Scanning and channel hopping question...

[WD4SDC]

Hi All,

I've been gathering information on the scanning feature of the KX3 (not an owner......yet - VERY tempting).
I have the basics - VFO scan, channel hopping, live scan, muted scan, the rules for channel hopping.
I found this:

"Scanning while muted (normal scanning mode)
allows the K3 to ignore stable carriers, unmuting
only when "interesting" signals are found."

...from the K3 manual - which appears to be a close DSP cousin to the KX3, and I've also found some scattered bits about the KX3 that refers to stopping when a "modulated signal" is found.  So, what exactly triggers a stop scan?  It seems to be a bit more sophisticated then just an S meter threshold - maybe using the AFV measurement?.  Is the scan signal detection done after signal processing like noise blanking, noise reduction, notch, etc?  That would make it REALLY good at scanning HF !

After scan stops on a signal, does it pause until the signal stops, or does it continue after some fixed time?

What is the scan (hopping) rate.  I see that in VFO scan you can make it effectively slow or fast by changing the increment step - , but in channel hop, the "increment" is one hop - just not clear on the hops per second.

And finally....how does the scanning stop/resume sequence work?
When a signal is detected, the scanning pauses for some interval, then resumes when the signal stops? Or after a time interval if the signal is still there it continues scanning until it hits the active channel again?

I know these are very narrow questions about a radio that has a LOT of capabilities, and maybe I'm the only guy that wants to know this....but at least if I ask it here, then the one other person that may be looking will find it here;)  I've used (channel) scanning on HF quite a bit.  Very useful now that VFOs are rock solid and tune in milliseconds.

Thanks to all on the site for LOTS of other very useful questions/answers/ideas.

Steve
WD4SDC

[wayne burdick]

> "Scanning while muted (normal scanning mode)
> allows the K3 to ignore stable carriers, unmuting
> only when "interesting" signals are found."

If the signal appears to be an unmodulated carrier, i.e. with little amplitude variation over a period of about 1 second, then it is skipped. Noise can fool the algorithm sometimes, of course.

There's actually a variable in the source code called "scanWorthy" that accrues intel about the signal :)


> ...from the K3 manual - which appears to be a close DSP cousin to the KX3,
> and I've also found some scattered bits about the KX3 that refers to
> stopping when a "modulated signal" is found.  So, what exactly triggers a
> stop scan?

It stops on any signal with a certain S+N/N ratio, then evaluates it as described above.


> Is the scan signal detection
> done after signal processing like noise blanking, noise reduction, notch,
> etc?  That would make it REALLY good at scanning HF !

Yes and yes. It's really useful for discovering signals on a "dead" band (they seldom are truly dead, you will discover).


> After scan stops on a signal, does it pause until the signal stops, or does
> it continue after some fixed time?

The latter. If the signal is "interesting" it will unmute the receiver and pause a lot longer.


> I see that in VFO scan you can make it
> effectively slow or fast by changing the increment step - , but in channel
> hop, the "increment" is one hop - just not clear on the hops per second.

I believe it's two hops per second if you use "live scan" (continuous, and unmuted) and 5 hops per second with regular scanning/hopping (muted).


> And finally....how does the scanning stop/resume sequence work?
> When a signal is detected, the scanning pauses for some interval, then
> resumes when the signal stops? Or after a time interval if the signal is
> still there it continues scanning until it hits the active channel again?

All of the above. It's not using AI or anything -- just simple rules -- and it will produce consistent results most of the time.


> I've used (channel) scanning on HF quite a bit.  Very useful
> now that VFOs are rock solid and tune in milliseconds.

As the guy who wrote the firmware, I'm happy to find that someone else finds it useful, *and* is curious about how it works. Thanks.

The K2 has the same scanning feature, by the way.

Wayne
N6KR



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[Bob-5]

I have been a devoted reader of the Reflector and can say in one word my
thoughts on Wayne's explanation: IMPRESSIVE.  Makes me want to buy another
K rig.  The openness of explanation and willingness to hear the thoughts of
others like us (some profound and some not so) on the Reflector is
legendary.  Hope that this company stays around forever so my grandson can
have the chance to buy an Elecraft.

Bob, NT6Y

On Fri, Dec 5, 2014 at 4:50 PM, Wayne Burdick <[hidden email]> wrote:

> > "Scanning while muted (normal scanning mode)
> > allows the K3 to ignore stable carriers, unmuting
> > only when "interesting" signals are found."
>
> If the signal appears to be an unmodulated carrier, i.e. with little
> amplitude variation over a period of about 1 second, then it is skipped.
> Noise can fool the algorithm sometimes, of course.
>
> There's actually a variable in the source code called "scanWorthy" that
> accrues intel about the signal :)
>
>
> > ...from the K3 manual - which appears to be a close DSP cousin to the
> KX3,
> > and I've also found some scattered bits about the KX3 that refers to
> > stopping when a "modulated signal" is found.  So, what exactly triggers a
> > stop scan?
>
> It stops on any signal with a certain S+N/N ratio, then evaluates it as
> described above.
>
>
> > Is the scan signal detection
> > done after signal processing like noise blanking, noise reduction, notch,
> > etc?  That would make it REALLY good at scanning HF !
>
> Yes and yes. It's really useful for discovering signals on a "dead" band
> (they seldom are truly dead, you will discover).
>
>
> > After scan stops on a signal, does it pause until the signal stops, or
> does
> > it continue after some fixed time?
>
> The latter. If the signal is "interesting" it will unmute the receiver and
> pause a lot longer.
>
>
> > I see that in VFO scan you can make it
> > effectively slow or fast by changing the increment step - , but in
> channel
> > hop, the "increment" is one hop - just not clear on the hops per second.
>
> I believe it's two hops per second if you use "live scan" (continuous, and
> unmuted) and 5 hops per second with regular scanning/hopping (muted).
>
>
> > And finally....how does the scanning stop/resume sequence work?
> > When a signal is detected, the scanning pauses for some interval, then
> > resumes when the signal stops? Or after a time interval if the signal is
> > still there it continues scanning until it hits the active channel again?
>
> All of the above. It's not using AI or anything -- just simple rules --
> and it will produce consistent results most of the time.
>
>
> > I've used (channel) scanning on HF quite a bit.  Very useful
> > now that VFOs are rock solid and tune in milliseconds.
>
> As the guy who wrote the firmware, I'm happy to find that someone else
> finds it useful, *and* is curious about how it works. Thanks.
>
> The K2 has the same scanning feature, by the way.
>
> Wayne
> N6KR
>
>
>
> ______________________________________________________________
> Elecraft mailing list
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> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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[WD4SDC]

>There's actually a variable in the source code called "scanWorthy" that accrues intel about the signal :)

Info at the speed of NOW - and from the guy who wrote the code, no less.  And I agree w/ NT6Y - it is impressive.  

>As the guy who wrote the firmware, I'm happy to find that someone else finds it useful, *and* is curious about how it >works. Thanks.

I think my curiosity has exceeded threshold and I'll have to become a customer.   I'm looking forward to being a happy user of your scanWorthy variable;)  

I think you guys have put the "art" back in state-of-the-art.

Steve.


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