JP2855842B2 - Multi-carrier transmitter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a multicarrier transmitting apparatus used in a digital radio system using multicarriers, for example, when one or three carriers out of a transmission signal composed of three carriers are cut off A synthesis part for converting the frequency of a synthesized signal obtained by synthesizing a plurality of intermediate frequency band signals to be input, with the aim of maintaining the output levels of the remaining carriers as they are. A variable gain amplifying section for supplying and amplifying the converted synthesized signal with a gain corresponding to the input gain control signal and transmitting the amplified signal as a transmission signal;
When the transmission signal has a transmission detection portion that commonly detects the transmission signal and obtains a transmission detection output, when all of the composite signals are composed of intermediate-frequency band signals having a specified level, the composite output level of the transmission signal becomes a predetermined level. A gain control signal for setting the gain of the variable gain amplifying portion so as to have a value is transmitted. However, when the level of a part of the intermediate frequency band signal constituting the composite signal changes, the variable gain amplifying signal is transmitted. A gain control signal generating means for transmitting a gain control signal so that the portion can keep the set gain is added.

[Industrial applications]

The present invention relates to a transmission device used for a digital radio system using a multicarrier.

Digital wireless system using multi-carrier have different intermediate frequencies respectively, for example, three series intermediate frequency band signal 3 to frequency conversion (hereinafter, IF _1, IF _2, IF ₃ abbreviated as) a common transmission plate This is a system in which the signal is converted into a series of transmission signals, then amplified in common, and transmitted to a partner station at a predetermined frequency and power.

Although this system IF ₁ ~IF ₃ is transmitting each specific data, making it impossible to transmit all the data when a failure occurs in the transmission board. However, even if IF ₁ fails, IF ₂ and IF ₃
Data can be transmitted, and IFs can be added one by one.

In addition, the transmitter uses an automatic level control (ALC) circuit to ensure that the combined output level of the three series of transmission signals is always a predetermined value.
Although it is set to be P ₀ , for example, if IF ₁ is cut off, I
Combined output level with two series of transmission signals corresponding to F ₂ and IF ₃
And transmits the P _0, the individual output levels of the two transmission signals is higher than a specified value.

Therefore, among the transmission signals constituted by three carriers with IF ₁ ～IF _3, that one or two carriers when they become cross, subsequently the output level of the remaining carriers, to as to hold the raw values is necessary.

[Conventional technology]

FIG. 6 is a block diagram of a conventional example, and FIG. 7 is an explanatory view of a problem of the conventional example. Hereinafter, the operation of FIG. 6 will be described assuming that the number of carriers, that is, the number of streams is 3.

First, the intermediate frequency band signals IF _{1 to} IF _{3 of} , for example, a 140 MHz band are synthesized by the synthesizer 11 and then applied to the frequency converter 12. Here, since the output of the transmission local oscillator 16 is also added, a microwave band (for example, 6G
The signal is frequency-converted into a synthesized signal in a frequency band (Hz wave band) and applied to a high-output amplifier with variable gain (hereinafter abbreviated as AGC high-output amplifier) 19.

Therefore, the composite signal in the microwave band is amplified by the amplifier 13 and then further amplified by the power amplifier 15 via the variable attenuator 14 and transmitted to the other party as a transmission signal.

In this case, after a portion of the transmission signal that is commonly detected by transmission detector 18, the detected voltage is compared with a threshold value corresponding to the specified output level P ₀ in the gain control signal generator 17. Then, a gain control signal corresponding to the comparison result is generated, and AG
AGC, because it is added to the variable attenuator 14 in the high power amplifier
Transmission signal output level P ₀ is sent from the high power amplifier.

Here, the variable attenuator 14, the power amplifier 15, the transmission detection part 1
8, the path through the gain control signal generator 17 and the variable attenuator 14 is ALC
It is a circuit.

Incidentally, when the output level due to deterioration of the AGC high-output amplifier 19 becomes lower than P _0, the gain control signal such as to compensate for this decrease is sent from the gain control signal generator 17 to the variable attenuator 14, AGC high the output level of the output amplifier is maintained at P _0.

[Problems to be solved by the invention]

As described above, in the multicarrier transmission apparatus using ALC circuit, always combined output level of the transmission signal and controls the gain of the AGC high power amplifier so as to become P _0.

That is, FIG. 7 - As shown in, # 1 transmission signal of the transmission signal output P ₁ sent from the AGC high power amplifier, # 2 transmission signal output P _2, # consists of three transmission signals output P ₃ It is assumed that it is. If P ₁ = P ₂ = P ₃ and the combined output level is P ₀ , the output level of each transmission signal is (P _0/3 ),
(P ₀ −4.8) dB. That is, the output level of each transmission signal is a value that is 4.8 dB lower than the combined output level.

Here, FIG. 7 - As shown in, the # 3 transmission signal is to become cross, since the combined output level # 1 transmit signal and the # 2 transmission signal must be P _0, the output of each transmission signal level _{(P 0/2) → (} P 0 -3) dB , and the relative when the transmission signal is of 3 series + 1.8 dB higher.

Further, FIG. 7 - As shown in, the # 2 transmission signal and the # 3 transmission signal is intercepted, since the only composite output level # 1 transmission signal must be P _0, when the transmission signal is of 3 series + 3dB higher than.

In other words, when the number of transmission signal sequences is 3, 2, 1,
Looking at the change in the output level of the # 1 transmission signal, when the number of sequences is 2, the output is +1.8 dB, and when the number of sequences is 1, the output level is +4.8 dB. There is a problem that the output level becomes higher than the output level.

An object of the present invention is, for example, when one or two carriers out of a transmission signal composed of three carriers are interrupted, the output levels of the remaining carriers can be maintained as they are. I do.

[Means for solving the problem]

FIG. 1 is a block diagram showing the principle of the first invention, and FIG.
1 shows a principle block diagram of the present invention.

In the drawing, reference numeral 2 denotes a combining unit for frequency-converting a combined signal obtained by combining a plurality of input intermediate frequency band signals, and reference numeral 3 denotes a frequency-combined combined signal having a gain corresponding to an input gain control signal. A variable gain amplifying section for amplifying and transmitting the transmission signal as a transmission signal. Reference numeral 4 denotes a transmission detection section for performing common detection on the transmission signal to obtain a transmission detection output.

Reference numeral 5 denotes a gain control signal for setting the gain of the variable gain amplifying portion so that the combined output level of the transmission signal becomes a predetermined value when the combined signals are all composed of intermediate frequency band signals of a specified level. The variable gain amplifier transmits a gain control signal such that the variable gain amplifier can continue to maintain the set gain when the level of a part of the intermediate frequency signal constituting the composite signal changes. It is a control signal generation means.

Furthermore, when the common detection of the synthesized signal composed of the intermediate frequency band signals of all the specified levels is performed, the reference synthetic detection output is transmitted, and the synthesized signal including the intermediate frequency band signal that does not reach the specified level is commonly detected. The time is a combined detection portion for transmitting the corresponding combined detection output. 52 is a first reference value that is generated and transmitted when the reference combined detection output is input, and the combined detection output is input. Time is the first reference value,
A reference value generation section for generating and sending a second reference value in which a value corresponding to a change between the reference combined detection output and the combined detection output is superimposed.

Further, 53 uses a first difference obtained by taking a difference between an input transmission detection signal and the first reference value when the first reference value is transmitted from the reference value generation portion. Generating a gain control signal for setting the gain of the variable gain amplifying part so that the transmission detection output becomes a predetermined value, wherein when the second reference value is transmitted, the change is more than the first difference; A gain control signal generating unit that generates a gain control signal that allows the variable gain amplifying unit to continuously maintain the set gain by using the second difference that is lower by a value corresponding to the minute.

[Action]

First, in FIG. 1, a plurality of series, for example, three series of intermediate frequency band signals to be input in the combining / frequency converting section are combined, then the frequency is converted and transmitted to the variable gain amplifying section. The variable gain control amplifying section commonly amplifies the frequency-converted synthesized signal with a gain corresponding to the input gain control signal and sends it out as a transmission signal. The transmission detection section performs common detection on a part of this transmission signal and transmits it. Extract the detection signal.

Now, the combined signal from the combining portion and the transmission detection signal from the transmission detection portion are input to the gain control signal generation means provided in the present invention.

The gain control signal generator sends out a gain control signal such that the transmission detection output becomes a predetermined value when the levels of the three series of intermediate frequency band signals constituting the composite signal are all at specified values. Becomes G.

Thereafter, when the gain control signal generating means recognizes that one or two series of intermediate frequency band signals among the three series of intermediate frequency band signals have been cut off, the variable gain amplifying portion continues to adjust the gain G. A gain control signal that can be held is generated and transmitted.

Next, according to a second aspect of the present invention, the gain control signal generation means is composed of a composite detection section, a reference value generation section, and a gain control signal generation section as shown in FIG. 2, which perform the following operations. To generate a desired gain control signal.

The combined detection section sends out a reference combined detection output when the input combined signals are all composed of intermediate frequency band signals of a specified level, but sends out a corresponding combined detection output when the input signal is not configured as described above.

Also, the reference value generation part uses the first reference value when the reference combined detection output is input, and the second reference value obtained by superimposing the value corresponding to the change on the first reference value when the combined detection output is used. It is generated and sent to the gain control signal generation part.

Therefore, the gain control signal generation part uses the first difference obtained by taking the difference from the transmission detection output when the first reference value is applied, so that the gain of the variable gain amplification part becomes G. When the second reference value is applied, the variable gain amplifier uses the second difference to generate and transmit a control signal that allows the variable gain amplifying section to keep the gain G.

Thus, for example, when one or two carriers out of a transmission signal composed of three carriers are cut off, the output levels of the remaining carriers can be maintained as they are.

〔Example〕

FIG. 3 is a block diagram of the first and second embodiments of the present invention, FIG. 4 is a schematic circuit diagram of a main part of FIG. 3, and FIGS.
The operation | movement explanatory drawing of a figure is shown.

Here, a synthesizer 21, a frequency converter 22, a transmission local oscillator 23
Is a constituent part of the combining part 2, an amplifier 31, a variable attenuator 32, and a power amplifier 33 are constituent parts of the variable gain amplifying part 3, a transmission detector.
41 is a component of the transmission detection part 4.

The amplifier A ₁ , the diodes D ₁ and D ₂ , the resistor R ₇ , and the capacitor C are components of the composite detection unit 51, and the amplifiers A ₃ , resistors R ₈ and R ₉ are components of the reference value generation unit 52, and the amplifier A _2, A _4, A _5, resistors R ₁
To R _6, the variable resistor R _V represents a component of the gain control signal generating portion 53.

Hereinafter, the intermediate frequency band signal is divided into three series as shown in FIGS.
The operation of FIG. 3 will be described with reference to FIG.

First, the synthesizer 21 generates a synthesized signal by synthesizing three series of intermediate frequency band signals IF ₁ , IF ₂ , IF ₃ each having a specified level, and combines the synthesized signal with the frequency converter 22 and the synthesized detection section 51. To send to. The frequency converter 22 uses the output of the transmitting local oscillator 23 to perform frequency conversion to a synthesized signal in the microwave band, and then passes through an AGC high-power amplifier composed of an amplifier 31, a variable attenuator 32, and a power amplifier 33. Send to the other party.

The combined detection section 51 converts the input combined signal into an amplifier A ₁
After that, a composite detection output corresponding to the average voltage of the composite signal (hereinafter referred to as a reference composite detection output) is extracted using the diodes D ₁ and D _{2, the} resistor R ₇ , and the capacitor C.

This reference synthesis detection output the output voltage of the resistor R _8, R ₉ V ₀ as shown in FIG. 5 is amplified by the amplifier A ₃ (b) having a gain defined by is obtained, this first added as a reference value of the amplifier a ₄ (+) terminal.

On the other hand, the transmission detector 41 is sent to an amplifier A ₂ having a transmission detection output obtained by detecting a portion of the composite output level sent from the power amplifier 33 a resistor R _1, R _2.

Amplifier A ₂ amplifies the resistor R _3, although delivered by R ₄ in the amplifier A ₄ the gain defined, here because it is applied a first reference value, the output corresponding to the difference amplifier It is added to the A _5. Therefore, since the amplifier A ₅ it is added to the third view of the variable attenuator 32 is amplified as a gain control signal to provide a corresponding attenuation to microwave synthesis signal passing therethrough.

Here, it is assumed that the combined output level of the transmission signal becomes P ₀ when the three series of center frequency band signals each having a specified level are combined and frequency-converted and amplified by an AGC high-output amplifier having a gain G.

In this case, FIG. 5 (a) - the output level of respective transmit signal as shown in the P _1, P _2, P ₃ is as above same, P ₀
-4.8 dB. Further, since the gain of the AGC high-output amplifier is G, the combined output level of the combined signal is P ₀ -G, and the output level of each intermediate frequency band signal is P ₀ -4.8-G.
The frequency conversion loss is assumed to be zero.

Next, as shown in FIG. 5 (a)-, when IF ₂ is cut off, if the combined output level of the transmission signal is P ₀ −1.8 dB,
The output levels of the transmission signals corresponding to IF ₁ and IF ₃ do not change. That is, the amount of attenuation of the variable attenuator 32 may be increased by 1.8 dB as compared with the case of three systems.

Therefore, the first reference value V ₀ as shown in FIG. 5 (b),
A voltage corresponding to the variation in the composite output level for were Na 2 series content, the amplifier output voltages V ₁ obtained by superposing a second reference value
And it sends it to the A _4. The difference between the transmission detection output which has passed through the amplifier second reference value in the A ₄ and the amplifier A ₂ is taken, the gain control signal such as to increase the only attenuation 1.8dB is further amplified by the amplifier A ₅ is variable attenuator Added to the vessel.

As a result, the combined output level of the transmission signal is P ₀ -1.8 dB
Therefore, the output level of each transmission signal is P ₀ −4.8 dB, which is the same as the case of the three series. The level of IF ₁ and IF ₃ is P ₀ −4.8−G, and the composite level of the composite signal is P ₀ −
1.8-G.

Furthermore, FIG. 5 (a) - although IF _2, IF ₃ as shown in the same as above even when the disconnection, the composite output level of the transmission signal 3
To reduce 4.8dB from the time of the series, the attenuation of the variable attenuator must be increased by 4.8dB.

Therefore, the reference value applied to the amplifier A ₄ as shown in FIG. 5 (b) is as high as V _2. As a result, the combined output level of the transmission signal becomes P ₀ -4.8 dB as shown in FIG.

When the transmission detection output changes without changing the reference value, the gain of the AGC high-output amplifier changes by ΔG so that the output level change of the transmission signal is compensated by the ALC circuit as in the conventional example.

Thus, for example, when one or two carriers out of a transmission signal composed of three carriers are cut off, the output levels of the remaining carriers can be maintained as they are.

〔The invention's effect〕

As described above in detail, according to the present invention, for example, 3
When one or two carriers out of the transmission signal composed of carriers are cut off, there is an effect that the output levels of the remaining carriers can be maintained as they are.

[Brief description of the drawings]

 FIG. 1 is a block diagram of the principle of the first invention, FIG. 2 is a block diagram of the principle of the second invention, FIG. 3 is a block diagram of an embodiment of the first and second inventions, FIG. 3 is a schematic circuit diagram of a main part of FIG. 3, FIG. 5 is an operation explanatory diagram of FIGS. 3 and 4, FIG. 6 is a block diagram of a conventional example, and FIG. . In the figure, 2 is a combining section, 3 is a variable gain amplifying section, 4 is a transmission detection section, and 5 is a gain control signal generating means.

Claims (2)

(57) [Claims] A synthesizing part for frequency-converting a synthesized signal obtained by synthesizing a plurality of series of intermediate frequency band signals to be input;
A variable gain amplifying part (3) for amplifying the frequency-converted synthesized signal in common with a gain corresponding to the input gain control signal and transmitting the signal as a transmission signal; and a transmission detection for obtaining a transmission detection output by performing common detection on the transmission signal (4) the variable gain amplifying section so that when all of the combined signals are composed of intermediate frequency band signals of a specified level, the combined output level of the transmission signal becomes a predetermined value. The gain control signal for setting the gain is transmitted, but when the level of a part of the signal in the intermediate frequency band signal constituting the composite signal changes, the variable gain amplifying section keeps the set gain. A multicarrier transmission apparatus characterized by adding a gain control signal generating means (5) for transmitting a gain control signal as possible. 2. When the control signal generating means performs common detection of a combined signal composed of all intermediate frequency band signals of a specified level, a reference synthesized detection output is sent out, and the intermediate frequency band signal not reaching the specified level is output. When the combined signal containing the common detection is sent, the combined detection part that sends out the corresponding combined detection output (51)
When the reference combined detection output is input, a predetermined first
When the combined detection output is input, a second value obtained by superimposing a value corresponding to a change between the reference combined detection output and the combined detection output on the first reference value is generated. A reference value generation part (52) for generating and sending the reference value of the first reference value;
Using the first difference obtained by taking the difference between the input transmission detection signal and the first reference value, the gain of the variable gain amplifier is set so that the transmission detection output becomes a predetermined value. A gain control signal is generated, and when the second reference value is transmitted, a gain of a second difference that is lower than the first difference by a value corresponding to the change is gained, and 2. The multicarrier transmission apparatus according to claim 1, further comprising: a gain control signal generation section (53) for generating a gain control signal capable of continuously holding the set gain.