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Crest Factor for multicarrier GSM signal???

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ajeetpal

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Hi All,

As per the GSM standard, GSM signal uses the GMSK modulation and crest factor for the GMSK modulated signal is 0dB. In that case, GSM signal should have PAR is 0dB for single carrier.

In the same way, for multicarrier GSM signal should also be 0dB PAR. But some of the places it varing according to the no. of carriers.

Could you please clarify the PAR for the multicarrier GSM signal??

Thanks in advance...!!!!
 

PAR-multicarrier[dB] = 10*LOG(Number-of-Carriers)

This is the worst case number for PAR, because in real multicarrier systems PAR is lower due to using multiple techniques for PAR reduction (coding and signal scrambling, signal distortion or clipping, etc).
 
@vfone:

As per the given formula, the PAR is 0dB for 1 carrier of GMSK modulated signal.
but this value is contradict with the data in the attachment. please validate it.

and is this formula applicable for the all modulated signal? As the crest factor for the GMSK modulated single carrier having a 0dB only.

View attachment GSM_crest_factor.pdf
 
The equation is for CW or constant envelope modulated signals (as GMSK). For other modulated signals (as EDGE/8PSK) there are more complicated interpretation of the signal, as you see also from the tables in the document you posted.
 
But in the document Table 1 shows 3dB crest factor for GSM signal for 1 carrier (that will be GMSK modulated).
 
ajeetpal said:
But in the document Table 1 shows 3dB crest factor for GSM signal for 1 carrier (that will be GMSK modulated).
Click to expand...

For 1 carrier it means peak sinusoid magnitude to sinusoid average ratio.
 

@ Mityan:

GSM uses GMSK modulation and GMSK modulated carrier having a crest factor of 0dB.
If multiple carrier are using then crest factor will change as per the formula given in above thread by vfone.

my main query is how it is changing the crest factor for multiple carrier (GMSK modulated) and why the given crest factor in the previous attachment for the GSM signal is different than the calculated PAR by the formula?
 

Excuse me, but the same that I posted is written in the document you referenced - II, paragraph 2.
I have no any suggestions on your query
 

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