RE: [Discuss-gnuradio] Help needed to understand scopesink2
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 ~ ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Help needed to understand scopesink2
On Fri, Sep 3, 2010 at 5:07 PM, Suleja, Lukasz 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 ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Help needed to understand scopesink2
> 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. > > I noticed that the scope base class makes references to message > queues; is the discrepancy simply an OS timing issue. > > Regards, > > Lukasz -- 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 ~ ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
