JPH10327020A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver with a simplified configuration. SOLUTION: In the case that a reception electric field strength is excellent, a switch (SW) 1 is thrown to a position (a) and a SW 2 is thrown to a position (b). A reception means 8A receives an RZ-SSB modulated wave with a desired user frequency, converts the wave into an intermediate frequency signal, which is outputted. The intermediate frequency signal is A/D-converted and given to an FM detector circuit 10 that conduct TAN-<1> detection providing a high AM suppressing degree, where the signal is FM- detected not through a limiter. A detected output from the FM detector circuit 10 is given to an equalizer means 22, where distortion is eliminated, the result is D/A- converted, amplified by an AF amplifier 23, and the amplified signal is outputted form a speaker 24. As a result, the radio wave is received with immunity to fading. In the case that the received electric field strength is deteriorated, the SW 1 is thrown to a position (b) and the SW 2 is thrown to a position (c). An automatic notch circuit 41 of an AM detection means 40 suppresses a carrier component of the intermediate frequency signal of the RZ-SSB modulation wave, and a product detection circuit 42 applies product detection to the resulting signal. The signal is D/A-converted, amplified by an AF amplifier 23 and outputted from the speaker 24. As a result, the radio wave is received with a high S/N.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a receiver, and more particularly, to a receiver capable of receiving an RZ-SSB (Real Zero SSB) modulated wave.

[0002]

2. Description of the Related Art As an AM modulation method which requires a small occupied bandwidth and is resistant to fading in mobile communication, RZ-
There is SSB. The RZ-SSB is a modulated wave that does not completely suppress the carrier, and the information of the original modulated signal exists in both the amplitude and the phase. Therefore, on the receiver side, RZ-SSB
By performing amplitude limitation and FM detection on the received signal of the modulated wave, the original modulated signal can be demodulated. FIG. 7 shows a configuration example of a receiver that receives an RZ-SSB modulated wave (Japanese Patent Publication No. 6-22).
No. 290, “Transistor Technology” 1 published by CQ Publishing Company
(See pages 343-345, February 997). In FIG. 7, the received signal of the RZ-SSB modulated wave at antenna 1 is R
High-frequency amplification is performed by the F-amplifier 2, mixed with the local oscillation signal input from the VCO 4 by the mixer 3, and converted into an intermediate frequency signal. A controller (not shown) variably sets a division ratio corresponding to a desired tuning frequency to the PLL circuit 5, and
The circuit 5 varies the control voltage of the VCO 4 according to the frequency division ratio,
The tuning frequency is varied by varying the local oscillation frequency.

The intermediate frequency signal output from the mixer 3 is I
After the intermediate frequency amplification by the F amplifier 6, only the intermediate frequency band component is extracted by the BPF 7. RF amplifier 2 to B
The receiving means 8 is configured up to the PF 7. The intermediate frequency signal of the RZ-SSB modulated wave band-limited by the BPF 7 is amplitude-limited by the limiter 9 and then FM-detected by the FM detection circuit 10 to demodulate the original modulated signal. However, since the output of the FM detection circuit 10 includes distortion, the integrator 11
, First, the differentiated signal is integrated (the limiter 9, the FM detection circuit 10, and the integrator 11 form a phase detection system). Assuming that the modulation index of the RZ-SSB modulated wave is m, the band-limited modulated signal is g (t), and the Hilbert transform of g (t) is g ^* (t), the output v (t) of the integrator 11 is v (t) = mg ^* (t) −m ² g (t) g ^* (t) + m ³ {g ² (t) g ^* (t) − (g ³ (t) / 3)} + O (m ⁴ (1) However, O (m ⁴ ) is the expansion term of the fourth and subsequent orders.

[0004] Since terms of the second order of m and higher are harmonic distortions, harmonic distortion is input to the linearizer 12 having the configuration shown in FIG. 8 to remove the harmonic distortions. The linearizer 12 has v
A Hilbert filter 13 that delays the phase of (t) by 90 ° and a delay unit 14 that delays v (t) by a certain time (time required for v (t) to pass through the Hilbert filter 13). Vessel 15, v (t)
Multiplied by the output of the Hilbert filter 13
6, a multiplier 17 for multiplying the output of the multiplier 16 by the output of the Hilbert filter 13, a multiplier 18 for multiplying the output of the multiplier 17 by 、, a cuber 19 for cubing v (t) 19, a cube of 3 Multiplier 20 for multiplying the output of the multiplier 19 by 1/6, and the delay unit 14
And an adder / subtractor 21 for adding the output of the multiplier 18 to the output of the multiplier 18 and subtracting the output of the multiplier 16 and the output of the multiplier 20. When the phase of the output of the delay unit 14 is viewed as a reference, the phase of the output of the
° Late.

The output u (t) of the linearizer 12 is v
Assuming that the Hilbert transform of (t) is v ^* (t), u (t) = v (t) −v (t) v ^* (t) + v (t) ｛v ^* (t)｝ ² / 2− ｛ ^{v (t)} 3/6} + O (m 4) ·· (2) where, O (m ⁴⁾ is the fourth order after expansion terms. (1),
From equation (2), u (t) = mg ^* (t) + O (m ⁴ ), and a demodulated signal from which distortion has been removed is obtained. Integrator 1
1 and the linearizer 12 constitute an equalizing means 22. The output of the linearizer 12 is output to the speaker 24 after being subjected to low frequency amplification by the AF amplifier 23.

[0006]

In the above-mentioned conventional RZ-SSB receiver, it is necessary to limit the amplitude of the RZ-SSB modulated wave output from the receiving means 8 by passing the wave through a limiter 9. Burden increases. In particular, RZ
In practical use of the SSB receiver, it is advantageous to implement the limiter 9 and the FM detection circuit 10 with a digital signal processing circuit in order to eliminate the need for critical adjustment work of the detection system. In order to avoid aliasing distortion due to intermodulation distortion generated in processing, the sampling frequency must be extremely high, and it is necessary to use an expensive, high-power-consumption, high-speed operation type for the digital signal processing circuit. To avoid this problem, the limiter 9 is constituted by an analog circuit, the output of the limiter 9 is passed through an anti-aliasing analog filter, A / D converted, and the FM detection circuit 1 constituted by a digital signal processing circuit.
Even when the signal is input to 0, the intermodulation distortion still occurs in the limiter 9 constituted by an analog circuit. Therefore, a high-order anti-aliasing analog filter having a large stop band attenuation must be used. There was a problem that it was expensive and required installation space.

Also, since the sensitivity of the FM detection circuit to the RZ-SSB modulated wave is low, unless a very high S / N type is used for the FM detection circuit, it is satisfactory when a high S / N is required for the demodulated output. In some cases, the S / N cannot be obtained, or the S / N becomes too bad at the time of weak input, so that reception becomes impossible. The present invention has been made in view of the above-described problems of the related art, and has as its object to provide a receiver whose configuration can be simplified.
It is another object of the present invention to improve the S / N of the demodulated output as required. It is another object of the present invention to enable reception of an SSB-SC modulation wave or an FM modulation wave.
It is another object of the present invention to reduce distortion by completely tuning a received wave.

[0008]

According to a first aspect of the present invention, there is provided a receiver for receiving an RZ-SSB modulated wave transmitted at a desired frequency and converting the modulated wave into an intermediate frequency signal, and an output from the receiving means. The obtained intermediate frequency signal is input without passing through the amplitude limiting means, and the FM detecting means having a high degree of AM suppression for performing FM detection, and the distortion removal in the output of the FM detection of the RZ-SSB modulated wave by the FM detecting means are performed. And an equalizing means. This makes it possible to demodulate the RZ-SSB modulated wave without using a limiter, thereby simplifying the configuration of the receiver. In particular, when the FM detection means is configured using a digital signal processing circuit, it is not necessary to consider the effects of aliasing distortion due to intermodulation distortion in the limiter, so that the digital signal processing circuit does not have to be an expensive high-speed operation type. In addition, A before the FM detection means
It is not necessary to increase the stop band attenuation of the anti-aliasing analog filter used in combination with the / D converter.

The receiver according to claim 2 of the present invention is characterized in that, in the receiver according to claim 1, the FM detection means performs TAN- ¹ type detection in a digital domain. Thereby, the degree of AM suppression in the FM detection means can be extremely increased, and the distortion of the demodulated signal is reduced.

According to a third aspect of the present invention, in the receiver according to the first aspect, the intermediate frequency signal output from the receiving means is input, and the AM for the RZ-SSB modulated wave is input.
It is characterized by comprising AM detection means for performing detection, and switching means for switching and outputting the output of the equalization means and the output of the AM detection means. Thus, when the received electric field strength is good or when a high S / N is not required, the switching means is switched to the equalizing means side to switch the RZ-S
By performing the FM detection of the SB modulated wave, it is possible to perform reception that is strong against fading, and when the reception electric field strength is deteriorated,
Alternatively, when a high S / N is required, or when the modulated signal is an FSK signal that is not easily affected by fading, the switching unit is switched to the AM detection unit to set the RZ-SS
By performing AM detection on the B modulated wave, reception at a high S / N is possible. The AM detecting means of claim 3 may be, for example, a synchronous detecting means often used for detecting an AM modulated wave. When the receiving means can also receive the AM modulated wave by using the synchronous detecting means, the AM detecting means detects the AM modulated wave. Demodulation output is also possible.

According to a fourth aspect of the present invention, in the receiver according to the third aspect, at least one of the equalizing means and the FM detecting means is provided while the switching means is switched to the AM detecting means. It is characterized in that one operation is stopped. Thus, power consumption can be reduced.

According to a fifth aspect of the present invention, in the receiver according to the third aspect, the AM detection means includes an RZ-S
It is characterized by including a carrier suppression unit for suppressing a carrier component in the SB modulated wave, and a product detection unit for performing product detection by inputting the RZ-SSB modulated wave whose carrier has been suppressed by the carrier suppression unit. Thereby, RZ-S
The AM detection can be performed on the SB modulated wave without distortion.

According to a sixth aspect of the present invention, in the receiver according to the fifth aspect, the receiving means includes an RZ-SSB.
A modulation wave and an SSB-SC modulation wave can be received, and the AM detection means is provided with switching means for switching the input side of the product detection means between the output side of the carrier suppression means and the output side of the reception means. Features. This allows
If the input side of the product detection means in the AM detection means is switched to the output side of the carrier suppression means, RZ-
SSB-modulated waves can be received, and SSB-SC modulated waves can be received by switching the input side of the product detection means to the output side of the reception means.

According to a seventh aspect of the present invention, there is provided the receiver according to the first aspect, wherein the intermediate frequency signal output from the receiving means is input, and the AM detection means performs envelope detection on the RZ-SSB modulated wave. Switching means for switching between the output of the FM detection means and the output of the AM detection means and outputting the output to the equalization means.
As a result, even if the carrier suppression means is not provided, the RZ-SS
AM detection of the B-modulated wave becomes possible, and distortion of the demodulated signal can be reduced.

According to the receiver of the present invention, in the receiver of the first aspect, the receiving means can receive an RZ-SSB modulated wave and an FM modulated wave. Switching means for outputting the output of the detection means to the subsequent stage without passing through the equalization means is provided. Thereby, by inputting the output of the FM detection means to the equalization means, it becomes possible to receive and demodulate the RZ-SSB modulated wave,
By outputting the output of the FM detection means to the subsequent stage without passing through the equalization means, it becomes possible to receive and demodulate the FM modulated wave.

In a receiver according to a ninth aspect of the present invention, in the receiver according to the first aspect, the receiving means can receive an RZ-SSB modulated wave and an FM modulated wave. It is characterized in that de-emphasis means for performing de-emphasis on the output of the detection means and switching means for outputting the output of the de-emphasis means to the subsequent stage in place of the output of the equalization means are provided. Thereby, by inputting the output of the FM detection means to the equalization means, the RZ-SSB
Modulation waves can be received and demodulated, and the output of the FM detection means is passed through the de-emphasis means and then output to the subsequent stage instead of the output of the equalization means. Reception and demodulation become possible.

In the receiver according to a tenth aspect of the present invention, in the receiver according to the ninth aspect, the equalizing means integrates the output of the FM detection means and the integration means when the RZ-SSB modulated wave is received. Linearizer means for removing distortion remaining in the output of the means by performing predetermined arithmetic processing, and the de-emphasis means is also used as an integrating means of the equalizing means. Accordingly, it is not necessary to provide a de-emphasis unit separately from the equalization unit, and the configuration is simplified.

In the receiver according to the present invention, a carrier frequency detecting means for detecting a frequency of a carrier in a received wave, and a carrier frequency detecting means for detecting the frequency of the carrier in the received wave. Control means for controlling the tuning frequency of the receiving means based on the carrier frequency detected by the means.
This optimizes the operating point of the receiver and reduces the distortion of the demodulated signal.

According to a twelfth aspect of the present invention, in the receiver according to the fifth or sixth aspect, the carrier suppressing means suppresses a carrier component while following a frequency change of the RZ-SSB modulated wave. And a control means for controlling the tuning frequency of the receiving means based on the notch frequency in the auto notch filter. As a result, the operation point of the receiver can be optimized to reduce the distortion of the demodulated signal, and the configuration can be simplified because a dedicated means for detecting the frequency of the carrier wave in the received wave is not required.

[0020]

Next, an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows FM (voice) according to the present invention.
8 is a configuration diagram of a multi-mode receiver of / RZ-SSB (voice) / RZ-SSB (FSK for teletype) / SSB-SC (voice), and the same components as those in FIG. I have. Reference numeral 1 denotes an antenna, and 8A denotes an FM which receives a signal received by the antenna 1 and is transmitted at a frequency desired by the user.
Receiving means for receiving a modulated wave, an RZ-SSB modulated wave, or an SSB-SC modulated wave, of which 2 is an RF amplifier for amplifying the antenna received signal at a high frequency, 3 is a mixer, and the output of the RF amplifier 2 is The signal is mixed with the local oscillation signal input from the VCO 4 and converted into an intermediate frequency signal. When the user performs the operation frequency variable operation, a system controller, which will be described later, variably sets frequency control data (frequency division data) corresponding to the user's desired operation frequency in the PLL circuit 5, and the PLL circuit 5 changes the frequency control data. According to VC
The tuning frequency is varied by varying the control voltage of O4 and varying the local oscillation frequency.

6A is a variable gain IF amplifier for amplifying the intermediate frequency signal output from the mixer 3, 7 is a BPF for limiting the band of the output of the IF amplifier 6A, and 30 is an AGC.
A circuit that performs DC detection on the output of the BPF 7 to create an AGC voltage proportional to the received electric field strength, and increases the gain of the IF amplifier 6A when the AGC voltage is small;
When the AGC voltage is high, the gain is reduced to output an intermediate frequency signal having a substantially constant level regardless of the increase or decrease of the received electric field strength. Multiplying the AGC by the AGC circuit 30 allows FGC to be described later irrespective of the fluctuation of the received electric field strength.
The input level of the intermediate frequency signal to the M detection means or the AM detection means can be appropriately maintained, the fluctuation of the demodulation output level can be suppressed, and the occurrence of cross modulation and intermodulation distortion can be prevented. Here, RZ-SS viewed at the output point of BPF7
(Smallest value distortion of RZ-SSB modulated wave when it passes through the BPF 7) optimum frequency value of the carrier component of the B-modulated wave is assumed to be set to f _0.

Reference numeral 31 denotes an A / D converter for A / D converting the intermediate frequency signal output from the receiving means 8A, and reference numeral 10 denotes an FM detection circuit having sufficiently high AM suppression as FM detection means. When a user desires FM detection to prevent fading at the time of receiving a modulated wave or receiving an RZ-SSB modulated wave (voice), the intermediate frequency signal output from the A / D converter 31 is passed through a limiter. And FM detection in the digital domain. FM with high AM suppression
As the detection circuit 10, for example, TAN ^-1 as shown in FIG.
A mold may be used. In the circuit of FIG. 2, the input intermediate frequency signal S _IN is passed through the Hilbert filter 32 to delay the phase by 90 ° to be a Y signal, and the delay unit 33 sets the Y signal for a predetermined time (for the S _IN passing through the Hilbert filter 32). (The required time) to form an X signal (when viewed with reference to the phase of the X signal, the phase of the Y signal output from the Hilbert filter 32 is delayed by 90 °). The Hilbert filter 32 and the delay unit 33 constitute a Hilbert transformer 34. Then, in the TAN- ¹ type phase detector 35, tan
^-1 (X / Y) calculation, FM modulated wave or RZ-S
FM detection is performed by obtaining the phase change of the SB modulated wave.

If the degree of AM suppression of the FM detection circuit 10 is sufficiently high, the detection output of the FM detection circuit 10 is faded when receiving an FM modulated wave or an RZ-SSB modulated wave (voice) without providing a limiter in the preceding stage. In addition, distortion due to amplitude fluctuation of the intermediate frequency signal due to noise or the like does not appear. By eliminating the need for a limiter, the circuit configuration can be simplified.
In addition, since the aliasing distortion caused by the generation of the intermodulation distortion in the limiter does not cause a problem, it is not necessary to increase the sampling frequency of the A / D converter 31.
About twice the upper limit of the pass band. Therefore, a low-cost and low-power-consumption type digital signal processing circuit that implements the FM detection circuit 10 can be used. Also, an anti-aliasing analog filter (not shown) provided in the preceding stage of the A / D converter 31 can use a lower-order type because the required level of the attenuation of the stop band is low, and it is inexpensive and the installation space is narrow. I can do it.

SW1 is an FM detection circuit 10 and an AM (to be described later).
This is a switch for switching the output of the detection means, and is switched to the FM detection circuit 10 when performing FM detection when receiving an FM modulated wave or receiving an RZ-SSB modulated wave (voice). Reference numeral 22 denotes an equalizing unit that performs signal processing in the digital domain to remove distortion remaining when the RZ-SSB modulated wave is FM detected by the FM detection circuit 10. The equalizer 22 includes an integrator (see reference numeral 11 in FIG. 7) for performing phase detection on the RZ-SSB modulated wave together with the FM detection circuit 10, and a linearizer (refer to reference numeral 12 in FIG. 7) for removing distortion in the output of the integrator. , FIG. 8). 7 and 8, the equalizing means 22 has a large circuit scale and a large power consumption during operation. For this reason, when it is not necessary to perform the distortion removing operation, the operation is stopped by the system controller to save power.

SW2 is an FM detector 10 and an equalizer 22.
And a switch for switching the output of the AM detection means.
When receiving the M-modulated wave, the output side of the FM detection circuit 10 and the RZ-
The FM detection is performed when receiving the SSB modulated wave (voice), the output side of the equalizer 22 is used, the AM detection is performed when the RZ-SSB modulated wave (voice) is received, and the SSB-SC modulated wave (voice) is used. ) Is switched to the output side of the AM detector 40. 36 is a D for performing D / A conversion of the output of the switch SW2.
A / A converter 23 is an AF amplifier for amplifying the output of the D / A converter 36 at low frequency, and 24 is a speaker driven by the output of the AF amplifier 23.

Reference numeral 40 denotes A for performing signal processing in the digital domain.
M detection means, which is used when a user desires AM detection at the time of receiving an SSB-SC modulated wave (voice) or at the time of receiving an RZ-SSB modulated wave (voice), and at the time of receiving an RZ-SSB modulated wave (F
When receiving (SK), the intermediate frequency signal input from the A / D converter 31 is detected by AM and output. 41 is an auto notch circuit for suppressing the carrier component contained in the RZ-SSB modulated wave in the AM detection means 40. The auto notch circuit 41 is composed of an IIR type adaptive digital notch filter. The filter coefficient is updated by, for example, the stochastic gradient method (SGA) to automatically follow the frequency fluctuation of the carrier wave component and to perform RZ-SSB modulation. Outputs a signal obtained by removing the carrier component from the intermediate frequency signal of the wave (for details, Shigenori Kaneshiro and Norika Kamibayashi, "Configuration of IIR Adaptive Notch Filter Using Improved Stochastic Gradient Method", IEICE Transactions (A ) VoL.J74-A No.7 pp _. 1014-1022 19
91/7).

The auto notch circuit 41 is as shown in FIG.
Of the filter coefficient groups a _{0 to} a ₂ , b ₁ , b ₂ of the secondary IIR digital filter provided between the input and output, a ₀ and a ₂
Is fixed, b ₂ is fixed to r ² , and when a ₁ = W and b ₁ = rW, W is adaptively and successively updated, the transfer function H (z) between the input and output is H (Z) = (1 + Wz ^-1 + z ^-2 ) / (1 + rWz ^-1 + r
² z ^-2 ). The notch angular frequency ω _n is obtained from W as ω _n = cos ⁻¹ (−W / 2), and the notch frequency f _n is f _n = 2πω _n = 2π cos ⁻¹ (−W / 2) (3) Is obtained as r is a coefficient that determines the sharpness of the notch characteristics of the notch filter, and is fixed to an appropriate value within the range of 0 <r <1.

The notch frequency f _n indicates the frequency f ₁ of the carrier component of the RZ-SSB modulated wave, and changes following the frequency fluctuation of the carrier component. Therefore, the auto notch circuit 41 also has a function as a carrier frequency detecting means of the RZ-SSB modulated wave viewed from the intermediate frequency signal, and outputs the value of W to the system controller every time W is updated. When the system controller receives the RZ-SSB modulated wave, the value is input each time the auto notch circuit 41 updates W while the tuning knob described later is not operated by the user,
Calculate the frequency of the carrier component from equation (3) and calculate RZ-SS
The difference Δf (= f ₁ −f ₀ ) from the frequency value f ₀ of the optimum operating point with respect to the B modulated wave is subtracted from the operating frequency F desired by the user to obtain a corrected operating frequency F ′, and the frequency corresponding to F ′ The control data is set in the PLL circuit 5 to correct the tuning frequency of the receiving means 8A.

SW3 is a switch for switching between the output of the A / D converter 31 and the output of the auto notch circuit 41.
When the Z-SSB modulated wave is to be detected by AM, the output is switched to the output side of the auto notch circuit 41. When the SSB-SC modulated wave is detected by AM, the output is switched to the output side of the A / D converter 31. 42 is a product detector circuit which performs detection in product detection method in the digital domain to RZ-SSB modulated wave or SSB-SC modulated wave after carrier suppression, of which, 43 frequency generating a carrier wave of fixed f ₀ BFO 44 is the RZ input from switch SW3.
-SSB modulated wave or SSB-SC modulated wave and BFO43
This is a mixer that mixes the carrier waves from the CDMA and extracts the difference frequency component. An LPF 45 for removing unnecessary components from the output of the mixer 44 outputs a demodulated signal of an RZ-SSB modulated wave or an SSB-SC modulated wave from the LPF 45.

Reference numeral 46 denotes the input of the demodulated signal from the AM detector 40 when the RZ-SSB modulated wave is an FSK signal,
FS that performs K demodulation and outputs "1" and "0" data
The K demodulation circuit 47 is a teletype that prints out based on data input from the FSK demodulation circuit 46. 5
Reference numeral 0 denotes an operation panel. A tuning knob 51 for a user to increase or decrease the operation frequency of the set, a key 52 for instructing a reception mode for FM detection of an RZ-SSB modulated wave (voice), an RZ-SSB modulated wave ( Key 53 for instructing a reception mode for AM detection of sound, RZ-SSB modulated wave (FS
Key 54 for instructing the reception mode for AM detection of K), S
A key 55 for instructing a reception mode of an SB-SC modulated wave (voice), a key 56 for instructing a reception mode for FM detection of an FM modulated wave (voice), and the like are provided.

Reference numeral 60 denotes a system controller having a microcomputer structure that controls the entire receiver, and performs tuning control and reception mode switching control (including switching control of SW1 to SW3) in accordance with an operation on the operation panel 50.

Next, the operation of the above embodiment will be described. (1) FM detection of FM modulated wave (voice; here, there is no pre-emphasis on the transmitting side) When receiving FM modulated wave (voice), press key 56. Then, the system controller 60 switches the switch SW2 to the a side, stops the power supply to the equalizing unit 22, and stops the equalizing unit 22, thereby saving power. When the user operates the tuning knob 51, the system controller 60 increases or decreases the operating frequency F managed by the internal memory (not shown) according to the operating direction, and sends the frequency control data corresponding to the increased or decreased operating frequency F to the PLL circuit 5. By setting, the tuning frequency of the receiving means 8A is changed to match the receiving frequency desired by the user.

In this state, if an FM modulated wave (voice) is received by the receiving means 8A, it is converted into an intermediate frequency signal and output. The intermediate frequency signal is A / D converted by the A / D converter 31 and then input to the FM detection circuit 10 having a high degree of AM suppression and subjected to FM detection. Then, D / A converter 36 outputs D
/ A conversion, amplified by the AF amplifier 23, and then acoustically converted by the speaker 24. Since the FM detection circuit 10 has a high AM suppression degree, no distortion occurs in the audio output even if the amplitude of the intermediate frequency signal fluctuates due to fading or noise.

(2) FM of RZ-SSB modulated wave (voice)
When the RZ-SSB modulated wave (voice) is to be received without the influence of fading, the key 52 is pressed. Then, the system controller 60 switches SW1 to the a side and SW2 to the b side, and energizes the equalizing means 22 to bring it into the operating state. When the user operates the tuning knob 51, the system controller 6
0 increases or decreases the operating frequency F managed by the built-in memory according to the operation direction, sets frequency control data corresponding to the increased or decreased operating frequency F in the PLL circuit 5, and sets the receiving means 8A
Is tuned to a desired reception frequency by the user.

In this state, the receiving means 8A uses the RZ-SS
When a B-modulated wave (voice) is received, it is converted into an intermediate frequency signal and output. The intermediate frequency signal is A / D-converted by the A / D converter 31, and then the FM detection circuit 1 having a high AM suppression degree
The signal is input to 0 for FM detection, and then input to the equalizing means 22 to remove distortion. Then, it is D / A converted by the D / A converter 36, amplified by the AF amplifier 23, and then acoustically converted by the speaker 24. RZ-SSB modulated wave is FM
Since the signal is detected, it is possible to listen to a sound which is not affected by fading.

(3) AM of RZ-SSB modulated wave (voice)
Detection When the user wants to listen to the RZ-SSB modulated wave (voice) at a high S / N, or when the FM detection is buried in noise and cannot hear the voice due to weak input, the key 53 is pressed. Then, the system controller 60 switches SW2 to the c-side and SW3 to the b-side, and stops power supply to the equalizing means 22 to stop the operation, thereby saving power. In this state, R
When the Z-SSB modulated wave (voice) is received, the intermediate frequency signal A / D converted by the A / D converter 31 is input to the AM detector 40. Then, in the auto notch circuit 41, R
The carrier component in the Z-SSB modulated wave is removed, and the product detection circuit 42 detects the product. The demodulated signal after product detection is D / A converted by a D / A converter 36, amplified by an AF amplifier 23, and then acoustically converted by a speaker 24. Since the RZ-SSB modulated wave is subjected to AM detection, it is possible to listen to a sound having a good S / N.

Here, in order to perform product detection without distortion, it is desirable that the frequency of the carrier wave of the RZ-SSB modulated wave seen from the intermediate frequency signal is f ₀ . The auto notch circuit 41 adaptively changes the filter characteristics of the notch filter according to the frequency fluctuation of the carrier wave component in the RZ-SSB modulated wave, and updates the system controller 60 every time the W that determines the filter characteristics is updated. Outputting value. The system controller 60 transmits the RZ-SSB modulated wave (voice,
In the reception mode in the AM detection of FSK), while the user is not operating the tuning knob 51, the RZ viewed from the intermediate frequency signal from the equation (3) using W input from the auto notch circuit 41 is periodically used. calculating a carrier frequency f ₁ of -SSB modulated wave set by operating the shift amount Δf (= f ₁ -f ₀₎ a user tuning knob 51 from RZ-SSB frequency value f ₀ of the optimal operating point for the modulation wave The corrected operating frequency F 'is obtained by subtracting from the desired operating frequency F, and the frequency control data corresponding to F' is set in the PLL circuit 5 to correct the tuning frequency of the receiving means 8A. As a result, the receiver operates at the optimum operation point, and an audio output with small distortion can be obtained.

In addition, instead of subtracting Δf (= f ₁ −f ₀ ) from F, when Δf is plus, a constant value f _C (>
0. For example, the corrected operation frequency F ′ may be obtained by subtracting +100 Hz, +50 Hz, etc., and adding a constant value f _C (> 0, eg, +100 Hz, +50 Hz, etc.) when Δf is negative. The tuning control of the tuning frequency is performed while the user does not operate the tuning knob 51 in the reception mode in the FM detection of the RZ-SSB modulated wave (voice) or / and the reception of the FM modulated wave. Is also good.

(4) A of RZ-SSB modulated wave (FSK)
Press the key 54 to receive the RZ-SSB modulated wave of the FSK signal. Then, the system controller 60 sets S
W3 is switched to the b side, and the energization of the equalizing means 22 is stopped to bring it into a stopped state. In this state, R
When the Z-SSB modulated wave (FSK) is received, the intermediate frequency signal A / D converted by the A / D converter 31 is input to the AM detector 40. Then, the carrier component in the RZ-SSB modulated wave is removed by the auto notch circuit 41, and the product detection is performed by the product detection circuit 42. The FSK signal after product detection is demodulated to “1” and “0” by the FSK demodulation circuit 46 and input to the teletype 47. The teletype 47 prints out according to the input data.

Since the FSK signal is resistant to fading, it is not necessary to perform FM detection, and power can be saved by stopping the equalizing means 22. Further, since the system controller 60 corrects the tuning frequency of the receiving means 8A using W input from the auto notch circuit 41 and optimizes the operating point, the demodulation error of the FSK signal is reduced.

(5) AM of SSB-SC modulated wave (voice)
Detection 5 To listen to the SSB-SC modulated wave (voice), press key 5.
Press 5. Then, the system controller 60 switches SW2
Is switched to the c side, and SW3 is switched to the a side. The power supply to the equalizing means 22 is stopped to stop the equalization means 22, thereby saving power. In this state, the SSB-SC modulated wave (voice) is received by the receiving means 8A.
Is received, the intermediate frequency signal A / D converted by the A / D converter 31 is input to the AM detector 40. Then, product detection is performed by the product detection circuit 42. The demodulated signal after product detection is D / A converted by a D / A converter 36, amplified by an AF amplifier 23, and then acoustically converted by a speaker 24. Therefore, it is possible to listen to a sound having a good S / N received by the SSB-SC. In addition, SSB
In the receiving mode of the SC modulation wave (voice), the system controller 60 does not perform the tuning control of the tuning frequency.

According to the above embodiment, the demodulation of the RZ-SSB modulated wave can be performed without using a limiter, so that the configuration of the receiver can be simplified. In particular, when the FM detection circuit 10 is configured using a digital signal processing circuit, it is not necessary to consider the influence of aliasing distortion due to intermodulation distortion in the limiter, so that the digital signal processing circuit does not have to be an expensive high-speed operation type. In addition, it is not necessary to increase the stop band attenuation of the anti-aliasing analog filter used in combination with the A / D converter 31 at a stage prior to the FM detection circuit 10. Also, the FM detection circuit 10
Performs the TAN- ¹ type detection in the digital domain, so that the AM suppression degree in the FM detection circuit 10 can be extremely increased, and the FM modulation wave or the RZ-SSB modulation wave
The distortion of the demodulated signal at the time of detection is reduced.

Further, the demodulation of the RZ-SSB modulated wave can be performed by both the FM detection system and the AM detection system. When the reception electric field strength is good or when a high S / N is not required, the RZ-SSB modulation wave can be demodulated. By performing FM detection on the modulated wave, reception that is strong against fading can be performed. When the received electric field strength deteriorates, when high S / N is required, or when the modulated signal is an FSK signal that is not easily affected by fading. By performing AM detection of the RZ-SSB modulated wave, reception at a high S / N can be performed, and the equalizer 22 can be stopped to save power.

In addition, RZ-SSB modulated wave or SSB-
Since the product detection is performed at the time of AM detection of the SC modulation wave, AM detection can be performed without distortion. In addition, when receiving an RZ-SSB modulated wave, the carrier frequency in the intermediate frequency signal is detected and the tuning frequency is corrected so as to eliminate the deviation from the optimum value, so that the operating point of the receiver is automatically optimized. As a result, the distortion of the demodulated signal is reduced. In addition, since the detection of the carrier frequency in the intermediate frequency signal is performed by the auto notch circuit 41 for suppressing the carrier wave, there is no need to provide a special circuit for frequency detection.

In the above embodiment, the FM detection circuit 10 performs TAN- ¹ type detection, but another detector having a sufficiently high AM suppression degree may be used. For example, A
Quadrature digital FM with M suppression function
Demodulator (Minoru Takahashi "Digital FM Demodulator with AM Suppression Function" Proceedings of the 1989 National Convention of the Institute of Television Engineers of Japan 10-3,205
Pp. 206-206). Further, the receiver may be capable of receiving even when the FM modulated wave is pre-emphasized on the transmission side. In this case, the receiver includes the components from the FM detection circuit 10 to the D / A converter 36 in FIG.
The configuration is changed as shown in (1), a d terminal is newly provided in the switch SW2, and the output side of the FM detection circuit 10 is connected to the d terminal of the switch SW2 via the integrator 61.
Then, when receiving the FM modulated wave pre-emphasized on the transmission side, the switch SW2 is switched to the d terminal, the power supply to the equalizing means 22 is stopped, and the output of the FM detection circuit 10 is de-emphasized by the integrator 61. When the FM modulated wave that is not pre-emphasized on the transmission side is received, the switch SW2 is switched to the terminal a, the power supply to the equalizing means 22 is stopped, and the output of the FM detection circuit 10 is output. To the D / A converter 36 as it is.

Alternatively, the de-emphasis is performed by the equalizing means 22.
In this case, the configuration from the FM detection circuit 10 to the D / A converter 36 in FIG. 1 is changed to a configuration as shown in FIG. 4B, and a new d terminal is provided in the switch SW2. Is connected to the output side of the integrator 11.
When receiving the FM modulated wave pre-emphasized on the transmitting side,
The switch SW1 is switched to the a-side and the switch SW2 is switched to the d-side. At the same time, only the linearizer 12 of the equalizing means 22 is de-energized, and the integrator 11 is energized. D after emphasis
/ A converter 36. When receiving an FM modulated wave that is not pre-emphasized on the transmitting side, switch SW
2 is switched to the a side, and the power supply to the entire equalizing means 22 is stopped.

Further, except for the case where the RZ-SSB modulated wave is detected by FM detection and the case where the FM modulated wave is received, the FM
The operation of the detection circuit 10 may be stopped. Conversely, the operation of the AM detection means 40 is stopped when the RZ-SSB modulated wave is detected by FM detection and when the FM modulated wave is received. You may do it.

Also, the auto notch circuit 41 in the AM detection means 40 in FIG. 1 is omitted, and the product detection circuit 42 is replaced with a synchronous detection circuit as shown in FIG. The AM detection of the SSB modulated wave may be performed by synchronous detection. The synchronous detection circuit 70 shown in FIG. 5 is for performing synchronous detection in the digital domain, and the R detection signal input from the A / D converter 31 in FIG.
The carrier component C is extracted from the Z-SSB modulated wave by the BPF 71, and the PLL circuit 72 creates a synchronous carrier C 'synchronized with the frequency and phase of the carrier component C. RZ
The −SSB modulated wave and the synchronous carrier C ′ are mixed by the mixer 73 to extract the difference frequency component, and then the unnecessary component is removed by the LPF 74. LPF74 to RZ-S
The demodulated signal of the SB modulated wave is output to c of SW2 in FIG. By using the synchronous detection circuit 70, the receiving means 8A
When the M-modulated wave can be received, the demodulated output of the AM-modulated wave is also possible. When receiving the RZ-SSB modulated wave or the AM modulated wave and performing synchronous detection, it is preferable to stop power supply to the FM detection circuit 10 and the equalizing means 22 to stop the operation and save power.

Also, the auto notch circuit 41 in the AM detection means 40 in FIG. 1 is omitted, and the product detection circuit 42 is replaced with an envelope detection circuit as shown in FIG. SS
The AM detection of the B modulated wave may be performed by envelope detection. The envelope detection circuit 80 shown in FIG. 6 performs envelope detection in the digital domain.
The Hilbert filter 8 of the Hilbert converter 81 is based on the RZ-SSB modulated wave input from the A / D converter 31 of FIG.
2, a U whose phase is delayed by 90 ° is generated, and a delay unit 83 generates a V in which the input RZ-SSB modulated wave is delayed by a fixed time (delay by the Hilbert filter 82). When viewed on the basis of the phase of V, the phase of U is delayed by 90 °. Then, (U ² + V ² ) ^1/2 is obtained by the multipliers 84 and 85, the adder 86, and the square root calculator 87, and the envelope component of the RZ-SSB modulated wave is created. Then, after the unnecessary components are removed by the LPF 88, the unnecessary components are guided to b of SW1 and c of SW2 in FIG.

By using the envelope detection circuit 80, if the receiving means 8A can also receive an AM modulated wave, A
Demodulation output of M modulated waves is also possible. However, RZ-SSB
When receiving a modulated wave and performing envelope detection, distortion remains in the detection output, so switch SW1 and SW2 to the b side,
What is necessary is just to input the envelope detection output to the equalizing means 22 and operate the equalizing means 22 to remove distortion. R
When the Z-SSB modulated wave is received and envelope detection is performed, power supply to the FM detection circuit 10 is stopped to stop the operation, thereby saving power. When the AM modulated wave is detected by the envelope detection, no distortion occurs in the detection output, so that SW2 is switched to the c side to convert the envelope detection output to the D / A converter 36.
Input. At this time, it is preferable to stop the power supply to the FM detection circuit 10 and the equalizing means 22 to stop the operation, thereby saving power.

[0051]

According to the present invention, a receiving means for receiving an RZ-SSB modulated wave transmitted at a desired frequency and converting it into an intermediate frequency signal, and an amplitude limiting means for converting the intermediate frequency signal output from the receiving means into an amplitude limiting means. FM detection means with high AM suppression, which inputs without passing through and performs FM detection, and RZ-SS with FM detection means
Equipped with an equalizing means for removing distortion in the output of the FM detection of the B modulated wave, so that the RZ-SS
Demodulation of the B-modulated wave becomes possible, and the configuration of the receiver can be simplified. In particular, when the FM detection means is configured using a digital signal processing circuit, it is not necessary to consider the effects of aliasing distortion due to intermodulation distortion in the limiter, so that the digital signal processing circuit does not have to be an expensive high-speed operation type. In addition, it is not necessary to increase the stop band attenuation of the anti-aliasing analog filter used in combination with the A / D converter before the FM detection means.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a multi-mode receiver according to one embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of an FM detection circuit in FIG.

FIG. 3 is a circuit diagram equivalently showing a function of an auto notch circuit in FIG. 1;

FIG. 4 is a partially omitted circuit diagram of a multimode receiver according to an embodiment obtained by modifying FIG. 1;

FIG. 5 is a circuit diagram showing another embodiment of the AM detection means in FIG. 1;

FIG. 6 is a circuit diagram showing another embodiment of the AM detection means in FIG. 1;

FIG. 7 is a circuit diagram of a conventional RZ-SSB receiver.

FIG. 8 is a circuit diagram showing a specific configuration of the linearizer in FIG. 7;

[Explanation of symbols]

8A Receiving means 10 FM detecting circuit 11, 61 Integrator 12 Linearizer 22 Equalizing means 23 AF amplifier 24 Speaker 31 A / D converter 34 Hilbert converter 35 TAN- ¹ type phase detector 36 D / A converter 40 AM detection Means 41 Auto notch circuit 42 Product detection circuit 46 FSK demodulation circuit 47 Teletype 50 Operation panel 60 System controller 70 Synchronous detection circuit 80 Envelope detection circuit SW1, SW2, SW3 Switch

Claims (12)

[Claims] 1. A receiving means for receiving an RZ-SSB modulated wave transmitted at a desired frequency and converting it into an intermediate frequency signal, and inputting the intermediate frequency signal output from the receiving means without passing through an amplitude limiting means, FM with high AM suppression performing FM detection
A receiver comprising: a detection unit; and an equalization unit that removes distortion in an output obtained by FM-detecting the RZ-SSB modulated wave by the FM detection unit. 2. The FM detector has a TA in a digital domain.
The receiver according to claim 1, wherein N- ¹ type detection is performed. 3. An intermediate frequency signal output from a receiving means, which performs AM detection on an RZ-SSB modulated wave.
The receiver according to claim 1, further comprising: M detection means; and switching means for switching and outputting the output of the equalization means and the output of the AM detection means. 4. The receiver according to claim 3, wherein the operation of at least one of the equalizer and the FM detector is stopped while the switch is switched to the AM detector. . 5. An AM detector comprising: a carrier suppressor for suppressing a carrier component in an RZ-SSB modulated wave; and a product for inputting the RZ-SSB modulated wave after suppressing the carrier by the carrier suppressor and performing product detection. The receiver according to claim 3, further comprising: detection means. 6. The receiving means receives the RZ-SSB modulated wave and the SS
B-SC modulated waves can be received, and AM detection means is provided with switching means for switching the input side of the product detection means between the output side of the carrier suppression means and the output side of the reception means. The receiver according to claim 5, wherein 7. An AM detector which receives an intermediate frequency signal output from a receiver and performs envelope detection on an RZ-SSB modulated wave, and an equalizer which switches between an output of the FM detector and an output of the AM detector. 2. The receiver according to claim 1, further comprising: switching means for outputting the signal to the receiver. 8. The receiving means is capable of receiving an RZ-SSB modulated wave and an FM modulated wave, and has a switching means for outputting the output of the FM detecting means to a subsequent stage without passing the output of the FM detecting means to the equalizing means when receiving the FM modulated wave. The receiver according to claim 1, wherein the receiver is provided. 9. The receiving means is capable of receiving an RZ-SSB modulated wave and an FM modulated wave. When receiving the FM modulated wave, the receiving means performs de-emphasis on the output of the FM detecting means. 2. The receiver according to claim 1, further comprising: switching means for outputting an output of the de-emphasis means to a subsequent stage instead of the output. 10. The equalizing means includes an integrating means for integrating the output of the FM detecting means, and a linearizer means for removing a distortion remaining in the output of the integrating means when receiving the RZ-SSB modulated wave by performing a predetermined arithmetic processing. 10. The receiver according to claim 9, wherein the de-emphasis means is also used as an integration means of the equalization means. 11. A carrier frequency detecting means for detecting a frequency of a carrier wave in a received wave, and a control means for performing correction control of a tuning frequency for the receiving means based on the carrier frequency detected by the carrier frequency detecting means. The receiver according to claim 1, 3, 5, or 6. 12. The carrier suppression means is an auto notch filter which suppresses a carrier component while following a frequency change of an RZ-SSB modulated wave, and controls a tuning frequency of a receiving means based on a notch frequency in the auto notch filter. The receiver according to claim 5, further comprising control means for performing the control.