Difference b/w sample rate and symbols per second

GNU Radio
1

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

2

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

3

Thanx Martin,but where in GRC we can set samples per symbol??I am new
to this so i don’t know yet…

Ali

4

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

5

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??

6

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?

7

Not at all, because for these blocks, symbols have no meaning.

8

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

9

ok thanx for the replies!

10

You may refer to this example to see how to transmit 9.6kbps GFSK
signal through an AWGN channel.

11

Also, see
http://gnuradio.org/redmine/projects/gnuradio/wiki/SignalProcessing
where
some of my own questions have been answered.

Very Respectfully,

Dan CaJacob