JPH07118672B2 - 2 station simultaneous transmission diversity wave receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-station simultaneous transmission diversity wave receiver for transmitting the same information from two transmitting stations at substantially the same radio frequency with mutually shifted phases in the field of wireless communication. .

[0002]

2. Description of the Related Art In a two-station simultaneous transmission diversity system and its apparatus, the receiver obtains substantially the same FM demodulated signal from the output signal of the FM detection circuit and the output signal of the AM detection circuit in different systems. The FM demodulation signal obtained from the output signal of the FM detection circuit (hereinafter, FM detection system FM
F) obtained from the output signal of the AM detection circuit)
A signal having a good signal-to-noise power ratio is selected from among the M demodulated signals (hereinafter referred to as AM demodulated FM demodulated signals) to obtain a final FM demodulated signal.

FIG. 7 shows a block circuit diagram of a conventional receiver. The signal S ₂₀ (t) received by the antenna 20 is
It is given by the following equation [Equation 1].

[Equation 1] However, φ (t) is a transmission signal, a (t), b (t), and u ₁ (t) and u ₂ (t) are amplitudes and phases of received waves from two transmitting stations, f ₁ , f ₂ and m ₁ , m ₂ are the frequency and modulation index of the tone signal added at the transmitting station, and ω ₁ , ω
₂ is the angular frequency of the carrier wave transmitted from each of the two transmitting stations.

In addition, a (t), b (t), u ₁ (t),
u ₂ (t) varies with time due to fading. FM
The output signal S ₁ (t) of the detection circuit 1 is given by the following equation [Equation 2].

[Equation 2] However, Δω = ω ₂ −ω ₁ , u (t) = u ₂ (t) −u
₁ (t).

The output signal S ₂ (t) of the AM detection circuit 2 is given by the following equation.

A method of obtaining an FM demodulated signal from the output signal S ₁ (t) of the FM detection circuit 1 will be described. In the multiplication circuit 9,
S ₁ (t) and S ₂ (t) are applied, and S ₁ (t) and S ₂
A signal S ₉ (t) obtained by multiplying (t) is output. S
₉ (t) is shown in the following equation [Equation 3].

[Equation 3]

The output signal S ₉ (t) of the multiplication circuit 9 is applied to the amplitude ratio detection circuit 21 whose configuration example is shown in FIG. The amplitude ratio detection circuit 21 first separates the two different tone signals applied at the transmitting station side, and then detects the amplitudes of the two different tone signals by the peak hold circuits 22 and 23, respectively. When the modulation indexes of the two tone signals are equal, the output signals S of the peak hold circuits 22 and 23
₂₁ (t) and S ₂₂ (t) are shown in the following equations. S ₂₁ (t) = a ² (t) ………… (7) S ₂₂ (t) = b ² (t) ………… (8)

Next, using S ₂₁ (t) and S ₂₂ (t), a comparator output signal S ₂₃ (t) and an amplitude ratio output signal S ₂₄ (t) shown in the following equations are obtained.

An interference noise elimination circuit 24 having a configuration example shown in FIG.
An output signal S ₉ (t) of the multiplication circuit 9, a comparator output signal S ₂₃ (t), and an amplitude ratio output signal S ₂₄ (t) are applied to.

In the interference noise elimination circuit 24, first, the BPF
At 25, only the FM demodulated signal is taken out. Next, using S ₂₃ (t) and S ₂₄ (t), an FM demodulated signal S ₁₂ (t) whose code and amplitude do not depend on the values of a (t) and b (t) is obtained. The FM demodulated signal S ₁₂ (t) is shown in the following equation. S ₁₂ (t) = φ (t) / 2π …………… (11)

Next, the output signal S of the AM detection circuit 2
_A method of obtaining the FM demodulated signal from ₂ (t) will be described. Figure 1
The AM detection FM demodulation circuit 26 whose configuration example is shown in FIG.
Output signal S ₂ (t) of detection circuit 2, interference noise removal circuit 2
4 output signal S ₁₂ (t), amplitude ratio detection circuit 21 output signal S ₂₄ (t), and switching signal generator 27 output signal S ₂₅ (t) are applied.

In the AM detection FM demodulation circuit 26, first, S
_{Using 24} (t), a signal S ₂₆ (t) independent of the values of a (t) and b (t) is obtained. S ₂₆ (t) is shown in the following equation. S ₂₆ (t) = cos θ (t) (12) Next, S ₂₆ (t) is converted into a signal S ₁₃ (t) shown in the following equation. Furthermore, only the FM demodulated signal is detected from S ₁₃ (t),
An FM demodulation signal S ₁₄ (t) of the AM detection system that matches the amplitude of the FM demodulation signal S ₁₂ (t) of the FM detection system is obtained. S
₁₄ (t) is shown in the following equation. S ₁₄ (t) = φ (t) / 2π ………… (14) or S ₁₄ (t) = − φ (t) / 2π ………… (15) Finally, S ₁₄ (t) is Due to the nature of the detection method, equations (14) and (1
Since the equation (5) cannot be distinguished, the FM demodulation signal S of the FM detection system
₁₂ (t) and the output signal S ₂₅ of the switching signal generator 27
By using (t), an FM demodulation signal S ₁₅ (t) of the AM detection system whose sign matches S ₁₂ (t) is obtained.

In the changeover switch 28, the FM demodulation signal S ₁₂ (t) of the FM detection system and the FM demodulation signal S of the AM detection system S
_{Both 15} (t) are applied and the switching signal generator 2
The output signal S ₂₅ (t) of No. 7 is used as a switching signal, and a signal having a good signal-to-noise power ratio is output as a final FM demodulation signal.

In the switching signal generator 27,
The output signal S ₂₄ (t) of the amplitude ratio detection circuit 21 is applied,
At time t that satisfies the equation (16), the FM demodulation signal S ₁₅ (t) of the AM detection system is output, and at time t that satisfies the equation (17), the FM demodulation signal S ₁₂ (t) of the FM detection system. A switching signal S ₂₅ (t) for controlling the changeover switch 28 so as to output is output. S ₂₄ (t)> m ………… (16) S ₂₄ (t) ≦ m ………… (17) where m is the threshold value (0 <m of the comparator in the switching signal generator 27. <1).

[0015]

When the amplitude ratio of a (t) and b (t) is close to 1, a two-wave interference causes an extremely large frequency shift. In such a case, generally, the FM detection circuit 2 does not operate normally, and as a result, the output signal S ₉ (t) of the multiplication circuit 9 is not output as shown in the expression (6). Therefore, in the amplitude ratio detection circuit 21,
The values of ² (t) and b ² (t) cannot be detected accurately,
Comparator output signal S ₂₃ (t) and amplitude ratio output signal S
₂₄ (t) is also not output as shown in equations (9) and (10).

When the amplitude ratio of a (t) and b (t) is close to 1, the FM demodulated signal S ₁₅ (t) of the AM detection system is converted into the final F
The output signal S of the AM detection circuit 2 is used as the M demodulation signal.
_{At the} stage of obtaining the FM demodulated signal from ₂ (t), S
_{Since 23} (t) and S ₂₄ (t) are used, there is a problem that the FM demodulation signal S ₁₅ (t) of the AM detection system cannot be accurately demodulated.

Further, as described above, the F of the AM detection system is used.
Since the equations (14) and (15) cannot be distinguished from the M demodulated signal S ₁₄ (t), the FM demodulated signal S ₁₂ of the FM detection system
When switching from (t) to the FM demodulation signal S ₁₄ (t) of the AM detection system, it is necessary to match the signs of the FM demodulation signals. However, in the conventional receiver, since this code matching is always performed, when the amplitude ratio of a (t) and b (t) is close to 1, the FM demodulation signal S of the AM detection system S
There was a problem that the sign of ₁₅ (t) was wrong.

When the amplitude ratio between a (t) and b (t) is close to 1, the amplitude ratio output signal S ₂₄ (t) is not accurately output, so the output signal S of the switching signal generator 27 is output.
There is also a problem that ₂₅ (t) is not accurately output and a malfunction occurs in the changeover switch 28.

An object of the present invention is to receive the received waves from the two transmitting stations by the AM detection system and the FM detection system, even if the amplitude ratio of these received waves is close to 1, the F of the AM detection system.
An object of the present invention is to provide a receiver in which an M demodulated signal is demodulated with high accuracy and a malfunction of a changeover switch that selects one of the outputs of both detection systems is hardly caused.

[0020]

SUMMARY OF THE INVENTION A two-station simultaneous transmission diversity wave receiver according to the present invention is a radio frequency signal angularly modulated by the same transmission signal with different codes from two transmission stations, but with substantially the same carrier frequency. An FM detection circuit for receiving an IF signal obtained by receiving the transmission diversity wave and detecting a frequency variation thereof for receiving the transmission diversity wave to be transmitted, and a signal proportional to the square of the envelope of the IF signal. An AM detection circuit for detecting a signal, a multiplication circuit for receiving an output signal of the FM detection circuit and the output signal of the AM detection circuit, and outputting an FM demodulation signal containing almost no interference noise, and reception from each of the two transmission stations. An amplitude detection circuit for detecting the magnitude of the amplitude of the wave, and an interference noise removal circuit for making the amplitude and sign of the output signal of the multiplication circuit constant without depending on the amplitude ratio of the received wave. An amplitude constant circuit that receives the output signal of the AM detection circuit and has an output signal that is proportional to the square of the envelope having signal power that does not depend on the amplitude ratio of the received wave, and an output signal of the constant amplitude circuit. An AM detection FM demodulation circuit which receives and outputs an FM demodulation signal, a signal having a better signal-to-noise power ratio is selected from the output signals of the interference noise removal circuit and the AM detection FM demodulation circuit, and finally selected. And a changeover switch for outputting as an FM demodulated signal.

[0021]

In the two-station simultaneous transmission diversity wave receiver of the present application, the output signal of the AM detection circuit is used to obtain a (t) and b.
When the amplitude ratio of (t) is detected and the FM demodulated signal of the AM detection system is used as the final FM demodulated signal, the code of the FM demodulated signal of the AM detection system is made to match the code of the FM demodulated signal of the FM detection system. Try to stop things. This enables AM without using the information of the output signal of the FM detection system.
It is possible to accurately obtain an FM demodulation signal of the AM detection system from the output signal of the detector and prevent malfunction of the changeover switch.

[0022]

Embodiments of the present invention will be described with reference to the drawings and mathematical expressions. Also in the receiver of the embodiment of the present invention shown in FIG. 1, FM detection circuit 1 of the output signal S ₁ (t) and the AM detection circuit substantially the same FM 2 output signal S ₂ from the (t) at each different type Obtained demodulated signal, FM detection system FM
A signal having a good signal-to-noise power ratio is selected from the demodulated signal and the FM demodulated signal of the AM detection system to obtain the final FM demodulated signal.

In FIG. 1, the constant amplitude circuit 3 has an AM
The output signal S ₂ (t) of the detection circuit is applied, and a signal S ₈ (t) that does not depend on the amplitude ratio of a (t) and b (t) is output. A configuration example of the constant amplitude circuit 3 is shown in FIG.

[0024] In constant amplitude circuit 3, the output signal S ₃ of the peak hold circuit 4 (t), the output signal S ₄ of the peak hold circuit 5 (t), the output signal S of the dividing circuit 6
₅ (t), shows the output signal S ₆ of the subtracting circuit 7 (t), the output signal S ₇ of the subtracting circuit 8 (t) and the output signal S ₈ of constant amplitude circuit 3 (t) to the following equation. S ₃ (t) = 1 ... (18) S ₈ (t) = (1 + cos θ (t)) / 2 ……………… (23)

From the output signal S ₁ (t) of the FM detection circuit to F
A method of obtaining the M demodulated signal will be described. In the multiplication circuit 9, S
₁ (t) and S ₂ (t) is applied, S ₁ and (t) S
A signal S ₉ (t) obtained by multiplying ₂ (t) is output.
S ₉ (t) is shown in the following equation.

S ₉ (t) is branched into two, one of which is applied to the amplitude detection circuit 10 shown in FIG. 3 and the other of which is applied to the code and amplitude constant circuit 11 shown in FIG.

In the amplitude detecting circuit 10, first, two different tone signals added on the transmitting station side are separated, respectively, and then a
The magnitude of the amplitude of (t) and b (t) is determined. The output signal S ₁₀ (t) of the amplitude detection circuit 10 is given by the following equation when the modulation indexes of the two tone signals are equal.

[0028] code and a constant amplitude circuit 11, the output signal S ₉ (t), the output signal S ₆ of the output signal S ₁₀ (t) and the subtraction circuit 7 of constant amplitude circuit 3 of the amplitude detection circuit 10 of the multiplier circuit 9 (T) is applied. In the sign / amplitude constant circuit 11, the BPF 12 extracts only the FM demodulated signal from S ₉ (t) and uses S ₁₀ (t) and S ₆ (t) to determine the sign and amplitude of a (t) and b (t). Signal S ₁₁ (t) independent of the value of
Is output.

In the delay circuit 13, the output signal S ₁₁ (t) of the sign and amplitude constant circuit 11 is applied, and the F of the AM detection system is applied.
The FM demodulated signal is obtained by correcting the delay time with the M demodulated signal. The FM demodulated signal S ₁₂ (t) of the FM detection system is given by the following equation. S ₁₂ (t) = φ (t) / 2 π ……………… (11)

Next, the output signal S of the AM detection circuit 2
_A method of obtaining the FM demodulated signal from ₂ (t) will be described. AM
The value of the output signal S ₂ (t) of the detection circuit 2 is a (t) and b
Since it depends on the amplitude ratio of (t), a
Signal S ₈ (t) that does not depend on the amplitude ratio of (t) and b (t)
After being converted to, the signal is applied to the AM detection FM demodulation circuit 14 shown in FIG.

In the AM detection FM demodulation circuit 14 shown in FIG. 5, first, from S ₈ (t), the signal S ₁₃ (t) shown in the following equation is obtained.
Is converted to. Next, from S ₁₃ (t), only the FM demodulated signal is detected, and F
Match the amplitude with the FM demodulation signal S ₁₂ (t) of the M detection system
An FM demodulated signal S ₁₄ (t) of the M detection system is obtained. S
₁₄ (t) is shown in the following equation. S ₁₄ (t) = φ (t) / 2π ………… (14) or S ₁₄ (t) = − φ (t) / 2π ………… (15)

In the switching circuit 15 shown in FIG. 6, the FM demodulation signal FM demodulation signal S ₁₂ (t), the AM detection system FM demodulation signal S ₁₄ (t) and the peak hold 5 of the constant amplitude circuit 3 are provided.
Output signal S ₄ (t) is applied.

In the switching circuit 15, the FM of the AM detection system is used.
Since the demodulated signal S ₁₄ (t) cannot be distinguished from the equations (14) and (15) due to the nature of the detection method, the initial condition is determined from the FM demodulated signal S ₁₂ (t) of the FM detection system. However, a
When the amplitude ratio of (t) and b (t) is close to 1, S ₁₂ (t)
Since the signal-to-noise power ratio of S is significantly deteriorated, the sign of S ₁₄ (t) is changed to FM at time t when Eq. (26) is satisfied.
Match the sign of the demodulated signal S ₁₂ (t) of the detection system, and (2
At time t that satisfies the expression (5), the sign of S ₁₄ (t) is made to stop matching with the sign of the demodulated signal S ₁₂ (t) of the FM detection system. In this way, the demodulated signal S ₁₅ (t) of the AM detection system whose sign has been determined is obtained. And
The FM demodulation signal S ₁₅ (t) of the AM detection system is output at the time t that satisfies the equation (25), and the FM demodulation signal S ₁₂ (t) of the FM detection system at the time t that satisfies the equation (26). Is output. S ₄ (t)> n (25) S ₄ (t) ≦ n (26) n is a threshold value (0 <n <1) of the comparator.

[0034]

According to the present invention, by providing the constant amplitude circuit, the AM without using the signal information of the FM detection system.
It becomes possible to accurately demodulate the detection system signal. Further, at time t that satisfies the expression (25), to stop matching the code of the FM demodulated signal S ₁₄ (t) of the AM detection system with the code S ₁₂ (t) of the FM demodulated signal of the FM detection system. , It is possible to prevent the inversion of the sign of the FM demodulation signal S ₁₄ (t) of the AM detection system. Even when the amplitude ratio of a (t) and b (t) is close to 1, since the output signal S ₄ (t) of the peak hold circuit 5 of the amplitude constant circuit 3 is used as a switching signal, the switching circuit 15 may malfunction. Can be prevented. Therefore, there is an advantage that the FM demodulated signal can be accurately demodulated. The present invention has such an effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a receiver according to the present invention.

FIG. 2 is a block diagram showing an example of a constant amplitude circuit used in the configuration of FIG.

FIG. 3 is a block diagram showing an example of an amplitude detection circuit used in the configuration of FIG.

4 is a block diagram showing an example of a code and constant amplitude circuit used in the configuration of FIG.

5 is a block diagram showing an example of an AM detection FM demodulation circuit used in the configuration of FIG.

6 is a block diagram showing an example of a switching circuit used in the configuration of FIG.

FIG. 7 is a block diagram showing a basic configuration example of a conventional receiver.

8 is a block diagram showing an example of an amplitude ratio detection circuit used in the configuration example of FIG.

9 is a block diagram showing an example of an interference noise elimination circuit used in the configuration example of FIG.

10 is an AM detection FM used in the configuration example of FIG.
It is a block diagram which shows an example of a demodulation circuit.

[Explanation of symbols]

 1 FM detection circuit 2 AM detection circuit 3 Amplitude constant circuit 4,5,22,23 Peak hold circuit 6 Multiplication circuit 7,8 Subtraction circuit 9 Multiplication circuit 10 Amplitude detection circuit 11 Sign and amplitude constant circuit 12,25 BPF 13 Delay circuit 14,26 AM detection FM demodulation circuit 15 Switching circuit 21 Amplitude ratio detection circuit 24 Interference noise removal circuit 27 Switching signal generator 28 Changeover switch

Claims (1)

[Claims] 1. A transmitter diversity wave is received from two transmitter stations for receiving a transmitter diversity wave, in which a radio frequency signal angularly modulated by the same transmission signal having different codes is transmitted at substantially the same carrier frequency. An FM detection circuit for receiving the IF signal obtained as described above and detecting the frequency fluctuation thereof; an AM detection circuit for receiving the IF signal and detecting a signal proportional to the square of the envelope; and an FM detection circuit and an AM detection circuit. A multiplication circuit that receives both output signals and outputs an FM demodulated signal that contains almost no interference noise, an amplitude detection circuit that detects the magnitude of the amplitude of the received wave from each of the two transmitting stations, and the amplitude of the received wave. An interference noise elimination circuit that makes the amplitude and sign of the output signal of the multiplication circuit constant without depending on the ratio, and an output signal of the AM detection circuit that does not depend on the amplitude ratio of the received wave. A constant amplitude circuit having an output signal that is proportional to the square of the envelope having a large signal power, an AM detection FM demodulation circuit that receives the output signal of the constant amplitude circuit and outputs an FM demodulation signal, and the noise interference canceller A final FM is selected by selecting a signal having a better signal-to-noise power ratio from the output signal of the circuit and the output signal of the AM detection FM demodulation circuit.
2 equipped with a selector switch for outputting as a demodulated signal
Receiver for simultaneous diversity transmission of stations.