JPH02159105A - Demodulating device - Google Patents

Abstract

PURPOSE:To fix the frequency of the signal inputted to a demodulator at a demodulatable level by controlling the oscillation frequency of an oscillator with an oscillation control signal and changing the shift frequency of a frequency shifter according to the inputted frequency modulating signal. CONSTITUTION:The output signals of a delay unit 102 and a -90 deg. phase shifter 103 are multiplied by the output signal of an oscillator 104 which is controlled by an oscillation control signal 105 via the multipliers 106 and 107 respectively. Thus the angle frequency of the input signal of a demodulator 110 is set at a demodulatable level. Thus the angle frequency set by the oscillator 104 is controlled to a level in response to each mode and then fixed at a demodulatable level. As a result, an accurate demodulating job is secured in each mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a demodulator in a frequency modulation system.

2. Description of the Related Art In recent years, with the development of the communication field, many frequencies have come to be used in frequency modulation systems, and there has been a demand for demodulators that are compatible with these many frequencies.

A conventional demodulator will be described below.

FIG. 2 shows a conventional demodulator having four frequency modes. 201 is a frequency modulation signal A, 202 is a frequency modulation signal B, 203 is a frequency modulation signal C, 204
are frequency modulated signals, each with a different center frequency. 205 is a demodulator A1206 that demodulates the frequency modulation signal A201, a demodulator B that demodulates the frequency modulation signal B2O2, 207 is a demodulator C that demodulates the frequency modulation signal C203, and 208 is a demodulator that demodulates the frequency modulation signal D204. be. 209 is the demodulated signal A that is the output of the demodulator A205, 210 is the demodulated signal B that is the output of the demodulator B206, 211 is the demodulated signal C that is the output of the demodulator C207, and 212 is the demodulated signal that is the output of the demodulator D208. It is.

In the demodulation device configured as described above, each of the frequency modulation signal A201, frequency modulation signal B2O2, frequency modulation signal C203, and frequency modulation signal D204 is transmitted to the demodulator A205, demodulator 8206, demodulator C207, and demodulator D208. A demodulated signal A209, a demodulated signal B210°, a demodulated signal C211, and a demodulated signal D21 are output from the demodulator, respectively, in correspondence with demodulated frequencies.
2 are accurately demodulated signals.

Problems to be Solved by the Invention However, in the conventional configuration described above, the frequency that can be demodulated by one demodulator is determined due to the nature of the frequency modulation method. One demodulator is required for each frequency mode, and it has the disadvantage that it is difficult to realize a compact demodulator.

The present invention is intended to solve the above-mentioned conventional problems, and aims to provide a compact demodulator that is compatible with multiple frequency modes.

Means for Solving the Problems The demodulator of the present invention has a frequency modulated signal inputted to the demodulator.
a 0° phase shifter and a delay device, an oscillator whose oscillation frequency is controlled by an input oscillation control signal and outputs a sine wave and a cosine wave, and an output signal of the -90" phase shifter and a sine from the oscillator. a first multiplier that multiplies a wave, a second multiplier that multiplies the output signal of the delay device by a cosine wave from the oscillator, and an adder that adds the output signals of the first and second multipliers. The system is equipped with a frequency shifter configured with a frequency shifter, and a demodulator having a function of demodulating a frequency-modulated signal output from the frequency shifter.

According to this configuration, by controlling the oscillation frequency of the oscillator with the oscillation control signal and changing the shift frequency of the frequency shifter according to the input frequency modulation signal,
The frequency of the signal input to the demodulator can be fixed to a frequency that can be demodulated.

Embodiment An embodiment of the demodulator of the present invention will be described with reference to the block diagram shown in FIG.

This circuit has a delay device 102 to which the frequency modulation signal 101 is input, a -90" phase shifter 103 to which the frequency modulation signal 101 is input, the oscillation frequency is controlled by an oscillation control signal 105, and outputs a sine wave and a cosine wave. an oscillator 104 that multiplies the output signal of the delay device 102 and the cosine output wave of the oscillator 104, a multiplier 107 that multiplies the output signal of the -90° phase shifter 103 and the sine output wave of the oscillator 104; Frequency shifter 10 consisting of an adder 108 that adds the outputs of 106 and 107
9 and a demodulator 110 to which the output signals of the adder 108 are input.
A demodulated signal 111 is output from the demodulator 110.

The operation of the demodulator configured as described above will be described below.

First, the delay device 102 is adjusted to delay by the same amount of time as the delay time generated by the 90' phase shifter 103. Here, the center angular frequency of the frequency modulation signal 101 is ω
If the displacement angular frequency is ωd, the frequency modulation signal 101
can be expressed as As1nl(ω.±ωd)tl. Furthermore, when the oscillation angular frequency of the oscillator 104 is adjusted by more than ω by the oscillation control signal 105, the output signal of the delay device 102 is As1n lωc (t + d t ), where the delay time in the delay device 102 is dt. ±ωd(t+d
t)).

On the other hand, the output signal of the -90" phase shifter 103 is As1n (cc, .(t+dt)±ωd(t+dt)
90” f=−Acos lωc (t +dt
)±ωd(t+dt)1.

Here, if t+dt is replaced by t, the output signal of the delay device 102 becomes As1n I (ωc±ωd)tl and -
The output signal of the 90° phase shifter 103 is −Acos
It can be expressed as l (ω.±ωd)tl.

A multiplier 10 adds the output signal of the oscillator 104 to these output signals.
Multiplying each by 6 and 107, the output signal of the multiplier 106 is As1n I (ωC±ωd) t l XC0
The output signal of the 9ωa1 multiplier 107 is −Acosl(ωC±ωd) t f X5inωat
Therefore, the output signal of the adder 108 is As1n I (ωC±ωa) t I xcosωa
t-Acos l (ωc±ωd) tl X5inc
c>at=Asin l (ωc−ωa±ωd)tl. As a result, the angular frequency of the input signal to the demodulator 110 becomes (ω0-ω8±ωd). At this time, the angular frequency (ω
. -ω3) is equal to the input angular frequency that can be demodulated by the demodulator 110, then the demodulated signal 111 will be accurate.

Therefore, since the angular frequency isthmus is fixed and known in each mode, the angular frequency ω3 formed by the oscillator 104 is controlled to the frequency according to each mode to obtain the angular frequency (ω.−ω3). By fixing the angular frequency to a demodulated angular frequency, accurate demodulation can be performed in all modes. Note that the relationship between the frequency f and the angular frequency ω is ω=2πf.

As described above, according to this embodiment, the frequency shifter 109 that can freely change the frequency and the demodulator 110 that has the function of demodulating the frequency modulated signal are provided, and the oscillation frequency of the oscillator is adjusted according to each mode. By controlling this, it is possible to accurately demodulate many modes using only one demodulator.

Effects of the Invention According to the demodulation device of the present invention, a frequency shifter that can freely change the frequency and a demodulator that has a function of demodulating a frequency-modulated signal are provided, and the oscillation frequency of the oscillator is adjusted to each frequency mode. By controlling the shift frequency in the frequency shifter and fixing the frequency of the frequency modulated signal that is input to the demodulator to a frequency that can be demodulated by the demodulator, many modes can be achieved with just one demodulator. can be demodulated accurately. As a result, it is possible to implement a compact demodulator that supports multiple modes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the demodulator of the present invention,
FIG. 2 is a block diagram of a conventional demodulator. 101... Frequency modulation signal, 102...
・Delay device, 103...-90° phase shifter,
104... Oscillator, 105... Oscillation control signal, 106, 107... Multiplier, 108...
... Adder, 109 ... Frequency shifter, 110 ... Demodulator, 111 ... Demodulated signal. Name of agent: Patent attorney Shigetaka Awano One idiot Figure 2

Claims (1)

[Claims] -90° phase shifter and delay device into which a frequency modulation signal is input, an oscillator whose oscillation frequency is controlled by the input oscillation control signal and outputs a sine wave and a cosine wave, and the -90° phase shifter. a first multiplier that multiplies an output signal by a sine wave from the oscillator; a second multiplier that multiplies the output signal of the delay device by a cosine wave from the oscillator; and the first and second multipliers. 1. A demodulation device comprising: a frequency shifter configured with an adder that adds an output signal; and a demodulator having a function of demodulating a frequency-modulated signal output from the frequency shifter.