# Difference b/w sample rate and symbols per second **URL:** \ **Category:** GNU Radio\ **Created:** [June 26, 2014, 11:07am UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619 "2014-06-26T11:07:44Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [June 26, 2014, 11:07am UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/1 "2014-06-26T11:07:44Z")
Hi, I am bit confused b/w the two terms.I have read some material and i got the following relationship b/w the two: samples/second =samples/symbol \* symbols/second And i think in GRC samples per symbol is 1(plz correct if i am wrong).So sample rate becomes equal to baud rate(symbols/second)?? Regards, Ali ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 1, 2014, 11:19am UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/2 "2014-07-01T11:19:39Z")
On 06/26/2014 11:06 AM, jason sam wrote: > I am bit confused b/w the two terms.I have read some material and i > got the following relationship b/w the two: > samples/second =samples/symbol \* symbols/second > And i think in GRC samples per symbol is 1(plz correct if i am > wrong).So sample rate becomes equal to baud rate(symbols/second)?? samples per symbol is whatever you set it to; common values are 2 and 4 (this also depends on the modulation used). Higher values are often used for demo purposes. M ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 4, 2014, 8:34am UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/3 "2014-07-04T08:34:13Z")
Thanx Martin,but where in GRC we can set samples per symbol??I am new to this so i don’t know yet… Ali ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 4, 2014, 3:09pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/4 "2014-07-04T15:09:51Z")
Hi Ali, as said several times: Sampling rate, samples per symbol etc are concepts that are meaningful only for certain blocks, and thus there is no sense in setting those globally. Greetings, Marcus ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 4, 2014, 5:39pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/5 "2014-07-04T17:39:56Z")
Yes Marcus,u are r right and i am also asking about such blocks like the FM Mod block…In this block u have an option to set sample rate but how can u set samples per symbol?? ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 5, 2014, 10:00am UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/6 "2014-07-05T10:00:22Z")
Sorry for prolonging the discussion but I am a bit confused here.The sensitivity parameter for Freq Mod block is defined as: sensitivity = (pi \* modulation\_index) / samples\_per\_symbol where, modulation\_index = deviation / (baud\_rate / 2) So what values should i plug in for samples\_per\_symbol and baud\_rate in the formulas? ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 4, 2014, 6:15pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/7 "2014-07-04T18:15:41Z")
Not at all, because for these blocks, symbols have no meaning. ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 5, 2014, 4:01pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/8 "2014-07-05T16:01:40Z")
We might be talking about different blocks. I’m referring to gr::analog::frequency\_modulator\_fc, where the documentation only says[1] radians/sample = amplitude \* sensitivity From what you paste as formulas this does not look like the general frequency modulation, but like a digital modulation scheme, e.g. GMSK. Anyway, we will not be able to tell you what you’ll need to use as parameters for your transmitter – that is something that you, based on your communication engineering skills, will need to decide yourself. Sincerely, Marcus Müller [1][GNU Radio Manual and C++ API Reference: gr::analog::frequency\_modulator\_fc Class Reference](http://gnuradio.org/doc/doxygen/classgr_1_1analog_1_1frequency __modulator__ fc.html#a9c252eeb8c9daf6ccd50427d3bc55bd3) ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 5, 2014, 5:38pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/9 "2014-07-05T17:38:13Z")
ok thanx for the replies! ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 5, 2014, 4:20pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/10 "2014-07-05T16:20:45Z")
You may refer to this example to see how to transmit 9.6kbps GFSK signal through an AWGN channel. [![](https://img.youtube.com/vi/N1hR6VgWeow/maxresdefault.jpg "grc gfsk example") ](https://www.youtube.com/watch?v=N1hR6VgWeow) ---
**Author:** ![jason\_sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/7993a0/32.png) [@jason\_sam](https://www.ruby-forum.com/u/jason_sam)\ **Post date:** [July 5, 2014, 8:02pm UTC](https://www.ruby-forum.com/t/difference-b-w-sample-rate-and-symbols-per-second/230619/11 "2014-07-05T20:02:17Z")
Also, see [http://gnuradio.org/redmine/projects/gnuradio/wiki/SignalProcessing](http://gnuradio.org/redmine/projects/gnuradio/wiki/SignalProcessing) where some of my own questions have been answered. Very Respectfully, Dan CaJacob