阅读说明：本技术 一种一体化数字解调方法及装置 (Integrated digital demodulation method and device ) 是由 张建军 范玉进 颜凯 董悦 郝帅龙 于 2020-12-14 设计创作，主要内容包括：本发明提供了一种一体化数字解调方法及装置,其中,所述方法包括：对接收到的信号进行正交调制,得到I、Q两路分解正交信号；将所述I、Q两路分解正交信号分别通过低通滤波器进行滤波；在所述信号为AM信号时,将滤波后I、Q两路分解正交信号通过调谐器调谐得到相应的AM信号。可以针对不同的信号分别进行后续处理,利用同一调谐器和多个乘法器以及寄存器的组合,实现对三种不同信号的数字化处理,与现有技术相比,由于采用了多个逻辑模块复用,在保证信号解调准确性的前提下,有效节省了逻辑模块的数量。(The invention provides an integrated digital demodulation method and device, wherein the method comprises the following steps: carrying out quadrature modulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals; filtering the I, Q two paths of decomposed orthogonal signals through low-pass filters respectively; and when the signal is an AM signal, tuning the filtered I, Q two paths of decomposed orthogonal signals through a tuner to obtain a corresponding AM signal. The digital signal demodulation circuit can respectively carry out subsequent processing aiming at different signals, and realizes the digital processing of three different signals by utilizing the combination of the same tuner, a plurality of multipliers and registers.)

1. An integrated digital demodulation method, the method comprising:

carrying out quadrature modulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals;

filtering the I, Q two paths of decomposed orthogonal signals through low-pass filters respectively;

and when the signal is an AM signal, tuning the filtered I, Q two paths of decomposed orthogonal signals through a tuner to obtain a corresponding AM signal.

2. The integrated digital demodulation method of claim 1 further comprising:

when the signals are FM signals, storing the filtered I, Q two paths of decomposed orthogonal signals into a register respectively;

respectively delaying the I, Q two paths of decomposed orthogonal signals stored in the register by one beat; and filtering through a second filter

And processing the I, Q two paths of decomposed orthogonal signals after being filtered by the second filter by a second multiplier, and respectively performing addition and subtraction processing on the processed IQ two paths of signals respectively obtained by modulating the processed IQ two paths of signals by a demodulator.

3. The integrated digital demodulation method of claim 1 further comprising:

removing a direct current component from the AM or FM signal.

4. The integrated digital demodulation method of claim 1 further comprising:

when the signal is an SSB signal, multiplying the I, Q two paths of decomposed orthogonal signals after filtering by a carrier signal;

or the I, Q two paths of decomposed orthogonal signals after filtering are subjected to phase shift operation;

and obtaining the SSB original signal by adding and subtracting the signal.

5. The integrated digital demodulation method according to claim 1, wherein the tuning the filtered I, Q two-way decomposed orthogonal signal through a tuner to obtain a corresponding AM signal comprises:

the method is realized by the following steps: the demodulated signal can be obtained by squaring and root-cutting:

6. an integrated digital demodulating apparatus for performing the integrated digital demodulating method according to any one of claims 1 to 5, comprising:

the orthogonal demodulator is used for carrying out orthogonal demodulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals;

the low-pass filter is used for performing low-pass filtering on the I, Q two-path decomposed orthogonal signals;

the tuner is used for demodulating I, Q two-path decomposition orthogonal signals after low-pass filtering;

the quadrature demodulator includes: two multipliers and 3 NCO;

the tuner includes: two DSPs;

the multiplier includes: two DSPs; the multiplier is implemented by two DSPs.

7. The integrated digital demodulating apparatus according to claim 6, further comprising:

the register is used for storing I, Q two paths of decomposed orthogonal signals, performing delay processing and multiplying the orthogonal signals subjected to delay processing by the multiplier;

the switch is used for storing I, Q two paths of decomposed orthogonal signals into the register when the FM signals are judged to be the FM signals;

the second low-pass filter is used for low-pass filtering the I, Q two-path decomposed orthogonal signals again;

the second multiplier is used for multiplying the I, Q two paths of decomposed orthogonal signals subjected to low-pass filtering again;

and the signal adder-subtractor is used for adding and subtracting the multiplied signals.

8. The integrated digital demodulating apparatus according to claim 6, further comprising:

and the direct current component removing module is used for removing the direct current component in the AM or FM signal.

9. The integrated digital demodulating apparatus according to claim 6, further comprising:

the second low-pass filter is used for low-pass filtering the I, Q two-path decomposed orthogonal signals again so as to meet the processing requirement of the SSB signals;

an SSB processing multiplier for multiplying the filtered I, Q two-way decomposed quadrature signal with a carrier signal when the signal is an SSB signal,

or the I, Q two paths of decomposed orthogonal signals after filtering are subjected to phase shift operation;

and the signal adder-subtractor is used for adding and subtracting the multiplied signals or the signals subjected to phase shift operation to obtain the SSB original signals.

Technical Field

The invention belongs to the technical field of communication, and particularly relates to an integrated digital demodulation method and device.

Background

The analog modulation can be divided into linear modulation and nonlinear modulation, and on the waveform, the amplitude of a modulated signal changes in proportion to the rule of a baseband signal; on the spectral structure, its spectrum is simply a shift (to a constant factor accurate) of the baseband signal spectrum in the frequency domain. Since this shift is linear, amplitude modulation is often referred to as linear modulation.

In the process of implementing the present invention, the inventor finds that in the prior art, when digital modulation is adopted, digital demodulation of three signals can be implemented only by requiring more logic units, and there is more resource waste in integrated demodulation of multiple signals.

Disclosure of Invention

In view of the above, the present invention is directed to an integrated digital demodulation method and apparatus, so as to solve the technical problem in the prior art that the integrated digital demodulation needs more logic units to be implemented.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

in one aspect, an embodiment of the present invention provides an integrated digital demodulation method, including:

carrying out quadrature modulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals;

filtering the I, Q two paths of decomposed orthogonal signals through low-pass filters respectively;

and when the signal is an AM signal, tuning the filtered I, Q two paths of decomposed orthogonal signals through a tuner to obtain a corresponding AM signal.

Further, the method further comprises:

when the signals are FM signals, storing the filtered I, Q two paths of decomposed orthogonal signals into a register respectively;

respectively delaying the I, Q two paths of decomposed orthogonal signals stored in the register by one beat; and filtering through a second filter

And processing the I, Q two paths of decomposed orthogonal signals after being filtered by the second filter by a second multiplier, and respectively performing addition and subtraction processing on the processed IQ two paths of signals respectively obtained by modulating the processed IQ two paths of signals by a demodulator.

Further, the method further comprises:

removing a direct current component from the AM or FM signal.

Further, the method further comprises:

when the signal is an SSB signal, multiplying the I, Q two paths of decomposed orthogonal signals after filtering by a carrier signal;

or the I, Q two paths of decomposed orthogonal signals after filtering are subjected to phase shift operation;

and obtaining the SSB original signal by adding and subtracting the signal.

Furthermore, the tuning of the filtered I, Q two-way decomposed orthogonal signal by a tuner to obtain a corresponding AM signal includes:

the method is realized by the following steps: the demodulated signal can be obtained by squaring and root-cutting:

on the other hand, an embodiment of the present invention further provides an integrated digital demodulation apparatus for implementing the integrated digital demodulation method according to any one of the above embodiments, including:

the orthogonal demodulator is used for carrying out orthogonal demodulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals;

the low-pass filter is used for performing low-pass filtering on the I, Q two-path decomposed orthogonal signals;

the tuner is used for demodulating I, Q two-path decomposition orthogonal signals after low-pass filtering;

the quadrature demodulator includes: two multipliers and 3 NCO;

the tuner includes: two DSPs;

the multiplier includes: two DSPs; the multiplier is implemented by two DSPs.

Further, the integrated digital demodulation apparatus further includes:

the register is used for storing I, Q two paths of decomposed orthogonal signals, performing delay processing and multiplying the orthogonal signals subjected to delay processing by the multiplier;

the switch is used for storing I, Q two paths of decomposed orthogonal signals into the register when the FM signals are judged to be the FM signals;

the second low-pass filter is used for low-pass filtering the I, Q two-path decomposed orthogonal signals again;

the second multiplier is used for multiplying the I, Q two paths of decomposed orthogonal signals subjected to low-pass filtering again;

and the signal adder-subtractor is used for adding and subtracting the multiplied signals.

Further, the integrated digital demodulation apparatus further includes:

and the direct current component removing module is used for removing the direct current component in the AM or FM signal.

Further, the integrated digital demodulating apparatus further includes:

the second low-pass filter is used for low-pass filtering the I, Q two-path decomposed orthogonal signals again so as to meet the processing requirement of the SSB signals;

an SSB processing multiplier for multiplying the filtered I, Q two-way decomposed quadrature signal with a carrier signal when the signal is an SSB signal,

or the I, Q two paths of decomposed orthogonal signals after filtering are subjected to phase shift operation;

and the signal adder-subtractor is used for adding and subtracting the multiplied signals or the signals subjected to phase shift operation to obtain the SSB original signals.

Compared with the prior art, the integrated digital demodulation method and the integrated digital demodulation device have the following advantages:

the integrated digital demodulation method and the device of the invention carry out quadrature modulation on the received signals to obtain I, Q two paths of decomposed quadrature signals; filtering the I, Q two paths of decomposed orthogonal signals through low-pass filters respectively; the method is characterized in that the method comprises the steps of carrying out subsequent processing on different signals respectively, and realizing digital processing on three different signals by utilizing the combination of the same tuner, a plurality of multipliers and registers.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic flow chart of an integrated digital demodulation method according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an integrated digital demodulation apparatus according to an embodiment of the present invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

Example one

Fig. 1 is a schematic flow diagram of an integrated digital demodulation method according to an embodiment of the present invention, and referring to fig. 1, the integrated digital demodulation method includes:

s110, carrying out quadrature modulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals.

FM/WFM is one type of angular modulation. In angle modulation, there is no linear correspondence between the frequency spectrum of the modulated signal and the frequency spectrum of the modulated signal, but it is generated from a new frequency component different from the frequency spectrum shift, and thus it exhibits the characteristic of a nonlinear process, and is also called nonlinear modulation. The angle modulation can be divided into frequency modulation and phase modulation, and the frequency modulation is widely used in practical applications.

AM demodulation is an amplitude modulation that may include conventional double sideband Amplitude Modulation (AM), suppressed carrier double sideband amplitude modulation (DSB-SC), single sideband modulation (SSB), and vestigial sideband modulation (VSB). Which in turn can be divided into upper sideband modulation (USB) and lower sideband modulation (LSB).

In this embodiment, the digital demodulation of the three signals can be realized by the same digital demodulation device. In the processing of the three signals, the signals need to be orthogonally demodulated first.

To improve spectrum utilization, communication systems often employ quadrature modulation. In quadrature demodulation, the existing modulation is converted to a corresponding I/Q baseband signal. Quadrature demodulation is not limited to signals originally generated by quadrature modulation. Quadrature demodulation can be achieved using existing techniques. A

In conventional AM modulation, the envelope of the output modulated signal is proportional to the input modulated signal, with the time waveform expressed as:

S_AM(t)＝[A₀+f(t)]×cos(w_ct+θ_c)

in the above formula, f (t) is a modulation signal, A₀For an additional DC component,. w_cBeing the angular frequency, theta, of the carrier signal_cIs the initial phase of the carrier signal.

The original modulation signal can be restored by using an envelope detection method, and in order to ensure that the envelope detection does not generate distortion, the following requirements must be met:

A₀+f(t)≥0

the demodulation of the AM is generally realized by using an analog circuit for envelope detection, but all the demodulation in the system is realized in an FPGA platform, so that the demodulation of the AM must be realized by using digital demodulation. An AM quadrature demodulation scheme is adopted in the scheme.

The received signals are:

S_AM(t)＝[A₀+f(t)]×cos(w_ct+θ_c)+n

the I path signal after quadrature demodulation:

q path signals after quadrature demodulation:

and S120, filtering the I, Q two paths of decomposed orthogonal signals through low-pass filters respectively.

The I, Q two-way decomposed quadrature signals can be filtered separately by low pass filters.

And S130, when the signal is an AM signal, tuning the filtered I, Q two-path decomposed orthogonal signal through a tuner to obtain a corresponding AM signal.

When directed to an AM signal, the tuner can demodulate the signal by squaring and root-opening:

"squaring and root cutting" this step can be carried out by the CORDIC (Xilinx support) to obtain the amplitude A₀+f(t)。

In a preferred implementation of this embodiment, the method may further include the steps of: and removing the direct current component in the AM signal. The average value of the signal (dc component a0) is subtracted to obtain the modulation signal f (t).

Correspondingly, in this embodiment, the input signal may also be an FM signal, and for the FM signal, the digital demodulation of the FM signal may be implemented by using the above processing procedure for the AM signal and adding a corresponding processing step.

Since FM/WFM is one type of angular modulation. In angle modulation, there is no linear correspondence between the frequency spectrum of the modulated signal and the frequency spectrum of the modulated signal, but it is generated from a new frequency component different from the frequency spectrum shift, and thus it exhibits the characteristic of a nonlinear process, and is also called nonlinear modulation. The angle modulation can be divided into frequency modulation and phase modulation, and the frequency modulation is widely used in practical applications.

Therefore, in this embodiment, for the FM signal, the method further includes the steps of: storing the I, Q two paths of decomposed orthogonal signals after filtering into registers respectively; respectively delaying the I, Q two paths of decomposed orthogonal signals stored in the register by one beat; and multiplying the I, Q paths of decomposed orthogonal signals delayed by one beat, and sending the multiplied signals to a tuner for tuning to obtain corresponding FM signals.

In FM modulation, the frequency of the modulated signal controls the variation of the frequency of the carrier, the instantaneous frequency offset of which varies in direct proportion to the modulated signal f (t), i.e.

Δw＝K_FMf(t)

Instantaneous phase of carrier:

in the above formula, K_FMIs the frequency modulation constant (sensitivity).

Modulated frequency-modulated signal of

S_FM(t)＝Acos[w_ct+K_FM∫f(t)dt]。

Correspondingly, when the signal is an SSB signal, the logic unit and the step of digitally demodulating AM and FM can still be multiplexed, and the digital demodulation of the SSB signal is realized by adding the corresponding step.

Illustratively, the method further comprises: when the signal is an SSB signal, multiplying the I, Q two paths of decomposed orthogonal signals after filtering by a carrier signal; or the I, Q two paths of decomposed orthogonal signals after filtering are subjected to phase shift operation; and obtaining the SSB original signal by adding and subtracting the signal.

Single sideband modulated SSBs only transmit one sideband of a double sideband modulated signal, so the most intuitive way to generate a single sideband signal is to pass the double sideband signal through a single sideband filter. The LSB and USB signals may be expressed as:

whereinIs f (t) Hilbert transformed signal

Generally, the following two technical schemes can be adopted for digitally demodulating the single sideband; one method is a phase shift method, which is mainly obtained by performing phase shift operation on I, Q two paths of decomposed orthogonal signals after filtering. The other method is a wife method, which is mainly realized by multiplying the filtered I, Q two paths of decomposed orthogonal signals by a carrier signal. When multiplying the carrier signals, a corresponding clock signal needs to be input.

The frequencies of two local clocks in the Weifu method need to satisfy:

in this embodiment, the received LSB signal is:

through and w_aAnd obtaining two paths of signals I/Q after quadrature demodulation and filtering.

Defining the center frequency point of a signal spectrum as:

the Q signal is actually a Hilbert transform of the I signal.

The I/Q path signal passes through AND w_bCan be obtained by local carrier multiplication

The corresponding signal is obtained by adding one to subtract the two paths of IQ signals, namely, the delta theta is set to be 0, and the digital demodulation of the signal is realized, namely, when the delta theta is 0, the corresponding signal is obtained.

In this embodiment, I, Q two paths of decomposed orthogonal signals are obtained by performing orthogonal modulation on a received signal; filtering the I, Q two paths of decomposed orthogonal signals through low-pass filters respectively; the method is characterized in that the method comprises the steps of carrying out subsequent processing on different signals respectively, and realizing digital processing on three different signals by utilizing the combination of the same tuner, a plurality of multipliers and registers.

Example two

Fig. 2 is an integrated digital demodulation apparatus provided in the second embodiment of the present invention, which can be used to implement the integrated digital demodulation method provided in the foregoing embodiment, and referring to fig. 2, the integrated digital demodulation apparatus includes:

the orthogonal demodulator is used for carrying out orthogonal demodulation on the received signals to obtain I, Q two paths of decomposed orthogonal signals; the low-pass filter is used for performing low-pass filtering on the I, Q two-path decomposed orthogonal signals; the tuner is used for demodulating I, Q two-path decomposition orthogonal signals after low-pass filtering; the quadrature demodulator includes: two multipliers and 3 NCO; the tuner includes: two DSPs; the multiplier includes: two DSPs; the multiplier is implemented by two DSPs and three NCO. The digital demodulation of the AM signal can be realized by utilizing the device. Accordingly, the tuner CORDIC may be implemented by two DSPs.

Correspondingly, the integrated digital demodulation device further comprises: the register is used for storing I, Q two paths of decomposed orthogonal signals, performing delay processing and returning the orthogonal signals after the delay processing to the multiplier of the orthogonal demodulator for multiplication; and the switch is used for storing I, Q two paths of decomposed orthogonal signals into the register when the FM signal is judged, connecting the register with the second multiplier through the switch, multiplying the delayed signals, respectively adding or subtracting the delayed signals and the two paths of signals which are not subjected to the second low-pass filtering, and removing direct current in the later period to obtain the digitally demodulated FM signal.

Correspondingly, the integrated digital demodulation device further comprises: and the direct current component removing module is used for removing the direct current component in the AM or FM signal.

When the SSB signal is digitally demodulated, the integrated digital demodulation apparatus further includes: the second low-pass filter is used for low-pass filtering the I, Q two-path decomposed orthogonal signals again so as to meet the processing requirement of the SSB signals; the SSB processing multiplier is used for multiplying the I, Q two paths of decomposed orthogonal signals after filtering by a carrier signal or carrying out phase shift operation on I, Q two paths of decomposed orthogonal signals after filtering when the signals are SSB signals; a signal adder-subtractor for adding and subtracting the multiplied signals or the phase-shifted signals to each other, specifically, for subtracting the signals when the signals are the upper sidebands; in the case of the lower sideband, signal addition is used. For obtaining the SSB original signal.

The device can effectively reduce the use of the logic modules through the multiplexing of each logic module. In this embodiment, the resources occupied by the integrated digital demodulation apparatus are estimated. Mainly uses 2 multipliers, 3 NCO, 2 LPF, 1 CORDIC and 2 dividers; other logic functions are implemented using a logic unit LE; the occupied resource is small.

The following table gives the resource estimates.

As can be seen from the above table, the integrated digital demodulation apparatus provided by this embodiment occupies fewer resources, and effectively saves the number of logic modules on the premise of ensuring the accuracy of signal demodulation.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.