JP2954181B1 - Single frequency broadcast wave repeater - Google Patents

Abstract

[PROBLEMS] In a conventional repeater of the transmission / reception separation system, it is necessary to newly install a receiving station, but enormous expenses are required for securing land for the receiving station, construction cost of the receiving station building, and the like. Take it. SOLUTION: A phase detector 7 detects a phase difference between a received signal and each pilot signal in a transmission signal, supplies the phase difference detection signal to a variable phase adjuster 11, and determines a phase of the transmission signal as a reception signal. Adjust to be the same. Level detector 8
Detects the level difference between the pilot signal in the received signal and the pilot signal in the transmitted signal, and outputs the level difference detection signal to the variable attenuator 12.
And the level of the transmission signal is adjusted to be the same as that of the reception signal. The output signal of the variable attenuator 12 is
, And are combined with the reception signal in the opposite phase, only the fog component of the own station is canceled from the reception signal, and only the single frequency broadcast wave signal from the master station is extracted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single frequency broadcast wave relay device, and more particularly to a single frequency broadcast wave relay device for relaying a single frequency broadcast wave.

[0002]

2. Description of the Related Art In terrestrial digital television broadcasting scheduled to be implemented in the future, broadcasting using a single frequency broadcast wave is being studied from the viewpoint of effective use of frequency. In this case, a relay device is required.

[0003] Such a relay apparatus receives a radio broadcast wave signal by a receiving antenna, amplifies the signal, and retransmits it as a transmission signal at the same frequency as the received broadcast wave signal from the transmission antenna. A part of is re-received by the receiving antenna as a wraparound radio wave through the space, so-called own station fogging occurs, and due to this own station fogging, a transmission signal due to wraparound acts as an interference signal with respect to a regular received signal, Since the function as a relay device such as the oscillation of the device is hindered, how to overcome this is a major problem.

[0004] Therefore, conventionally, a pilot signal is transmitted from a receiving antenna, and the amplitude and phase of the feedback loop signal are controlled by detecting a canceling residual component between the feedback loop signal and the interference signal with respect to the pilot signal. There is known a relay apparatus which realizes optimally optimal compensation conditions and reduces the influence of a pilot signal on a transmission signal (Japanese Patent Publication No. Sho 64-3099).

[0005] Conventionally, a transmission / reception separation system is also known as a countermeasure against fogging of the own station. This transmission / reception separation system has a configuration in which a transmitting station and a receiving station are separated.

[0006]

However, the conventional apparatus described in the above-mentioned publication is actually difficult to realize. That is, the wireless relay apparatus generally has a gain of about 100 dB, and the amount of wraparound from the transmitting antenna to the receiving antenna is about -100 dB. On the other hand, a filter for detecting a pilot signal is connected to the transmitting antenna, and the vector modulator is controlled based on information on detection of the in-phase component and the quadrature component of the pilot signal separated by the filter. The signal is amplified by an amplifier and retransmitted as a transmission signal from the transmission antenna at the same frequency as the reception signal. Therefore, since what is required as a signal input to the pilot signal detection filter is the pilot signal received from the transmission antenna, the signal path from the reception antenna to the transmission antenna via the amplifier is used to remove the pilot signal. Filter is required. However, this pilot signal removing filter requires an attenuation of 200 dB or more including the above-mentioned amount of wraparound, and is not feasible.

Further, in the latter conventional apparatus of the transmission / reception separation system, it is necessary to newly install a receiving station. However, enormous costs are required for securing land for the receiving station and for constructing a receiving station building. For this reason, little is done at present. For this reason, the channel (frequency) is changed between transmission and reception instead of single frequency relay.

[0008] The present invention has been made in view of the above points,
It is an object of the present invention to provide a single-frequency broadcast wave relay device capable of reducing a fog component of its own station without performing transmission / reception separation.

[0009]

In order to achieve the above object, the present invention provides a receiving antenna for receiving a single frequency broadcast wave, and a pilot signal generator for generating a pilot signal having a frequency different from the broadcast wave. a first filter and, when receiving the same frequency of a single frequency broadcast waves received that separates and extracts the pilot signal from the received signal from the receiving antenna
And the pilot signal from the pilot signal generator
Of inputs and transmitting antenna for transmitting, to the transmission antenna with
Received single frequency broadcast wave and pilot signal generator
A second filter for separating and extracting a pilot signal from a transmission signal including the pilot signal, and a phase difference detection signal and a level difference detection by comparing the phases and levels of respective output signals of the first and second filters. A comparison unit that outputs a signal, and based on the phase difference detection signal and the level difference detection signal from the comparison unit, adjusts the phase and level of the transmission signal so as to eliminate the phase difference and the level difference. Processing means for synthesizing the received signal in reverse phase, and generating a transmission signal by synthesizing a pilot signal from a pilot signal generator with the reception signal extracted from the processing means,
This is a configuration having a transmitting antenna and a first combiner for outputting the transmitting signal to the processing means.

According to the present invention, a pilot signal is included in a local station fog component re-received by a receiving antenna as a part of a transmission signal transmitted from a transmitting antenna through a space as a radio wave. Separates and extracts the above pilot signal from the received signal mixed with the received single frequency broadcast wave, and combines the transmitted signal and the transmitted signal in the opposite phase so that they have the same phase and the same level as the pilot signal in the transmitted signal Therefore, the local fog component in the received signal can be substantially canceled and removed to obtain the transmission signal.

Further, the comparing means in the above invention comprises a phase detector for detecting a phase difference between each output signal of the first and second filters, and a level difference between each output signal of the first and second filters. It is characterized by comprising a level detector for detection, and constituting a detector together with the first and second filters.

Further, the processing means in the above invention adjusts the phase and the level of the transmission signal based on the phase difference detection signal and the level difference detection signal from the comparison means so as to eliminate the phase difference and the level difference. And a second combiner for combining the output signal of the adjusting means with the received signal from the receiving antenna in the opposite phase and outputting the combined signal to the first combiner.

Further, the present invention is to achieve the above object, a receiving antenna for receiving a single frequency broadcast wave, a pilot signal generator for generating a pilot signal of a frequency different from the broadcast wave, received single Receive one frequency broadcast wave
At the same frequency as when, and from the pilot signal generator
A transmitting antenna to transmit with the pilot signal,
Receiving single frequency broadcast wave and pilot
After adjusting the phase and level of the transmission signal including the pilot signal from the G signal generator based on the control signal, processing means for combining in reverse phase with the reception signal from the reception antenna,
A filter for separating and extracting a pilot signal from an output signal of the processing means, a level detector for detecting a level of an output signal of the filter, and an output detection signal of the level detector,
A control signal for instructing the phase control amount and the level adjustment amount to the processing means is supplied , and the detection signal level at that time is supplied.
After storing the phase control amount and the level
Control signal that slightly changes the instruction content of the
Supply and read the detection signal level at that time.
To compare the previous detection signal level with the lower detection signal level.
Remembering the bell is repeated the specified number of times
An arithmetic means for outputting a control signal to the processing means when the minimum value of the detection signal level is obtained , and a pilot signal from a pilot signal generator for a reception signal extracted from the processing means. The transmission signal is generated by synthesis, and the transmission signal is output to the transmission antenna and the processing unit.

According to the present invention, a pilot signal is included in a local station fog component re-received by a receiving antenna as a part of a transmission signal transmitted from a transmitting antenna through a space as a radio wave. Is mixed with the received signal mixed with the received single-frequency broadcast wave, the transmission signal whose level and phase are controlled is combined in reverse phase, the pilot signal is separated and extracted from the combined signal, and the pilot signal level is Since the phase control amount and the level adjustment amount in which the minimum value is minimized are obtained, the fog component of the own station in the received signal can be almost canceled and removed to obtain the transmission signal.

Further, the pilot signal in the present invention is:
It is a carrier of an unused single frequency among the allocated frequencies, or the frequency band differs from the single frequency broadcast wave,
In addition, a plurality of carrier waves having different frequencies are provided.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a single-frequency broadcast wave relay apparatus according to the present invention. The single frequency broadcast wave relay device shown in FIG.
And a transmission unit 3 connected to the reception unit 2 and the transmission antenna 4. The reception unit 2 includes a reception amplification unit 5, a filter 6, a phase detector 7, a detector 10 including a level detector 8 and a filter 9, and a variable phase adjustment for adjusting a phase of a transmission signal based on an output signal of the detector 10. Vessel 1
1, a variable attenuator 12 for adjusting the level of the transmission signal based on the output signal of the detector 10, and a synthesizer 13 for synthesizing the received signal with the opposite phase. Also, the transmitting unit 3
Is composed of a combiner 14 that receives a signal from the combiner 13 as an input signal, a pilot signal generator 15 that oscillates and outputs a pilot signal of a predetermined frequency, and a transmission amplifier 16.

Next, the operation of this embodiment will be described with reference to the frequency spectrum diagram of FIG. FIG.
The pilot signal generated from the pilot signal generator 15 in the transmitting section 3 generates a signal of an unused frequency among the allocated channels that are received and retransmitted by the relay device. Therefore, the signal of the channel that this relay apparatus receives from the master station and retransmits (single frequency broadcast wave)
Is a signal in a frequency band as shown by I in FIG. 2A (center frequency f1), the combiner 14 performs frequency division multiplexing of the received signal and a pilot signal from the pilot signal generator 15. Thus, a signal b having a frequency spectrum as shown in FIG. 2B is transmitted from the transmission antenna 4 through the transmission amplifier 16. Here, in FIG. 2B, II is the above pilot signal.

In this repeater for retransmitting at a single frequency, the receiving antenna 1 receives the signal a indicated by III in FIG.
At the same time, the own station fogging occurs in which the own station also receives a transmission signal transmitted from the transmitting antenna 4. I ′ and II ′ in FIG. 2C indicate a local fog component composed of a signal transmitted from the transmitting antenna 4 and received by the receiving antenna 1 and a pilot signal.

The frequency spectrum III and the frequency spectrums I ', II', and I 'of FIG. 2C and FIG.
A phase difference is shown between V and V. Here, in both figures, the phase difference between the frequency spectrum III and the frequency spectrums I ′ and II ′ is illustrated at approximately 90 °, but this is an example for simplicity of illustration, and the phase difference is Of course, it is not limited to this.

After these signals c received by the receiving antenna 1 are amplified by the receiving amplifying unit 5 in the receiving unit 2, after the filter 6 extracts only the pilot signal in the own-station fog component, It is supplied to a phase detector 7 and a level detector 8. On the other hand, the transmission signal extracted from the combiner 14 is supplied to a filter 9 where only a pilot signal is extracted, and then supplied to a phase detector 7 and a level detector 8. The phase detector 7 detects a phase difference between each pilot signal in the reception signal and the transmission signal, supplies the phase difference detection signal to the variable phase adjuster 11, The phase of the transmission signal is adjusted to be the same as that of the reception signal. The level detector 8 detects a level difference between each pilot signal in the reception signal and the transmission signal, supplies the level difference detection signal to the variable attenuator 12, and Is adjusted so that the level of the transmission signal from the receiver becomes the same as that of the reception signal.

As a result, a transmission signal having substantially the same phase as that of the local fog component of the reception signal c extracted and amplified by the reception amplification unit 5 is extracted from the variable attenuator 12 and supplied to the synthesizer 13. And the received signal c
Is synthesized with When the frequency spectrum of the output signal of the variable attenuator 12 is in the opposite phase, it comprises a transmission signal component indicated by IV and a pilot signal component indicated by V in FIG. The components I 'and II' have opposite phases, and the combiner 12 cancels out the local fog component in the received signal.

As described above, the combiner 13 combines the transmission signal with the reception signal in the opposite phase, so that only the fog component of the own station is canceled from the reception signal, and the single-frequency broadcast wave signal (from the master station) is cancelled. Frequency spectrum III in FIG. 2 (D))
Is extracted and supplied to a combiner 14, where it is combined with a pilot signal from a pilot signal generator 15, one is input to a filter 9 and a variable phase adjuster 11, and the other is input to a transmission amplifier 16. The signal is amplified and transmitted from the transmitting antenna 4.

Therefore, according to this embodiment, it is possible to transmit a signal in which the pilot signal is multiplexed to the received signal from which the fog component of the own station has been canceled. Oscillation can be suppressed, and even if oscillation does not occur, characteristic degradation due to ghost caused by fog at the own station can be reduced.

Next, another embodiment of the present invention will be described. FIG. 3 is a block diagram showing another embodiment of the single frequency broadcast wave relay apparatus according to the present invention. In the figure, the same components as those of FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The single frequency broadcast wave relay device shown in FIG. 3 includes a receiving unit 20 connected to the receiving antenna 1, and a transmitting unit 3 connected to the receiving unit 20 and the transmitting antenna 4. Receiver 20
Is a reception amplifier 5, a filter 21 for separating and filtering a pilot signal, a level detector 22 for detecting a level of an output signal of the filter 21, and a central processing unit (CPU) to which an output signal of the level detector 22 is input. 23, a variable phase adjuster 11 for adjusting the phase of the transmission signal, a variable attenuator 12 for adjusting the level of the transmission signal based on the output signal of the CPU 23, and a synthesizer 13 for synthesizing the reception signal with the opposite phase. Have been.

Next, the operation of this embodiment will be described. The single-frequency broadcast wave signal from the master station (not shown) received by the receiving antenna 1 is amplified by the receiving amplifier 5 in the receiving section 20 together with the local station fog component, and the phase of the local station fog component is synthesized by the combiner 13. After being combined with a signal having the same level as that of the signal in the opposite phase, only the pilot signal is extracted by the filter 21.

The level of the pilot signal extracted by the filter 21 is detected by a level detector 22, and the level detection signal is input to the CPU 23. Here, in the synthesizer 13, unless the signal input from the variable attenuator 12 is completely the same level as the fog component of the local station in the received signal input from the reception amplifying unit 5 and is not in the opposite phase, the signal in the received signal is The local fog component is not completely removed but is taken out of the synthesizer 13 in a state where the local fog component remains at a small level. Accordingly, a pilot signal of a level corresponding to the local fog component remaining in the output received signal of the synthesizer 13 is extracted from the filter 21, and the level is detected by the level detector 22.

The CPU 23 gives instructions to the variable phase adjuster 11 and the variable attenuator 12 according to the flowchart of FIG. That is, the CPU 23 refers to the table of the level difference and the phase difference previously measured and set based on the residual pilot signal level corresponding to the residual local station fog component input from the level detector 22 and refers to the variable phase adjuster 11.
And a variable attenuator 12 (step 101), and read the residual pilot signal level L1 from the level detector 22 after the command (step 102). Subsequently, the CPU 23 outputs to the variable phase adjuster 11 and the variable attenuator 12 an instruction signal having a slightly different phase difference and a slightly different level from the previously output instruction signal (step 103). Then, the residual pilot signal level L2 from the level detector 22 after the instruction is read again (step 104).

Next, one of the detection levels L1 and L2 having a smaller residual pilot signal level is selected and temporarily stored (step 105). Next, the CPU 23 determines whether or not the above-mentioned series of operations has been repeated a predetermined number of times (step 106).
To 105 are performed again.

In this way, steps 101 to 105
Is repeated a predetermined number of times, the CPU 23 selects an instruction signal having the smallest residual pilot signal level from the obtained smaller residual pilot signal levels, and instructs the variable phase adjuster 11 and the variable attenuator 12 to the instruction signal. The content is controlled (step 107). As a result, the received signal having the minimum fog component of the own station is extracted from the combiner 13, multiplexed with the pilot signal by the combiner 14, and transmitted via the transmission amplifier 16 and the transmission antenna 4.

The present invention is not limited to the above embodiment. For example, only a single frequency carrier may be used, but the distance between transmission and reception is usually several meters to several tens of meters. And the phase may be delayed by several tens of cycles. Thus, for example, two different carriers capable of measuring relatively long distances may be used as pilot signals. In this case, two sets of the detector 10, the filter 21, and the level detector 22 are required.

[0031]

As described above, according to the present invention,
Since the fog component of the own station is almost canceled and removed from the received signal, and only the single frequency broadcast wave from the master station is extracted as the received signal, it can be used as the transmission signal. Oscillation due to station fogging can be suppressed, and even when oscillation does not occur, characteristic degradation due to ghosting caused by own station fogging can be reduced. It is not necessary to perform so-called transmission / reception separation, which is installed away from the receiving antenna and the transmitting antenna in order to avoid station fogging, so that equipment costs can be reduced. Further, according to the present invention, the amount of wraparound from the transmitting antenna to the receiving antenna is -100.
Even a normal relay device having a dB level can be sufficiently used in practical use.

[Brief description of the drawings]

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

FIG. 2 is a frequency spectrum diagram for explaining the operation of each unit in FIG. 1;

FIG. 3 is a block diagram of another embodiment of the present invention.

FIG. 4 is a flowchart for explaining an operation of a main part of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving antenna 2, 20 Receiving part 3 Transmitting part 4 Transmitting antenna 5 Transmitting amplifying part 6, 9, 21 Pilot signal separation filter 7 Phase detector 8, 22 Level detector 10 Detector 11 Variable phase adjuster 12 Variable attenuator 13, 14 synthesizer 15 pilot signal generator 16 transmission amplifier 23 central processing unit (CPU)

Claims (6)

(57) [Claims] 1. A receiving antenna for receiving a single frequency broadcast wave, a pilot signal generator for generating a pilot signal having a frequency different from the broadcast wave, and separating and extracting the pilot signal from a received signal from the receiving antenna first filter and the same frequency and time of reception of the single frequency broadcast waves received to
And the pilot signal from the pilot signal generator
A transmitting antenna for transmitting with the transmitting signal, and the receiving single frequency broadcasting input to the transmitting antenna.
Transmission and the pilot from the pilot signal generator
A second filter for separating and extracting the pilot signal from a transmission signal including a signal and a phase difference detection signal and a level difference detection signal by comparing phases and levels of respective output signals of the first and second filters. Comparing means for outputting the phase difference and the level difference detection signal from the comparison means, adjusting the phase and level of the transmission signal so as to eliminate the phase difference and the level difference, Processing means for combining the reception signal from the antenna in a reverse phase; and combining the reception signal extracted from the processing means with a pilot signal from the pilot signal generator to generate the transmission signal. A single-frequency broadcast wave relay device comprising a transmitting antenna and a first combiner for outputting to a processing means. 2. A phase detector for detecting a phase difference between output signals of the first and second filters,
2. The apparatus according to claim 1, further comprising a level detector for detecting a level difference between output signals of the first and second filters, and constituting a detector together with the first and second filters. Single frequency broadcast wave relay device. 3. The adjusting means for adjusting the phase and level of the transmission signal based on the phase difference detection signal and the level difference detection signal from the comparing means so as to eliminate the phase difference and the level difference. And a second combiner for combining an output signal of the adjusting means with a received signal from the receiving antenna in a reverse phase and outputting the combined signal to the first combiner. Single frequency broadcast wave repeater. 4. A single frequency and receiving antenna for receiving a broadcast wave, a pilot signal generator for generating a pilot signal having a frequency different from said broadcast wave, said received single-frequency broadcast wave same frequency as when receiving the
And the pilot signal from the pilot signal generator
A transmitting antenna for transmitting with the transmitting signal, and the receiving single frequency broadcasting input to the transmitting antenna.
Transmission and the pilot from the pilot signal generator
Processing means for adjusting the phase and level of the transmission signal including the signal based on the control signal, and then combining the signal and the reception signal from the reception antenna in reverse phase; separating and extracting the pilot signal from the output signal of the processing means A filter to detect, a level detector that detects a level of an output signal of the filter, and the control that instructs the processing unit to perform the phase control amount and the level adjustment amount according to an output detection signal of the level detector. Signal, and the detection signal at that time is supplied.
After storing the signal level, the phase for the processing means
Instructions of control amount and level adjustment amount are slightly changed from the previous time
To supply the control signal to
Read out signal level and compare with previous detection signal level
Storing the lower detection signal level.
After changing the display contents and repeating it a predetermined number of times,
Calculating means for outputting the control signal when the minimum value of the bell is obtained to the processing means; and combining the pilot signal from the pilot signal generator with the reception signal extracted from the processing means to obtain the transmission signal. A single frequency broadcast wave relay device comprising: a combiner for generating and transmitting the transmission signal to the transmission antenna and the processing means. 5. The single frequency broadcast wave relay according to claim 1, wherein the pilot signal is a carrier of an unused single frequency among assigned frequencies. apparatus. 6. The pilot signal according to claim 1, wherein the pilot signal is a plurality of carrier waves having different frequency bands from the single frequency broadcast wave and different frequencies from each other. Single frequency broadcast wave relay device.