Yes, that is it. Thanks a lot for your help Josh.
On Mon, Jun 28, 2010 at 4:26 PM, Josh Blum <[email protected]> wrote: > That ratio of frequency/sample_rate tells the signal source how much to > change the output per sample such that it will take 1.0/ratio samples to > make a complete sinusoid period or cycle. > > Try this out in grc. Look at the signal source in the scope sink, and then > try it with 1.0 as the sample rate and freq/samp_rate as the frequency. It > will look the same. > > -Josh > > > On 06/28/2010 03:56 PM, John Andrews wrote: > >> But still there is a problem. 1000/100,000 = 0.01 so the channel_model >> must >> consume 100,000 samples coming into it to represent an offset of 1000Hz. >> How, does it know how many samples to consume as the ratio can be the same >> for a different combination such as 100/10000. >> >> If x(i) = sin(2*pi*freq_offset_ratio*i) , i must vary from >> {1,sampling_rate}. >> >> On Mon, Jun 28, 2010 at 3:00 PM, Josh Blum<[email protected]> wrote: >> >> For some reason, the channel model's frequency_offset is not in Hz. >>> Rather >>> its a fraction of the sample rate. You should pass in >>> my_offset_in_hz/my_sample_rate to this parameter. >>> >>> The signal source works like that. I suppose that means that the sample >>> rate and frequency are redundant because you really only care about the >>> ratio between them. >>> >>> _josh >>> >>> oh consistency... >>> >>> >>> On 06/28/2010 02:12 PM, John Andrews wrote: >>> >>> Hi, >>>> I have a nagging doubt about how the channel model is implemented in >>>> gnuradio. Suppose I have an input signal entering the channel model at >>>> 100,000 samples/sec. Let's say the channel model has to add an offset of >>>> 1000Hz to the input signal. Then I must have 100,000 samples of a 1000Hz >>>> SINE_WAVE signal and multiply each input sample with a corresponding >>>> input >>>> sample. Am I right? If I am right then i don't see this happening here >>>> with >>>> the sampling rate given as 1 in the line below >>>> >>>> d_freq_offset = gr_make_sig_source_c(1, GR_SIN_WAVE, frequency_offset, >>>> 1.0, >>>> 0.0); >>>> >>>> If I am wrong then will someone please correct me here. >>>> >>>> thank you very much >>>> John >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> [email protected] >>>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> [email protected] >>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >>
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