JP4767211B2 - Carrier frequency abnormality detection means - Google Patents

Description

  The present invention relates to a system that performs modulation using a carrier wave. In particular, in a system that requires detection of a frequency abnormality of a carrier wave used for frequency modulation, a carrier wave whose detection accuracy can be arbitrarily set with a simple configuration for detecting a carrier frequency abnormality. The present invention relates to a frequency abnormality detection means.

Generally, there is a tendency for reliability, safety, and soundness related to products to be demanded.
In a system that outputs using modulation, a technique for monitoring the level and frequency of an output signal by monitoring the output signal of a modulated wave as monitoring whether an appropriate signal is being output has been known. The soundness of the carrier frequency had to be confirmed separately.

Conventionally, as a carrier frequency abnormality detecting means, as shown in Patent Document 1, in a pulse width modulation driving circuit, a current flowing through a load is detected, and a component corresponding to the frequency of the pulse width modulation is detected as a band pass filter. There has been known a method of detecting an abnormality of a carrier frequency by extracting using the.
JP-A-3-139190

  However, in the conventional frequency abnormality detection method described above, as shown in FIG. 6 of the above publication, only CT (Current Transformer: instrument current transformer) for detecting load current or detection frequency is taken out. There is a problem that the circuit scale becomes large, such as using a band-pass filter and a detection circuit.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a carrier wave frequency component to a modulated wave output from a modulation signal generator in a device having a modulation means using a carrier frequency. It is an object to provide means for taking out frequency information of a carrier wave from a modulated wave and making it possible to configure an abnormality detection of the carrier wave frequency with a simple circuit.

  Another object of the present invention is to provide a means for detecting an abnormality of the carrier wave frequency, which can be easily implemented as an LSI and contributes to downsizing of the apparatus.

  The carrier frequency abnormality detecting means of the present invention comprises: arithmetic means for performing calculation and information processing; signal wave generating means for converting data output from the arithmetic means into a waveform; and carrier wave generation for generating a carrier wave used for modulation Means for detecting a carrier frequency abnormality in a modulation signal generator, wherein the carrier wave is used to modulate the signal wave output from the signal generation means and output a modulated wave. Means for detecting the characteristic that the modulated wave output from the modulation means changes within one period unit of the carrier wave using the reference clock output from the clock generation means for generating a large frequency; Means for detecting an abnormality in the carrier frequency by detecting that the number of changes per unit time in the characteristics of the carrier detected by the means deviates from a predetermined range. , Characterized by comprising a.

  Further, the change in the carrier wave per unit time is obtained by counting rising edges per unit time of the modulated wave and detecting that the count number deviates from a predetermined range. Means are obtained.

  Further, the change in the carrier wave per unit time is obtained by counting zero crosses per unit time of the modulation signal and detecting that the count number deviates from a predetermined range. Is obtained.

  According to the present invention, it is possible to constitute a carrier frequency abnormality detection with a simple circuit in a modulation signal generator.

  Further, according to the present invention, it is possible to detect an abnormality of the carrier frequency in a system in which the carrier frequency itself cannot be observed from the outside.

  According to the present invention, by multiplying and dividing a count value by a predetermined value, it is possible to detect a normal carrier frequency and to measure fluctuations in the carrier frequency.

  According to the present invention, since the elements constituting the circuit can be constituted by logic circuits, integration is easy, and there is an effect that contributes to downsizing of the device.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a conceptual configuration diagram for explaining a carrier frequency abnormality detecting means of the present invention.
In FIG. 1, 1 is a calculation means (CPU), 2 is a signal generation means (D / A), 3 is a carrier wave generation means (XL1), 4 is a modulation means (MOD), 5 is a clock generation means (XL2), 6 Is a carrier frequency abnormality detection circuit (LOGIC), 7 is a clock generation means 1 (XL2), and 8 is a calculation means (CPU).

  The signal generation means (D / A) 2 D / A converts the data from the calculation means (CPU) 1 to generate a signal wave. The modulation means (MOD) 4 obtains a modulation wave by comparing the carrier wave from the carrier wave generation means (XL1) with the signal wave.

  The carrier frequency abnormality detection circuit (LOGIC) 6 inputs the modulated wave, analyzes the modulated wave using the reference clock from the clock generating means (XL2) 5, and determines the number of changes in the carrier wave per unit time. The carrier frequency abnormality is detected by detecting the deviation from the above range.

  FIG. 2 is a diagram illustrating a carrier frequency abnormality detection unit according to the first embodiment of the present invention. In FIG. 2, 8 is a calculation means, which operates with a clock obtained from the 7 clock generation means 1 (XL2) and outputs the calculation result as data.

  In FIG. 2, reference numeral 10 denotes signal generating means (D / A), which operates according to the D / A clock obtained from the clock generating means 2 (XL), and generates the signal wave 17 of FIG. 3 using the data.

  In FIG. 2, reference numeral 12 denotes a modulation means (PWM), which connects a predetermined constant RC circuit (RC) 11 to generate a carrier wave 18 by internal oscillation and modulates the signal wave 17 by comparison with the carrier wave 18. Wave 19 is obtained.

  In FIG. 2, reference numeral 13 denotes an amplifying means (AMP) that amplifies the modulated wave 19 and outputs it to a load (LOAD) 14.

  The clock generating means (XL2) 7 to the amplifying means stage (AMP) 13 is a modulated wave generating device that applies an amplified modulated wave to a load.

Here, means for detecting abnormality of the carrier frequency from the modulated wave will be described.
A simulation trigger 15 passes a pulse signal obtained by binarizing the modulated wave 19 obtained from the modulation means (PWM) 12 to the modulation frequency abnormality detection means (PLD) 16.

  FIG. 4 is a block diagram of the logic circuit of the rising edge counter according to the second embodiment of the modulation frequency abnormality detection means (PLD) of the present invention.

  In FIG. 4, the reference clock obtained from the clock generating means 1 (XL2) 7 of FIG. 2 is used as the reference clock input 23, and a timer 24 for defining a predetermined time is obtained.

  A pulse signal obtained by binarizing the modulated wave 19 in FIG. 2 is used as the modulated wave input 22, and the rising edge of the modulated wave 22 is counted by the pulse counter 25.

  The counter value is stored in the register 26 at every predetermined time defined by the timer 24 and the counter value of the pulse counter 25 is cleared. Data stored in the register 26 is output from the data output 27.

  The calculation means (CPU) 8 in FIG. 2 reads the count value stored in the register of the modulation frequency abnormality detection means (PLD) 16, and discriminates the abnormality of the carrier frequency according to the flowchart of FIG.

  In FIG. 5, the register value read by the carrier frequency register reading operation in step 28 is converted into the threshold value 1 and larger than the threshold value 1 by threshold determination 1 in step 29 and threshold determination 2 in step 30. When the predetermined threshold value 2 deviates from a predetermined range, carrier wave abnormality detection in step 31 is reached.

  In signal output means including audio / video processing, the present invention can be applied to carrier frequency abnormality detection means for monitoring carrier frequency for the purpose of protecting a transmission load using an amplifier.

  The present invention is also applicable to carrier frequency abnormality detection means in a modulation system in which the modulated wave always has one rising edge and zero cross within one cycle of the carrier frequency.

  The present invention is also applicable to a carrier frequency abnormality detection means in a system that performs frequency modulation in which the carrier frequency is twice or more the signal frequency.

It is a conceptual block diagram for demonstrating the abnormality detection means of the carrier frequency of this invention. It is a figure which shows the abnormality detection means of the carrier frequency of Example 1 of this invention. It is a conceptual diagram of the PWM modulation wave for demonstrating the principle of the carrier wave abnormality detection of this invention. It is a block diagram of the logic circuit for demonstrating the rising edge counter of the abnormality detection means of the carrier frequency of Example 2 of this invention. It is a flowchart which shows the abnormality detection operation | movement of a carrier frequency.

Explanation of symbols

1. Calculation means (CPU)
2 Signal generation means (D / A)
3 Carrier wave generation means (XL1)
4 Modulation means (MOD)
5 Clock generation means (XL2)
6 Carrier frequency abnormality detection circuit (LOGIC)
7 Clock generation means 1 (XL2)
8 Calculation means (CPU)
9 Clock generation means 2 (XL1)
10 Signal generation means (D / A)
11 RC circuit (RC)
12 Modulation means (PWM)
13 Amplification means (AMP)
14 Load (LOAD)
15 Schmitt trigger 16 Modulation frequency abnormality detection means (PLD)
17 Signal wave 18 Carrier wave (triangular wave)
19 Modulated wave (output pulse train)
20 rising edge 21 zero cross 22 modulation wave input 23 reference clock input 24 timer 25 pulse counter 26 register 27 data output 28 register read 29 threshold discrimination 1
30 threshold discrimination 2
31 Carrier wave abnormality detection

Claims (4)

A computing means for performing computation and information processing;
Signal wave generation means for converting data output from the calculation means into a waveform;
Carrier wave generating means for generating a carrier wave used for modulation;
Modulation means for modulating the signal wave output from the signal generating means using the carrier wave and outputting a modulated wave;
An anomaly detection means for a carrier frequency of a modulation signal generator comprising:
Means for detecting a characteristic that the modulated wave output from the modulating means changes within one period unit of the carrier wave using the reference clock output from the clock generating means for generating a frequency higher than the carrier wave;
Means for detecting an abnormality in the carrier frequency by detecting that the number of changes per unit time of the characteristics of the carrier detected by the means for detecting deviates from a predetermined range;
An abnormality detection means for carrier frequency, comprising: In the carrier wave frequency abnormality detecting means according to claim 1,
The carrier frequency abnormality detecting means characterized in that the change in the carrier wave per unit time is obtained by counting rising edges per unit time of the modulated wave and detecting that the count number deviates from a predetermined range. In the carrier wave frequency abnormality detecting means according to claim 1,
The carrier frequency anomaly detecting means characterized in that the change in the carrier wave per unit time counts zero crosses per unit time of the modulated signal and detects that the count number deviates from a predetermined range. Carrier wave frequency abnormality detection means according to any one of claims 1 to 3,
The modulation signal generator of the transmission means is provided in the reception means in a transmission / reception system comprising a transmission means having the modulation signal generator and a reception means for receiving the modulated wave output from the transmission means. An abnormality detecting means for detecting the carrier frequency of the carrier frequency.

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