Intelligent terminal and demodulation method and device for Gaussian frequency-shift keying signal thereof

Abstract

The invention discloses an intelligent terminal and a demodulation method and device for Gaussian frequency-shift keying signal thereof. The method comprises the steps: carrying out the matching filtering of a receiving signal and all possible signal modes in the time period from nT to (n+3)T according to a phase estimated value (shown in the description) of the receiving signal and I<n-1>, and obtaining the optimal matching waveform of the receiving signal in the time period from nT to (n+3)T; judging I<n> according to the optimal matching waveform of the receiving signal in the time period from nT to (n+3)T; obtaining the maximum correlation value angle delta (theta<n>) of the receiving signal in the time period from nT to (n+3)T according to the receiving signal and the optimal matching waveform of the receiving signal in the time period from nT to (n+3)T; calculating the result of the following formula (shown in the description) according to the phase estimated value (shown in the description) of the receiving signal, I<n> and the maximum correlation value angle delta (theta<n>); carrying out the above steps in a circulating manner according to the result of the formula and I<n>; and obtaining all to-be-modulated data through recursion. The method integrates matching filtering and angle iteration, employs the maximum correlation value angle delta (theta<n>) obtained in matching filtering to participate the angle iteration, carries out frequency loop tracking, and reduces the influence caused by frequency changes.

Description

technical field [0001] The present invention relates to the technical field of wireless communication, in particular to an intelligent terminal and a method and device for demodulating a Gaussian frequency shift keying signal thereof. Background technique [0002] Frequency Shift Keying (FSK) is a digital modulation technique widely used in medium and low-speed data transmission, which uses the frequency change of the carrier to transmit digital information. [0003] Gaussian frequency shift keying (GaussFrequencyShiftKeying, GFSK) modulation is a digital modulation method that pre-modulates and filters the signal through a Gaussian low-pass filter, and then performs frequency shift keying modulation. While maintaining a constant amplitude, it can control the spectral width of the signal by changing the bandwidth of the Gaussian low-pass filter. It has the desired characteristics of wireless communication systems such as constant amplitude envelope, power spectrum concentrat...

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Problems solved by technology

For example, for the coherent demodulation scheme in the prior art, it is greatly affected by the rapid change of the frequency offset and the uncertainty of the modulation index; and for the differential demodulation scheme in the prior art, although it can be affected by the frequency Compared with the coherent demodulation scheme, the impact of rapid changes and the uncertainty of the modulation index is small, but its receiving sensitivity will be 3-4dB lower than that of the coherent demodulation scheme

[0008] Considering the characteristics of the basic rate signal of Bluetooth, the uncertainty of its modulation index is large. As mentioned above, it will fluctuate in the range of 0.28~0.35, and the relevant protocol regulations limit the rapid change of its frequency and the resulting The frequency deviation is large

Therefore, in the prior art, a differential demodulation scheme is usually used to demodulate it, but this also leads to a short effective transmission distance of the signal

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