JPS5838804B2 - radio control device receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiver for a radio control device (hereinafter referred to as a radio control device) having an improved squelch circuit to reliably prevent malfunctions of operating parts.

Radio-controlled devices that use radio waves to remotely control controlled objects such as model cars and model airplanes use a modulation method that controls on/off a high-frequency carrier signal formed in a transmitter according to the amount of stick operation and emits it as a radio wave. It is widely adopted.

On the other hand, in order to accurately control the controlled object using radio waves from the transmitter, the operation part must be driven by external noise other than the radio waves transmitted from the transmitter, or by noise components generated inside the receiver or the controlled object. It is necessary to prevent malfunction of the parts.

Particularly in recent years, various wireless devices have come into widespread use, and more and more radio waves from these wireless devices are entering receivers of radio-controlled devices as noise components.

Therefore, instead of the above-mentioned conventional modulation method, a type of FM modulation method that is less susceptible to the influence of various noise components has come to be adopted in radio-controlled devices.

In other words, in correspondence with conventional on/off control, the carrier wave high-frequency signal is transmitted with different frequencies in the on period and off period, and the receiver side discriminates the frequency of the received modulated wave and controls each control period. A pulse signal having a pulse width corresponding to the pulse width is extracted and sent to the drive section of each operating part.

As mentioned above, radio control equipment using this FM modulation method has a large noise suppression effect, and the sideband of the radio waves emitted from the transmitter can also be made small, reducing interference with other receivers and increasing the altitude. This FM modulation method is gradually being adopted in radio-controlled equipment that requires high maneuverability.

By the way, when receiving radio waves using this FM modulation method,
If radio waves in the frequency band assigned to the receiver (hereinafter referred to as own radio waves) are being received, unnecessary noise components are largely suppressed due to the noise suppression effect, but if the own radio waves are lost, the receiver Due to its high degree of amplification, it exists in countless numbers in nature, and the weak radio waves that enter the receiver through the antenna and the noise generated inside the receiver are amplified.
There is a problem in that these noise components are detected by the detection section, causing the operation part to malfunction.

Therefore, in the receiver of an FM modulation type radio control device, as in the case of a mobile FM receiver, when the level of the input signal at the antenna is below a certain level, the signal is sent to the servo section for driving the operating part. A noise suppression circuit, a so-called squelch circuit, is provided to prevent output.

For example, there is a receiver equipped with the above-mentioned squelch circuit as shown in FIG.

The receiver shown in FIG.
The M modulated wave and the high frequency signal output from the local oscillation section 2 are introduced into the frequency mixing section 3, where they are converted into an intermediate frequency signal, and then sent to the intermediate frequency amplifying section 5 via the filter section 4 made of a ceramic filter or the like. Send and amplify.

Furthermore, the intermediate frequency signal amplified by the intermediate frequency amplifying section 5 is detected via the intermediate frequency transformer IFT and the coupling capacitor C7, which is connected to the power supply 8 with a resonance capacitor C1 inserted in parallel on the negative side. 6 and demodulates the FM modulated wave to form a pulse signal having an on period or an off period depending on the amount of each stick operation on the transmitter side.

The detection output signal of the detection section 6 is amplified to an appropriate level by the amplification section 7 and given to the decoder 8, and the decoder 8 distributes it to the servo section 9 that drives each operation part to drive the manipulated object. Remote control using radio waves will become possible.

On the other hand, the output signal of the intermediate frequency amplification section 5 is also introduced into the squelch circuit section 10 via the coupling capacitor C3, where the output signal is rectified by the diodes D, , D, and further transmitted to the squelch circuit section 10 via the coupling capacitor C3. The DC signal is smoothed by the capacitor C6, and this DC signal is connected to the resistor R1.
It appears as a terminal voltage of , and is sent to the amplification section 7 as a control signal.

Therefore, when the antenna 1 receives its own radio wave and there is an input signal to the receiver, a high level output signal is generated in the intermediate frequency amplifying section 5, so that the terminal of the resistor R1 of the squelch circuit section 10 The voltage also becomes high level, and the amplifying section 7 is operated by this high level control signal.

On the other hand, for example, if the signal from the transmitter is blocked and the radio waves received by the antenna 1 contain only noise components, the signal output to the intermediate frequency amplification section 5 will contain external noise components and the receiver. Since it is only the noise component generated internally,
Its signal level is extremely low.

Therefore, the terminal voltage of the resistor R1 of the squelch circuit section 10 also becomes a low level, and when the terminal voltage of this resistor R1, that is, the control signal for the amplifying section 7 is at a low level, the amplifying section 7 is made inoperable. The noise components detected by the detection section 6 are prevented from being input to the decoder 8, and malfunctions of the servo section 9 due to the various noise components are prevented.

By the way, in a radio-controlled device, if there is another radio wave with a frequency close to the frequency of the own radio wave (hereinafter referred to as an adjacent band radio wave), and the radio wave in this adjacent band is strong, the sideband component of this adjacent band often becomes strong enough to be received by the receiver, and the sideband components of this adjacent band are amplified by the intermediate frequency amplification section 5 and demodulated by the detection section 6, causing the servo section 9 to malfunction. The squelch circuit of a radio-controlled device needs to be able to sufficiently distinguish between the sideband components of such adjacent bands and its own radio waves to perform a reliable squelch operation.

In addition, it is necessary to prevent the servo section 9 from malfunctioning due to noise generated inside the receiver or the controlled object, especially noise caused by metal contact at the operating part of the servo section 9's motor or the controlled object. .

Furthermore, it is required to prevent the servo section 9 from malfunctioning even if the center frequency of the transmitter or the local oscillation frequency of the receiver is slightly shifted.

However, in the conventional circuit shown in FIG. 1 described above, the received signal of the own radio wave on the output side of the intermediate frequency amplification section 5 is detected and introduced into the squelch circuit section 10 to perform the squelch operation. There is.

However, in general, in this type of circuit, when the radio waves in the adjacent band are strong, sideband components included in the adjacent band may be amplified by the intermediate frequency amplification section 5 and generated as an output, and accurate squelch operation cannot be performed. There is a problem that it is no longer possible.

Further, there is a problem in that noise components are also easily amplified in the same way, and the noise components are detected as signals and sent to the squelch circuit section 10.

Furthermore, the conventional circuit shown in FIG. 1 described above requires a diode DIFD2 and the like for rectifying the output signal of the intermediate frequency amplifying section 5 to form a squelch signal, making the configuration of the squelch circuit section 10 complicated. In addition, since the squelch circuit section 10 is directly connected to the output side of the intermediate frequency amplification section 5, there is a problem that the operation of the intermediate frequency amplification section 5 tends to become unstable.

On the other hand, general radio equipment that uses the FM modulation method uses a so-called noise squelch method that detects noise components and controls the operation of the final stage amplifier, etc., unlike the circuit method shown in Figure 1 described above. As is known, in the case of a radio-controlled device, for example, when the AM modulation wave of an adjacent band is strong, the frequency mixer 3 etc. removes the cross-modulation, and the output signal of the intermediate frequency amplification unit 5 produces spike-like noise. Components often get mixed in, and when this noise squelch method is adopted for radio control equipment, there is a problem that the squelch circuit is activated even though it is receiving its own radio waves, and the signal is not transmitted to the servo unit 9. .

Therefore, the noise squelch method is not suitable for radio-controlled devices, and at present no squelch circuit suitable for radio-controlled devices has been obtained.

The present invention was made in view of the above-mentioned circumstances, and
In the case of FM modulation type radio control equipment, we focused on the fact that a signal that shows sharp selectivity only to the own radio waves is obtained from the detection section of the receiver, and we It is an object of the present invention to provide a receiver for a radio-controlled device that can perform an accurate squelch operation with a simple circuit configuration by deriving a signal obtained from the squelch signal and using it as a squelch signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a receiver for a radio-controlled device according to the present invention will be described below with reference to the drawings in which parts having the same functions as those in FIG.

FIG. 2 is a configuration diagram of main parts showing an embodiment of a receiver for a radio-controlled device according to the present invention.

Here, 6 is for demodulating the FM modulated wave as a test wave frequency signal that is amplified by the intermediate frequency amplifying section 5 and given via the intermediate frequency transformer IFT and the coupling capacitor C7, and forming a drive signal for the servo section. This detection unit 6 is a detection unit in which a filter element CF made of, for example, ceramics and a capacitor 04 are connected in series, and a filter element O
Diodes D3 and D4 of the indicated polarity for rectifying passing signals are connected in parallel to F and capacitor C4, respectively, and resistors R3 and R3, which serve as loads for these diodes D and D, are connected in parallel, respectively. It has the following structure.

Furthermore, the output of the detection section 6 is given to the amplification section 7 via a resistor R4, and the channel signal demodulated by the detection section 6 is amplified.

Reference numeral 11 denotes a squelch circuit section into which the terminal voltage of the resistor R8 of the detection section 6 is introduced, and this terminal voltage is waveform-shaped to produce a squelch signal. A transistor Q is connected to VB and outputs a high/low binary signal of the voltage of the power supply VB or the ground potential depending on the terminal voltage.

Q2 is a switching transistor that is controlled on and off by the collector voltage of the transistor Q, and a diode D that defines the threshold level of the transistor Q is inserted into the emitter, and the collector is connected to the preamplification section 7. The control circuit is connected to the output side of the switch and lowers the connection point to zero level when turned on to perform a squelch operation.

That is, the receiver of the radio-controlled device according to the present invention is configured to waveform-shape the signal extracted from the detection section 6 and generate a squelch signal.

Next, the operation in the above configuration will be explained.

Since the detection unit 6 includes the filter element OF as described above, a signal near the resonance frequency f of the filter element OF is applied to the detection unit 6 via the intermediate frequency transformer IFT and the capacitor C7. The maximum voltage is obtained at the resonant frequency f.

Furthermore, if the frequency of the signal input to the detection section 6 deviates from the resonance frequency due to the difference in phase characteristics between the filter element OF and the capacitor C4, the diode D3
and D4, the current flowing through resistors R7 and R3 rapidly attenuates, and the current reaches a minimum at a point f, which is shifted from the frequency f by a predetermined frequency.

Therefore, the resistors R= and Rs each have a diode D4. The signal rectified by D3 flows into both ends of each resistor, VB2. A voltage signal proportional to the amplitude of the test wave frequency signal is generated as shown by VRJ.

The difference between the terminal voltages VR2tVR3 becomes the voltage Va shown by the broken line in FIG. 3, and is output to point A in FIG. 2.

That is, a signal having a voltage value corresponding to the frequency of the signal input to the detection section 6 is obtained at point A via the intermediate frequency transformer IFT and the capacitor C6, and as a result, the demodulation of the FM modulated wave is performed. The demodulated signal is amplified by the amplifier section 1 and sent to the decoder section 8.

In this case, the terminal voltages VR2 and VB3 generated at the resistors R2 and R3 are voltages having sharp selection characteristics due to the resonance frequency of the filter element CF, due to the characteristics of the filter element CF.

Furthermore, in the receiver of the radio control device, the center frequency of its own radio waves or the frequency defining each control section is set in advance so as to match the resonance frequency of the filter element OF.

Therefore, the terminal voltages R2 and VRs have a characteristic of rising steeply only when the own radio waves are being received.

The terminal voltage VR8 of the resistor R3 is introduced into the squelch circuit section 11, applied to a filter circuit consisting of a resistor R6 and a capacitor C3, and further waveform-shaped by a transistor Q to form a squelch signal.

That is, when the receiver receives its own radio wave, the terminal voltage VHs of the resistor R8 of the detection section 6 increases, and as a result, the terminal voltage of the capacitor C6 of the squelch circuit section 11 increases to the base-emitter voltage of the transistor Q. When the voltage exceeds 0, the transistor Q enters the active region, the base potential of the transistor Q2 becomes close to the ground potential, and the transistor Q2 is turned off.

Therefore, the impedance seen from the output side of the amplification section 7 to the transistor Q2 side becomes extremely high, and the signal demodulated by the detection section 6 and amplified by the amplification section 7 is sent to the decoder 8 side and is processed by the servo section (not shown). Normal operation will now occur.

On the other hand, when the receiver is not receiving its own radio waves, the terminal voltage VR8 of the resistor Rs of the detection section 6 is small, and almost no collector current flows through the transistor Q1 of the squelch circuit section 11.

Therefore, a base current flows from the power supply VB to the base of the transistor Q via the resistor R6, turning on the transistor Q, and the output side of the amplifier 7 is fixed at approximately ground potential, and the decoder 8 receives the input signal as well. Not given.

In other words, the squelch operation is performed, and malfunction of the servo section when its own radio waves are not being received is reliably prevented.

In this case, various noise radio waves having frequencies close to the frequency of the own radio waves are received by the antenna, or noise components having frequencies close to the frequency of the own radio waves are included in the internally generated noise components. If there is a radio wave in an adjacent band, and if the sideband component is close to the frequency of the own radio wave, these noise components are amplified by the intermediate frequency width section 5 and sent to the detection section 6. It's being input.

However, as described above, since the detection section 6 exhibits sharp selection characteristics only for its own radio waves, the terminal voltage VRs of the resistor R8 due to the various noise components mentioned above is low, and the transistor Q of the squelch circuit section 11 is inoperable. The output side of the amplifying section 7 maintains approximately the ground potential.

Further, in the illustrated embodiment, the base circuit of the transistor Q of the squelch circuit section 11 is formed by the resistor R6 and the capacitor C3, so that the terminal voltage of the capacitor C3 is equal to or higher than a predetermined voltage (in the illustrated embodiment, the base circuit of the transistor Q, base·
(or higher than the emitter voltage), the transistor Q
, does not enter the active region, and transistor Q2 remains on.

Therefore, even if the detection unit 6 detects a noise component in the same frequency band as its own signal radio wave, if the level of this noise component is lower than the signal component, the squelch operation will continue. Thus, it becomes possible to reliably prevent malfunctions of the servo unit due to the above-mentioned noise components.

In this way, in the radio control device receiver according to the present invention, a signal having sharp selection characteristics with respect to its own radio waves is extracted from the detection section 6, and this signal is shaped into a squelch signal, so that it is not mixed from the antenna. Reliable squelch operation is possible against radio noise and various noise components generated internally.

By the way, in the embodiment described above, the voltage between the base and emitter of the transistor Q1 is set to the squelch signal formation level.
The terminal voltage of the resistor R3 of the detection unit 6 ■When R3 becomes below this level, the squelch circuit unit 11 is activated and a squelch operation is performed. Adjust as appropriate depending on the situation,
It is also possible to ensure that the optimum squelch operation is always performed.

For example, as shown in FIG. 4, the terminal voltage of capacitor C5 is introduced into the inverting input terminal (c) of operational amplifier OP, while the variable power supply Vr is connected to the non-inverting input terminal (g) of operational amplifier OP. If the squelch circuit section 11 is configured as follows,
By adjusting the output voltage of the variable power supply Vr, the squelch signal formation level can be adjusted as appropriate, making it possible to always perform an optimal squelch operation.

The detection section 6 also includes a filter element CF as shown in FIG.
It goes without saying that the present invention is not limited to the detection section composed of the following, but can also be applied to receivers using other conventionally known detection sections.

Furthermore, in the embodiment shown in FIG. 2, when the own radio wave is not received, the transistor Q is turned on and the output side of the amplifier section 7 is set to approximately the ground potential to perform a squelch operation. This may be accomplished by setting the input side of the amplifying section 7 to a ground potential, or by disabling the amplifying section 1 to perform the squelch operation.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

As described above, the receiver of the radio-controlled device according to the present invention extracts a signal from the detection section that outputs only its own radio waves with sharp selection characteristics, and shapes the waveform of this signal to generate a squelch signal. It is something.

Therefore, the effect of suppressing various noise components other than the own radio waves is extremely large, the squelch operation is always accurate, and malfunctions in the servo section can be reliably prevented.

In addition, in the receiver of the radio-controlled device according to the present invention, the squelch signal can be obtained by simply waveform-shaping the signal obtained from the detection section, so the circuit configuration is extremely simple and there is no adverse effect on other parts of the receiver. This has the advantage that the receiver as a whole can always be expected to operate stably.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing a conventional radio-controlled device receiver, FIG. 2 is a main part configuration diagram showing an embodiment of a radio-controlled device receiver according to the present invention, and FIG. 3 is a diagram showing the same embodiment. FIG. 4 is a diagram for explaining the operation of the radio-controlled device according to another embodiment of the present invention. 6...Detection section, 11...Squelch circuit section, R3...Resistor, C1...Capacitor, Q, ,Q,...Transistor , Vr...
...Variable power supply.

Claims (1)

[Claims] I FM modulated radio waves are received, amplified, and introduced into the detection section, and the detected output is amplified by the amplification section and distributed to each operation part of the controlled object by the decoder section. A receiver for a radio control device that forms signals for driving various operating parts of the body includes a filter element, a rectifying element that rectifies the signal passing through this filter element, and a load resistance of this rectifying element, and a frequency signal to be detected is introduced. a squelch circuit section which receives a voltage signal proportional to the amplitude of the detected wave frequency signal generated in the load resistance in the detection section and outputs a high and low binary signal according to the level of the voltage signal. and a switching element connected to the downstream stage of the detection section and activated by a signal output from the squelch circuit section when the output of the detection section becomes below a predetermined level, and a connection point with the downstream stage of the detection section. A receiver for a radio control device comprising: a control circuit unit that brings the signal to zero level; 2. The receiver for a radio control device according to claim 1, wherein the control circuit section is connected to an output side of an amplification section that amplifies the output of the detection section. 3. The receiver for a radio control device according to claim 1, wherein the control circuit section is connected to an input side of an amplification section that amplifies the output of the detection section. 4. The squelch circuit section receives input of a voltage signal proportional to the amplitude of the test wave frequency signal generated in the load resistor in the detection section and the output of a variable power supply section whose output can be adjusted,
A receiver for a radio control device according to claim 1, comprising an amplifier circuit whose output level is switched when the level of the voltage signal exceeds the output of the variable power supply section.