Hi Sandhya,
You need atleast 2 samples/symbol for demodulation.
Normally when there are sharp transitions in modulated carrier, it results
in high frequency components in the frequency domain. This is a problem
because there will be power across frequencies beyond the bandwidth of the
signal. Hence pulse shaping is employed where the time domain waveform is
smoothened so that all the power in the freq domain is concentrated only
within the bandwidth of signal and that prevents ISI. Hence because the
waveform transitions are smoothened, there will be a need for higher
samples/symbol to demodulate the symbol.
On Tue, Dec 3, 2013 at 4:35 PM, Sandhya G <[email protected]> wrote:
> Hi karan ,
> Thanks for reply .
> well ya in gnuradio also if i set the value of samples/symbol below 2 it
> is throwing me an error .
> So is there any specific reason behind using the value greater than 2?
> and is that higher the value of samples/second the smoother will be the
> waveform? please correct me if i'am wrong .
>
> Thanks
> Sandhya
>
>
> On Tue, Dec 3, 2013 at 4:28 PM, Karan Talasila <[email protected]>wrote:
>
>> Hi,
>> Bits/symbol depends on modulation scheme that you use to transmit.
>> For BPSK, it is 1 bit/symbol, for QPSK it is 2 bit/symbol and for 64-QAM
>> it is 6 bits/symbol. So you can set it according to modulation scheme you
>> use.
>>
>> Samples/symbol is normally default set to 2. I am not aware in gnuradio
>> but in certain other implementations samples/symbol is kept greater than 2,
>> say 4 or 8 to account for pulse shaping.
>>
>>
>> On Tue, Dec 3, 2013 at 2:33 PM, Sandhya G <[email protected]> wrote:
>>
>>> Hi everyone,
>>> i'am trying to do simply QAM modulation for that the source i
>>> used is vector source which gives 1byte of 1's and 0's which is fed to QAM
>>> modulator .
>>>
>>> Can anyone tell me how do i calculate samples/symbol .I know the
>>> traditional formula
>>>
>>> samples/symbol=(samples/second)/(symbols/second).
>>>
>>> symbols/sec= (Bits/sec)/(Bits/symbol)
>>>
>>> I having the problem to decide bits/symbol and bits/sec.Please help me
>>>
>>> Thanks
>>> Sandhya
>>>
>>> _______________________________________________
>>> Discuss-gnuradio mailing list
>>> [email protected]
>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>
>>>
>>
>>
>> --
>> Regards
>> Karan Talasila
>>
>
>
--
Regards
Karan Talasila
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