
From:  Marcus Müller 
Subject:  Re: [Discussgnuradio] create lookup tables 
Date:  Sat, 26 Dec 2015 17:45:12 +0100 
Useragent:  Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 
Hi Andy,So if i want to have a sine with frequency 1 hz and 256 samples per sine period i have to set samplerate to 256 ? yes, this is DSP, so all we care about is rates relative to the sampling rate. I got into the habit of thinking of the sampling rate as always being "1", and then your sine has a frequency of 1/256, ie. it takes 256 samples for a full period. The head block has 2 parameters: number of items, vector lengthThe signal source spits out single samples, so your vector length is 1. Now this is non specific gnuradio question, but how is it possible with python to create a sine with 1 hz from this lookup table.For any frequency of sines you'd want to generate, you'd advance at a speed of len_of_table*relative_frequency. Think of it as this  if a sine that is generated by taking every sample from your table one after the other has frequency f_sample/256, then the sine of twice that frequency has every second sample, and so on. My first idea is: python has to sample the 256 samples (for one period) from lookup table in exactly one second. So i think i need a timer which calls the next sample in the lookup table all 3,9 ms.no! GNU Radio is NOT a system where samples are processed samplebysample, with a fixed precise sampling rate. Each block is just asked to process/generate/sink as many samples as possible, and the result is passed on to the next block as fast as possible. Best regards, Marcus On 12/26/2015 05:28 PM, Andreas Ladanyi
wrote:
Hi Marcus, 
[Prev in Thread]  Current Thread  [Next in Thread] 