In that case, just use nitems_read() [1] in your delay block to inherently calculate "simulated time".
However, I'm a bit curious about the effects of using delay to do this: Because, as long as the satellite is approaching you, you're occasionally dropping samples, whereas you're inserting zeros while it moves away from the observer. Unless your 10.23MHz signal contains only a oversampled signal you care about and then decimated after delay [2] this potentially really differs from what you'd be seeing in a real world receiver. Greetings, Marcus [1] http://gnuradio.org/doc/doxygen/classgr_1_1block.html#a2279d1eb421203bc5b0f100a6d5dc263 [2] in which case that kind of has a doppler-y touch to it... On 08.10.2014 13:33, Carlos Alberto Ruiz Naranjo wrote: > Yes, it is not a real time clock. This "clock" tracks the current time of > the signal in GNURadio. clock2 and clock1 have a drift because the number of > counted samples are different. > > For example, if it pass 10230000 samples the delay block is entering the > delay in signal time = 1 second. > 1 second in the real world (later I replay the signal with a USRP). > > 2014-10-08 13:18 GMT+02:00 Martin Braun <martin.br...@ettus.com>: > >> If you don't have hardware involved, you have no 'clock'. And as such, >> it can't drift. >> >> M >> >> On 10/08/2014 12:29 PM, Carlos Alberto Ruiz Naranjo wrote: >>> Sorry, I have explained bad: S >>> I have the signal saved in a file and 10230000 samples are one second >>> (in the real world). >>> >>> In the first graph I have two clocks (counters samples). When passing >>> 102300 samples it increase0.01 seconds. >>> In the first watchthis time controls the position of the satellite and >>> hisdelay in this time. It allows to know what signal time is passing in >>> the delay block. >>> >>> >>> But I have a problem: clock 2 (a test clock) and clock 1 haven't the >>> same time; it has a drift. >>> >>> >>> Then, I must use clock 2 ( >>> count the samples in the delay block output, not input). But it creates >>> a loop. >>> >>> >>> >>> 2014-10-08 12:07 GMT+02:00 Marcus Müller <marcus.muel...@ettus.com >>> <mailto:marcus.muel...@ettus.com>>: >>> >>> Hello Carlos, >>> On 08.10.2014 09:10, Carlos Alberto Ruiz Naranjo wrote: >>> > I generate the signal from a file (10230000 samples/s) to a file. >> My >>> > sampling clock drifts significantly :S >>> No. Unless I misunderstood you, you have a big misconception: >>> "sampling clock" is *not* the rate at which your samples pass through >>> your processing chain (ie. GNU Radio). It is the time base at which >> they >>> are measured, or simulated to, mathematically. >>> The device/software that actually captures the samples and saves them >>> has a fixed clock. If that clock changes too much a) compensate that >> in >>> software, if possible or b) get a better device. >>> This is digital signal processing. Real world time has *no* meaning >>> here, everything is measured relative to the interval between two >>> sampling times. You can process the signal as fast or slow as you >> want >>> to (as long as that doesn't lead to things like overflows), and >> nothing >>> in the processing chain should care. >>> > >>> > - Picture one: Counter Clock 2 is correct but Counter Clock 1 no. >>> > Then I should use the second configuration, but it is not allowed >> because I >>> > have a loop, right? >>> I don't understand your graph, sorry :( >>> >>> Greetings, >>> Marcus >>> >>> >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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