CN201160271Y - Quadrature Detector Used in Upgrading and Transformation of HF Analog Receiver - Google Patents

Abstract

Quadrature detector used for upgrading shortwave analog receiver, including oscillator, pulse generation circuit, dual analog switch, dual voltage follower, double integrator, double inverting proportional amplifier, the device is connected to shortwave analog receiver Between the personal computer with a sound card, the upgrade of the shortwave analog receiver can be completed. The device has the characteristics of novelty, simplicity, flexibility, and convenient debugging. It can change the traditional way of upgrading analog receivers, thereby greatly improving performance.

Description

Quadrature Detector Used in Upgrading and Transformation of HF Analog Receiver

(1) Technical field

The utility model relates to an upgrading and reforming device of a radio receiver, in particular to an orthogonal wave detector used for upgrading and reforming a short-wave analog receiver.

(2) Background technology

Among short-wave receiving equipment, analog receivers (hereinafter referred to as "simulators") still have a large amount of possession in various relevant departments including the military, non-committee at all levels, navigation, time service, meteorology, broadcasting, etc. . This part of the simulator is completely based on hardware and has a single function. Facing various challenges brought about by the continuous development of modern communication technology (more complex and harsh channel environment, endless new coding and modulation methods, etc.), it seems powerless. Moreover, due to the constraints of various factors such as the replacement cycle and funds, it is unlikely to be completely eliminated in a short period of time. Therefore, how to transform them according to local conditions and make them adapt to the development of the situation has very practical significance.

The software defined radio technology develops rapidly in recent years, has the characteristic such as strong expansibility, flexibility and common use, has represented the development direction of the radio technology. Digital transformation of the traditional analog machine and the introduction of software radio technology can greatly improve its performance and make it keep up with the pace of technological development.

In order to extract the "baseband" signal with a lower frequency from the IF signal from the analog machine, the traditional mixing method is that the local oscillator generates a local oscillator output equal to the carrier frequency of the IF signal, which is transformed into a phase difference after a phase shifter. The 90-degree two-way orthogonal signals are mixed with the intermediate frequency signal respectively to generate "sum frequency" and "difference frequency" outputs. After the "sum frequency" component is filtered out by the low-pass filter, the "difference frequency" component is the required two-way "baseband" signal. Although the "baseband" signal extraction can be realized, the circuit structure of this method is complex, and debugging is difficult. Because the harmonic components generated by the nonlinear effect of the mixer are rich and the loss is large, the application is limited.

(3) Contents of the invention

In order to overcome the defects of the prior art, the utility model provides a quadrature detector used for upgrading and reforming short-wave analog receivers.

A quadrature detector for upgrading shortwave analog receivers, including an oscillator, a pulse generating circuit, a dual analog switch, a dual voltage follower, a dual integrator, and a dual inverting proportional amplifier. The pulse generating circuit consists of a class D Composed of a trigger and a logic circuit, it is characterized in that the oscillator is connected to the pulse generating circuit, the output terminals of the logic circuit of the pulse generating circuit are respectively connected to the control terminals of the dual analog switch, and the output terminals of the dual analog switch are respectively connected to the dual The input terminal of the voltage follower and the output terminal of the dual voltage follower are respectively connected to the double integrator, and a double inverting proportional amplifier is respectively connected behind the double integrator, and the output terminal of the dual inverting proportional amplifier is connected to an output coupling circuit.

When the utility model is used, the intermediate frequency output end of the short-wave analog receiver is connected with the input end of the quadrature detector; the output end of the quadrature detector is connected with the linear input end of the sound card of the personal computer, and after the signal enters the sound card sampling, the Use a personal computer to perform a series of operations such as spectrum display, digital filtering, demodulation, and noise cancellation to realize the upgrade of the shortwave analog receiver.

The working process of the quadrature detector in the utility model is: the oscillator produces a clock frequency 4 times the frequency of the intermediate frequency, and the logic circuit outputs two sampling pulses through the pulse generation circuit (see sampling pulses 4 and 5 in Fig. 2) , the pulse width is T, the cycle is T ₀ , and T ₀ =4T (where T is the clock cycle, T ₀ is the intermediate frequency cycle.), and the phase difference of the two sampling pulses is 90 degrees, respectively controlling the "closed" and "open" (high level is "closed", low level is "open"). The input terminals of the two analog switches receive the intermediate frequency signal coupled and fed by the analog receiver, and the output terminals of the two analog switches are connected with the two voltage followers to perform impedance transformation, and then enter the two integrators to "extract" the sound card. Processed low frequency "baseband" signals. The sound card of a personal computer is a complete hardware system including analog/digital, digital/analog conversion, and digital signal processing chips to process "baseband" signals. The linear input port (Line In) of sound card receives two-way (R sound channel and L sound channel) stereo signal, and in the present invention, correspondingly receives the required two-way quadrature signal (1 way and Q road). After the I-channel and Q-channel "baseband" signals enter the sound card for sampling, the algorithm for processing orthogonal "baseband" signals can be used for calculation and processing, and a series of operations such as spectrum display, digital filtering, demodulation, and noise elimination can be completed.

The principle of the utility model "extracting" the "baseband" signal by the quadrature detector is as follows: the intermediate frequency signal from the simulator is an unmodulated pure carrier, which is the sinusoidal voltage signal 6 whose period is T ₀ in Fig. 2 . It is coupled to the double integrator through dual analog switches, each switch can allow the sinusoidal signal 6 within T time to pass. After T time, the dual analog switch is closed, and the dual integrator integrates to obtain the average voltage of the sinusoidal signal within T time, and maintains the voltage value until the next dual analog switch is turned on. Because the period of the sampling pulse is equal to the period of the sinusoidal signal, it can be seen that the average value of the voltage obtained on the double integrator is equal each time, that is, the two output voltages of the double integrator are constant. If the two-sampling pulse width T and period T ₀ are kept unchanged, and the sinusoidal signal period is changed to make it equal to T ₀ +ΔT, then the output voltage on the double integrator is no longer a constant value, but changes with ΔT. From the frequency domain analysis, in the communication system, after the "baseband" signal modulates the carrier, a frequency spectrum with the carrier as the center frequency is generated, which corresponds to the period increment ΔT in the time domain. It can be seen that the role of the double integrator is exactly from the intermediate frequency signal Extracts the "baseband" signal. At the same time, since the two sampling pulses 4 and 5 are exactly 1/4 period different from the intermediate frequency frequency, that is, the phase difference is 90 degrees, the "baseband" signal extracted by the double integrator 10 is correspondingly two signals with a phase difference of 90 degrees, namely The I road and the Q road are respectively sent to the linear input end of the sound card of the personal computer.

Compared with the upgrading method based on quadrature mixer, the upgrading method based on quadrature detector has the following beneficial effects:

1. Use sampling pulses with a phase difference of 90 degrees for "asynchronous" sampling, avoiding the phase-shifting circuit of local oscillator signals required for "synchronous" mixing by quadrature mixers; using double integrators to extract "baseband" signals, saving The mixer and its paranoid circuit are removed, so the circuit structure is greatly simplified;

2. As a "digital" detector, compared with the analog mixer, the debugging process is greatly simplified, and it can be connected to the system to play a role without debugging;

3. The output of the mixer includes "sum frequency", "difference frequency" and various harmonic components and their sum and difference components. Among them, only the "difference frequency" component is effective, and the conservative loss is greater than 6dB; quadrature detector Only output the "difference frequency" component, the conversion loss is very small, and it can reach 0.9dB without considering the device loss;

4. Since there is no need to consider the nonlinear effect of the mixer, the quadrature detector has a large dynamic range and small distortion, and can be connected to various types of simulators, and has a wide range of applications;

5. The whole system platform is novel, simple, flexible and convenient for debugging. Due to the rapid popularization of personal computers, users can realize the upgrade and transformation of the simulator on the basis of almost no additional hardware investment.

(4) Description of drawings

Fig. 1 is a schematic diagram of the connection of the utility model, Fig. 2 is a schematic diagram of the sampling pulse timing and sampling principle of the quadrature detector, and Fig. 3 is a circuit diagram of an embodiment of the quadrature detector of the utility model.

Among them: 1. Quadrature detector, 2. Analog receiver, 3. Personal computer (including sound card), 4. 5. Sampling pulse, 6. Intermediate frequency signal, 7. Oscillator, 8. Pulse generating circuit, 9. Dual Analog switch, 10. Double integrator, 11, 15, 16, 19, 21, 24, 27, 28, 29, 34, 42, 43, 50, 51, 52, 53, 57, 58, 60. Capacitor, 12, 13, 18, 20, 30, 31, 35, 40, 41, 44, 45, 46, 47. Resistor, 14. Crystal, 17. Transistor, 22, 23. D flip-flop, 25, 26. Logic Circuit, 32. Analog receiver output connector, 33. Intermediate frequency transformer, 36, 37. Dual analog switch, 38, 39. Dual voltage follower, 48, 49. Double inverting proportional amplifier, 54, 55. Audio transformer, 56. Two-way interface, 59 three-terminal voltage regulator integrated block, 61. The intermediate frequency output signal from the analog receiver, 62. The "baseband" signal extracted by the quadrature detector.

(5) Specific implementation methods

Example

The utility model uses connection as shown in Figure 1, and the intermediate frequency output end of shortwave analog receiver 2 is connected with the input end of quadrature detector 1; The output end of quadrature detector 1 is connected with the sound card linear input end of personal computer 3, After the signal enters the sound card for sampling, a series of operations such as spectrum display, digital filtering, demodulation, and noise elimination can be performed with the help of the personal computer 3, so as to realize the upgrade and transformation of the shortwave analog receiver 2.

The embodiment of the quadrature detector of the present utility model is shown in Fig. 3, comprising an oscillator 7, a pulse generating circuit 8, a dual analog switch 9, a dual voltage follower 38, 39, a dual integrator 10, and a dual inverse proportional amplifier 48 , 49, the pulse generation circuit 8 is made up of D-type flip-flops 22,23 and logic circuit "and" gates 25,26, the oscillator 7 is connected with the pulse generation circuit 8, and the logic circuit "and" gate 25 of the pulse generation circuit 8 , 26 output ends are respectively connected to the control end of the dual-way analog switch 9, the output ends of the double-way analog switch 9 are respectively connected to the input ends of the dual voltage follower 38, 39, and the output ends of the dual voltage follower 38, 39 are respectively connected to The double integrator 10 is connected with double inverting proportional amplifiers 48 and 49 respectively behind the double integrator 10, and the output terminals of the double inverting proportional amplifiers 48 and 49 are connected to the output coupling circuit.

Among them: capacitors 11, 15, 16, 19, resistors 12, 13, 18, 20, triode 17, and crystal 14 form a crystal oscillator circuit, which generates a clock frequency 4 times the frequency of the intermediate frequency, and is coupled to a D-type flip-flop 22 via a capacitor 21 , 23, the pulse generation circuit 8 that " and " gate 25,26 is formed, produces control pulse; Two-way analog switch 9 comprises two separate analog switches 36,37, and the control pulse that pulse generation circuit 8 produces controls analog switch 36 , 37 state (high level is "closed", low level is "open"). The input terminals of the analog switches 36 and 37 receive the intermediate frequency signal coupled from the analog machine by the coupling network composed of the analog receiver output connector 32 , the intermediate frequency transformer 33 , the capacitor 34 and the resistor 35 . The output terminals of the analog switches 36 and 37 are connected with the voltage followers 38 and 39 composed of high-speed operational amplifiers for impedance transformation, and then enter the integrator composed of resistors 40 and 41 and capacitors 42 and 43 .

The "baseband" signal I and Q routes extracted by capacitors 42 and 43 pass through resistors 44, 45, 46 and 47, and operational amplifiers 48 and 49. The inverse proportional amplifying circuit is composed of capacitors 52 and 53 and audio transformers 54 and 55. Coupled to the R, L interface of the linear input of the personal computer sound card.

Capacitors 57, 58, 60 and three-terminal voltage stabilizing integrated block 59 form a voltage stabilizing circuit to provide 5V power for the entire quadrature detector 1 . Capacitors 24, 27, 28, 29, 50, 51 and resistors 30, 31 form a bias network and a high frequency bypass circuit.

Claims (1)

1. A quadrature detector for upgrading and transforming short-wave analog receivers, including an oscillator, a pulse generating circuit, a dual analog switch, a dual voltage follower, a dual integrator, and a dual inverting proportional amplifier. The pulse generating circuit consists of Composed of a D-type flip-flop and a logic circuit, it is characterized in that the oscillator is connected to the pulse generating circuit, the output terminals of the logic circuit of the pulse generating circuit are respectively connected to the control terminals of the dual analog switch, and the output terminals of the dual analog switch are respectively connected to to the input terminals of the dual voltage follower, and the output terminals of the dual voltage follower are respectively connected to the dual integrators, and behind the dual integrators are respectively connected to dual inverting proportional amplifiers, and the output terminals of the dual inverting proportional amplifiers are respectively connected to output coupling circuits.

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