Which is the digital modulation used today in telecomn?
(whatever his question meant the answer was CDMA)
2) Why is walse code used? then, noncoherent detection,
coherent detection, Pn code(y it is used?) etc
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Answer / kenneth yindi
Currently the digital modulation used in telecom is GSMK
GMSK is a form of modulation used in variety of digital
radio communication systems.It has an advantage4s of being
able to carry digital modulation while still using the
spectrum efficiently.
One of the problems with other forms of phase shift keying
is that the sidebands extend outwards from the main
carrierand this can cause interference to the other radio
communication systems using nearby channels.
| Is This Answer Correct ? | 7 Yes | 0 No |
Answer / santoshmore
GMSK for gsm with gprs only,
8psk for gsm with EDGE support.
| Is This Answer Correct ? | 7 Yes | 1 No |
Answer / amisha
in GSM we use GMSK
Spreading Code are use for following reason:
The effectiveness of CDMA scheme relies on the mutual
orthogonality of spreading codes to minimize the cross
interference among physical code channels.Therefore
spreading code should be consistently defined and generated
at transmitters and receivers such that this orthogonality
can be achieved and maintained across the radio link.
Walsh Code:Walsh Code are set of perfectly orthogonal codes
typically used for channelization ,that is,separating
different physical channels transmitted by a node.
PN Code:PN codes are set of psuedo-random but
deterministically generated sequences .
Properties of Psuedo Code are:
1Sharp Autocorrelation ,so that any time shifted version of
a PN code has almost no correlation with the original sequence
2 Equal number of '1' andd '0' in any long segment of the
sequence ,so that the signal has no bias
3 Random and independent appearances of '1' and '0' so that
it is difficult to to reconstruct from any short segment
Basically PN codes act as Base station signature.
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Answer / santosh kumar nigam
In GSM GMSK FOr Voice & 8-PSK & GMSK For Data.
In CDMA OffsetQPSK
| Is This Answer Correct ? | 5 Yes | 1 No |
Answer / suhas dinesh
ASK, PSK, FSK, GMSK, QAM, OFDM, M-PSK, APSK.
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Answer / nsn
GMSK in GSM
QPSK,16 QAM and 64 QAM in CDMA. It totally depends upon CQI.
If CQI>16 16 QAM or 64 QAM is used depending upon the NW
implementaion.
| Is This Answer Correct ? | 1 Yes | 1 No |
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