This is the traditional discrete signal FM demodulation method, and it is based on copyrighted material from “Understanding Digital Signal. this with digital signal processing. In an earlier semester project, four FM demodulation algo- are are implemented on the DSP (TMSCDSK). radio provider organizations are planning to replace their traditional analog FM-based. the demodulation of signals that follow the AM-FM model. Traditional such as CPM, CPFSK, FSK, MSK, GMSK and other forms of digital modulation, can be reformulated as digital FM mod- ulation and component AM-FM signal demodulation. The ESA and . threshold around Yo = dB the MESA-based demodu-.
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The method of demodulating recited in claim 18 wherein the demoeulation of computing a correlation output is performed by computing a first correlation by summing a sequence of multiplications of the output of the matched filter with a first correlation function based on past bit decisions.
The base-band in-phase signal component is multiplied by sine theta in a first multiplier Multi-level quadrature amplitude modulator system with fading compensation means. In one embodiment, a delay element is incorporated to accommodate for certain types of fading of the receive signal as the receiver travels through various geographic areas.
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Time acquisition system using a single synchronization word and method of using same. The correction signal is derived from the in-phase coherent carrier signal diigtal the quadrature carrier signal to produce a correction signal representative of a correction angle required to demodulate the GMSK.
The transmission of angle modulated carrier signals having substantially constant amplitude and continuous phase such as FSK, MSK, and GMSK signalsand of similar signals having nonconstant amplitudes, to convey binary data over a radio frequency communication resource is well understood in the art. The method of claim 16 including the step of temporally delaying said first and second signals before producing detected in-phase and quadrature components.
The information bit stream is determined by the following differential decoding: An improved method and apparatus for demodulators for MSK signals. The output of the divider circuit yields a phase angle theta which is a correction factor required to demodulate the base-band in-phase and the base-band quadrature signals. A first stage in the demodulator is a coherent carrier recovery unit 20 which receives the digitized base-band in-phase component B I and the base-band quadrature component B Q and produces two new signals and which represent the magnitude of the real and which represent the magnitude of the real and imaginary components of the base-band in-phase and base-band quadrature carrier signals, B I and B Q respectively.
The base-band in-phase and base-band quadrature signals, B I and B Q are received at the coherent carrier recovery unit 20 as shown. The correction factor dxp, theta from the correction signal unit 40 is used in a correction unit 60 to demodulate the base-band in-phase and base-band quadrature signals, B I and B Q to yield an in-phase coherent data signal and a quadrature coherent data signal as demodulationn. The method of claim 16 wherein said first and second signals are baseband signals.
US5131008A – DSP-based GMSK coherent detector – Google Patents
For digital matched filter implementations, z t should be appropriately sampled; i. This is a realization of equation 4 where the digital filter performs EQU6 where EQU7 Note that match filtering is done over a 2-bit time period.
The improved performance of the demodulator is achieved by using old decisions in the ML decision logic. An incoming signal is received at an antenna 2 and processed in an superheterodyne receiver 3 which produces a first intermediate frequency IF 4.
The demodulator recited in claim 1 wherein said matched filter filters the sampled received signal according to EQU13 where EQU US USA en Method for signal transmission using spectrally efficient orthogonal modulation.
A digital signal processor is preferably used. Method and apparatus for combined frequency offset and timing offset estimation. The method of claim 26 including the step of multiplying said first signal by a first correction signal providing a first product signal and multiplying said second signal by a second correction signal providing a second product signal.
USA – DSP-based GMSK coherent detector – Google Patents
Foe device recited in claim 11 wherein said device is implemented with a digital signal processor. The local oscillator 5 is passed through a phase shifter 6 which phase shifts the output of the local oscillator 5 90 degrees. Method and apparatus for real-time demodulation of a GMSK signal by a non-coherent receiver.
The method of claim 16 further including the step of multiplying said in-phase coherent and quadrature coherent signals by said clock signal producing, respectively, an in-phase coherent carrier component gmzk a quadrature coherent carrier component.
Method and circuitry for determining symbol timing for time division multiple access radio systems. The demodulator recited in claim 4 wherein said matched filter, said non-coherent correlator and said maximum likelihood decision logic are implemented with a digital signal processor. The detector of claim 1 wherein said means for providing in-phase and quadrature coherent carrier signals by factoring the first and second signals includes means for mathematically squaring said first and second signals and providing in-phase and quadrature portions of said first and second signals.
And, p t is a pulse shaping function described as EQU2. The method of claim 26 including demodulafion step of multiplying said second signal by a first correction signal providing a third product signal and multiplying said second signal by a second correction signal providing a fourth product signal.
The base-band in-phase signals as well as the base-band phase quadrature signals B I and B Q are also multiplied together in a multiplier to produce a signal that is the magnitude of the imaginary component of the GMSK signal, Referring now to FIG.
Having thus described our invention, what we claim as new and desire to secure by Letters Patent is as follows: Referring now to the drawings, and more particularly to FIG.