Frequency-shift-keying demodulator and method of frequency-shift-keying

Abstract

The present invention relates to a frequency-shift-keying demodulator (1,1') comprising a phase shifter 2 for shifting the phase of an input signal i(t) by a predetermined degree and for outputting a shifted signal Id(t), a combining unit (3, 4; 31, 32, 33, 41, 42) for combining the input signal i(t) and the shifted signal Id(t) output by the phase shifter 2 and for outputting a corresponding signal r(t) and a low-pass filter 5 for filtering the signal r(t) output by the combining unit (3, 4; 31, 32, 33, 41, 42), and for outputting a low-pass filtered signal r LP (t) the bandwidth of said low-pass filter 5 being matched with the bandwidth of a data signal contained in said input signal i(t). According to the present invention said combining unit (3, 4; 31, 32, 33, 41, 42) comprises at least one adder (3; 31, 32) for adding the input signal i(t) and the shifted signal Id(t) output by the phase shifter 2 and for outputting an added signal and at least one square law detector (4; 41, 42) for receiving the added signal output by the adder (3; 31, 32) and for outputting a squared signal r(t) which is the square of the added signal wherein the combining unit (3, 4;31, 32, 33, 41, 42) outputs the squared signal r(t) to the low-pass filter 5. Furthermore, the present invention relates to a method of frequency-shift-keying demodulating an input signal i(t).

Description

technical field [0001] The invention relates to a frequency shift keying demodulator comprising the features of the preamble of independent claim 1 and to a method of frequency shift keying demodulation of an input signal comprising the steps of the preamble of independent claim 7 . Background technique [0002] In order to reduce the power consumption of a power amplifier used for wireless communication at the transmitter and to achieve bandwidth efficient wireless transmission, various continuous phase Frequency Shift Keying (FSK) type modulation schemes are known. For example, Minimum Frequency Shift Keying (MSK) and Gaussian Frequency Shift Keying (GFSK) are widely used in wireless communication systems, eg according to the GSM or Bluetooth standards. [0003] Regarding demodulation of signals, frequency discriminators or FM-AM converters are the most common forms of demodulators because of their simplicity. [0004] In the following, a receiver and a demodulator for fr...

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Problems solved by technology

[0033] A disadvantage of the above-mentioned differential frequency shift keying demodulator according to the prior art is that an active mixer is required to obtain sufficient signal strength of the FSK signal

Active mixers re

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