JPH11163933A - Bidirectional reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a pull-in time of a received signal of both a server and a bidirectional receiver, to enable the reception of a signal with large deviations in the frequency and phase of a carrier wave and of a clock, to eliminate destruction of data by a collision at the time of TDMA reception or to prevent deterioration of data transmission efficiency by a collision countermeasure. SOLUTION: A bidirectional receiver A2 inserts reception conditions into a private incoming packet at a transmission processing circuit in a receiver, and modulates it at a TDMA-QPSK modulator 16 in the receiver to perform TDMA transmission to a server 1. The server 1 which receives this signal is constituted such the signal that is demodulated at a TDMA-QPSK demodulator 9 in the server, further this private incoming packet is extracted in a reception data processing circuit 10 in the server of a rear step, wherein a QAM modulator 6 in the server or the like establishes a transmission condition in accordance with the reception condition of this bidirectional receiver A2 to be transmitted to the bidirectional receiver A2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional receiving system capable of bidirectionally transmitting and receiving a plurality of TV signals and data signals.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram of a bidirectional CATV receiving system shown in DAVIC (Digital Audio Visual Council) which is an example of a conventional bidirectional receiving system. DAVIC is a private-sector standardization organization established in 1994 to standardize systems for interactive multimedia services represented by video-on-demand.
In the figure, reference numeral 1 denotes a server which is a device on the broadcast station side for transmitting a plurality of TV signals (including digital TV signals) and data signals to a plurality of terminals;
Bidirectional receivers A, B, C, and 5, which are terminals that receive V signals and data signals, are transmission lines that transmit these signals.

The inside of the server 1 has the following configuration. Numeral 6 denotes a QAM (Quadrature Amplitude) which is a digital quadrature amplitude modulation of the plurality of TV signals and data signals.
udeModulation) A QAM modulator in the server that performs modulation and transmission, 7 is a transmission data processing circuit in the server that processes transmission data for performing various controls, and 8 is a digital quadrature modulation of a signal from the transmission data processing circuit 7 in the server. A certain QPSK (Quadrature Phase Shift Keying) in-server QPSK modulator that modulates and transmits data, 9 is a TDMA-QPSK demodulator in the server that receives TDMA data for performing various controls and performs QPSK demodulation, and 10 is a TDMA-in-server TDMA- A receiving data processing circuit in the server that processes the data signal demodulated by the QPSK demodulator 9.
Reference numerals 7, 8, 9, and 10 are collectively called control channel blocks for six main channel blocks.

Next, the insides of the bidirectional receivers 2, 3, and 4 have the following configuration. 11 is the above plurality of TVs
QA in a receiver that receives signals and data signals and performs QAM demodulation
M demodulator, 12 is a TV signal processing circuit at the subsequent stage for performing processing such as MPEG decoding of this signal, 13 is a QPSK demodulator in a receiver that receives data for performing various controls and QPSK demodulates, and 14 is a QPSK demodulator in the receiver. A reception data processing circuit in the receiver for processing the data signal demodulated by the QPSK demodulator 13; a transmission data processing circuit 15 in the receiver for processing transmission data for performing various controls;
Reference numeral 6 denotes an in-receiver TDMA-Q for QPSK-modulating a signal from the in-receiver transmission data processing circuit 15 and performing TDMA transmission
It is a PSK modulator. 13, 14, 15, 16 is 1
The 1 and 12 main channel blocks are collectively called a control channel block.

Next, the operation will be described. First, the server 1 modulates a plurality of TV signals and data signals by the QAM modulator 6 in the server by the server 1, and transmits the modulated signals to the bidirectional receivers A 2, B 3, and C 4 via the transmission line 5. Each of the two-way receivers A2, B3, and C4 demodulates this signal in the QAM demodulator 11 in the receiver, and outputs the TV
The signal is sent to the signal processing circuit 12.

Next, the control channel block will be described. Since the control channel block is a two-way communication, the control channel block is in the upward direction (from the two-way receivers 2, 3, and 4 to the server 1) and in the downward direction (from the server 1 to the two-way receivers 2, 3, and so on).
4) Each direction will be described. First, in the downlink direction, a data signal for performing various controls is subjected to protocol processing and the like in a transmission data processing circuit 7 in the server, and QPSK modulated in a QPSK modulator 8 in the server, and is subjected to QPSK modulation via a transmission path 5. To the receivers A2, B3, and C4. Each two-way receiver A2, B3, C4 has a Q
This signal is QPSK-demodulated by the PSK demodulator 13 and sent to the reception data processing circuit 14 in the receiver at the subsequent stage. Next, in the upstream direction, a data signal for performing various controls is subjected to protocol processing and the like in a transmission data processing circuit 15 in the receiver, and a TDMA-QPSK modulator 16 in the receiver performs
QPSK-modulated and transmitted to server 1 via transmission path 5 in TDMA
Sent. The server 1 receives this signal by TDMA-QPSK demodulator 9 in the server and performs QPSK demodulation.
It is sent to the server-side received data processing circuit 10 at the subsequent stage.

Here, QPSK and QAM modulation / demodulation will be briefly described. QPSK modulation means that the signal to be transmitted is 2
The carrier is converted into a series (serial-parallel conversion), and two carrier waves having phases different from each other by 90 ° are modulated by the two series of binary signals, and a modulated signal is obtained by synthesizing them. Also, QAM
The modulation is obtained by adding amplitude information to the QPSK modulation.

There are various types of QPSK and QAM demodulators. For example, an AGC circuit for detecting the level of a received signal transmitted and automatically correcting the level, and detecting a frequency and a phase error of a carrier wave. Automatically corrects carrier recovery circuit, detects clock frequency and phase error,
Some are configured with a clock recovery circuit or the like that performs automatic correction.

Next, TDMA transmission and reception will be described in detail. TDMA is a time division multiple access communication system in which stations installed in physically different locations transmit signals only during a specific allocated time zone to perform communication.

Here, a plurality of bidirectional receivers A2, B
3 and C4 transmit data to one server 1, each of the two-way receivers A2, B3 and C4
Since the data is transmitted only at a different timing (time) determined from, the server 1 can receive each data.

However, the arrival times of the signals from the plurality of bidirectional receivers A2, B3, and C4 to the server 1 differ depending on the difference in the distance and the capacity of the transmission path. Are overlapped in time, and the signal may be broken (this phenomenon is called collision). As a countermeasure, invalid data which is called a guard band and may be destroyed is inserted before and after each data. .

[0012]

In the conventional two-way receiving system, the server does not look at the receiving state of the two-way receiver, and conversely, the two-way receiver does not see the receiving state of the server at all. If the received signal becomes worse due to aging and the received signal amplitude level becomes smaller, the receiving side increases the signal level with an AGC circuit that automatically performs level correction. There was a problem that it would take.

The received signal amplitude level is, for example, DAV
Since it is determined by the IC according to the standard, a receiver conforming to the DAVIC does not receive (do not pull in) if the receiver is compliant with the DAVIC. If the deviation becomes large due to a change or the like, there is a problem that not only the time required for reception (pulling in the signal) is required but also that the reception may not be possible in the worst case.

In the case of TDMA communication, if a transmission signal is greatly delayed by a transmission line, the effective data from another two-way receiver may be destroyed beyond the guard band signal, which is a countermeasure for the collision described above. There was a problem.

On the other hand, when there is not much difference in the signal arrival time from a plurality of bidirectional receivers to the server, the guard band signal, which is invalid data, is almost unnecessary, and the data transmission efficiency is reduced. There were also points.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and shortens the time required for receiving signals from both a server and a bidirectional receiver, and significantly deviates the frequency and phase of a carrier wave and a clock. It is an object of the present invention to provide a bidirectional receiving system which can receive a received signal, prevent data destruction due to collision at the time of TDMA reception, or prevent data transmission efficiency from deteriorating due to collision countermeasures.

[0017]

According to a first aspect of the present invention, there is provided a bidirectional receiving system comprising: a server for transmitting a plurality of TV signals (including digital TV signals) and data signals to a transmission line; In a two-way receiving system having a plurality of receivers for receiving data, and a transmission function of transmitting an uplink data signal from the plurality of receivers to a transmission path, and a function of a server receiving the uplink data signal, A dedicated uplink packet for sending the reception status of the device to the server is provided, and the transmission status of the server is changed according to the information.

Further, the two-way receiving system according to the second configuration of the present invention includes a dedicated downlink packet for sending the receiving status of the server to a plurality of receivers, and according to the information, the transmission status of each of the receivers Is to change.

Further, the bidirectional receiving system according to the third configuration of the present invention comprises a dedicated uplink packet for sending the reception status of the receiver to the server, and a dedicated downlink packet for sending the reception status of the server to the receiver. And changes the transmission state of the server and the transmission state of the receiver according to the information.

Further, the bidirectional receiving system according to the fourth configuration of the present invention uses the amplitude level of the received signal for the data of the reception status dedicated packet of the receiver and the server.

Further, the bidirectional receiving system according to the fifth configuration of the present invention uses the frequency and phase error of the carrier of the received signal for the data of the reception status dedicated packet of the receiver and the server.

Further, the bidirectional receiving system according to the sixth configuration of the present invention uses the frequency and phase error of the clock of the received signal for the data of the reception status dedicated packet of the receiver and the server.

Further, the bidirectional receiving system according to the seventh configuration of the present invention uses a predetermined data sequence for the data of the reception status dedicated packet of the receiver and the server,
An error rate can be calculated in each of the receiver and the server.

Further, in the bidirectional receiving system according to the eighth configuration of the present invention, data identical to the data transmitted from each of the server and the receiver is returned to the data of the reception status dedicated packet of the receiver and the server. By server,
The error rate can be calculated in each of the receivers.

Also, in the bidirectional reception system according to the ninth configuration of the present invention, the receiver includes a dedicated uplink packet having a predetermined data sequence in the transmission signal, and the server determines the transmission time from each receiver during transmission. The time division multiple access communication method (Time Division Multiple Acces
(s: TDMA) transmission order.

The bidirectional receiving system according to the tenth configuration of the present invention includes a dedicated packet for enabling the server to measure the time transmitted to each receiver and returned, and the server responds to the information. The order of transmission of the time division multiple access (TDMA) of each receiver is controlled.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described with reference to the drawings showing the embodiments.

Embodiment 1 FIG. 1 is a block diagram showing the configuration of the first embodiment of the bidirectional receiving system of the present invention. In the figure, reference numeral 1 denotes a server, which is a device on the broadcast station side that sends a plurality of TV signals (including digital TV signals) and data signals to a plurality of terminals, and 2, 3, and 4 denote the plurality of TV signals and data. The bidirectional receivers A, B, C, and 5, which are terminals for receiving signals, are transmission lines for transmitting these signals.

The inside of the server 1 has the following configuration. Reference numeral 6 denotes a QAM modulator in a server that QAM-modulates and transmits the plurality of TV signals and data signals, 7 denotes a transmission data processing circuit in a server that processes transmission data for performing various controls, and 8 denotes a transmission data in the server. A QPSK modulator in the server that QPSK modulates and transmits a signal from the processing circuit 7. A TPS 9 in the server that receives TDMA data for performing various controls and performs QPSK demodulation.
DMA-QPSK demodulator 10 is TDMA in the server
A reception data processing circuit in the server for processing the data signal demodulated by the QPSK demodulator 9; 7, 8, 9, 10
Are collectively called control channel blocks for the six main channel blocks. Also, 50 is Q
AGC data signal path for AM, 51 is QPSK in server
AGC data signal path for APS, 52 is A for QPSK in server
The GC detection output path 53 is an intra-server packet delivery path.

Next, the insides of the bidirectional receivers 2, 3, and 4 have the following configuration. 11 is the above plurality of TVs
QA in a receiver that receives signals and data signals and performs QAM demodulation
M demodulator, 12 is a signal processing circuit in the subsequent stage for performing processing such as MPEG decoding of this signal, 13 is a QPSK demodulator in a receiver that receives data for performing various controls and QPSK demodulates, and 14 is a QPSK demodulator in the receiver. Demodulator 1
A receiving data processing circuit in the receiver for processing the data signal demodulated in 3; a transmission data processing circuit in the receiver for processing transmission data for performing various controls; and a signal from the transmission data processing circuit in the receiver QP
TDMA-QPS in receiver that performs SK modulation and TDMA transmission
K modulator. 13, 14, 15, 16 are 11, 1
The two main channel blocks are collectively called a control channel block. 54 is QAM
AGC detection output path for 55, AG for QPSK in receiver
A C detection output path, 56 is an AGC data signal path for QPSK in the receiver, and 57 is a packet transfer path in the receiver.

Next, the operation of the first to fifth embodiments will be described. Embodiment 1 FIG. Here, the main channel block Q
The transmission from the server 1 to the plurality of bidirectional receivers A2, B3, and C4 on the AM modulation / demodulation path will be described. Also, the amplitude level of the received signal is used for a dedicated uplink packet for sending the reception status of the bidirectional receivers A2, B3, and C4 to the server 1.

First, the server 1 modulates a plurality of TV signals and data signals in the server QAM modulator 6, and transmits the modulated signals to the respective bidirectional receivers A 2, B 3, C 4 via the transmission line 5. Each of the two-way receivers A2, B3, and C4 demodulates this signal in the QAM demodulator 11 in the receiver, and outputs the TV
The signal is sent to the signal processing circuit 12. At this time, conventionally, the level of the transmitted transmission signal is detected by the signal amplitude detector in the QAM demodulator 11 in the receiver and the level is automatically corrected (hereinafter, this action is referred to as Automatic Gain Control: AGC).
Control), the level information of the detected transmission signal is sent to the transmission data processing circuit 15 in the receiver via the AGC detection output path for QAM 54, and this information is inserted into the dedicated uplink packet, and the TDMA-QPSK in the receiver is inserted. Modulator 16 modulates M and transmits to server 1 by TDMA. Upon receiving this signal, the server 1 demodulates the data in the TDMA-QPSK demodulator 9 in the server, and further performs a reception data processing circuit 10 in the server at a subsequent stage.
In accordance with the value of the level information of the transmission signal calculated by, for example, extracting the dedicated uplink packet and averaging the data from each of the two-way receivers A2, B3, and C4.
Through the AGC data signal path 50 for use, the QAM modulator 6 in the server varies the level of the modulated signal to be transmitted to each of the bidirectional receivers A2, B3, and C4.

As described above, the server 1 monitors the reception signal levels of the respective bidirectional receivers A2, B3, and C4, and varies the level of the transmission signal from the server 1 according to the value. Therefore, the reception signal levels of the bidirectional receivers A2, B3, and C4 do not greatly deviate from the center value as compared with the related art, and the reception signal pull-in time is shortened.

Embodiment 2 FIG. Here, transmission from the server 1 to the plurality of bidirectional receivers A2, B3, and C4 on the QPSK modulation / demodulation path that is a control channel block will be described. Also, the amplitude level of the received signal is used for a dedicated uplink packet for sending the reception status of the bidirectional receivers A2, B3, and C4 to the server 1.

First, the server 1 performs protocol processing and the like on a data signal for controlling the respective bidirectional receivers A2, B3 and C4 in the transmission data processing circuit 7 in the server, and modulates it in the QPSK modulator 8 in the server. And transmission line 5
To each of the two-way receivers A2, B3, C4. Each of the bidirectional receivers A2, B3, and C4 demodulates this signal in the in-receiver QPSK demodulator 13 and sends the signal to the subsequent-stage in-receiver received data processing circuit 14. At this time, the level of the transmitted signal is detected by the signal amplitude detector in the QPSK demodulator 13 in the receiver, and the AGC as described above is performed.
Control, the level information of the detected transmission signal is sent to the transmission data processing circuit 15 in the receiver via the AGC detection output path 55 for QPSK in the receiver, and this information is inserted into a dedicated uplink packet, and the TDMA in the receiver is inserted. -Modulate by the QPSK modulator 16 and transmit to the server 1 by TDMA. Upon receiving this signal, the server 1 receives the TDMA-QPSK in the server.
The data is demodulated by the demodulator 9 and the dedicated upstream packet is extracted by the received data processing circuit 10 in the server at the subsequent stage, and the data is calculated by averaging the data from the respective bidirectional receivers A2, B3 and C4. In accordance with the value of the level information of the transmitted signal, the modulation signal level to be transmitted to each of the bidirectional receivers A2, B3, and C4 in the QPSK modulator 8 in the server via the AGC data signal path 51 for QPSK in the server. Make it variable.

As described above, the server 1 monitors the received signal level of each of the bidirectional receivers A2, B3, and C4, and varies the level of the transmission signal from the server 1 according to the value. Therefore, the reception signal levels of the bidirectional receivers A2, B3, and C4 do not greatly deviate from the center value as compared with the related art, and the reception signal pull-in time is shortened.

Embodiment 3 FIG. Here, transmission from a plurality of bidirectional receivers A2, B3, and C4 to the server 1 in a QPSK modulation / demodulation path, which is a control channel block, will be described. Also, the amplitude level of the received signal is used for a dedicated downlink packet for sending the reception status of the server 1 to the bidirectional receivers A2, B3, and C4.

First, a data signal to be transmitted to the server 1 is subjected to protocol processing and the like by a transmission data processing circuit 15 in the receiver by the bidirectional receiver A2, and TDMA-QPSK in the receiver is processed.
The signal is modulated by the modulator 16 and transmitted to the server 1 by TDMA. Upon receiving this signal, the server 1 transmits the TDMA-QPS in the server.
The signal is demodulated by the K demodulator 9 and sent to the received data processing circuit 10 in the server at the subsequent stage. At this time, TDMA-QP in the server
The signal amplitude detector in the SK demodulator 9 detects the level of the transmitted transmission signal and corrects the level. The level information of the detected transmission signal is stored in the APS for QPSK in the server.
The information is sent to the transmission data processing circuit 7 in the server via the GC detection output path 52, and this information is inserted into the dedicated downlink packet.
The signal is modulated by the QPSK transmitter in the server and transmitted to the bidirectional receiver A2. The bidirectional receiver A2 that has received this signal demodulates the signal with the QPSK demodulator 13 in the receiver, extracts the dedicated downlink packet in the reception data processing circuit 14 in the receiver at the subsequent stage, and converts the value into the level information value of the transmission signal. Accordingly, the level of the modulation signal to be transmitted to server 1 is varied by TDMA-QPSK modulator 16 in the receiver via AGC data signal path 56 for QPSK in the receiver. Other two-way receiver B
3 and C4.

As described above, the bidirectional receivers A2, B3,
C4 monitors the server reception signal level of the modulation signal transmitted to the server 1, and according to the value, the bidirectional receiver A2,
Since B3 and C4 individually change the level of the transmission signal, the reception signal level of the server 1 does not greatly deviate from the center value as compared with the related art, and the reception signal pull-in time is shortened. . Example 3
Since the server 1 performs TDMA reception, it is necessary to pull in a burst-like signal instantaneously, and it is very significant that the pull-in time of the received signal is shortened.

The use of the carrier frequency of the received signal, the frequency of the clock, the phase error, and the error rate for the data of the packet dedicated to the reception status is almost the same as the use of the amplitude level of the received signal. Therefore, the description is omitted here.

Embodiment 4 FIG. Here, each of the bidirectional receivers A2, B3, and C4 transmits a dedicated uplink packet having a predetermined data sequence to the server 1, and
Describes the transmission time from each of the two-way receivers A2, B3, and C4 and controls the TDMA transmission order accordingly.

First, each bidirectional receiver A2, B3, C4
Thus, a dedicated uplink packet having a predetermined data sequence is inserted by the transmission data processing circuit 15 in the receiver, and is modulated by the TDMA-QPSK modulator 16 in the receiver.
TDMA transmission to the server 1 is performed. The server 1 receiving this signal demodulates the signal in the TDMA-QPSK demodulator 9 in the server, and further extracts the dedicated uplink packet in the reception data processing circuit 10 in the server at the subsequent stage. The time transmitted from B3 and C4 can be grasped. Based on this information, the transmission order of each of the two-way receivers A2, B3, and C4 in TDMA communication is reset so that collision does not occur, and the information is transmitted to each of the two-way receivers A2, B3, and C4.

As described above, the server 1 observes the transmission time from each of the two-way receivers A2, B3, and C4, so that each of the two-way receivers A2, T2 in the TDMA communication.
Since the transmission order of B3 and C4 is determined again, collisions are less likely to occur and data errors are reduced. Alternatively, the number of guard bands for collision prevention can be reduced, thereby improving the data transmission efficiency.

Embodiment 5 FIG. Here, the server 1 includes a dedicated downlink packet for transmitting data to each of the two-way receivers A2, B3, and C4 and enabling measurement of the time to be returned. Receiver A
Control of the TDMA transmission order of 2, B3 and C4 will be described.

First, the server 1 sends a dedicated downlink packet for enabling the response time from each of the two-way receivers A2, B3, and C4 to be measured.
, Modulated by the QPSK modulator 8 in the server, and transmitted to the respective bidirectional receivers A2, B3, C4 via the transmission path 5. Each of the bidirectional receivers A2, B3, and C4 demodulates this signal in the in-receiver QPSK demodulator 13 and sends the signal to the subsequent-stage in-receiver received data processing circuit 14. And
The information of the dedicated downlink packet is inserted into the dedicated uplink packet by the transmission data processing circuit 15 in the receiver via the packet transfer path 57 in the receiver, modulated by the TDMA-QPSK modulator 16 in the receiver, and transmitted to the server 1 by TDMA. Upon receiving this signal, the server 1 demodulates the signal in the TDMA-QPSK demodulator 9 in the server, extracts the dedicated uplink packet in the received data processing circuit 10 in the server at the subsequent stage, and transmits the packet through the packet delivery path 53 in the server. By sending the signal to the internal transmission data processing circuit 7, the time when the signal transmitted from the server 1 is returned from each of the two-way receivers A2, B3, C4 can be grasped. Based on this information, the transmission order of each of the two-way receivers A2, B3, and C4 in TDMA communication is reset so that collision does not occur, and the information is transmitted to each of the two-way receivers A2, B3, and C4.

As described above, the server 1 observes the response time from each of the two-way receivers A2, B3, and C4, thereby enabling each of the two-way receivers A2, B in the TDMA communication.
3. Since the transmission order of C4 is determined again, collisions are less likely to occur and data errors are reduced. Or there is less guard band for collision measures than this,
Data transmission efficiency is improved. In addition, since predetermined data is not used unlike the fourth embodiment, data transmission efficiency is further improved.

[0047]

Since the present invention is configured as described above, it has the following effects.

According to the bidirectional receiving system of the first configuration of the present invention, the reception signal pull-in time of a plurality of receivers can be shortened.

According to the bidirectional receiving system of the second configuration of the present invention, the reception signal pull-in time of the server can be shortened. Also, for example, a server specified by DAVIIC performs TDMA reception, so it is necessary to pull in a burst signal instantaneously. Since the reception time of a received signal is shortened, the number of receivers connected to the server may be increased. it can.

According to the bidirectional receiving system of the third configuration of the present invention, it is possible to shorten the reception signal pull-in time of a plurality of receivers and servers.

According to the bidirectional receiving system of the fourth configuration of the present invention, the reception signal pull-in time (AGC control time) of a plurality of receivers and servers can be shortened.

According to the bidirectional reception system of the fifth configuration of the present invention, the reception signal pull-in time (regeneration time of the carrier wave) of the plurality of receivers and the server can be shortened, and the reception has not been possible conventionally. It becomes possible to receive even a signal having a large carrier frequency and phase shift.

According to the bidirectional reception system of the sixth configuration of the present invention, the reception signal pull-in time (clock recovery time) of the plurality of receivers and the server can be shortened, and the reception has not been possible conventionally. It becomes possible to receive even a signal having a large clock frequency and phase shift.

According to the bidirectional receiving system of the seventh configuration of the present invention, since the ultimate purpose of transmission / reception is how to eliminate errors, it is the most reliable method to use the error rate for the receiving situation. .

According to the bidirectional receiving system of the eighth configuration of the present invention, since the transmission / reception error rate is checked, errors can be reduced more than in the sixth invention, and a predetermined value such as in the seventh invention is determined. Since no data sequence is provided, data transmission efficiency can be improved.

According to the bidirectional receiving system of the ninth configuration of the present invention, the possibility of collision in TDMA communication is reduced, and data errors are reduced. Alternatively, the number of guard bands for collision prevention can be reduced, thereby improving the data transmission efficiency.

According to the bidirectional receiving system of the tenth configuration of the present invention, the possibility of occurrence of collision in TDMA communication is reduced, and data errors are reduced.
Alternatively, the number of guard bands for collision prevention can be reduced, thereby improving the data transmission efficiency. In addition, since there is no predetermined data sequence as in the ninth configuration of the present invention, data transmission efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a bidirectional receiving system according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a bidirectional CATV receiving system which is an example of a conventional bidirectional receiving system.

[Explanation of symbols]

1 server, 2, 3, 4 bidirectional receivers A, B, C, 5
Transmission line, 6 server QAM modulator, 7 server transmission data processing circuit, 8 server QPSK modulator, 9 server TDMA-QPSK demodulator, 10 server reception data processing circuit, 11 receiver QAM demodulator, 13
QPSK demodulator in receiver, 14 Receive data processing circuit in receiver, 15 Transmit data processing circuit in receiver, 16 TDMA-QPSK modulator in receiver, AG for 50 QAM
C data signal path, 51 AGC data signal path for QPSK in server, 52 AGC detection output path for QPSK in server, 53 Packet transfer path in server, 54 Q
AGC detection output path for AM, 55 AGC detection output path for QPSK in receiver, 56 AGC for QPSK in receiver
Data signal path, 57 Packet transfer path in the receiver.

Claims (10)

[Claims] 1. A server for transmitting a plurality of TV signals (including digital TV signals) and data signals to a transmission path, a plurality of receivers for receiving the signals from the transmission path, and
In a two-way receiving system having a transmission function of transmitting uplink data signals from a plurality of receivers to a transmission path and a server having a function of receiving the uplink data signal, a dedicated uplink packet for transmitting the reception status of the receiver to the server. And a transmission state of a server is changed according to the information. 2. The apparatus according to claim 1, further comprising a dedicated downlink packet for transmitting the reception status of the server to a plurality of receivers, and changing the transmission status of each receiver according to the information. Receiving system. 3. A dedicated uplink packet for sending the reception status of the receiver to the server, and a dedicated downlink packet for sending the reception status of the server to the receiver, and the transmission status of the server according to the information. 2. The bidirectional reception system according to claim 1, wherein the transmission state of the receiver is changed. 4. The two-way receiving system according to claim 3, wherein the amplitude level of the received signal is used for the data of the reception status dedicated packet of the receiver and the server. 5. The bidirectional reception system according to claim 3, wherein the frequency of the carrier of the received signal and the phase error are used for the data of the packet dedicated to the reception status of the receiver and the server. 6. The bidirectional receiving system according to claim 3, wherein a frequency and a phase error of a clock of a received signal are used for data of a packet dedicated to the reception status of the receiver and the server. 7. The bidirectional reception according to claim 3, wherein a predetermined data sequence is used for the data of the reception status dedicated packet of the receiver and the server, and the error rate can be calculated in each of the receiver and the server. system. 8. The server and the receiver can calculate the error rate by using the same data as the data transmitted from each of the server and the receiver and returning the data of the packet dedicated to the reception status of the receiver and the server. The two-way receiving system according to claim 3, wherein: 9. A receiver comprises a dedicated uplink packet having a predetermined data sequence in a transmission signal, and a server performs time-division multiple access communication of each receiver according to a transmission time from each receiver. Time Division Multiple Access:
2. The method according to claim 1, wherein the order of TDMA transmission is controlled.
A two-way receiving system as described. 10. A server includes a dedicated packet for enabling a server to transmit and return a time to each of the receivers, and the server performs time-division multiple access communication of each of the receivers according to the information. Time Division Multiple Access: TDM
2. The bidirectional receiving system according to claim 1, wherein the order of the transmission in A) is controlled.