JPH1084223A - Noise fm signal generation circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise FM width fluctuation against a wide range of ambient temperature by preparing a pseudo noise generation means which generates a noise voltage of a pseudo Gaussian distribution based on a clock. SOLUTION: A pseudo random generation circuit 11 generate the random signals in synchronism with the clock sent from a clock generation circuit 10 and converts the random signals into a pseudo Gaussian distribution via a ROM 12. The output of the ROM 12 is converted into a voltage signal by a D/A converter(DAC) 13 and added to the control voltage received from a central frequency setting circuit 6 by an adder circuit 7. This addition signal is used as the control signal of a voltage control oscillator(VCO) 9 which produces a noise FM signal based on the control signal. Thus, the pseudo noises are generated by a digital circuit not by the thermal noises and accordingly the amplitude fluctuation due to the ambient temperature is reduced and the generated noise signal has a high level. As a result, a stable noise FM signal generation circuit is obtained without increasing the signal amplification factor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ECM (Electric
The present invention relates to a noise FM signal generation circuit for generating a noise FM signal having a pseudo Gaussian distribution used for a device related to a ronic counter (Measure).

[0002]

2. Description of the Related Art The configuration of a conventional noise FM signal generating circuit will be described with reference to FIG. FIG. 5 is a block diagram partially showing the configuration of a conventional noise FM signal generation circuit.

In FIG. 5, 1 is a noise diode for generating Gaussian noise, 2 is a resistor for biasing the noise diode 1, 3 is a capacitor for removing a DC component from a noise signal, 4 is an amplifier for amplifying a noise voltage, 5
Is a capacitor for removing a DC component from a noise signal.

In FIG. 1, reference numeral 6 denotes a center frequency setting circuit for setting a center frequency of a voltage controlled oscillator (VCO) described later, 7 denotes an addition circuit for adding a Gaussian distribution voltage and a center frequency setting voltage, and 8 denotes a adding circuit. A drive circuit that drives the voltage controlled oscillator by the output of the adder circuit 7, and a voltage controlled oscillator 9 that generates a noise FM signal by the output of the drive circuit 8.

Next, the operation of the conventional noise FM signal generation circuit will be described with reference to FIG. FIG. 6 is a characteristic diagram showing a relationship between a control voltage and an oscillation frequency of a voltage controlled oscillator of a conventional noise FM signal generation circuit. In the figure, the horizontal axis represents the control voltage, and the vertical axis represents the oscillation frequency.

First, a voltage is applied to the noise diode 1 through a resistor 2. By doing so, Gaussian noise, which is thermal noise, is generated by being superimposed on the reverse voltage of the noise diode 1, and the amplitude of the noise voltage is proportional to the square root of temperature because it is thermal noise.

[0007] Only the noise voltage is extracted by the capacitor 3 and input to the amplifier 4. The noise voltage obtained from the noise diode 1 is usually several μV, and the required noise voltage is several V. Therefore, the amplification factor of the amplifier 4 is tens of thousands or more.

The noise voltage thus obtained is added to the center frequency control voltage from the center frequency setting circuit 6 by the adding circuit 7, and the output is input to the drive circuit 8. Voltage controlled oscillator 9 which is the output of drive circuit 8
Is input to the voltage-controlled oscillator 9.

[0009] The voltage controlled oscillator 9 generates a noise FM signal having an FM width corresponding to the amplitude of the noise voltage around the set center frequency.

FIG. 6 shows the relationship between the center frequency control voltage and the noise voltage and the FM width of the noise FM signal in an example of the control voltage versus oscillation frequency characteristics of the voltage controlled oscillator.

In the noise FM signal generated in this manner, since the control voltage noise has a Gaussian distribution, the output of the voltage controlled oscillator 9 also has a Gaussian distribution, and the signal density near the center frequency is high.

In an ECM device, such a circuit is generally used when the frequency band is expanded for the purpose of improving the frequency matching degree.

[0013]

In the conventional noise FM signal generation circuit as described above, when a wide ambient temperature range is required as in an ECM device or the like, the noise FM width fluctuates, and a correction circuit therefor is used. However, there is a problem in that the circuit becomes complicated, for example, and that the structure becomes large due to the use of a thermostat.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a high density near the center frequency, a small variation in the noise FM width over a wide ambient temperature, and a small and stable noise. An object is to obtain an FM signal generation circuit.

[0015]

The noise F according to the present invention is provided.
M signal generation circuit includes: clock generation means for generating a clock; pseudo noise generation means for generating a noise voltage having a pseudo Gaussian distribution based on the clock; a center frequency setting circuit for outputting a center frequency control voltage; An addition circuit that adds a voltage and the center frequency control voltage, a drive circuit that outputs a frequency control signal based on an output of the addition circuit, and a voltage control oscillator that generates a noise FM signal based on the frequency control signal. It is provided with.

Further, in the noise FM signal generating circuit according to the present invention, the pseudo noise generating means generates a random signal having a uniform distribution according to the cycle of the clock; And a digital / analog converter for converting the pseudo Gaussian random signal into a noise voltage.

Further, in the noise FM signal generating circuit according to the present invention, the distribution converting means is a ROM in which data of uniform distribution and corresponding data of pseudo Gaussian distribution are stored.

Further, the noise FM signal generating circuit according to the present invention further comprises a distribution selection circuit for storing one or more sets of distribution conversion data in the ROM, wherein the ROM stores a plurality of sets of distribution conversion data. It is a thing.

In the noise FM signal generating circuit according to the present invention, the clock generating means is a random clock generating circuit for generating a random clock.

Further, in the noise FM signal generating circuit according to the present invention, the pseudo noise generating means generates a signal having a uniform distribution in accordance with the clock cycle;
It has distribution conversion means for converting the signal having a uniform distribution to a signal having a pseudo-Gaussian distribution, and a digital / analog converter for converting the signal having a pseudo-Gaussian distribution to a noise voltage.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Noise F according to Embodiment 1 of the present invention
The configuration of the M signal generation circuit will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of the first embodiment of the present invention. In the drawings, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, reference numeral 10 denotes a clock generation circuit for generating a clock, 11 denotes a pseudo-random generation circuit for generating a random signal having a uniform distribution according to a clock cycle output from the clock generation circuit 10, and 12 denotes a pseudo-random generation circuit. A read-only memory (ROM) 11 converts an output distribution (uniform distribution) into a pseudo Gaussian distribution, and a digital-analog converter (DAC) 13. Reference numeral 5 denotes a capacitor for removing a DC component from a noise signal.

In FIG. 1, reference numeral 6 denotes a center frequency setting circuit for setting a center frequency of a voltage controlled oscillator (VCO) described later, 7 denotes an adding circuit for adding a pseudo Gaussian distribution voltage and a center frequency setting voltage, and 8 Is a drive circuit that drives the voltage controlled oscillator by the output of the adder circuit 7, and 9 is a voltage controlled oscillator that generates a noise FM signal by the output of the drive circuit 8.

Next, the operation of the first embodiment will be described.

The pseudo random generation circuit 11 generates a random signal in synchronization with the clock from the clock generation circuit 10. For example, if the upper 8 bits are output by a 16-bit pseudo-random generator, “0” to “25” are output.
With the random signal of "5", a uniformly distributed random signal whose output frequency is 256 times is generated.

According to the ROM 12, 0 is set around "127".
Alternatively, the output frequency is reduced to 256 as the distance to 255 is reduced, thereby converting to a pseudo Gaussian distribution. This ROM1
2 is converted into a voltage signal by the DAC 13 and added to the control voltage from the center frequency setting circuit 6 by the adding circuit 7. This addition signal is used as a control signal of the voltage controlled oscillator 9 through the drive circuit 8.

The voltage controlled oscillator 9 generates a noise FM signal in accordance with the control signal. The output frequency of the oscillation frequency near the set center frequency is high, and the output frequency becomes lower as the oscillation frequency is outside the FM width.

As described above, since the pseudo noise is generated by the digital circuit instead of the thermal noise, the amplitude fluctuation due to the ambient temperature is small, and the level of the generated noise signal is large. Therefore, it is not necessary to increase the amplification factor in the signal amplification. A stable circuit can be supplied.

The distribution can be freely changed by changing the contents of the ROM 12, and the cycle can be changed by controlling the clock generation circuit 10, thereby increasing the degree of freedom of setting as an ECM device. Further, the circuit configuration has many digital circuits, and can be reduced in size.

Embodiment 2 FIG. Second Embodiment A noise FM signal generation circuit according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of the second embodiment of the present invention.

In FIG. 2, reference numeral 14 denotes a random clock generation circuit for generating a random clock, 11 denotes a pseudo random generation circuit for generating a random signal having a uniform distribution in accordance with the output of the random clock generation circuit 10, and 12 denotes a pseudo random generation circuit 11. Is a read-only memory (ROM) for converting the output distribution (uniform distribution) of the data into a pseudo Gaussian distribution, and 13 is a digital-analog converter (DAC). Also, 5
Is a capacitor for removing a DC component from a noise signal.

In the same figure, reference numeral 6 denotes a center frequency setting circuit for setting a center frequency of a voltage controlled oscillator (VCO) described later, 7 denotes an adding circuit for adding a pseudo Gaussian distribution voltage and a center frequency setting voltage, and 8 Is a drive circuit that drives the voltage controlled oscillator by the output of the adder circuit 7, and 9 is a voltage controlled oscillator that generates a noise FM signal by the output of the drive circuit 8.

In the second embodiment, the random clock generation circuit 14 is used as the clock generation circuit, and the randomness of the noise FM signal is changed by generating a random clock to make it random not only in frequency but also in time. Accordingly, the same effect as in the first embodiment can be obtained.

Embodiment 3 Third Embodiment A noise FM signal generation circuit according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of the third embodiment of the present invention.

In FIG. 3, reference numeral 10 denotes a clock generation circuit for generating a clock, 15 denotes a counter circuit for counting clocks, and 12 denotes an output of the counter circuit 15 (uniform distribution).
Into a pseudo Gaussian distribution (R)
OM) and 13 are digital-to-analog converters (DACs). Reference numeral 5 denotes a capacitor for removing a DC component from a noise signal.

In the same figure, reference numeral 6 denotes a center frequency setting circuit for setting a center frequency of a voltage controlled oscillator (VCO) described later, 7 denotes an adding circuit for adding a pseudo Gaussian distribution voltage and a center frequency setting voltage, and 8 Is a drive circuit that drives the voltage controlled oscillator by the output of the adder circuit 7, and 9 is a voltage controlled oscillator that generates a noise FM signal by the output of the drive circuit 8.

In the third embodiment, the counter circuit 15 is used in place of the pseudo-random generating circuit, and the randomness is impaired, but the radar or the like which is the target of the ECM device integrates and processes the signal with time. Therefore, substantially the same effects as in the first embodiment can be obtained.

Embodiment 4 FIG. Embodiment 4 A noise FM signal generation circuit according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a configuration of the fourth embodiment of the present invention.

In FIG. 4, reference numeral 10 denotes a clock generation circuit for generating a clock, 11 denotes a pseudo-random generation circuit for generating a random signal having a uniform distribution in accordance with a clock cycle output from the clock generation circuit 10, and 12 denotes a pseudo-random generation circuit. A read-only memory (ROM) 11 converts an output distribution (uniform distribution) into a pseudo Gaussian distribution, and a digital-analog converter (DAC) 13. Reference numeral 5 denotes a capacitor for removing a DC component from a noise signal. Reference numeral 16 denotes a distribution selection circuit for selecting a data group in the ROM 12.

In the same figure, reference numeral 6 denotes a center frequency setting circuit for setting a center frequency of a voltage controlled oscillator (VCO) to be described later, 7 denotes an addition circuit for adding a pseudo Gaussian distribution voltage and a center frequency setting voltage, and 8 Is a drive circuit that drives the voltage controlled oscillator by the output of the adder circuit 7, and 9 is a voltage controlled oscillator that generates a noise FM signal by the output of the drive circuit 8.

In each of the above embodiments, the distribution conversion by the ROM 12 is performed in a single manner. In the fourth embodiment, a plurality of distribution conversion data are stored in the ROM 12 and the distribution selection circuit 1
By selecting the distribution conversion data according to 6, an efficient circuit can be supplied.

That is, the noise FM signal generation circuit according to each embodiment of the present invention uses a pseudo-Gaussian voltage signal generated by the DAC 13 by performing a distribution conversion of the pseudo-random signal having a uniform distribution by the ROM 12, Fluctuations in the noise FM width can be reduced in response to changes in the ambient temperature, and there is no need to increase the amplification factor of the noise signal. Thus, a stable circuit can be formed, and the size of the digital circuit can be reduced.

[0043]

As described above, the noise FM signal generating circuit according to the present invention comprises: a clock generating means for generating a clock; a pseudo noise generating means for generating a noise voltage having a pseudo Gaussian distribution based on the clock; A center frequency setting circuit that outputs a center frequency control voltage; an addition circuit that adds the noise voltage and the center frequency control voltage; a drive circuit that outputs a frequency control signal based on an output of the addition circuit; A voltage-controlled oscillator that generates a noise FM signal based on a control signal can reduce fluctuations in the noise FM width in response to changes in ambient temperature. A stable circuit is not required because it is not necessary to increase the amplification factor of the noise signal. This configuration has an effect that the size of the digital circuit can be reduced.

As described above, in the noise FM signal generating circuit according to the present invention, the pseudo noise generating means generates the random signal having a uniform distribution in accordance with the clock cycle. Conversion means for converting a random signal having a uniform distribution into a random signal having a pseudo Gaussian distribution, and a digital / analog converter for converting the random signal having a pseudo Gaussian distribution into a noise voltage. Since the width fluctuation can be reduced and the amplification rate of the noise signal does not need to be increased, a stable circuit can be formed, and the size of the digital circuit can be reduced.

Further, in the noise FM signal generating circuit according to the present invention, as described above, the distribution converting means includes a ROM storing the uniform distribution data and the corresponding pseudo Gaussian distribution data. Therefore, the fluctuation of the noise FM width with respect to the change in the ambient temperature can be reduced, and it is not necessary to increase the amplification factor of the noise signal. Therefore, a stable circuit can be formed, and the size of the digital circuit can be reduced.

As described above, in the noise FM signal generating circuit according to the present invention, the ROM stores a plurality of sets of distribution conversion data and a distribution for selecting any of the plurality of sets of distribution conversion data. Since the selection circuit is further provided, there is an effect that an efficient circuit can be supplied.

In the noise FM signal generating circuit according to the present invention, as described above, the clock generating means is a random clock generating circuit for generating a random clock. The effect is that the randomness of the noise FM signal can be changed.

Further, as described above, in the noise FM signal generation circuit according to the present invention, the pseudo noise generation means generates a signal having a uniform distribution in accordance with the clock cycle; It has distribution conversion means for converting a signal into a signal having a pseudo-Gaussian distribution and a digital / analog converter for converting the signal having a pseudo-Gaussian distribution into a noise voltage.
Since the width fluctuation can be reduced and the amplification rate of the noise signal does not need to be increased, a stable circuit can be formed, and the size of the digital circuit can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a noise FM signal generation circuit according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a noise FM signal generation circuit according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a noise FM signal generation circuit according to Embodiment 3 of the present invention.

FIG. 4 is a block diagram showing a configuration of a noise FM signal generation circuit according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional noise FM signal generation circuit.

FIG. 6 is a characteristic diagram showing a relationship between a control voltage and an oscillation frequency of a voltage controlled oscillator of a conventional noise FM signal generation circuit.

[Explanation of symbols]

Reference Signs List 5 capacitor, 6 center frequency setting circuit, 7 addition circuit, 8 drive circuit, 9 voltage controlled oscillator, 10 clock generation circuit, 11 pseudo random generation circuit, 12
Read only memory (ROM), 13 digital / analog converter (DAC), 14 random clock generation circuit, 15 counter circuit, 16 distribution selection circuit.

Claims (6)

[Claims] 1. A clock generation means for generating a clock; a pseudo noise generation means for generating a pseudo Gaussian noise voltage based on the clock; a center frequency setting circuit for outputting a center frequency control voltage; An adder circuit for adding a frequency control signal based on the output of the adder circuit; and a voltage control oscillator for generating a noise FM signal based on the frequency control signal. Noise F characterized by having
M signal generation circuit. 2. A pseudo-random generating circuit for generating a random signal having a uniform distribution according to a period of the clock, and a distribution for converting the random signal having the uniform distribution into a random signal having a pseudo-Gaussian distribution. 2. The noise FM signal generation circuit according to claim 1, further comprising a conversion unit, and a digital-to-analog converter for converting the pseudo Gaussian random signal into a noise voltage. 3. The noise FM signal generating circuit according to claim 2, wherein said distribution conversion means is a ROM storing data of uniform distribution and data of pseudo Gaussian distribution corresponding thereto. . 4. The ROM according to claim 3, wherein said ROM stores a plurality of sets of distribution conversion data, and further comprises a distribution selection circuit for selecting one of said plurality of sets of distribution conversion data. Noise FM signal generation circuit. 5. The noise FM signal generating circuit according to claim 1, wherein said clock generating means is a random clock generating circuit for generating a random clock. 6. A counter circuit for generating a signal having a uniform distribution according to a cycle of the clock, a distribution converting means for converting the signal having a uniform distribution into a signal having a pseudo Gaussian distribution, 2. The noise FM signal generating circuit according to claim 1, further comprising: a digital-to-analog converter for converting a signal having a pseudo Gaussian distribution into a noise voltage.