Forum: GNU Radio difference b/w sample rate and symbols per second

5fd1e4f6f03488a54ea5b31a1ef94886?d=identicon&s=25 jason sam (Guest)
on 2014-06-26 11:07
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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
B4ffbc711addde4c649b1ed526df6157?d=identicon&s=25 Martin Braun (Guest)
on 2014-07-01 11:19
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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
5fd1e4f6f03488a54ea5b31a1ef94886?d=identicon&s=25 jason sam (Guest)
on 2014-07-04 08:34
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Thanx Martin,but where in GRC we can set samples per symbol??I am new
to this so i don't know yet...

Ali
D17685d174fee4ca258c75cce7bc2202?d=identicon&s=25 Marcus Müller (Guest)
on 2014-07-04 15:09
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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
5fd1e4f6f03488a54ea5b31a1ef94886?d=identicon&s=25 jason sam (Guest)
on 2014-07-04 17:39
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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??
D17685d174fee4ca258c75cce7bc2202?d=identicon&s=25 Marcus Müller (Guest)
on 2014-07-04 18:15
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Not at all, because for these blocks, symbols have no meaning.
5fd1e4f6f03488a54ea5b31a1ef94886?d=identicon&s=25 jason sam (Guest)
on 2014-07-05 10:00
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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?
D17685d174fee4ca258c75cce7bc2202?d=identicon&s=25 Marcus Müller (Guest)
on 2014-07-05 16:01
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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]http://gnuradio.org/doc/doxygen/classgr_1_1analog_...
F18b7b61dfbfe46c7af3cbcbda568c4f?d=identicon&s=25 Vanush Vaswani (Guest)
on 2014-07-05 16:20
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You may refer to this example to see how to transmit 9.6kbps GFSK
signal through an AWGN channel.

https://www.youtube.com/watch?v=N1hR6VgWeow&featur...
5fd1e4f6f03488a54ea5b31a1ef94886?d=identicon&s=25 jason sam (Guest)
on 2014-07-05 17:38
(Received via mailing list)
ok thanx for the replies!
62e152f885746ecd6f9d2e470722bed1?d=identicon&s=25 Dan CaJacob (Guest)
on 2014-07-05 20:02
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Also, see
http://gnuradio.org/redmine/projects/gnuradio/wiki...
where
some of my own questions have been answered.

Very Respectfully,

Dan CaJacob
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