JPH07193522A - Method for generating multiplex demodulation reception circuit - Google Patents

Abstract

PURPOSE:To obtain a simple and inexpensive circuit which can eliminate disturbance by means of an adjacent unnecessary signal by injecting the low frequency detection output of an ultra-reproduction reception circuit to the negative feedback amplifier circuit of a high input impedance, injecting the output to a low frequency tuning amplifier circuit and selecting/detecting the signal component of a specific frequency. CONSTITUTION:This circuit is composed of resistances R1-R11, capacitors C1-C9, an inductor L1, transistor Q1 and Q2 and an ultra-reproduction circuit SRG. The subsequent amplifying stage of the ultra-reproduction circuit SRG is set to be the high input impedance. A tuning amplifier circuit making a frequency characteristic to be flat to a wide area by the high input impedance negative feedback amplifier circuit and selecting/amplifying a carrier signal component since a sub-carrier signal detected in the ultra-reproduction circuit SRG includes a comparatively high frequency component is provided. When a multiplex modulation transmission signal radio wave is received, the sub-carrier signal of a comparatively high frequency is detected in the ultra-reproduction circuit SRG, and only the sub-carrier signal component is amplified in a tuning amplifier so as to eliminate the adjacent unnecessary signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses weak signal radio waves in a noisy radio wave environment as high quality information data.
And it's perfect for areas where you have to receive at a low price.

[0002]

2. Description of the Related Art A super-reproducing circuit includes a high-frequency oscillation circuit (hereinafter referred to as RF oscillation) that oscillates at the same frequency as the reception frequency and a quenching oscillation circuit that automatically switches between oscillation and non-oscillation at high speed. It is a receiving circuit that demodulates the signal by using two transistors. Many circuits have been developed in the past, but the newest super-regeneration circuit uses a surface acoustic wave oscillator (hereinafter referred to as SAW oscillator) as shown in FIG. In FIG. 2, R21 to R
25 is a resistor, C21 to C27 are capacitors, L21 to L
Reference numeral 23 is an inductor, SAW is a SAW oscillator, LPF is a low-pass filter, Q21 is a transistor, ANT is an antenna, VB is a power supply line, and VOUT is a detection output line. The basic component of this circuit is transistor Q21
Then, + B power is supplied from the power supply line VB through the resistor R24 and the inductor L22. Transistor Q2
The base potential that determines the operating point of 1 is determined by the voltage division ratio of the resistance R21 and the resistance R22 of the power supply line VB, but since the base is grounded by the capacitor C21 in order to improve the frequency characteristics, the input impedance becomes low. The resistor R23 is inserted in the series to give the base potential while raising the input impedance. The collector output of the transistor Q21 is connected to the base of the transistor Q21 through the SAW oscillator and the inductor L23 to form a feedback loop. The capacitor C22 is the inductor L2
1 determines the quenching oscillation frequency of the quenching oscillation circuit. The inductor L22 is for impedance matching between the transistor Q21 and the SAW oscillator, and adjusts the power level of the oscillator. Consider the case where a modulated high frequency signal has not arrived. Transistor Q
21 is conductive because the forward base bias current flows through the resistors R21, R22, and R23. On the other hand, this base current charges the capacitor C22. Both of these actions raise the emitter potential of the transistor Q21, and finally drive the transistor Q21 into cutoff. When the transistor Q21 is cut off, the charge accumulated in the capacitor C22 is transferred to the inductor L21,
After being discharged through the capacitor C23 and the resistor R25, the transistor Q21 is made conductive again and the same operation is repeated. This intermittent oscillation is the quenching oscillation. On the other hand,
Since the SAW oscillator acts as an inductor, a Colpitts oscillating circuit is formed by the inter-electrode capacitance between the collector, the emitter and the base of the transistor Q21, and the base bias potential of the transistor Q21 changes to the Colpitts during the quenching oscillation. The RF oscillation rises from the time when the oscillation condition of the oscillation circuit is satisfied, and the maximum value of the quenching oscillation amplitude is reached, and the RF oscillation amplitude is also maximized. The RF oscillation is also stopped when the oscillation condition of the Colpitts oscillation is not satisfied while the quenching oscillation is stopped from the maximum.
That is, the RF oscillation rises just after the rising of the quenching oscillation, reaches its maximum at the maximum time of the quenching oscillation, and stops at the time just after the trailing edge of the quenching oscillation. That is, the RF oscillation is superposed on the quenching oscillation. Next, consider the case where a high frequency modulated signal arrives at this state. When a signal radio wave arrives at the antenna, it is injected into the collector of the transistor Q21 and the SAW oscillator through the capacitor C27.
The injected high frequency modulation signal is fed back to the base of the transistor Q21 through the feedback loop of the SAW oscillator and the inductor L23. Moreover, the capacitor C22 is connected there. The fed-back high-frequency signal charges the capacitor C22 by an amount equivalent to the amount of feedback, and the transistor Q21
In order to raise the base bias potential of the RF oscillation, the RF oscillation starts oscillating faster than when there is no signal, and at the same time reaches the maximum value faster. Inductor L22
The high frequency component is removed by the LPF formed by the capacitor C26 and the signal component of the high frequency modulated signal injected into the LPF through the capacitor C25 is detected. A SAW oscillator is used in the feedback loop to obtain RF oscillation with good frequency stability against temperature changes and power supply voltage, and at the same time, the SAW Q is much larger than the Q of the tuning circuit made up of the inductor and capacitor, so the receiver When viewed as, a super-reproduction circuit with good selectivity can be formed. FIG. 3 shows a general super reproduction circuit composed of an inductor and a capacitor.
L31 and trimmer capacitor TC in the feedback loop
This is an example of a conventional technique using a parallel resonance circuit (hereinafter referred to as a tank circuit) made by and. In FIG. 3, R31 to R3
4 is a resistor, C31 to C36 are capacitors, L31 to L3
3 is an inductor, TC is a trimmer capacitor, Q31 is a transistor, VB is a power supply line, and VOUT is a detection output line. Inductor L3 in the feedback loop
1. A capacitor C32 is connected to one end of the tank circuit of the trimmer capacitor TC and is injected into the base of the transistor Q31. The quenching oscillating circuit comprises a circuit in which an inductor L33 and a resistor R33 are connected in parallel to the collector of the transistor Q31 and the other end of the transistor is connected to the emitter of the transistor Q31 through a capacitor C34. The operating principle is
It is similar to the one using the SAW oscillator. Waveforms with and without a high frequency signal are shown in the following figures. 5 is a waveform of a signal to be transmitted, FIG. 6 is a detection output waveform of the super reproduction circuit, FIG. 7 is a portion D of FIG. 6 and an enlarged portion E of FIG. 3 is a quenching waveform, FIG. 9 is a portion F of FIG. The RF oscillation waveform is superimposed on the quenching waveform when a high-frequency signal arrives in the expanded waveform of Fig. 10. Fig. 10 is the enlarged waveform of the G part of Fig. 8 in which the RF oscillation waveform is superimposed on the quenching waveform when there is no signal. What was done. From these figures, the operation and principle of the above-mentioned super reproduction circuit can be understood. In the case where a tank circuit made up of an inductor and a capacitor is used for a feedback loop, the Q of the tank circuit is low and the selectivity is poor when viewed as a receiver. The super reproducing circuit is low in cost because it has a small number of parts and a simple circuit, and the sensitivity is high, usually 2 to 7 μV at the antenna input end. The super playback circuit has features not found in other high-end models. In principle, the super reproduction circuit has amplitude modulation (hereinafter referred to as AM modulation), amplitude shift keying (hereinafter referred to as ASK modulation), frequency modulation (hereinafter referred to as FM modulation), frequency shift keying (hereinafter referred to as FSK modulation),
Phase modulation (hereinafter referred to as PM modulation), sideband modulation (hereinafter referred to as S
Various modulation signals such as SB modulation) are demodulated.

[0003]

The super regenerative circuit of the prior art has a simple circuit and a low cost. However, since a tank circuit having a low Q made up of an inductor and a capacitor is used as a feedback loop, a -3 dB reception bandwidth is obtained. Is about 6 MHZ,
Even if the SAW oscillator is used for the feedback loop, it is 200 KHZ. Usually, the receiving bandwidth of a receiver used for such an application is 10 KHZ, so that it must be said that it is a very wide-band receiver.
One of the challenges is to use this wideband super regenerative circuit with a reception bandwidth of 1
It is to set to 0KHZ. Further, the super reproduction circuit does not have good adjacent unnecessary signals, fluctuations in power supply voltage, and noise resistance. This is because the super regenerative circuit is a wide band receiver and the simple ASK
This is because the emphasis was placed on detecting the modulation and the FSK modulation with high sensitivity, and is closely related to the transmission technology as well as the reception technology. As described above, the conventional super-regenerative receiver circuit has the ability to demodulate various modulated signals in principle, and combined with the fact that it has a wide band, its performance is greatly improved and adjacent unnecessary signals are The goal is to develop new technology to prevent interference and improve noise immunity. Moreover, considering that the super reproducing circuit can be constructed at a low cost, the newly developed technology must be simple and low cost. SUMMARY OF THE INVENTION The present invention solves the problems of the prior art super-regeneration circuit, eliminates the interference due to adjacent unnecessary signals, and provides a simple and inexpensive multiplex demodulation receiving circuit.

[0004]

A multiplex demodulation receiving circuit according to the present invention solves the above problems, and is paired with a utility model registration application, reference number H5-1002, and a device name multiplex modulation transmitting circuit. It is a technology. The radio wave signal subjected to the multiple modulation is first demodulated by the super-reproducing circuit into a subcarrier (one wave of 30 KHZ to 150 KHZ) by utilizing its wide band property. Since the super playback circuit is a very fine and delicate receiving circuit from both the principle and the circuit configuration,
The circuit in the next stage is a high input impedance amplifier so as not to affect the super reproduction circuit, and the frequency to be handled is 30 KHZ ~
Since it is 150 KHZ, the negative feedback amplifier circuit is used in consideration of the frequency characteristic. It is also possible to provide a tuning amplifier circuit in this portion. The output of this high input impedance negative feedback amplifier circuit is injected into the next stage tuning amplifier circuit by capacitor coupling. This tuning amplifier circuit amplifies only those having the frequency component of the target subcarrier signal. Since the selectivity Q of the tuning amplifier circuit is about 10 to 20, it is possible to amplify only the target subcarrier frequency component, and the total of the receiving circuit is -3.
The dB bandwidth can be 10 KHZ or less. This is a multiplex demodulation receiver circuit configured to amplify the output of the tuning amplifier circuit, shape the waveform, and then digitally detect it by using a normal detection circuit or a retriggerable one-shot multi circuit to extract a target signal.

[0005]

According to the present invention, by constructing the multiplex demodulation receiving circuit as in the previous period, the narrowband property and the multiplex demodulation function comparable to those of ordinary communication equipment are combined, and the signal arrives close to the desired reception signal. Since it suppresses unnecessary noise and suppresses noise, it has the ability to receive a weak desired signal with a good S / N ratio. Further, structurally, by using the transistor as a main component and appropriately adjusting the operating condition, that is, the so-called DC bias condition, the power supply voltage can be as low as 1.5 V to 6 V, and the low voltage operation can be performed, and the operation is stable against the fluctuation. Can be done. If the frequency of the incoming multi-modulation transmission signal is stable, it is hardly affected by the wide band property of the super-regeneration circuit even with respect to temperature change. The subcarrier signal of the detection output of the super-regeneration circuit is one of 30 KHZ to 150 KHZ, but the selectivity Q of the tank circuit made up of the inductor and the capacitor of the tuning amplifier circuit is 10 even if the temperature changes slightly. ~
If there is 20, due to the pull-in phenomenon peculiar to the tank circuit,
Only the subcarrier signal is selectively amplified. In this way, it has the effect of operating stably in terms of temperature.

[0006]

Embodiment 1 Embodiment 1 will be described with reference to FIG. In FIG. 1, R1-R11 are resistors C1-C9 are capacitors,
L1 is an inductor, Q1, Q2 are transistors, SRG
Is a super reproduction circuit, A is the output of the super reproduction circuit, B is the output of the subcarrier demodulation circuit, and VB is the power supply line. Since the super regenerative circuit is a very sensitive circuit, the subsequent amplification stage must have a high input impedance. The high input impedance amplifier circuit divides the base bias potential that determines the DC operating point of the transistor Q1 by the resistors R1 and R2 into the power supply voltage VB, and the resistor R3 is added to the series in order to obtain a high input impedance. It is injected into the base of the transistor Q1 together with the subcarrier detection output of. The transistor Q1 is supplied with power from the power supply line VB through the load resistor R4 of the transistor Q1.
The capacitor C2 is a bypass capacitor that prevents a high frequency signal from leaking to the power supply line. The emitter bias resistor connected to the emitter of the transistor Q1 is divided into resistors R5 and R6, and the resistor R5 is AC short-circuited by the capacitor C3 to increase the AC gain. In addition, here, the output of the tuning amplifier in the next stage is AC negatively fed back to the emitter of the transistor Q1 through a negative feedback loop formed by the capacitor C8 and the resistor R11.
The frequency characteristics are flattened to the high range. Part of the negative feedback is through the capacitor C1 and the resistor R3, and the transistor Q1
Is injected into the base of. The capacitor C4 is a coupling capacitor with the next-stage tuning amplifier circuit, and is intended to cut the direct current component. The tuning amplifier circuit injects a DC bias that determines the operating point of the transistor Q2 into a DC bias potential by dividing the power supply voltage VB with the resistors R7 and R8 and injecting it into the base of the transistor Q2 together with the output of the preceding stage. The collector of the transistor Q2 is supplied with power from the power supply line VB through a tank circuit formed by the current limiting resistor R9, the capacitor C6 and the inductor L1. The emitter of the transistor Q2 has a resistor R1 for applying a DC emitter bias potential.
The resistor R10 is short-circuited in alternating current with 0, and the capacitor C7 for increasing the alternating current gain is inserted as a bypass capacitor. In the tank circuit of the inductor L1 and the capacitor C6, the inductance is increased, the capacitor is decreased to increase the circuit Q, and the voltage gain is further increased. It is composed of a capacitor C9 which outputs an output from the collector of the transistor Q2. The high-impedance negative feedback amplifier circuit in the first stage can be a high-input impedance tuning amplifier circuit.
It is also possible to use a wideband operational amplifier with high input impedance. As described above, the super-reproducing circuit detects the subcarrier signal, the amplification circuit for tuning and amplifying the subcarrier frequency component is provided, and the problem is eliminated by the detection.

[0007]

One of the effects of the present invention is that, when a multi-modulation transmission signal radio wave is received, a subcarrier signal of relatively high frequency is detected by a super-regeneration circuit and only a subcarrier signal component is amplified by a tuning amplifier. This eliminates adjacent unnecessary signals. This situation can be understood well by the figure. FIG. 5 shows a digital signal to be transmitted, and FIG. 12 (a) shows a radio wave waveform when it is radiated into space as the multiplex-modulated ASK modulated wave. When this radio wave is received, the detection waveform at point A in FIG. 1 becomes as shown in FIG. FIG. 7, which is an enlarged view of FIG. 6, includes the subcarrier components of the ASK-modulated wave that has been subjected to the multiple modulation. FIG. 11 shows a waveform at point B in FIG. 1 in which only the subcarrier component is tuned and amplified. As described above, the super reproducing circuit is basically AM, ASK, FM, FSK, PM, SSB.
In addition to being able to detect and demodulate a modulated carrier such as, for example, and to be a wide band receiver, a relatively high frequency (30 KH
It is possible to detect a subcarrier signal of one of Z to 150 KHZ. Since the subcarrier signal detected by the super reproduction circuit contains a relatively high frequency component, the next stage high input impedance negative feedback amplification circuit flattens the frequency characteristics to a wide range, and a tuning amplification circuit that selectively amplifies the carrier signal component is used. Providing a total -3dB bandwidth of 10KHZ
You can understand the effects of the following. Next, the greatest effect is the effect of preventing interference with adjacent unnecessary signals. Figure 1
The spectrum when the electric field strength at the reception point of the present invention of the multiple ASK modulated transmission radio wave waveform shown in FIG. 2 (a) is Es and this is 0 dB is shown in FIGS. FIG. 12B shows a radio wave waveform when a simple ASK modulated transmission radio wave having a carrier is a noise radio wave, and the electric field strength at the reception point of the present invention is En, and its spectrum is shown in FIG.
(C)-(2). The difference between the electric field strengths of Es and En is Δ
E (dB). FIG. 13 shows the output waveform at point B in FIG. 1 when the electric field strength of Es is kept constant and the electric field strength of En is variously changed. 13A is a waveform when Es = En, FIG. 13B is a waveform when Es <En and ΔE = 10 dB, and FIG. 13C is a waveform when Es <En and Δ = 20 dB. Is the waveform of. What can be judged from the above diagram is
It is shown that the noise can be demodulated even if the noise radio wave of the same carrier arrives and the noise radio wave intensity is 10 dB (about 3 times) larger than the signal radio wave intensity. The following is the data obtained by performing the reverse test as to how much the performance is improved. FIG. 14A shows a radio wave waveform when a simple ASK modulated signal radio wave is used as a signal, which is received by a conventional super reproduction receiver, and the electric field strength at the receiving point is Es ′ and the electric field strength is 0 dB. Fig. 14 (c)-
It shows in (1). FIG. 14B shows a radio wave waveform when the multiplexed ASK modulated signal radio wave is a noise radio wave. The electric field strength at the receiving point of the conventional super-regenerative receiver is En ', and the spectrum is shown in FIGS. 14 (c)-(2). The difference between the electric field strengths of Es ′ and En ′ is ΔE ′ (dB). FIG. 15 shows data obtained by waveform-shaping the detection output of the conventional super reproduction receiver when these two radio waves are radiated and received at the same time. Figure 15
(A) is a waveform when Es '= En', FIG. 15 (b)
Is a waveform when Es '>En' and ΔE '=-20 dB, and FIG. 15 (c) is a waveform when Es'> En 'and ΔE' =-26 dB. What can be judged from the data of this experiment is that the conventional super reproduction circuit cannot restore the original signal unless the electric field strength of the noise electric wave is less than -26 dB (about 1/20) than the electric field strength of the signal electric wave. There is. That is, it is shown that the present invention is superior in noise resistance of 30 dB (about 30 times) as compared with the conventional super reproduction circuit (the situation is almost the same in general communication equipment). Regarding the reception bandwidth, the tuning amplifier circuit of the present invention has a selectivity Q of about 20 and a subcarrier signal frequency of 7.5K even when the subcarrier signal frequency is 150KHZ.
It shows HZ, which is confirmed by experimental data. This is similar to general communication equipment. Despite the temperature change and power supply voltage change, the receiving sensitivity between -20 ° C and 60 ° C is 7μV ± 1μV and the receiving bandwidth is 7KHZ ± 2KHZ, which is almost the same data between 1.5V and 6V. Is getting As described above, the effect obtained with a simple circuit and without using special parts is that the reception sensitivity is rather low, and the noise resistance is far better than that of expensive communication equipment. Got

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

[Fig.2] Super regenerative circuit diagram using a conventional SAW oscillator

FIG. 3 is a conventional L / C super-regeneration circuit diagram.

FIG. 4 is a block diagram of FIG.

[Figure 5] Digital signal to be transmitted

6 is a waveform at a point A in FIG. 1, C is a boundary portion between where carrier is present and where carrier is not present, and D is a observing portion of a quenching waveform.

FIG. 7 is an enlarged view of part C in FIG. 6, subcarrier component waveform

FIG. 8 is an enlarged view of part D of FIG. 6, a quenching waveform.

9 is an enlarged view of the F portion of FIG. 8, a waveform in which an RF waveform at the time of signal is superimposed on the quenching oscillation.

FIG. 10 is an enlarged view of a G part of FIG. 8, a waveform in which an RF waveform when there is no signal is superimposed on a quenching oscillation.

11 is a waveform at point B in FIG. 1, an output waveform in which only subcarriers are tuned and amplified.

FIG. 12 (a) Multiple ASK modulated transmission radio wave waveform (b) Simple ASK modulated transmission radio wave waveform (c)-(1) Electric field intensity of (a) and spectrum Es = 0 dB at the receiving point of the circuit of the present invention. (C)-(2) Electric field intensity and spectrum of (b) at the receiving point of the circuit of the present invention

13 (a), FIG. 12 (a) at point B in FIG.
Waveforms when (b) is received simultaneously When electric field strength difference ΔE = 0 dB When (E) = 10 dB as in (b) (a) When ΔE = 20 dB as in (c) (a)

14 (a) Simple ASK modulated transmission radio wave waveform (b) Multiplex ASK modulated transmission radio wave waveform (c)-(1) Electric field intensity and spectrum of (a) at the reception point of the conventional super reproduction circuit, Es ′ = 0 dB (c)-(2) Electric field intensity and spectrum of (b) at the receiving point of the conventional super reproducing circuit

FIG. 15 (a) is a data output waveform of a conventional super reproduction receiver, and FIG. 14 (a) and (b) are output waveforms when ΔE ′ = 0 dB, which is the same as (b) (a). When ΔE ′ = − 20 dB, when ΔE ′ = − 26 dB as in (c) (a)

[Explanation of symbols]

R1-R11, R21-R25, R31-R34 are resistors C1-C9, C21-C27, C31-C36 are capacitors TC are trimmer capacitors L1, L21-L23, L31-L33 are inductors Q1, Q2, Q21, Q31 are transistors SRG is a block diagram of a conventional super regeneration circuit SAW is a 1 / 4λ surface acoustic wave oscillator LPF is a low pass filter VOUT is a detection output line ANT is an external antenna VB is a power supply line A is a conventional super regeneration circuit detection output observation Point B is the output observation point of the present invention. E is the observation point of the quenching oscillation waveform.

Claims (1)

[Claims] 1. A low-frequency detection output of a super-regenerative receiver circuit according to the prior art is injected into a negative feedback amplifier circuit of high input impedance, and the output is injected into a low-frequency tuning amplifier circuit to selectively detect a signal component of a specific frequency. Method for forming a multiplex demodulation receiving circuit configured to perform.