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Re: [Discuss-gnuradio] Delay block controlled by input

From: Martin Braun
Subject: Re: [Discuss-gnuradio] Delay block controlled by input
Date: Wed, 08 Oct 2014 13:21:22 +0200
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See also


On 10/08/2014 01:18 PM, Martin Braun wrote:
> 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 <address@hidden
>> <mailto:address@hidden>>:
>>     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
>> _______________________________________________
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