Hi Andrew, thanks for the reply. I need the RF Frontend to change. I'm doing measurements in order to find out how fast the RF Frontend can tune over more than 25 MHz (on a USRP2). I need some exact data here, e.g. plots. So in fact I want it to tune with no workarounds. And I want to see it tune ;)
I pinpoint the Transceiver of the XCVR (http://datasheets.maxim-ic.com/en/ds/MAX2828-MAX2829.pdf) in order to get a down-scaled frequency. I want to set a new frequency. An then I want to plot how long it takes the device to issue the change. That's UHD Device driver command + Ethernet latency + FPGA reaction. My problem is, that I know of no way to tune it. Automatically changing the center-frequency from GRC seems to be impossible to me. http://lists.gnu.org/archive/html/discuss-gnuradio/2011-09/msg00309.html - I found that. But uhd.tune_request(target_freq, dsp_freq=0, dsp_freq_policy=uhd.tune_request.POLICY_MANUAL) tells me, that it cannot be evaluated in GRC. Variables set of course. I guess the constructor changed, but there's no docu here. - I can use a WX GUI slider, but I need an automated change. Actually a switch between 50 and 75 MHz (so that my Oscilloscope copes with that). Here I use the WBX. My overall goal is to understand more about the hardware. So if someone knows how I can implement a callback or a polling function to make the device tune for real, but as fast as possible, that'd be very helpful. Best, Marius On 02/09/2012 10:41 PM, Andrew Davis wrote: > self.uhd_usrp_sink_0.set_center_freq(self.freq, 0) will take forever, the > whole front end has to re-settle. How far are you moving the center > frequency? If it's less than 50MHz you could change the sin signal > frequency. You could even hook up a Frequency modulator and change the > frequency continually and with absolutely no delay. > > On Thu, Feb 9, 2012 at 7:02 AM, Marius Ciepluch > <wishi...@googlemail.com>wrote: > >> Hi! >> >> I have put a Flow-Graph together, which is quite simple: >> Sine Signal -> USRP2 UHD >> >> Now I want to change the center-frequency as fast as possible. >> >> My initial idea was a while True loop and to issue the >> self.uhd_usrp_sink_0.set_center_freq(self.freq, 0) command from Python. >> This does not work. It remains at the initial frequency. >> >> Do you use the Function Probe block in GRC? Or is there any other way to >> make it tune without ending the Flow-Graph? >> >> Best, >> Marius >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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