'Counts' in WX Scope Plot

The vertical axis in Scope Plot is labelled as Counts. What does it
mean? How
is it related to the physical parameters of the signal like
amplitude/power?


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Hi Joseph (hope that’s the right name, if not, please correct me :wink: ),

well, GNU Radio is software defined radio; the data it processes are
simply numbers, so its unit is 1.
If your signal comes from an ADC, then it might be proportional to
Volts at the receiver; however, you usually do a lot of processing after
receiving, so using Volts as a unit is kind of wrong, because none of
the components consider these numbers to represent a voltage. If you
happen to square your signal, the display would be proportional to
power, instead, so there’s no way to tell you "the scope sink displays
physical entity "; it all depends on what you let it display.

I hope that helped a little,

Greetings,
Marcus M.

On Wed, Jul 9, 2014 at 11:09 AM, jsam45 [email protected]
wrote:

The vertical axis in Scope Plot is labelled as Counts. What does it mean? How
is it related to the physical parameters of the signal like amplitude/power?

It’s dependent on your hardware.

Basically ‘count’ is just the raw value and what that value means is
whatever the source block returned. It can be normalized between -1.0
and 1.0 or represent the raw adc value, and then what voltage the
represents depends on the ADC reference used in your hw. What power it
represent at the input depends on the total gain in the rx chain from
input to ADC …

All of that is out-of-scope for GR, you have to calibrate it out if
you want absolute/known units.

Cheers,

Sylvain

I think ‘Magnitude’ is better than counts, which is just confusing.

On 07/10/2014 05:33 AM, Vanush V. wrote:

I think ‘Magnitude’ is better than counts, which is just confusing.

There’s a difference: ‘Counts’ implies the digital nature of the signal,
and ‘Magnitude’ cannot be negative. ‘Amplitude’ would work, but again,
that doesn’t imply amplitude-discrete steps.

M

On Thu, Jul 10, 2014 at 5:23 AM, Martin B. [email protected]
wrote:

On 07/10/2014 05:33 AM, Vanush V. wrote:

I think ‘Magnitude’ is better than counts, which is just confusing.

There’s a difference: ‘Counts’ implies the digital nature of the signal,
and ‘Magnitude’ cannot be negative. ‘Amplitude’ would work, but again,
that doesn’t imply amplitude-discrete steps.

M

I generally agree with Martin, though I’m also generally not pedantic
about
this sort of thing. One issue to point out here, though, is that you
/can/
change this. If you open up the options of the scope sink, the last
parameter is “Y Axis Label” and you can set it to whatever unit you
like.
“Monkeys”, for example.

Tom

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