P3 Questions concerning measurement

[Fred Atchley]

Hi all. While waiting for the P3 I have a few questions on setup and
measurement. Since I have never used LP pan or similar devices I'll need
some Elmering. Specifically there are two capabilities listed in the
Elecraft P3 page that I need help on:

1.  Adjustable reference level and amplitude range scaling

2.  User calibration of the display to show absolute signal level in dBm

Number 1 suggests two parts. It has an "adjustable reference level".
Question: WRT what reference: 0 dBm, the bottom of the spectrum display
baseline or some particular value? The other part adds "amplitude range
scaling". Is this a separate function or is part 2 the conclusion of the
process?

My second question concerns the use of the absolute signal level in dBm. If
I am assisting a Ham friend in adjusting his signal, will this capability
allow me to evaluate such things as his BW and compression? I know that I
can do that now by ear but will the P3 give me a visual clue WRT onset of
changes over-the-air? I have an HP Spectrum Analyzer that I have used to
check my own K3 on- the-bench. So the phrase "over-the-air" is the big
question.  

These questions do not pertain to the main reason I am looking forward to
the P3 (I.e. operating) but rather to the "other" useful possibilities. I
appreciate the group's Elmering.

73, Fred, AE6IC, K3 #2241, P3 #?

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[Alan Bloom-2]

Hi Fred,

The amplitude scale on the P3 shows the signal level in dBm at the K3's
antenna connector.  As the K3 attenuator and preamp are turned on or
off, the P3 automatically adjusts its internal gain so the display
always reads the correct signal level.

The reference level and scale can be adjusted from the P3 front panel.
"Reference level" is the level in dBm at the bottom of the display.
"Scale" is the difference in dB between the top and bottom of the
display.  So, for example, if the REF LVL is -120 dBm and the SCALE is
80 dB, then signal levels between -40 dBm and -120 dBm can be seen.

One complicating factor is that the P3 automatically adjusts its DSP
sample rate proportional to the frequency span.  As a consequence, the
noise level drops as you narrow the span.  (That works both for thermal
noise and band noise coming in the antenna.)  There is a MENU option to
have the REF LVL change automatically as you vary the span to keep the
noise level at the same point on the display.  In this way you always
get the best possible dynamic range.

On my "to-do" list is to add a calibration routine, similar to the
S-meter calibration in the K3.  The signal level at the K3's IF output
connector changes somewhat from band to band and from unit to unit.  The
accuracy should be plenty good enough for giving signal reports on the
air, but for those who want to do more accurate measurements it would be
nice to be able to calibrate it.  Even without calibration, the RELATIVE
amplitude accuracy is excellent, limited only by the display resolution.
So if you tell Alex that his signal is 7 dB weaker than Monica's, he
will have no grounds for argument.  :=)

73,

Alan N1AL



On Sun, 2010-05-02 at 13:12 -0700, Fred Atchley wrote:

> Hi all. While waiting for the P3 I have a few questions on setup and
> measurement. Since I have never used LP pan or similar devices I’ll
> need some Elmering. Specifically there are two capabilities listed in
> the Elecraft P3 page that I need help on:
>
> 1.  Adjustable reference level and amplitude range scaling
>
> 2.  User calibration of the display to show absolute signal level in
> dBm
>
> Number 1 suggests two parts. It has an “adjustable reference level”.
> Question: WRT what reference: 0 dBm, the bottom of the spectrum
> display baseline or some particular value? The other part adds
> “amplitude range scaling”. Is this a separate function or is part 2
> the conclusion of the process?
>
> My second question concerns the use of the absolute signal level in
> dBm. If I am assisting a Ham friend in adjusting his signal, will this
> capability allow me to evaluate such things as his BW and compression?
> I know that I can do that now by ear but will the P3 give me a visual
> clue WRT onset of changes over-the-air? I have an HP Spectrum Analyzer
> that I have used to check my own K3 on- the-bench. So the phrase
> “over-the-air” is the big question.  
>
> These questions do not pertain to the main reason I am looking forward
> to the P3 (I.e. operating) but rather to the “other” useful
> possibilities. I appreciate the group’s Elmering.
>
> 73, Fred, AE6IC, K3 #2241, P3 #?
>
>

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[juergen piezo]

Hi Alan

Does the P3 also have a "peak hold" function? How does the P3 integrate with the K3 for transmit signal monitoring? How many markers can you set  and are the markers smart indicating peak or average values?

I am using a Perseus with Linrad in "TX TEST" mode, its excellent.
If the P3 can emulate some  of Linrads TX Test mode functionality it would be a  mandatory test tool for every ham station. I like the ability to monitor simultaneously average and peak signal traces in Linrad.

Anything that extends the P3's functionality beyond a simple panadapter would make it an attractive option. The pricing is  very close to the Perseus price. People will have to think hard and long about its purchase if the functionality is lacking  and they do want to go beyond a simple panadapter

John

--- On Sun, 5/2/10, Alan Bloom <[hidden email]> wrote:

> From: Alan Bloom <[hidden email]>
> Subject: Re: [Elecraft] P3 Questions concerning measurement
> To: "Fred Atchley" <[hidden email]>
> Cc: [hidden email]
> Date: Sunday, May 2, 2010, 5:44 PM
> Hi Fred,
>
> The amplitude scale on the P3 shows the signal level in dBm
> at the K3's
> antenna connector.  As the K3 attenuator and preamp
> are turned on or
> off, the P3 automatically adjusts its internal gain so the
> display
> always reads the correct signal level.
>
> The reference level and scale can be adjusted from the P3
> front panel.
> "Reference level" is the level in dBm at the bottom of the
> display.
> "Scale" is the difference in dB between the top and bottom
> of the
> display.  So, for example, if the REF LVL is -120 dBm
> and the SCALE is
> 80 dB, then signal levels between -40 dBm and -120 dBm can
> be seen.
>
> One complicating factor is that the P3 automatically
> adjusts its DSP
> sample rate proportional to the frequency span.  As a
> consequence, the
> noise level drops as you narrow the span.  (That works
> both for thermal
> noise and band noise coming in the antenna.)  There is
> a MENU option to
> have the REF LVL change automatically as you vary the span
> to keep the
> noise level at the same point on the display.  In this
> way you always
> get the best possible dynamic range.
>
> On my "to-do" list is to add a calibration routine, similar
> to the
> S-meter calibration in the K3.  The signal level at
> the K3's IF output
> connector changes somewhat from band to band and from unit
> to unit.  The
> accuracy should be plenty good enough for giving signal
> reports on the
> air, but for those who want to do more accurate
> measurements it would be
> nice to be able to calibrate it.  Even without
> calibration, the RELATIVE
> amplitude accuracy is excellent, limited only by the
> display resolution.
> So if you tell Alex that his signal is 7 dB weaker than
> Monica's, he
> will have no grounds for argument.  :=)
>
> 73,
>
> Alan N1AL
>
>
>
> On Sun, 2010-05-02 at 13:12 -0700, Fred Atchley wrote:
> > Hi all. While waiting for the P3 I have a few
> questions on setup and
> > measurement. Since I have never used LP pan or similar
> devices I’ll
> > need some Elmering. Specifically there are two
> capabilities listed in
> > the Elecraft P3 page that I need help on:
> >
> > 1.  Adjustable reference level and amplitude
> range scaling
> >
> > 2.  User calibration of the display to show
> absolute signal level in
> > dBm
> >
> > Number 1 suggests two parts. It has an “adjustable
> reference level”.
> > Question: WRT what reference: 0 dBm, the bottom of the
> spectrum
> > display baseline or some particular value? The other
> part adds
> > “amplitude range scaling”. Is this a separate
> function or is part 2
> > the conclusion of the process?
> >
> > My second question concerns the use of the absolute
> signal level in
> > dBm. If I am assisting a Ham friend in adjusting his
> signal, will this
> > capability allow me to evaluate such things as his BW
> and compression?
> > I know that I can do that now by ear but will the P3
> give me a visual
> > clue WRT onset of changes over-the-air? I have an HP
> Spectrum Analyzer
> > that I have used to check my own K3 on- the-bench. So
> the phrase
> > “over-the-air” is the big question. 
> >
> > These questions do not pertain to the main reason I am
> looking forward
> > to the P3 (I.e. operating) but rather to the
> “other” useful
> > possibilities. I appreciate the group’s Elmering.
> >
> > 73, Fred, AE6IC, K3 #2241, P3 #?
> >
> >
>
>
> ______________________________________________________________
> 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

     
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[Geoffrey Mackenzie-Kennedy]

Hi John,

Indeed it would.

The only and very small nit-pick I have about Perseus is that I wish that it
had more than the 4 markers available, at times I could use more markers
when using it as a Spectrum Analyser.

In case you have not seen it, the May 2010 issue of Radcom includes a review
of Perseus by Peter Hart, G3SJX.

73,
Geoff
GM4ESD



From: "juergen" <[hidden email]>
Sent: Monday, May 03, 2010 10:52 AM

> Anything that extends the P3's functionality beyond a simple panadapter
> would make it an attractive option. The pricing is  very close to the
> Perseus price. People will have to think hard and long about its purchase
> if the functionality is lacking  and they do want to go beyond a simple
> panadapter







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[Eric Swartz - WA6HHQ]

Yes it does.
73,Eric  WA6HHQ
--

On 5/3/2010 2:52 AM, juergen wrote:
> Hi Alan
>
> Does the P3 also have a "peak hold" function?
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[Alan Bloom-2]

Hi John,

As you might imagine for a former Agilent/HP design engineer, I have all
kinds of grandiose fantasies about adding test equipment features to the
P3.  But panadapter operation comes first and I expect I'll be working
on that for some time.  

> Does the P3 also have a "peak hold" function?

Yes.  It's a MENU selection, but you can assign it to a
programmable-function key so you can toggle it on and off with a
keystroke.  Averaging is available also.  It has its own dedicated
front-panel key function.

Alan


On Mon, 2010-05-03 at 02:52 -0700, juergen wrote:

> Hi Alan
>
> Does the P3 also have a "peak hold" function? How does the P3 integrate with the K3 for transmit signal monitoring? How many markers can you set  and are the markers smart indicating peak or average values?
>
> I am using a Perseus with Linrad in "TX TEST" mode, its excellent.
> If the P3 can emulate some  of Linrads TX Test mode functionality it would be a  mandatory test tool for every ham station. I like the ability to monitor simultaneously average and peak signal traces in Linrad.
>
> Anything that extends the P3's functionality beyond a simple panadapter would make it an attractive option. The pricing is  very close to the Perseus price. People will have to think hard and long about its purchase if the functionality is lacking  and they do want to go beyond a simple panadapter
>
> John
>
> --- On Sun, 5/2/10, Alan Bloom <[hidden email]> wrote:
>
> > From: Alan Bloom <[hidden email]>
> > Subject: Re: [Elecraft] P3 Questions concerning measurement
> > To: "Fred Atchley" <[hidden email]>
> > Cc: [hidden email]
> > Date: Sunday, May 2, 2010, 5:44 PM
> > Hi Fred,
> >
> > The amplitude scale on the P3 shows the signal level in dBm
> > at the K3's
> > antenna connector.  As the K3 attenuator and preamp
> > are turned on or
> > off, the P3 automatically adjusts its internal gain so the
> > display
> > always reads the correct signal level.
> >
> > The reference level and scale can be adjusted from the P3
> > front panel.
> > "Reference level" is the level in dBm at the bottom of the
> > display.
> > "Scale" is the difference in dB between the top and bottom
> > of the
> > display.  So, for example, if the REF LVL is -120 dBm
> > and the SCALE is
> > 80 dB, then signal levels between -40 dBm and -120 dBm can
> > be seen.
> >
> > One complicating factor is that the P3 automatically
> > adjusts its DSP
> > sample rate proportional to the frequency span.  As a
> > consequence, the
> > noise level drops as you narrow the span.  (That works
> > both for thermal
> > noise and band noise coming in the antenna.)  There is
> > a MENU option to
> > have the REF LVL change automatically as you vary the span
> > to keep the
> > noise level at the same point on the display.  In this
> > way you always
> > get the best possible dynamic range.
> >
> > On my "to-do" list is to add a calibration routine, similar
> > to the
> > S-meter calibration in the K3.  The signal level at
> > the K3's IF output
> > connector changes somewhat from band to band and from unit
> > to unit.  The
> > accuracy should be plenty good enough for giving signal
> > reports on the
> > air, but for those who want to do more accurate
> > measurements it would be
> > nice to be able to calibrate it.  Even without
> > calibration, the RELATIVE
> > amplitude accuracy is excellent, limited only by the
> > display resolution.
> > So if you tell Alex that his signal is 7 dB weaker than
> > Monica's, he
> > will have no grounds for argument.  :=)
> >
> > 73,
> >
> > Alan N1AL
> >
> >
> >
> > On Sun, 2010-05-02 at 13:12 -0700, Fred Atchley wrote:
> > > Hi all. While waiting for the P3 I have a few
> > questions on setup and
> > > measurement. Since I have never used LP pan or similar
> > devices I’ll
> > > need some Elmering. Specifically there are two
> > capabilities listed in
> > > the Elecraft P3 page that I need help on:
> > >
> > > 1.  Adjustable reference level and amplitude
> > range scaling
> > >
> > > 2.  User calibration of the display to show
> > absolute signal level in
> > > dBm
> > >
> > > Number 1 suggests two parts. It has an “adjustable
> > reference level”.
> > > Question: WRT what reference: 0 dBm, the bottom of the
> > spectrum
> > > display baseline or some particular value? The other
> > part adds
> > > “amplitude range scaling”. Is this a separate
> > function or is part 2
> > > the conclusion of the process?
> > >
> > > My second question concerns the use of the absolute
> > signal level in
> > > dBm. If I am assisting a Ham friend in adjusting his
> > signal, will this
> > > capability allow me to evaluate such things as his BW
> > and compression?
> > > I know that I can do that now by ear but will the P3
> > give me a visual
> > > clue WRT onset of changes over-the-air? I have an HP
> > Spectrum Analyzer
> > > that I have used to check my own K3 on- the-bench. So
> > the phrase
> > > “over-the-air” is the big question.  
> > >
> > > These questions do not pertain to the main reason I am
> > looking forward
> > > to the P3 (I.e. operating) but rather to the
> > “other” useful
> > > possibilities. I appreciate the group’s Elmering.
> > >
> > > 73, Fred, AE6IC, K3 #2241, P3 #?
> > >
> > >
> >
> >
> > ______________________________________________________________
> > 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
>
>
>      

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