Help needed to understand scopesink2

As I increase the frequency of the sine wave to 100kHz, the resolution
I noticed that the scope base class makes references to message
queues; is the discrepancy simply an OS timing issue.

Regards,

Lukasz

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On Fri, Sep 3, 2010 at 5:07 PM, Suleja, Lukasz
[email protected] wrote:

I am using the following code snippet to view a 100kHz sinewave on a virtual
oscilloscope:

self.interface_rate = 1e9
self.src = gr.sig_source_c(self.interface_rate, gr.GR_SIN_WAVE, 1e3, 1)
self.scope = scopesink2.scope_sink_c(panel, sample_rate=self.interface_rate)
self.connect(self.src, self.scope)

As I increase the frequency of the sine wave to 100kHz, the resolution of
the plotted points deteriorates.

With a sampling rate of 1MHz and a sine wave frequency of 100kHz, I would
expect the time interval between plotted point to always be 1us. However, if
I reduce the time-base and select the marker to be “Dot Larg” I can clearly
see that the time-period is not the expected 1us.

Please could some one shed some light on why there appears to be a
discrepancy; or are my expectation just incorrect.

You use sample rate 1e9 = 1 Gsps - I think that’s slightly above what
is possible on standard PC. Maybe that’s just a typo?

Alex

Thanks to Alex for pointing out a mistake in the code snippet, it should
read:

self.interface_rate = 1e6 # i.e. 1 MS/s

Roke Manor Research Ltd, Romsey,
Hampshire, SO51 0ZN, United Kingdom

A Siemens company
Registered in England & Wales at:
Siemens plc, Faraday House, Sir William Siemens Square,
Frimley, Camberley, GU16 8QD. Registered No: 267550

Visit our website at www.roke.co.uk

The information contained in this e-mail and any attachments is
proprietary to Roke Manor Research Ltd and must not be passed to any
third party without permission. This communication is for information
only and shall not create or change any contractual relationship.

Please consider the environment before printing this email
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