Re: [Elecraft] KX3 - dBV question

2014-10-23 Thread Lyle Johnson

Hallo Ralf!

Yes.

The measurements are taken post-filter and post-AGC.

73,

Lyle KK7P

Hi Lyle,

So I actually measure a quantity that is proportional to the energy (signal + noise) that 
has been collected in the display update time, am I getting this right?

Greetings

Ralf, DL6OAP



Am 20.10.2014 um 14:31 schrieb Lyle


The DSP uses audio samples at a 12 kHz rate and performs a true RMS calculation 
on the samples.  The result is computed over the display update time (1 
second?) the buffer flushed and the process repeated..

73,

Lyle KK7P


... but am not sure, if I can
compare the values directly, since I do not know how the data is being
generated and processed. Maybe someone on the list or at Elecraft can help
me out.


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Re: [Elecraft] KX3 - dBV question

2014-10-20 Thread Lyle
The DSP uses audio samples at a 12 kHz rate and performs a true RMS calculation 
on the samples.  The result is computed over the display update time (1 
second?) the buffer flushed and the process repeated..

73,

Lyle KK7P

 ... but am not sure, if I can
 compare the values directly, since I do not know how the data is being
 generated and processed. Maybe someone on the list or at Elecraft can help
 me out.
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Re: [Elecraft] KX3 - dBV question

2014-10-20 Thread Ralf Wilhelm
Hi Lyle,

So I actually measure a quantity that is proportional to the energy (signal + 
noise) that has been collected in the display update time, am I getting this 
right?

Greetings

Ralf, DL6OAP



Am 20.10.2014 um 14:31 schrieb Lyle

 The DSP uses audio samples at a 12 kHz rate and performs a true RMS 
 calculation on the samples.  The result is computed over the display update 
 time (1 second?) the buffer flushed and the process repeated..
 
 73,
 
 Lyle KK7P
 
 ... but am not sure, if I can
 compare the values directly, since I do not know how the data is being
 generated and processed. Maybe someone on the list or at Elecraft can help
 me out.
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Re: [Elecraft] KX3 - dBV question

2014-10-20 Thread Matt Zilmer
Hi Ralf,

Lyle explained how the dBV value is derived.  It's a pretty useful
measurement.

One way to use it is to disable AGC, then measure different signal
levels.  This makes dBV a linear measurement, up until the signal
level causes hardware AGC to activate.  

Be cautious with your hearing when AGC is disabled.

73,
matt
W6NIA

On Mon, 20 Oct 2014 01:45:24 -0700 (PDT), you wrote:

Hi,

I have been playing around with the dBV-Feature of my KX3 for some time. I
understood how to use it and that it measures a relative input level into
the AF stage of the KX3, but my question is if there is any kind of data
processing involved, in other words: the display is updated roughly once in
a second, and my question is if is the input level to the AF stage just
being sampled once a second, is the value being displayed something like the
peak level that occured during this one second interval between two updates
of the value or is something like the average of the signal level during
this second being displayed?

We have been discussing the system advantage of CW compared to SSB in the
german QRP facebook group, I tried to measure my personal ability to copy
weak SSB and CW signals by using this dBV display, but am not sure, if I can
compare the values directly, since I do not know how the data is being
generated and processed. Maybe someone on the list or at Elecraft can help
me out.


Vy 73

Ralf, DL6OAP
Matt Zilmer, W6NIA
--
Give me six hours to chop down a tree and I will
spend the first four sharpening the axe. -A. Lincoln
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