JP2002094390A - Working / Preliminary Non-linear Compensation Device and Working / Preliminary Non-linear Compensation Method for Digital Broadcasting Modulated Signal Transmission System - Google Patents

Abstract

(57) [Summary] [Problem] When switching between active and standby digital broadcast modulation signals,
It is possible to continuously compensate for the non-linear characteristics of the amplifier without deteriorating the characteristics. An operating compensator obtains an input amplitude-to-output amplitude characteristic and an input amplitude-to-output phase characteristic from an output signal of an amplifier, obtains compensation data from the inverse of these characteristics, and compensates for an output signal of the ALC. Add data.
Then, the operating compensator 103 notifies the obtained compensating data to the waiting compensator 113 in real time, and during this waiting period, the compensator 113 transmits the notified compensation data to A
It is added to the output signal of LC112. The compensator 10
ALCs 102 and 112 are provided before 3 and 113, and AL
C102 and 112 adjust the amplitude values of the input signals of the compensators 103 and 113 to the set amplitude values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital broadcast modulation signal transmission system having a working / spare duplex structure and handling a modulated digital broadcast modulation signal, and more particularly to a non-linear amplifier for use in this system. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active / backup nonlinear compensation device for compensating characteristics and an active / backup nonlinear compensation method.

[0002]

2. Description of the Related Art Conventionally, broadcast transmission equipment has generally been provided with a dual working / standby configuration for troubleshooting and maintenance of equipment.

Here, in an analog broadcast transmission system,
In order to make the shock inconspicuous at the time of switching between the working and the standby, it is sufficient to perform the switching at the frame position after synchronizing the frames, and it is sufficient to take measures against noise generated when the contacts are switched.

In a digital broadcast transmission system, signals to be handled are, for example, OFDM (Orthogonal Frequent
Since modulation is performed by the ncy Division Multiplex (orthogonal frequency division multiplexing) method, linearity from a low level to a high level and phase rotation without slight disturbance are required. For this reason, in a digital broadcast transmission system,
In switching between active and standby, it is not possible to simply perform frame synchronization and switch at a frame position as in analog broadcasting.

FIG. 5 is a block diagram showing a digital broadcasting transmission system having a dual working / standby configuration when the above measures are taken.

In FIG. 5, the working system is composed of a modulator 11, a compensator 12, and a frequency converter 13, and the protection system is composed of a modulator 21, a compensator 22, and a frequency converter 23. You.

First, in a working system, a digital broadcast signal is converted into an IF (intermediate frequency) signal by a modulator 11, processed by a compensator 12, and processed by a frequency converter 13.
After that, the signal is converted into an RF (radio frequency) signal and supplied to the changeover switch 31. In the standby system, similarly to the active system, the digital broadcast signal is converted into an IF signal by the modulator 21, processed by the compensator 22, and converted into an RF signal by the frequency converter 23.
It is supplied to the changeover switch 31.

The switch 31 selectively derives either the working RF signal or the protection RF signal according to the working / standby switching trigger signal. After the output signal of the changeover switch 31 is power-amplified by the amplifier 32,
It is transmitted as a broadcast wave by an antenna (not shown).

Since the compensators 12 and 22 are adaptive compensators for compensating for non-linear characteristics caused by the operating temperature and aging of the amplifier 32, the output signal of the amplifier 32 is fed back to calculate optimal compensation data. Are added to the output signals of the converters 11 and 21, respectively.
When the compensator 12 is in operation, it is necessary to turn off the adaptive system by turning off the standby feedback circuit by the changeover switch 33 in order to prevent the compensator 22 from erroneously calculating the compensation data.

However, when switching from the active system to the standby system, the compensator 22 uses the stored compensation value, so that optimal compensation immediately after the switching becomes impossible, and as a result, the output of the amplifier 32 has a characteristic. Deterioration will occur. That is, when the feedback circuit is turned on after the switching, the compensator 22 starts to operate adaptively and calculates the optimum value of the compensation data, but this calculation process requires several tens of seconds.

[0011]

As described above, in the conventional measures for compensating for the nonlinear characteristic of the amplifier in the dual working / standby configuration of the digital broadcasting transmission system, the conventional technique involves the following steps: A waiting time is required from the start of the adaptive operation to the calculation of the optimum value of the compensation data, and there is a problem that characteristic deterioration occurs in the waiting time.

An object of the present invention is to provide a digital broadcast modulation signal transmission system capable of continuously compensating for the non-linear characteristics of an amplifier without deteriorating the characteristics when the digital broadcast modulation signal is switched between active and standby. It is an object of the present invention to provide a working / standby nonlinear compensation device and a working / standby nonlinear compensation method.

[0013]

SUMMARY OF THE INVENTION A working / standby nonlinear compensator for a digital broadcasting modulation signal transmission system according to the present invention uses a working / standby digital modulation signal modulated independently of each other in a working system and a protection system. After being selectively derived according to the switching signal, it is used in a digital broadcast modulation signal transmission system that amplifies the power and broadcasts it as a broadcast wave. A working / spare non-linear compensator for compensating for non-linear characteristics of an amplifier that amplifies and sends out, and is provided in each of a working system and a protection system.
A working compensator and a spare compensator for obtaining the non-linear characteristics of the amplifier from the output signal of the amplifier, obtaining compensation data from their inverse characteristics, and performing compensation processing on the input digital broadcast modulation signal with the compensation data; Before the standby switching signal is input, a compensation data communication means for transmitting and receiving the obtained compensation data between the active system compensation unit and the standby system compensation unit is provided.

More specifically, the working compensating section and the standby compensating section each include a characteristic calculating means for calculating an input amplitude versus output amplitude characteristic and an input amplitude versus output phase characteristic of the amplifier from the output signal of the amplifier, Compensation data calculation means for obtaining compensation data for amplitude characteristics and compensation data for phase characteristics from respective inverse characteristics of the input amplitude versus output amplitude characteristics and the input amplitude versus output phase characteristics obtained by the calculation means, and the compensation data calculation means And compensating means for adding the compensated data of the amplitude characteristic and the compensated data of the phase characteristic to the input digital broadcast modulation signal.

According to this configuration, the compensation data obtained by the active working compensator is notified to the standby spare compensator in standby in real time. Since the notified compensation data is added to the input digital broadcast modulation signal, when switching from the working system to the standby system, the nonlinear characteristic of the amplifier obtained before switching to the standby digital broadcast modulation signal and The signal can be input to the amplifier with the opposite characteristic, and the distortion component due to the nonlinear characteristic of the output of the amplifier can be compensated.

For this reason, when switching from the active system to the standby system, the standby system compensator does not need to perform feedback processing to calculate the optimal compensation data, so that the waiting time can be eliminated. It is possible to prevent the deterioration of the characteristic of the output signal of the amplifier, and thereby to continuously compensate the nonlinear characteristic of the amplifier. Furthermore, the signal before and after switching is beautifully connected,
A digital broadcast modulation signal without disturbing information can be transmitted.

Further, in the above configuration, a working system amplitude adjustment unit and a protection system for adjusting the amplitude value of the input digital broadcast modulation signal to a predetermined value are provided before each of the working system compensation unit and the protection system compensation unit. An amplitude adjuster is provided, and a phase adjuster for adjusting the phase of the digital broadcast modulation signal between the two systems is provided.

By doing so, the amplitude of the digital broadcast modulation signal is adjusted to a predetermined amplitude value between the two systems before being input to the working compensator and the standby compensator, and the digital broadcast modulation signal is Since the phases are matched between the two systems, even if the amplitude and phase of the digital broadcast modulation signal fluctuate between the two systems, it is possible to cope with these fluctuations. It does not interfere with compensation.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a digital broadcast modulation signal transmission system according to the present invention.

In FIG. 1, the working system is a modulator 101,
ALC (Auto Level Controller) 102 and compensator 1
03, and a frequency converter 104. The standby system includes a modulator 111, an ALC 112, a compensator 113,
And a frequency converter 114.

First, in a working system, a digital broadcast signal is converted into an IF (intermediate frequency) signal by a modulator 101, and the amplitude of an output signal of the modulator 101 is adjusted by an ALC 102 to a predetermined set amplitude value. . And AL
The output signal of C 102 is processed by the compensator 103, converted to an RF (radio frequency) signal by the frequency converter 104, and then supplied to the changeover switch 121. Further, in the standby system, the digital broadcast signal is converted into an IF signal by the modulator 111 and the A
The amplitude of the output signal of the modulator 111 is adjusted by the LC 112 to a predetermined set amplitude value. And ALC112
Is processed by the compensator 113, converted into an RF signal by the frequency converter 114, and supplied to the changeover switch 121.

The changeover switch 121 responds to an active / standby switching trigger signal by using an active RF signal and a standby RF signal.
Either one of the signals is selectively derived. The output signal of the switch 121 is power-amplified by the amplifier 122 and then transmitted as a broadcast wave by an antenna (not shown).

The output signal of the amplifier 122 is supplied to a changeover switch 123. This changeover switch 123
Is used in response to the active / standby switching trigger signal.
Is selectively derived to the compensator 103 or the compensator 113.

FIG. 2 is a block diagram showing the configuration of the compensators 103 and 113. In FIG. 2, the compensator 10
3 will be described.

In FIG. 2, a compensator 103 includes a characteristic detecting section 1031, a compensation data calculating section 1032, and an adding section 1.
033 and a compensation data communication unit 1034.

The output signal of the amplifier 122 input to the compensator 103 is supplied to a characteristic detector 1031. The characteristic detecting unit 1031 detects the output signal of the amplifier 122 from the amplifier 1
22 non-linear characteristics are detected. The nonlinear characteristics of the amplifier 122 include an input amplitude versus output amplitude characteristic (characteristic of an A curve in FIG. 3) as shown in FIG. 3 and an input amplitude versus output phase characteristic (a Φ curve in FIG. 4) as shown in FIG. 2)
There is one. Since the non-linear characteristics of the amplifier 122 change due to external environmental conditions and aging, it is desirable to adaptively compensate and improve the characteristics.

Therefore, the characteristic detecting section 1031 includes an amplifier
122, the input amplitude versus output amplitude characteristic and the input
Calculate the amplitude versus output phase characteristics, and find the input amplitude versus output
Compensate the amplitude characteristic signal and the input amplitude vs. output phase characteristic signal.
The data is output to the data operation unit 1032. Compensation data calculator 10
32 is an inverse characteristic of the input amplitude-output amplitude characteristic (A in FIG. 3).
^-1Curve characteristics), and similarly, input amplitude vs. output phase characteristics
(In FIG. 4, Φ ^-1Curve characteristics), amplitude and phase
The addition unit 1033 and the compensation data are used as compensation data indicating compensation components.
Output to the compensation data 1034, respectively.

The adder 1033 receives the output signal of the ALC 102 and the compensation data, and adds compensation data to the output signal of the ALC 102. By doing so, the amplifier 122 approaches the characteristics of a linear amplifier.

The compensation data communication section 1034 transmits the compensation data obtained by the compensation data calculation section 1032 to the compensator 113 on the standby side. When the active system is on standby, it receives compensation data from compensator 113 and outputs it to adder 1033.

Next, the operation of the compensator 103 shown in FIG. 2 for compensating the nonlinear characteristic of the amplifier 122 will be described.

Now, let the carrier frequency be ω ₀ , r (t) and φ
Assuming that (t) is the envelope amplitude and phase angle of the modulated signal, the input signal of the amplifier 122 is expressed as x (t) = r (t) cos [ω ₀ t + φ (t)]. Here, the input amplitude versus output amplitude characteristic is A
(R), assuming that the input amplitude versus output phase characteristic is Φ (r),
The output signal of the amplifier 122 is y (t) = A [r (t)] cos [ω ₀ t + φ (t) +
Φ (r (t))].

Therefore, in the compensator 103, compensation data A ⁻¹ (r of amplitude characteristic such that A [A ⁻¹ (r (t))] = B [r (t)] (B is a linear characteristic) (T)) is calculated by the compensation data calculation unit 1032.

Similarly, compensation data calculation section 1032 calculates compensation data Φ ⁻¹ [of phase characteristics such that −Φ [r (t)] + Φ ⁻¹ [A ⁻¹ (r (t))] = 0. A ^-1 (r
(T))] is calculated.

The obtained compensation data is added to the adder 1033
To the output signal of the modulator 102, the compensator 1
03 is given by: y (t) = A ⁻¹ [r (t)] cos [ω _IF t + φ (t)
−Φ (r (t))] ω _IF : IF signal center frequency of converter output.

The frequency converter 104 converts the IF signal into a carrier frequency, and when the gain is set to 0 dB, the input signal of the amplifier 122 becomes y (t) = A ^-1 [r (t)] cos [ω ₀ t + φ (t )
−Φ (r (t))]. When this signal is amplified by the amplifier 122, the output becomes y (t) = A [A ^-1 (r (t))] cos [ω ₀ t + φ
(T) −Φ (r (t))] + Φ ⁻¹ [A ⁻¹ (r (t))] = B [r (t)] cos [ω ₀ t + φ (t)] Become.

Further, the compensation data transmitted to the compensator 113 during standby indicates compensation data A ^-1 (r) of the amplitude characteristic and compensation data Φ ^-1 (r) of the phase characteristic. By making the signals equal, it is possible to maintain the characteristics before switching when switching from the active system to the standby system.

In the above configuration, the outputs of the modulators 101 and 111 are connected to the ALC 102 and
It is indispensable to make the input amplitudes of the two compensators 103 and 113 the same with the intervention of the 112. Here, assuming that the gain of the adaptive nonlinear compensation is 0 dB and the gains of the two frequency converters 101 and 111 are the same, the compensation data of the two compensators 103 and 113 are the same. here,
When adding the ALCs 102 and 112 and adjusting the gain of each device, the data of the active compensator is transmitted to the standby compensator, and the standby compensator uses the data to switch the system. Sometimes the amplifier 12
Compensation for the non-linear characteristic of No. 2 can be performed.

As described above, according to the above embodiment,
The compensation data obtained by the operating compensator 103 is notified in real time to the standby compensator 113. During this standby period, the compensator 113 adds the notified compensation data to the output signal of the ALC 112. Therefore, when switching from the active system to the standby system is performed by the changeover switch 121, the standby digital broadcasting modulation signal is given an inverse characteristic to the nonlinear characteristic of the amplifier 122 obtained before the switching and is given to the amplifier 122. It can be input, and can compensate for a distortion component due to the non-linear characteristic of the output of the amplifier 122.

Therefore, when switching from the active system to the standby system, it is not necessary to perform feedback processing in the compensator 113 to calculate optimal compensation data. It is possible to prevent the output signal of the amplifier 122 from deteriorating in characteristics, whereby the non-linear characteristic of the amplifier 122 can be continuously compensated. Further, the signals before and after the switching are clearly connected, and a digital broadcast modulation signal without any disturbance in information can be transmitted.

In the above embodiment, the compensator 103,
An ALC that adjusts the amplitude value of the output signal of each of the modulators 101 and 111 to a predetermined set amplitude value in the preceding stage of each of the 113
102 and 112 are provided. Therefore, before the signals are input to the compensators 103 and 113, the amplitude of the digital broadcast modulation signal is adjusted to a predetermined set amplitude value between the two systems. Even when a fluctuation occurs, the fluctuation can be dealt with, and thus, there is no need to hinder the compensation of the nonlinear characteristic of the amplifier 122.

The present invention is not limited to the above embodiment.

For example, in the above embodiment, the compensator 10
A description has been given of an example in which ALCs 102 and 112 are provided in front of the respective compensators 103 and 113 to adjust the amplitude values of the input signals of the compensators 103 and 113 to a predetermined set amplitude value between the two systems. Alternatively, a phase adjuster may be provided. In this case, the phase adjuster detects the phase difference between the input signals of the compensators 103 and 113 between the two systems, and adjusts the phases of both input signals based on the phase difference.

By doing so, even if a phase change of the digital broadcast modulation signal occurs between the two systems, the phase change can be dealt with, and similarly, the compensation of the nonlinear characteristic of the amplifier 122 can be performed. There is no problem.

In addition, the configuration of the compensator, the type of compensation data, and each component circuit in the system can be variously modified without departing from the scope of the present invention.

[0046]

As described in detail above, according to the present invention,
Working / spare non-linear compensator and working / spare of digital broadcasting modulated signal transmission system capable of continuously compensating for nonlinear characteristics of amplifier without deteriorating characteristics at the time of working / spare switching of digital broadcast modulated signal A non-linear compensation method can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a digital broadcast modulation signal transmission system according to the present invention.

FIG. 2 is a block diagram showing a specific configuration of the compensator shown in FIG.

FIG. 3 is a diagram showing input amplitude versus output amplitude characteristics of the amplifier shown in FIG. 1;

FIG. 4 is a diagram showing input amplitude versus output phase characteristics of the amplifier shown in FIG. 1;

FIG. 5 is a block diagram showing a digital broadcasting transmission system having a dual working / standby configuration conventionally considered.

[Explanation of symbols]

 101, 111: modulator, 102, 112: ALC (Auto Level Controller), 103, 113: compensator, 104, 114: frequency converter, 121, 123: switch, 122: amplifier.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 1/22 H04L 1/22 5K060 27/10 27/10 A 27/12 27/12 Z H04N 5/40 H04N 5/40 F term (reference) 5C025 AA09 DA01 5J090 AA01 AA41 AA53 CA21 CA55 CA85 CA89 FA08 FA18 FA19 FA20 GN02 GN05 GN06 HA38 HN11 HN15 KA20 KA53 MA11 SA14 TA01 5K004 AA04 5K014 AA1 CA01 FA01 CC01 DD01 HH06

Claims (5)

[Claims] 1. A digital broadcast for selectively deriving a digital broadcast modulation signal modulated independently of each other in a working system and a protection system according to a working / standby switching signal, and then power-amplifying and broadcasting as a broadcast wave. Used for modulated signal transmission system,
A working / spare nonlinear compensator for compensating for nonlinear characteristics of an amplifier that power-amplifies and sends out a digital broadcast modulation signal selectively derived from the working system and the protection system, wherein the working system and the protection system respectively. For the operating system of the two systems, the nonlinear characteristic of the amplifier is obtained from the output signal of the amplifier, the compensation data is obtained from the inverse characteristic thereof, and the compensation data is used for the input digital broadcast modulation signal. A working compensator and a backup compensator that perform compensation processing, and before and after the working / preliminary switching signal is input, transfer of the obtained compensation data between the working compensator and the backup compensator. And a non-linear compensating device for use in a digital broadcast modulation signal transmission system, comprising: 2. The characteristic compensating means for calculating an input amplitude versus output amplitude characteristic and an input amplitude versus output phase characteristic of the amplifier from an output signal of the amplifier, respectively, Compensation data calculation means for obtaining compensation data for amplitude characteristics and compensation data for phase characteristics from respective inverse characteristics of the input amplitude versus output amplitude characteristics and the input amplitude versus output phase characteristics obtained by the calculation means, and the compensation data calculation means And a compensation means for adding the compensation data of the amplitude characteristic and the compensation data of the phase characteristic to the input digital broadcast modulation signal. Compensator. 3. A working system amplitude adjuster and a standby system amplitude adjuster for adjusting an amplitude value of an input digital broadcast modulation signal to a predetermined value before each of the working system compensator and the standby system compensator. The current / backup non-linear compensator for a digital broadcast modulation signal transmission system according to claim 1, further comprising a unit. 4. The apparatus according to claim 1, further comprising a phase adjustment unit that adjusts the phase of a digital broadcast modulation signal between the two systems before each of the working system compensation unit and the standby system compensation unit. Active / Preliminary Non-Linear Compensator for Digital Broadcast Modulation Signal Transmission System 5. A digital broadcast in which a digital broadcast modulation signal independently modulated by a working system and a protection system is selectively derived in accordance with a working / standby switching signal, and then power-amplified and broadcast as a broadcast wave. Used for modulated signal transmission system,
A method for compensating for non-linear characteristics of an amplifier for power-amplifying and transmitting a digital broadcast modulation signal selectively derived from the working system and the protection system, comprising: For the operating system, the input amplitude-to-output amplitude characteristic and the input amplitude-to-output phase characteristic of the amplifier are obtained from the output signal of the amplifier, and compensation data is obtained from the inverse characteristic thereof. A digital broadcast modulation signal to be switched to the amplifier with the compensation data notified from the operating system, while performing compensation processing on the standby system and notifying the standby system of the obtained compensation data. Current / preliminary non-linear compensation method for a digital broadcast modulation signal transmission system, wherein a compensation process is performed on the signal.