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... Gaussian Minimum Shift Keying (GMSK)
. ... GMSK Modulation
. ... GMSK Demodulation
. ... Then we move to discuss the multiple access scheme and GMSK modulation/demodulation in GSM. ... Gaussian Minimum Shift Keying (GMSK) GMSK is a form of continuous-phase Frequency Shift Keying (FSK), in which the phase is changed between symbols to provide a constant envelope. ... GMSK Modulation There are two methods to generate a GMSK modulated signal. ... m First GMSK Modulation Scheme Based on frequency shift keyed modulation, a GMSK signal can be generated by first passing it through a Gaussian low pass filter (LPF). ... Figure 2 GMSK based on frequency shift keying Figure 3 Gaussian Low Pass Filter response The GMSK VCO-modulator architecture, as shown above, is relatively simple, however, component tolerance problems make it unsuitable for coherent demodulation. ... d Second GMSK Modulation Scheme A second method to modulate a signal using GMSK is quadrature phase shift keyed modulation, as shown in Figure 4. ...
Figure 4 Second GMSK modulation scheme As the data passes through the LPF filter, it is shaped and Inter Symbol Interference (ISI) is introduced since more than one bit is passing through the filter at any one time. ... The I and Q baseband signals are added to form the GMSK modulated signal m(t), shown in Figure 7. ...
Figure 7 GMSK modulated signal 4. ... GMSK Demodulation GMSK demodulation can be achieved by coherently demodulating the in-phase and quadrature components separately. ... A block diagram of a coherent GMSK demodulator is shown in Figure 8. Figure 8 GMSK Demodulation As illustrated in Figure 8, r(t) is the received signal while d is an estimate of the original data. ... a GMSK signals can also be demodulated by a variety of non-coherent demodulation techniques. Particularly, the differential demodulator, the limiter discriminator, and variations on these two have been used and proposed for use with GMSK signaling.
Approximate Word count = 1463
Approximate Pages = 5.9
(250 words per page double spaced)
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