JPH0618333B2 - SSB receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used as a receiver for a single sideband (SSB) signal containing distortion.

INDUSTRIAL APPLICABILITY The present invention is suitable for use in a mobile radio communication receiver.

The present invention, in order to remove the amplitude distortion received in the propagation path,
In the SSB communication system using the amplitude limiter in the demodulation unit,
The present invention relates to a circuit for removing distortion included in a demodulated signal.

[Conventional technology]

A device having a configuration shown in FIG. 2 is known as a device for performing SSB modulation with an information signal on the transmission side, adding a carrier wave to the information signal, transmitting the signal as a transmission signal, and receiving the signal. That is, the SSB signal including the carrier wave is received by the receiving circuit 1, the amplitude is made constant by using the amplitude limiting circuit 2, and the frequency detecting circuit 3 and the integrating circuit 4 perform demodulation. In order to reduce demodulation distortion generated from the reception system configured as described above, an all-carrier SSB signal having a carrier level higher than that of the SSB signal is generated before the amplitude limiting circuit 2, and a distortion removing circuit is provided at the output. It is necessary to add 6 to remove demodulation distortion.

[Problems to be solved by the invention]

However, when the distortion removing circuit 6 has a low distortion removing capability, the carrier level must be increased, which results in a low information transmission efficiency.

In order to solve the above-mentioned problems, the present invention improves the distortion removal capability for removing the distortion generated in the demodulation unit, and has an SSB equipped with a distortion removal circuit that has high information transmission efficiency and enables high-quality transmission. An object is to provide a receiving device.

[Means for solving problems]

The present invention relates to a Hilbert transform pair generation circuit having the output of the SSB demodulation circuit as an input, and a Hilbert transform output obtained at the output of this circuit. And for the non-Hilbert transform output v, From the signal obtained at the output of this first computing means, where n is a natural number and is an integer determined from p = [n / 2] Is provided, and a distortion removing circuit including a third computing means for multiplying the output of the second computing means by a constant and taking a sum.

[Action]

An arithmetic process for removing not only low-order distortion but also high-order distortion from the Hilbert transform output and non-Hilbert transform output obtained at the output of the Hilbert transform pair generation circuit is executed. As a result, the modulation index m of the SSB signal before the amplitude limiting circuit can be reduced, so that the carrier component that does not carry information can be reduced, and the efficiency of information transmission is improved.

〔Example〕

1 and 2 are block diagrams of the apparatus of the embodiment of the present invention. The apparatus shown in FIG. 1 is a detailed configuration diagram of the distortion removing circuit 6 shown in FIG.

That is, the SSB receiving apparatus of the present invention includes a receiving circuit 1 that receives an SSB signal to which a carrier wave is added, and the receiving circuit 1
Of the SSB demodulation circuit including the frequency detection circuit 3 and the integration circuit 4 into which the output signal of the amplitude limiting circuit 2 is input, and the demodulation output signal of the SSB demodulating circuit is removed from the terminal 5. Input to the circuit 6.

The distortion removing circuit 6 includes a Hilbert transform pair generating circuit 8 which receives the output of the demodulating circuit as an input, and the Hilbert transform output obtained at the output terminal 9 of this circuit 8 and the same output terminal.
This is a circuit that executes arithmetic processing on the non-Hilbert transform output obtained in 10. The output signal of the distortion removing circuit 6 is sent from the output terminal 7 as the output of the synthesizing circuit 200.

Here, the multipliers 11 to 17 and 21 to 25 constitute the first arithmetic means, and the multipliers 31 to 38, 41 to 45, 51 to 54, 61 and 62 constitute the second arithmetic means for counting setting. Amplifiers 130-138, 140-
145, 150 to 153, 160 to 162, 170 and the synthesizing circuit 200 form a third calculating means.

Next, the operation of this distortion elimination circuit will be described. The transmitting side performs SSB modulation with an information signal, adds a carrier wave to this to form a transmitting signal, and the receiving side receives the signal. Then, the amplitude limiting circuit 2 is used to make the amplitude constant, and the frequency detecting circuit 3 When the signal V (t) / k demodulated by the integration circuit 4 is introduced into the input terminal 5 of the distortion removal circuit, the Hilbert conversion pair generation circuit 8 converts the signal V (t) / k.
That is, the signal V (t) / k from the non-Hilbert transform output terminal 10 and the signal V (t) / k from the Hilbert transform output terminal 9. Is obtained. Here, k is a constant.

Here, the principle that the distortion included in the signal V (t) / k can be removed by the distortion removing circuit of the present invention will be described using mathematical expressions. The signal V (t) / k is an information signal g (t) = g and the modulation index m However, it can be expressed as j = 1, 2, 3 ... here, Represents the Hilbert transform of g. The distortion removing circuit 6 is configured so that it can be described by the following governing equation. That is, For simplicity here, I put it. Then, substituting equation (1) into equation (2), And no distortion.

The embodiment of the present invention shown in FIG. 1 is configured so as to be able to remove up to the 9th-order distortion based on the operation principle based on the above formula. The operation will be described in detail. From the signal v obtained from the non-Hilbert transform output terminal 10, the multiplier 21 produces v ³ , the multiplier 22 produces v ⁵ , the multiplier 23 produces v ⁷ , and the multiplier 24 produces v ⁹ . Also, the signal obtained from the Hilbert transform output terminal 9 From the multipliers 11, 12 ... 17 To generate. And in the multiplier 31, 32, 33 ... 37 In the multipliers 41, 42, 43 ... 46 In the multipliers 51, 52, 53, 54 In the multipliers 61 and 62 To generate.

Further, a coefficient setting amplifier is connected to the output of each multiplier to set the coefficient. The gain of each of the coefficient setting amplifiers is as follows, referring to the result of the equation (2).

Amplifier 130 is 1 / k, amplifier 131 is -1, amplifier 132 is k / 2! , Amplifier 133 β ₂₁ k ^2/3! , Amplifier 134 is α ₃₁ k ^3/4! , Amplifier 135 is β ₃₁ k ^4/5! , Amplifier 136 is α ₄₁ k ^5/6! , Amplifier 137 β ₄₁ k ^6/7! , The amplifier 138 is α ₅₁ k ^7/8 ! , Amplifier 140 is (1/3) k / 2! , Amplifier 141 is β ₂₂ k ^2/3! , Amplifier 142 is α ₃₂ k ^3/4! , Amplifier 143 is β ₃₂ k ^4/5! , Amplifier 144 is α ₄₂ k ^5/6! , Amplifier 145 β ₄₂ k ^6/7! , The amplifier 146 is α ₅₂ k ^7/8 ! , Amplifier 150 α ₃₃ k ^3/4! , Amplifier 151 is β ₃₃ k ^4/5! , The amplifier 152 α ₄₃ k ^5/6! , Amplifier 153 is β ₄₃ k ^6/7! , The amplifier 154 is α ₄₃ k ^7/8 ! , Amplifier 160 is α ₄₄ k ^5/6! , Amplifier 161 is β ₄₄ k ^6/7! , The amplifier 161 is α ₅₄ k ^7/8 ! , The amplifier 170 is α ₅₅ k ^7/8 ! ,. The output of the output terminal 101 of the amplifier is connected to the input terminal 101 of the synthesis circuit 200, and the output of the output terminal 102 of the amplifier is connected to the input terminal 102 of the synthesis circuit 5 up to 125 in sequence. Removal circuit signal output terminals 6 to 9
A signal from which the next distortion has been removed is obtained. Here, if it is enough to remove the second-order distortion, the output of the amplifier is up to 102,
The amplifier output is up to 104 up to the third distortion, the amplifier output up to 106 up to the fourth distortion, the amplifier output up to 109 up to the fifth distortion, up to the sixth distortion. In this case, the output of the amplifier may be up to 112, in the case of up to the 7th distortion, the output of the amplifier may be up to 116, and in the case of up to the 8th distortion, the output of the amplifier may be up to 120.

FIG. 3 shows a block diagram of the apparatus of the second embodiment of the present invention. The signal V (t) / k = v applied to the signal input terminal 5 is converted into a digital signal by the D / A converter 71,
The digital Hilbert transform pair generation circuit 72 generates a Hilbert transform pair, and the digital signal processing device 73 performs the calculation shown in the equation (2) based on these signals. The output is converted into an analog signal by the D / A converter 74, and a signal from which the ninth distortion is removed is obtained at the signal output terminal 75. In this case, the processing is performed while paying attention to the relationship between the maximum frequency of the input signal, the order of the distortion elimination circuit, and the sampling frequency so that aliasing noise does not occur.

〔The invention's effect〕

As described above, according to the present invention, when the distortion removing circuit capable of removing even higher-order distortion is used, it is not necessary to increase the modulation index m of the general transmission SSB signal immediately before the amplitude limiting circuit. That is, since it is not necessary to make the carrier wave component that does not carry information larger than necessary, it is possible to improve the information transmission efficiency and obtain a demodulated signal of high quality.

[Brief description of drawings]

FIG. 1 is a block diagram of a distortion removing circuit according to the first embodiment of the present invention. FIG. 2 is a block diagram of the receiving apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram of the distortion removing circuit according to the second embodiment of the present invention. 1 ... Receiving circuit, 2 ... Amplitude limiting circuit, 3 ... Frequency detecting circuit, 4 ... Integrating circuit, 5 ... Distortion removing circuit signal input terminal, 6 ... Distortion removing circuit, 7 ... Distortion removing circuit Signal output terminal, 8 ... Hilbert conversion pair generation circuit, 9 ... Hilbert conversion output terminal, 10 ... non-Hilbert conversion output terminal,
11-17, 21-25, 31-38, 41-45, 51-54, 61, 62 ...
Multiplier, 71 ... A / D converter, 72 ... Digital Hilbert transform pair generation circuit, 73 ... Digital signal processing device,
74 …… D / A converter, 101 to 125 …… Coefficient setting amplifier output terminal, 101 to 125 …… Synthesis circuit input terminal, 130 to 13
8, 140 to 145, 150 to 153, 160 to 162, 170 ... Coefficient setting amplifier, 200 ... Synthesis circuit.

Claims (1)

[Claims] 1. A receiving circuit (1) for receiving an SSB signal to which a carrier wave is added, an amplitude limiting circuit (2) through which an output signal of this receiving circuit passes, and a frequency to which an output signal of this amplitude limiting circuit is input. In an SSB receiver provided with a detection circuit (3) and an SSB demodulation circuit including an integration circuit (4), a Hilbert transform pair generation circuit (8) having an output of the SSB demodulation circuit as an input, and an output of this circuit The resulting Hilbert transform output And for the non-Hilbert transform output v, And n is a natural number and is an integer determined from p = [n / 2], and from the signal obtained at the output of this first calculation means, The SSB receiving apparatus is provided with a distortion removing circuit including a second calculating means for generating a signal and a third calculating means for multiplying an output of the second calculating means by a constant to obtain a sum.