JP3150104B2 - Modulator and transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modulator and a transmitter suitable for a microwave digital communication apparatus and the like, and more particularly to a modulator and a modulator which do not cause interference or the like in adjacent channels due to unstable transmission of a modulation output signal or a transmission signal. And a transmitter.

[0002]

2. Description of the Related Art A conventional modulator and transmitter of this type have an unstable circuit operation when power is supplied to these devices, and a modulation output signal or a transmission signal has an excessive output and a modulation distortion exceeding a specified value. Due to an increase or the like, there is a possibility that interference and disturbance to adjacent channels may occur. Therefore, in the conventional modulator and transmitter, a narrow band filter is mounted on the output side of the transmitter to prevent adjacent channel interference from occurring.

[0003]

As described above, in the conventional modulator and transmitter, a narrow band filter is mounted on the output side of the transmitter to prevent adjacent channel interference from occurring. There is a disadvantage that the circuit becomes expensive due to an increase in circuit scale.

Accordingly, it is an object of the present invention to provide a modulator and a transmitter which can solve the above-mentioned disadvantages of the prior art and can prevent adjacent channel interference immediately after power-on with a simple configuration.

[0005]

[0006]

[0007]

[0008]

[0009]

[0010]

SUMMARY OF THE INVENTION A modulator according to the present invention comprises:
A modulator that multiplies the carrier signal by the transmission data to generate a modulation output, and a modulator that includes a level stabilization circuit that stabilizes and controls the modulation output to a predetermined output modulation output signal by negative feedback control. A stabilizing circuit that outputs alarm information when the level of the modulated output signal is outside a specified value, outputs the alarm release information when the level is within a specified value, and outputs a predetermined time after receiving the alarm information. is e Bei alarm time multiplier stop means for outputting a non-modulated signal to stop the multiplication by the multiplier, prior Symbol multipliers, transmission data 2 sequence is respectively converted into an analog signal by a digital / analog converter A four-phase PSK modulator for performing four-phase PSK modulation on the transmission data, wherein the alarm period multiplication stopping means is provided before each of the digital / analog converters. And the alarm information and the alarm release information output from the level stabilizing circuit are delayed by the predetermined time. If the delayed signal is the alarm information, the AND gate is turned off. And a time constant circuit for turning on the AND gate when the delayed signal is the alarm release information.

[0011]

[0012] The onset transmitter by Ming, and a transmitter for ALC amplified after which up-converts the modulated output signal from the modulator and the modulator.

The modulator and the transmitter according to the present invention are suitable for use in digital microwave communication devices using n-ary quadrature amplitude modulation or PSK modulation. A level stabilizing circuit for stabilizing and controlling the modulation output to a modulation output signal of a predetermined output by negative feedback control amplification is connected to a stage subsequent to the modulator.
In the subsequent stage, a transmitter constituting an ALC amplifier circuit is usually connected, and the whole constitutes a transmitter. When the power of the transmitter is turned on, each component, particularly a component having an active element, is in an unstable transient state, and an ALC (Automatic Level C) for controlling the output level of the transmitter is used.
(control) The output level control voltage of the control circuit becomes indefinite for a certain time.

Therefore, a phenomenon occurs in which the level of the transmission signal output from the transmitter, that is, the transmitter, becomes higher than a specified transmission output level. In this case, the transmission signal output from the transmitter causes modulation distortion, and the side lobe of the transmission signal rises, and the band (spectrum) of the transmission signal expands, thereby causing interference with the signal wave of the adjacent channel. Becomes

[0015] The modulator of the present invention causes the modulator and the transmitter to output an unmodulated wave signal for a predetermined time longer than the time when the output level control voltage of the transmitter becomes indefinite, and adjusts the band of the transmission signal. By narrowing, the interference with the signal band of the adjacent channel is eliminated.

[0016]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 1 shows a transmitter including a modulator 10 and a transmitter 20. This transmitter often forms a major part of the wireless device, including the receiver and the controller.

First, the steady operation of the transmitter shown in FIG. 1 will be described. Four-phase PSK modulator (4Phase S
The modulator 10, which is a high keying modulator, has two columns of digital signals and transmission data Da.
And Db are input. Note that the suffixes a and b of the code indicate that they are the a channel and the b channel, respectively. The transmission data Da and Db are input to corresponding DA (digital / analog) converters 1a and 1b, respectively. The transmission data Da and Db are DA
The data is converted into analog signals by the converters 1a and 1b to become transmission data Aa and Ab, and supplied to one of the signal input terminals of the switches (SW) 3a and 3b, respectively. The switches 3a and 3b are controlled by the time constant circuit 7 to switch the signal input terminal in addition to the transmission data Aa and Ab, as described later. In the steady state, the transmission data Aa and Ab are supplied to the transmission data input terminals of the multiplier 4, respectively.

The multiplier 4 performs two quadrature amplitude modulations on the transmission data Aa and Ab, respectively. For example, two multiplier circuits using a balanced mixer, and π /
A carrier signal oscillator for supplying a carrier signal with two phase differences;
A combiner that combines a result of multiplication of the transmission data Aa with the carrier signal and a result of multiplication of the transmission data Ab and the carrier signal having a π / 2 phase difference to generate a modulation output S1 that is a four-phase PSK wave; For example, a hybrid circuit is included. During a steady operation, the modulation output S1 has a specified frequency (the center frequency is the frequency of the carrier signal) and a specified output level.

The modulation output S1 is a variable gain amplifier (AM).
P) 5. The amplifier 5 constitutes an amplification circuit and a level stabilization circuit for the modulation output S1 together with the level detection circuit 6, amplifies the modulation output S1 to a specified (predetermined) level, and generates a level-stabilized modulation output signal S2. That is, the level detection circuit 6 outputs the modulated output signal S
2 is detected, a signal corresponding to the detected level is supplied to the gain control terminal of the amplifier 5, and the gain of the amplifier 5 is subjected to negative feedback control. When the level of the detected modulated output signal S2 is lower than a predetermined level, the level detection circuit 6 outputs ALM information S5. The ALM information S5 is used for monitoring the operation failure of the modulator 10, and the like.

The modulated output signal S2 is supplied to a signal input terminal of the multiplier 9 in the transmitter 20. The multiplier 9 includes a local oscillation signal Lo from a local oscillator 13 including a microwave direct oscillator stabilized by a dielectric resonator and a modulation output signal S2.
Is multiplied (up-converted) and the upper band is taken out as a high frequency signal S3. The high frequency signal S3 is supplied to a signal input terminal of a variable gain amplifier (AMP) 11. The amplifier 11 forms an amplification circuit and an ALC circuit for the high frequency signal S3 together with the ALC control circuit 12, amplifies the high frequency signal S3 to a specified (predetermined) level, and generates a level stabilized transmission signal S4. That is, the ALC control circuit 12 detects the level of the transmission signal S4 and supplies a signal corresponding to the detected level to the gain control terminal of the amplifier 11,
The gain of the amplifier 11 is controlled by negative feedback.

According to the above-described operation, the level and frequency (spectrum) of the modulated output signal S2 and the transmission signal S4 are within the specified range during normal operation, and the modulator 10 and the transmitter 2
In both cases, the modulation output signal S2 and the transmission signal S4 that do not cause adjacent channel interference are transmitted.

Next, the operation of the transmitter shown in FIG. 1 when the power is turned on will be described. The modulator 10 of the transmitter includes a PS information input circuit 8,
It includes a time constant circuit 7, switches 3a and 3b, and DC voltage setting circuits (DC) 2a and 2b.

The PS information input circuit 8 is connected to the modulator 10 by the control device and other components such as the amplifier 5.
And / or obtaining information on the presence or absence of power-on to the transmitter 20,
The presence / absence of the power-on is sent to the time constant circuit 7 with, for example, a logical value “1” and a logical value “0”. The time constant circuit 7 is a delay circuit, and a delay line or a CR time constant circuit can be used as an analog circuit, and a flip-flop circuit or a counter can be used as a digital circuit. The delay time of the time constant circuit 7 is set to a predetermined time longer than the time required for stabilizing all the components of the modulator 10 and the transmitter 20 after the power is turned on.

In this example, each of the switches 3a and 3b uses a switch having two signal input terminals and one signal output terminal. Each of the switches 3a and 3b receives transmission data Aa and Ab from one signal input terminal, and outputs a predetermined DC voltage including 0 V from the other signal input terminal from the DC voltage setting circuits 2a and 2b, respectively. input. The switching control of the switches 3a and 3b is performed by the output of the time constant circuit 7.

That is, the output of the time constant circuit 7 is a logical value "0".
In this case, since the predetermined time has not elapsed since the power was turned on, the switches 3a and 3b input a generally fixed DC voltage from the DC voltage setting circuits 2a and 2b. Then, only a DC voltage is supplied to the multiplier 4 instead of the transmission data Aa and Ab, so that the multiplier 4 outputs only the unmodulated signal (the carrier signal) as the modulation output S1. Immediately after the power is turned on, the modulator 10 is used because the level detection circuit 6 and the ALC control circuit 12 tend to maximize the amplifiers 5 and 11 because the circuit S is unstable and the output S1 and the signal S3 are not input. The modulation output signal S2 from the transmitter 20 and the transmission signal S4 from the transmitter 20 are excessively output, and this is a win. However, in the above circuit configuration,
Since the modulation output S1 and the transmission signal S4 are unmodulated signals and have only a narrow spectrum, the transmission signal S4 does not cause adjacent channel interference.

In order to convert the modulation output S1 and the transmission signal S4 into unmodulated signals, for example, the transmission data Aa and Ab need not be supplied to the multiplier 4. For this purpose, the switches 3a and 3b May be provided at the preceding stage of the DA converters 1a and 1b from the switches 3a and 3b provided here instead of the transmission data Da and Db to supply a DC voltage.

On the other hand, if the output of the time constant circuit 7 changes to the logical value "1" after the predetermined time has elapsed since the power was turned on,
The transmission data Aa is input to the signal input terminals of the switches 3a and 3b.
And Ab are provided, the transmitter of FIG. 1 returns to the steady state operation described above.

FIG. 2 is a block diagram showing another embodiment of the present invention. FIG. 2 shows only a modulator 10A similar to the modulator 10 and does not show the transmitter 20.

The modulator 10A of FIG. 2 is the same as the modulator 10 of FIG.
From the PS information input circuit 8, the switches 3a and 3b, and the DC voltage setting circuits (DC) 2a and 2b, and on the contrary, AND gates 14a and 14b are provided before the DA converters 1a and 1b.
Are provided. Transmission data Da and Db are AN
It is supplied to one input terminal of each of the D gates 14a and 14b. The transmission data Aa and Ab output from the DA converters 1a and 1b are directly supplied to the transmission data input terminals of the multiplier 4, respectively.

Here, when the level of the modulated output signal S2 detected from the output terminal of the amplifier 5 is outside the specified level, the level detection circuit 6 outputs ALM information S6 having a logical value "0", Is the logical value "1" of AL
It outputs M information (hereinafter, also referred to as ALM release information) S6. That is, the fact that the level of the modulation output signal S2 from the amplifier 5 is out of the specified value and generally becomes low immediately after the power of the modulator 10 is turned on. The ALM information S6 or the ALM release information S6 is supplied to the time constant circuit 7.

The output terminal of the time constant circuit 7 is an AND gate 1
ALM information S6 delayed by a predetermined time from the power-on is supplied to the other input terminals of 4a and 14b. That is, when the modulation output signal S2 is out of the specified level, the time constant circuit 7 outputs the ALM information S6 having the logical value “0” to the AN value.
The signals are output to the other input terminals of the D gates 14a and 14b, and the supply of the transmission data Da and Db to the DA converters 1a and 1b is stopped. Then, the transmission data A is stored in the multiplier 4.
Since a and Ab are not supplied, the modulation output S1 and the modulation output signal S2 are unmodulated signals and have only a narrow spectrum, so that even if the transmission signal S4 of the transmitter 20 has an excessive output, adjacent channel interference occurs. Never.

When the above-mentioned predetermined time during which each component of the modulator 10 stably operates has passed, the level detection circuit 6
Detects that the level is within the specified level from the unmodulated modulated output signal S2, and sends out the ALM release information S6 having the logical value "1". After receiving the ALM release information S6, the time constant circuit 7 sets the logic value “1” to A
The LM release information S6 is supplied to the other input terminal of the AND gates 14a and 14b, and the AND gates 14a and 14b
Converts the transmission data Da and Db into DA converters 1a and 1b
, The modulator 10 outputs a regulated output during steady operation and a modulated output signal S2 having a prescribed spectrum,
The transmitter 20 connected at the subsequent stage also outputs a transmission signal S4 having a specified output and a specified spectrum that does not cause adjacent channel interference.

[0033]

As described above, the modulator and the transmitter according to the present invention provide a multiplier for generating a modulation output by multiplying a carrier signal and transmission data, and a modulator for modulating a predetermined output by negative feedback control. A modulator provided with a level stabilizing circuit for stabilizing the output signal, for a predetermined time after power-on, or for a predetermined time thereafter when the level of the modulated output signal is outside a specified value. Further, the apparatus further comprises a multiplication stopping means for stopping the multiplication by the multiplier and outputting the unmodulated signal for a predetermined period, so that the transmission signal transmitted by the transmitter becomes excessively larger than a specified value when the power is turned on or during a transition period. Even in this case, since the modulator and the transmitter transmit an unmodulated signal, there is an effect of preventing transmission of a signal causing adjacent channel interference.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Modulator 20 Transmitter 1a, 1b DA converter 2a, 2b DC voltage setting circuit (DC) 3a, 3b Switching device (SW) 4, 9 Multiplier 5, 11 Amplifier (AMP) 6 Level detection circuit 7:00 Constant circuit 8 PS information input circuit 12 ALC control circuit 13 Local oscillator 14a, 14b AND gate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-77225 (JP, A) JP-A-4-23620 (JP, A) JP-A-4-133523 (JP, A) JP-A-9-99 275424 (JP, A) JP-A-8-88660 (JP, A) JP-A-3-76431 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/04 H03C 3 / 00 H04L 27/00-27/20

Claims (2)

(57) [Claims] 1. A multiplication of a carrier signal and transmission data to change the transmission signal.
A multiplier for generating a modulation output, and the modulation output for negative feedback control.
Therefore, the level at which stabilization control is performed to the modulated output signal of the predetermined output
And a stabilizing circuit, wherein the level stabilizing circuit adjusts the level of the modulated output signal.
Alarm information is output when the value is outside the specified value, and within the specified value
If it is, the alarm release information is output and the
The predetermined time after receiving the alarm information is a multiplier by the multiplier.
To the power of the alarm period to stop the calculation and output the unmodulated signal
Comprising a calculation stop means, the multiplier is a two series 4-phase PSK modulator for four-phase PSK modulation respectively converting said transmission data into analog signals transmitted data by a digital / analog converter, the alarm time Multiplication stopping means for delaying the alarm information and the alarm release information output from the level stabilizing circuit by the predetermined time, and an AND gate connected to the preceding stage of each of the digital / analog converters; And a time constant circuit for turning off the AND gate when the delayed signal is the alarm release information and turning off the AND gate when the delayed signal is the alarm release information. modulator that. Wherein the claim 1 Symbol placement modulator, after which the modulated output signal from the modulator upconverts AL
A transmitter comprising: a C-amplifying transmitter.