is added there is also
some noise component added.

I have had in-depth discussion with the likes of Rob Sherwood on the
topic. Part of this has to do with "is your antenna adequate to allow
weak signal copy". {Topic for different discussion.} Also having been
involved with another company that made ham radio products for 40+
years, I've had in-depth discussions with their engineering staff
regarding optimization of receiver performance. The general approach is
to add attenuation as needed and or reduce RF gain and the signal will
pop out of the noise. From these sources, the 10 dB to 15 dB number
seems to always come to the forefront of the discussion.

Here is a quote from my files:

<snip>

If receiver noise floor is 10 dB below band noise, the receiver is
contributing less than 0.5 dB of the total noise.

Band noise varies by band over 30 dB, 160-10 meters. It also varies by
direction and time of day, plus what the sun is doing. In an noisy urban
environment it is anybody's guess as to your band noise level.

A simple test is to see how much the noise coming out your speaker
increases when you switch between a dummy load and your antenna, when
tuned to a dead spot on the band.

Example on 10 meters at my rural QTH, IC-756 Pro III: preamp OFF, noise
goes up 3 dB. That means the receiver is contributing half the noise.
Preamp 1 ON, band noise goes up 9.5 dB.

Almost all legacy receivers are designed for 10 meters, and attenuation
is desirable on the low HF bands. Most SDR receivers have a preamp in
the circuit all the time to buffer the antenna connection to the ADC.
The Flex 6000 radios can have the preamp out of the circuit, and will
need the preamp enabled on some bands at certain times of day.

If you can barely hear your antenna connect, you are not going to hear
weak signals.

<snip>

73

Bob, K4TAX

On 8/26/2017 3:01 PM, Mike Markowski wrote:
> Bob K4TAX,
>
> Why 10 to 15 dB above - is your idea to have some margin for band
> noise floor changes? It seems you'd maximize dynamic range by making
> the two equal.
>
> Tnx es 73,
> Mike ab3ap

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]