JPH10322675A - Data communication system device, center device and terminal device - Google Patents

Abstract

(57) [Summary] To obtain an optimal coefficient according to a filter configuration and to share a filter for pre-equalization and a filter for band limitation. When a pre-equalization is set, a test signal generation circuit is set.
14 generates filter configuration information. This filter configuration information is inserted into the uplink signal by the uplink signal transmission block 15 and transmitted from the duplexer 11 as a test modulation signal. The terminal filter configuration identification circuit 8 of the center device 2 extracts filter configuration information included in the test modulation signal, and the pre-equalization coefficient calculation circuit calculates a coefficient according to the filter configuration information. This coefficient is inserted into the downlink signal and transmitted to the cable network 1. The tap coefficient control circuit 13 of the terminal device 3 sets the pre-equalization filter 17 using the coefficient transmitted from the center device. As a result, optimal coefficients corresponding to the configuration of the pre-equalization filter 17 are set, and sufficient pre-equalization performance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system device, a center device, and a terminal device suitable for a data communication system using a CATV network.

[0002]

2. Description of the Related Art In recent years, CATV (cable television) using a coaxial cable, an optical fiber cable, or the like as a transmission path has become widespread. Paying attention to the large capacity and bidirectionality of CATV, the use of CATV for multimedia has recently been considered. In addition, taking advantage of the fact that CATV has been increased in scale and multi-channel, CT
Asymmetric data communication systems using an AV network as a transmission path are also being constructed. For an overview of an asymmetric data communication system using a CATV network, see the document "Introduction to Cable TV Technology-From Basics to Applications-" (Corona)
(Edited by the Japan Electronic Opportunity Manufacturers Association, CATV Technical Committee) and the like.

In CATV, a center device and each terminal device are connected via a cable network.
In CATV, a pre-equalization system is sometimes employed to remove interference in a transmission path such as a cable network. In the pre-equalization system, each terminal device is provided with a pre-equalization filter to remove waveform distortion during transmission of uplink data.

[0004] Computation of the filter coefficients in each terminal device requires a relatively large computing capability. For this reason, CA
In the TV pre-equalization system, the pre-equalization filter is provided in the terminal device that is the transmission source, but the tap device of the pre-equalization filter is calculated by the center device that is the receiving side. That is, the center device calculates a tap coefficient according to the waveform distortion of a predetermined uplink signal from the terminal device, and transmits the calculated tap coefficient to the terminal device. The terminal apparatus sets the transmitted tap coefficient in the pre-equalization filter to reduce the waveform distortion of the uplink signal.

[0005] However, the center device calculates a coefficient with a fixed number of taps and a fixed tap interval. On the other hand, the number of taps and the tap interval of the pre-equalization filter provided in each terminal device are different for each terminal device. Therefore, each terminal device must extract and use only the tap coefficients suitable for its own pre-equalization filter from among the tap coefficients transmitted from the center device, or interpolate and use the transmitted tap coefficients. There are things you have to do. For this reason, the characteristics of the pre-equalization filter of the terminal device may not be sufficiently exhibited.

[0006] Further, the terminal device side uses an FIR (finite impulse filter) as a port-off filter for limiting the band of a transmission signal.
se response) often has a filter. It is not impossible that the roll-off FIR filter is also used as a pre-equalization filter so that the band limiting process and the pre-equalization process can be performed simultaneously. However, since the center device indicates a coefficient dedicated to pre-equalization, when the roll-off filter and the pre-equalization filter are shared, the roll-off filter is used based on the coefficient transmitted on the terminal device side. It is necessary to calculate a new coefficient that satisfies the characteristics and the pre-equalization characteristics. This calculation requires an extremely complicated calculation, and the provision of such a calculation function increases the circuit scale of the terminal device, resulting in an increase in cost.

[0007] In addition, providing the terminal device with not only a roll-off filter but also an FIR filter dedicated to pre-equalization in accordance with the coefficient transmitted from the center device naturally increases the circuit scale.

[0008]

As described above, conventionally, C
The pre-equalization system in the ATV has a problem that the characteristics of the pre-equalization filter of the terminal device may not be fully utilized. Further, adopting the pre-equalization system in CATV also has a problem that the circuit scale in the terminal device is increased and the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and enables a center device to transmit a coefficient corresponding to a configuration of a filter of a terminal device. It is an object of the present invention to provide a data communication system device, a center device, and a terminal device that can obtain the above.

Further, the present invention enables a center device to transmit a coefficient according to the configuration of a filter of a terminal device, thereby sharing a filter for pre-equalization and a filter for band limitation in the terminal device. It is an object of the present invention to provide a data communication system device, a center device, and a terminal device capable of reducing the circuit scale by making it possible.

[0011]

A terminal device according to a first aspect of the present invention is provided in an upstream transmission system for transmitting an upstream signal to a center device to a predetermined transmission line, and performs pre-equalization processing and bandwidth control. A filter for performing at least a pre-equalization process of the limiting process, information transmitting means for transmitting, as the uplink signal, information enabling the center device to grasp the configuration of the filter; and And a filter setting unit that sets the filter using information of a coefficient included in a downlink signal transmitted through the transmission path of (1). The center device according to claim 2 of the present invention, Extracting and extracting information that enables the configuration of the filter included in an uplink signal transmitted via a predetermined transmission path from a terminal device equipped with the filter to be grasped and extracted Filter configuration detecting means for detecting the configuration of the filter provided in the terminal device based on the obtained information, and coefficient calculation for calculating the coefficient of the filter provided in the terminal device based on the detection result of the filter configuration detecting device And transmitting means for transmitting the information of the coefficient calculated by the coefficient calculating means to the terminal device via the predetermined transmission line.
The data communication system device according to the terminal device,
A filter that is provided in an uplink transmission system for transmitting an uplink signal to a center device to a predetermined transmission path and performs at least a pre-equalization process of a pre-equalization process and a band limiting process; Information transmitting means for transmitting information enabling the configuration to be grasped as the upstream signal, and using information of a coefficient included in a downstream signal transmitted from the center device via the predetermined transmission path, A filter setting means for setting a filter, wherein in the center device, information enabling to grasp the configuration of the filter included in an uplink signal transmitted from the terminal device via the predetermined transmission path is provided. Filter configuration detecting means for extracting and detecting the configuration of the filter provided in the terminal device based on the extracted information; Coefficient calculating means for calculating a coefficient of the filter provided in the terminal device based on a detection result of the detecting means, and information of the coefficient calculated by the coefficient calculating means is transmitted to the terminal device via the predetermined transmission path. And sending means for performing the above.

According to the first aspect of the present invention, the information transmitting means transmits, as an uplink signal, information which enables the center device to grasp the configuration of the filter. The center device calculates the coefficient of the filter based on the uplink signal and transmits it as a downlink signal. The filter setting means sets a filter using the information on the coefficients included in the downlink signal. As a result, the filter is set with the optimum coefficient according to the configuration of the filter.

[0013] According to a second aspect of the present invention, the filter configuration detecting means extracts information enabling the configuration of the filter included in the uplink signal from the terminal device to be grasped, and based on the extracted information, detects the filter configuration. Detect configuration. The coefficient calculating means calculates a coefficient corresponding to the detected configuration of the filter. The calculated coefficient is sent to the terminal device via the transmission path by the sending means.

[0014] In claim 3 of the present invention, the information transmitting means transmits information that allows the configuration of the filter to be grasped as an upstream signal. The filter configuration detecting means of the center device extracts information that allows the configuration of the filter included in the uplink signal to be grasped, and detects the configuration of the filter based on the extracted information. The coefficient calculating means calculates a coefficient corresponding to the detected configuration of the filter. The calculated coefficient is sent to the terminal device via the transmission path by the sending means. The filter setting means of the terminal device sets a filter by using information of a coefficient included in the downlink signal. As a result, the optimum coefficient is set in the filter according to the configuration of the filter.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a data communication system device according to the present invention.

In FIG. 1, a center device 2 and a terminal device 3 are connected by a cable network 1. In the present embodiment, each terminal device 3 transmits a test modulation signal to the center device 2 as an uplink signal, and the center device 2 calculates a filter coefficient using the transmitted test modulation signal, thereby allowing each terminal device 3 to calculate a filter coefficient. A coefficient corresponding to the device is obtained.

The terminal device 3 includes a duplexer 11, a downlink signal receiving block 12, a tap coefficient control circuit 13, a test signal generation circuit 1,
4. It is composed of an upstream signal transmission block 15, a band limiting filter 16, a pre-equalization filter 17, and a modulation block 18. The demultiplexer 11 supplies the downstream modulated signal from the cable network 1 to the downstream signal receiving block 12 and sends the upstream modulated signal supplied from the modulation block 18 to the cable network 1. The downlink signal reception block 12 extracts tap coefficient information and the like from data obtained by demodulating the received downlink signal. The tap coefficient control circuit 13 controls the pre-equalization filter 17 based on information on tap coefficients from the downlink signal receiving block 12.

In this embodiment, a test signal generation circuit 14 is provided. The test signal generation circuit 14 generates data serving as a source of a test modulation signal. The data generated by the test signal generation circuit 14 also includes filter configuration information such as the number of taps and the tap interval of the pre-equalization filter 17. The data from the test signal generation circuit 14 is supplied to the upstream signal transmission block 15.

The upstream signal transmission block 15 converts the data supplied from the test signal generation circuit 14 or ordinary communication data into a bit stream that can be transmitted in the cable network 1 and outputs the same as an upstream signal. The band limiting filter 16 performs a band limiting process on the bit stream from the upstream signal transmission block 15 according to the bandwidth of the upstream transmission channel, and outputs the result to the pre-equalization filter 17.

The pre-equalization filter 17 is a tap coefficient control circuit.
The tap coefficient is set by 13 and the band limiting filter
The 16 outputs are equalized in waveform and output to the modulation block 18. The modulation block 18 modulates the upstream signal from the pre-equalization filter 17 and outputs the modulated signal to the duplexer 11.

The cable network 1 is, for example, a CATV
A transmission path constituted by a network or the like,
Data transmission between the terminal device 3 and the terminal device 3.

The center device 2 comprises a duplexer 5, an upstream signal receiving block 6, a pre-equalization coefficient calculation circuit 7, a terminal filter configuration identification circuit 8, and a tap coefficient transmission circuit 9. The duplexer 5 supplies the upstream modulated signal transmitted through the cable network 1 to the upstream signal receiving block 6. The uplink signal receiving block 6 demodulates the uplink modulated signal and outputs the demodulated signal to the pre-equalization coefficient calculation circuit 7 and the terminal filter configuration identification circuit 8. The terminal filter configuration identification circuit 8 extracts filter configuration information indicating a tap interval, a tap coefficient, and the like of the pre-equalization filter 17 from the input demodulated signal, and outputs the extracted filter configuration information to the pre-equalization coefficient calculation circuit 7. It has become.

The pre-equalization coefficient calculation circuit 7 collects waveform data of the input demodulated signal, and calculates tap coefficients of the pre-equalization filter 17 based on the waveform data. In the present embodiment, the pre-equalization coefficient calculation circuit 7 can obtain the maximum effect by the pre-equalization filter 17 provided in each terminal device based on the filter configuration information transmitted from the terminal device 3. A possible coefficient is calculated for each terminal device.

The pre-equalization coefficient calculation circuit 7 outputs the obtained tap coefficients to the tap coefficient transmission circuit 9 as tap coefficient information. The tap coefficient transmission circuit 9 inserts the input tap coefficient information into the downlink data, performs predetermined processing such as modulation, and outputs the result to the duplexer 5 as a downlink modulation signal. The duplexer 5 sends out the input downstream modulated signal to the cable network 1.

Next, the operation of the embodiment configured as described above will be described.

The setting for the pre-equalization processing of the terminal device 3 (hereinafter, referred to as pre-equalization setting) is performed at the time of registration of the terminal device 3 and at a predetermined timing. At the time of the pre-equalization setting, the test signal generation circuit 14 of the terminal device 3 generates a bit stream that is a source of the test modulation signal. This bit stream includes filter configuration information indicating the configuration of the filter such as the number of taps and the tap interval of the pre-equalization filter 17 of the terminal device 3.

The bit stream from the test signal generation circuit 14 is supplied to the upstream signal transmission block 15, inserted into the upstream signal, and supplied to the band limiting filter 16. The upstream signal is supplied to the pre-equalization filter 17 after the upstream signal is band-limited by the band limiting filter 16 according to the bandwidth of the upstream transmission channel of the cable network 1.

It is now assumed that the terminal device 3 has been registered. In this case, the tap coefficient of the pre-equalization filter 17 has not been set yet, and the uplink signal input to the pre-equalization filter 17 is supplied to the modulation block 18 without being equalized. The upstream signal is modulated by the modulation block 18, and the upstream modulation signal (test modulation signal) is transmitted from the duplexer 11 to the cable network 1.

The test modulation signal transmitted to the cable network 1 reaches the center device 2 in a distorted state due to the frequency characteristics of the transmission channel, the influence of reflection, and the like.

The branching filter 5 of the center apparatus 2 supplies the test modulation signal transmitted from the terminal apparatus 3 via the cable network 1 to the upstream signal receiving block 6.
The uplink signal receiving block 6 demodulates the test modulation signal, and supplies the demodulated output to the pre-equalization coefficient calculation circuit 7 and the terminal filter configuration identification circuit 8. The terminal filter configuration identification circuit 8 extracts filter configuration information indicating the tap interval and the number of taps of the pre-equalization filter 17 from the input demodulated signal, and supplies the extracted filter configuration information to the pre-equalization coefficient calculation circuit 7.

The pre-equalization coefficient calculation circuit 7 collects the waveform data of the demodulated signal from the uplink signal receiving block 6 and matches the tap interval and the number of taps obtained from the filter configuration information with the pre-equalization coefficient of the terminal device 3. A tap coefficient for the equalization filter 17 is calculated. This tap coefficient has a value that allows the pre-equalization filter 17 of the terminal device 3 that has transmitted the test modulation signal to sufficiently exhibit the equalization capability.

The calculated coefficients are supplied to the tap coefficient transmitting circuit 9 as tap coefficient information, and inserted into other downlink data. The downlink data is subjected to predetermined processing such as modulation, and the downlink modulation signal is transmitted from the duplexer 5 to the cable network 1.

The downstream modulated signal including the tap coefficient information reaches the terminal device 3 via the cable network 1 and is supplied to the downstream signal receiving block 12 by the demultiplexer 11.
The downlink signal receiving block 12 demodulates the downlink modulated signal and extracts tap coefficient information for the terminal device 3. The tap coefficient information is given to the tap coefficient control circuit 13, and the tap coefficient control circuit 13
Set 17 tap coefficients. As a result, in the subsequent communication processing, the pre-equalization filter 17 performs pre-equalization processing on the uplink signal using the set tap coefficients.

As described above, in the present embodiment, the terminal device 3 transmits a test modulation signal for performing pre-equalization setting, and the center device 2 responds to the filter configuration information inserted in the test modulation signal. The calculated tap coefficients are transmitted to the terminal device 3, and the optimum tap coefficients can be calculated for each terminal device. As a result, a sufficient effect of reducing waveform distortion can be expected by the pre-equalization processing in the terminal device 3.

In the above-described embodiment, an example has been described in which the terminal apparatus 3 transmits a test modulation signal including filter configuration information. However, the information included in the test modulation signal includes the filter configuration of the terminal apparatus in the center apparatus. Any information may be used as long as the information can directly grasp the number of taps of the pre-equalization filter. Further, the filter configuration information may be transmitted at a different time from the test modulation signal. If the filter configuration information is transmitted once at the time of registration, it need not be transmitted every time.

FIG. 2 is a block diagram showing another embodiment of the present invention. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. This embodiment shows an example in which terminal code information is used as information to be inserted into a test modulation signal.

In FIG. 2, the terminal device 28 differs from the terminal device 3 in FIG. 1 in that a terminal code generation circuit 29 is provided instead of the test signal generation circuit 14. The center device 21 is provided with a terminal code identification circuit 22 instead of the terminal filter configuration identification circuit 8 and a server access circuit 23 in FIG.
Is different from the center device 2.

In the present embodiment, the center device 21
Has means for accessing a database indicating the correspondence between the code number information unique to each terminal device and the configuration of the pre-equalization filter, and extracts the code number information contained in the uplink modulation signal from the terminal device. Thus, a coefficient corresponding to each terminal device is generated.

That is, the terminal code generation circuit 29 of the terminal device 28
Generates the code number information unique to the terminal device, which is the source of the test modulation signal, and outputs it to the uplink signal transmission block 15. The uplink signal transmission block 15 inserts the code number information into the uplink signal and supplies it to the band limiting filter 16 when pre-equalization is set.

On the other hand, the terminal code identification circuit 22 of the center device 21 receives the demodulated signal of the uplink signal from the uplink signal receiving block 6, extracts the code number information indicating the terminal device which has transmitted the test modulation signal, and performs server access. The signal is output to the circuit 23. The server access circuit 23 recognizes the manufacturer of the terminal device that has transmitted the test modulation signal based on the information of the code number, and transmits and receives data to and from the server 25 via the network 24. The information on the number of taps and the tap interval of the optimization filter 17 is taken in. Network 24 is, for example, the Internet or other similar networks.

The server 25 has a database 26,
Data can be transmitted to and received from the server access circuit 23 via the network 24. The database 26 stores unique code number information of all terminal devices manufactured by a predetermined maker and their filter configuration information in association with each other. The server access circuit 23 is a network
The filter configuration information stored in the database 26 is downloaded via the 24 and supplied to the pre-equalization coefficient calculation circuit 7.

Next, the operation of the embodiment configured as described above will be described.

When pre-equalization is set, the terminal code generation circuit
29 generates code number information unique to the terminal device as a source of the test modulation signal and outputs the code number information to the uplink signal transmission block 15.
The code number information is inserted into the uplink signal and supplied to the band limiting filter 16. The upstream signal is band-limited by the band-limiting filter 16 and provided to the modulation block 18 via the pre-equalization filter 17. The modulation signal is modulated in the modulation block 18, and the modulation signal (test modulation signal) is transmitted to the cable network 1 via the branching filter 11.

Also in the present embodiment, the test modulation signal transmitted to the cable network 1 reaches the center device 21 in a distorted state due to the influence of the frequency characteristics and reflection of the transmission channel, and the like.

The test modulation signal is supplied to the upstream signal receiving block 6 via the duplexer 5 of the center device 21. The uplink signal receiving block 6 demodulates the test modulation signal and supplies the demodulated signal to the terminal code identification circuit 22 and the pre-equalization coefficient calculation circuit 7. The terminal code identification circuit 22 extracts code number information unique to the terminal device that has transmitted the test modulation signal from the demodulated signal and outputs the extracted code number information to the server access circuit 23.

The server access circuit 23 specifies a manufacturer of the terminal device which has transmitted the test modulation signal from the input code number information, and stores a database 26 storing information on the terminal device manufactured by the manufacturer. 25 is accessed via the network 24.
The server access circuit 23 downloads, from the database 26, filter configuration information on the terminal device that has transmitted the test modulation signal, using the code number information for the search.

The filter configuration information downloaded by the server access circuit 23 is supplied to the pre-equalization coefficient calculation circuit 7. The pre-equalization coefficient calculation circuit 7 calculates tap coefficients based on the waveform data of the demodulated signal in accordance with the number of taps and the tap interval corresponding to the filter configuration information. As a result, the pre-equalization coefficient calculation circuit 7 can output the optimum tap coefficient for the terminal device that has transmitted the test modulation signal.

The calculated coefficients are supplied to the tap coefficient transmitting circuit 9 as tap coefficient information, inserted into other downlink data, subjected to modulation processing, and transmitted to the cable network 1 via the duplexer 5.

The downstream signal is supplied to the downstream signal receiving block 12 via the duplexer 11 of the terminal device 28. The downlink signal receiving block 12 demodulates the downlink signal, extracts a tap coefficient, and outputs the tap coefficient to the tap coefficient control circuit 13. The tap coefficient control circuit 13 sets the pre-equalization filter 17 using the tap coefficients extracted by the downlink signal receiving block 12.

The other operations are the same as those of the embodiment shown in FIG.

As described above, it is apparent that the same effects as those of the embodiment of FIG. 1 can be obtained in this embodiment.

In the present embodiment, the database in which the code number information of the terminal device and the filter configuration information are associated with each other has been described as being present in a server connected to another network. May have such a database.

FIG. 3 is a block diagram showing another embodiment of the present invention. 3, the same components as those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. The present embodiment is an example in which a filter for performing band limitation and a filter for performing pre-equalization processing are shared in a terminal device.

The terminal device 33 is provided with an FIR filter 34 instead of the band limiting filter 16 and the pre-equalization filter 17 and an additional tap coefficient initial value setting circuit 35 in FIG.
Is different from the terminal device 28 of FIG. The center device 31 differs from the center device 21 in FIG. 2 in that a pre-equalization and band limiting coefficient calculation circuit 32 is provided instead of the pre-equalization coefficient calculation circuit 7.

The FIR filter 34 of the terminal device 33 is used for both band limitation and pre-equalization. FIR filter 34
Is a tap coefficient control circuit 13 and a tap coefficient initial value setting circuit
Controlled by 35, the upstream signal from the upstream signal transmission block 15 is band-limited to the upstream channel band of the cable network 1, and subjected to an equalization process for removing waveform distortion during transmission, and modulated. Output to block 18.

Before the tap coefficients are transmitted from the center device 31, for example, at the time of registration of the terminal device 33, the tap coefficient control circuit 13 does not set the tap coefficients for the FIR filter 34. However, even in this case, it is necessary to limit the band of the uplink modulation signal. Therefore, the tap coefficient initial value setting circuit 35 sets the FIR filter 34 before the tap coefficient is set by the tap coefficient control circuit 13.
Is set. That is, the tap coefficient control circuit 13 sets a tap coefficient for the FIR filter 34 to limit the band of the upstream signal to the band of the upstream channel of the cable network 1.

The pre-equalization and band limiting coefficient calculation circuit 32 of the center device 31 is supplied with the demodulated signal from the upstream signal receiving block 6 and the filter configuration information from the server access circuit 23. The pre-equalization and band limiting coefficient calculation circuit 32 collects the waveform data of the input demodulated signal, and performs waveform equalization in the terminal device 33 according to the filter configuration information corresponding to the terminal device 33 that has transmitted the test modulation signal. Is calculated. Further, in the present embodiment, the pre-equalization and band limiting coefficient calculation circuit 32
Is based on the tap coefficients calculated for pre-equalization,
A new tap coefficient is calculated according to the band of the upstream channel of the cable network 1 so that the pre-equalization processing and the band limitation processing by the FIR filter 34 of the terminal device 33 can obtain the maximum effect. The calculated tap coefficients for pre-equalization and band limitation are supplied to a tap coefficient transmitting circuit 9.

Next, the operation of the embodiment configured as described above will be described.

The terminal code generation circuit 29 generates code number information unique to the terminal device for pre-equalization setting, and outputs the generated code number information to the uplink signal transmission block 15. Uplink signal transmission block 15
In, the code number information is inserted into the
It is supplied to the R filter 34. Now, assuming that the pre-equalization setting at the time of registration of the terminal device 33 is performed, the tap coefficient control circuit 13 has not set the tap coefficient for the FIR filter 34 at this time.

In this case, a tap coefficient initial value setting circuit
35 generates a coefficient for limiting the upstream signal to the band of the upstream channel of the cable network 1 and sets it as a tap coefficient of the FIR filter 34. Thereby, F
At this time, the IR filter 34 functions only as a band limiting filter. After the upstream signal is band-limited by the FIR filter 34, it is modulated in the modulation block 18 and transmitted from the duplexer 11 to the cable network 1.

The center device 31 receives the test modulation signal from the terminal device 33 via the duplexer 5 and demodulates the test modulation signal by the uplink signal receiving block 6. The demodulated signal from the upstream signal receiving block 6 is supplied to the terminal code identification circuit 22, where the code number information of the terminal device 33 that has transmitted the test modulation signal is extracted and supplied to the server access circuit 23. The server access circuit 23 downloads the filter configuration information of the FIR filter 34 of the terminal device 33 that has transmitted the test modulation signal from the server 25, and supplies it to the pre-equalization and band limiting coefficient calculation circuit 32.

The pre-equalization and band limiting coefficient calculation circuit 32
On the basis of the waveform data of the demodulated signal from the uplink signal receiving block 6 and the bandwidth of the uplink transmission channel of the cable network 1, tap coefficients according to the filter configuration information and tap coefficients corresponding to the tap intervals are calculated. That is, the tap coefficient from the pre-equalization and band limiting coefficient calculation circuit 32 is determined by the FIR filter 34 of the terminal device 33 that has transmitted the test modulation signal.
, The value enables the pre-equalization process and the band limiting process to be performed most effectively.

The tap coefficients from the pre-equalization and band-limiting coefficient calculation circuit 32 are supplied to a tap coefficient transmission circuit 9 and are transmitted from the duplexer 5 to the cable network 1 as a downstream modulated signal.
Sent to

The downstream modulated signal transmitted via the cable network 1 is supplied to the downstream signal receiving block 12 via the branching filter 11 of the terminal device 33, and is demodulated to extract tap coefficients. The tap coefficient is provided to the tap coefficient control circuit 13, and the tap coefficient control circuit 13 sets the tap coefficient of the FIR filter. Thereby, the FIR filter 34 can perform the pre-equalization process and the band limiting process on the upstream signal most effectively thereafter.

Other functions are the same as those of the embodiment shown in FIG.

As described above, also in this embodiment, FIG.
The same effect as that of the embodiment can be obtained. Furthermore,
In the present embodiment, the filter for band limitation and the filter for pre-equalization can be shared, and there is also an effect that the circuit scale can be significantly reduced.

Although the present embodiment has been described with respect to an example in which code number information is used as information included in a test modulation signal, it is apparent that the present embodiment may be applied to an example in which filter configuration information is used.

FIG. 4 is a block diagram showing a terminal device according to another embodiment of the present invention. 4, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the center device side is shown in FIG.
It is possible to employ a center device 31, a network 24 and a server 25 having the same configuration as the above. In the present embodiment, the tap coefficient control circuit 13 sets the tap coefficient for the FIR filter 34 to check whether or not the FIR filter 34 can reliably perform the band limitation. .

In FIG. 4, the terminal device 40 differs from the terminal device 33 in FIG. 3 in that an up signal transmission block 43 is used instead of the up signal transmission block 15 and a comparison circuit 41 and a reset circuit 42 are added. Uplink signal transmission block 43
Performs the same transmission processing as the uplink signal transmission block 15 and outputs a predetermined test signal to the FIR filter 34 immediately after the tap coefficient is set in the FIR filter 34 by the tap coefficient control circuit 13. I have.

The comparison circuit 41 is supplied with a test signal subjected to pre-equalization processing and band limitation processing by the FIR filter 34, measures the bandwidth of the test signal, and measures the bandwidth of the uplink transmission channel used by the terminal device 40. And outputs the comparison result to the reset circuit 42. The reset circuit 42 sets the tap coefficient of the FIR filter 34 to the tap coefficient only when the comparison result indicates that the bandwidth of the test signal from the FIR filter 34 is wider than the bandwidth of the upstream channel. The state before the change or the initial value set by the tap coefficient initial value setting circuit 35 is returned.

When the bandwidth is checked by the comparison circuit 41 and the reset circuit 42, the modulation block 18 is set in an operation stop state to prevent a signal exceeding the allowable band from leaking to the cable network. ing.

Next, the operation of the embodiment configured as described above will be described.

The operation until the tap coefficient included in the downlink signal transmitted from the center device is extracted in the downlink signal receiving block 12 and the tap coefficient control circuit 13 sets the tap coefficient in the FIR filter 34 is the same as that of FIG. Same as the form.

In the present embodiment, immediately after the tap coefficient control circuit 13 sets the tap coefficients for the FIR filter 34, the modulation block 18 is stopped, and the upstream signal transmission block 43 sends a predetermined test signal to the FI signal.
Output to the R filter 34. The FIR filter 34 performs pre-equalization processing and band limiting processing on the test signal using the tap coefficients set by the tap coefficient control circuit 13. FIR
The output of the filter 34 is supplied to the comparison circuit 41.

The comparison circuit 41 measures the bandwidth of the test signal from the FIR filter 34 and compares it with the bandwidth of the upstream channel. If the tap coefficient is correctly calculated in the center device, the FIR filter 34 performs pre-equalization processing according to distortion during transmission and performs band limiting processing according to the bandwidth of the uplink channel. However, when an error occurs in the calculation of the tap coefficient in the center device, the pre-equalization process and the band limiting process of the FIR filter 34 may not be appropriately performed. In this case, F
If the output of the IR filter 34 is output as it is, a signal exceeding the allowable band may be transmitted to the cable network.

Therefore, if the bandwidth of the output of the FIR filter 34 is wider than the bandwidth of the upstream channel, the reset circuit 42
The tap coefficient of the IR filter 34 is returned to the state before the tap coefficient change or the initial value set by the tap coefficient initial value setting circuit 35. As a result, the FIR filter 34 can reliably perform at least the band limiting process, and can prevent signals exceeding the allowable band from being transmitted to the cable network.

Other functions are the same as those of the embodiment shown in FIG.

As described above, in the present embodiment, the same effect as that of the embodiment of FIG. 3 can be obtained, and even if an error occurs in the calculation of the tap coefficient in the center device, the center band exceeds the allowable band. This has an effect that a signal can be prevented from being transmitted to the cable network.

FIG. 5 is a block diagram showing another embodiment of the present invention. 5, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. The present embodiment is also an example in which a signal exceeding the allowable band is prevented from being transmitted to the cable network.

In this embodiment, the center device side is shown in FIG.
It is possible to employ a center device 31, a network 24 and a server 25 having the same configuration as the above. In FIG. 5, the terminal device 50 differs from the terminal device 33 of FIG. 3 only in that a band estimation circuit 51 and a coefficient verification circuit 52 are added. Band estimation circuit
Reference numeral 51 denotes a tap coefficient included in the downlink signal transmitted from the center apparatus, which is given from the downlink signal reception block 12.
When the tap coefficient given from the downlink signal receiving block 12 is set in the FIR filter 34, the band estimation circuit 51
The bandwidth of the signal output from the IR filter 34 is estimated. The band estimation circuit 51 outputs the estimation result and the input tap coefficients to the coefficient verification circuit 52.

The coefficient verification circuit 52 compares the bandwidth indicated by the estimation result of the band estimation circuit 51 with the bandwidth of the uplink transmission channel used by the terminal device 50. When the bandwidth indicated by the estimation result is narrower than the bandwidth of the uplink transmission channel, the coefficient verification circuit 52 uses the tap coefficient transmitted from the center device as a tap coefficient control circuit.
The tap coefficient from the center device is not outputted to the tap coefficient control circuit 13 when the signal is output to the tap 13 and the band is wide.

The tap coefficient control circuit 13 includes a coefficient verification circuit 52
If the tap coefficient is supplied from, the tap coefficient is set in the FIR filter 34. If the tap coefficient is not supplied,
The setting of the FIR filter 34 is not performed. That is, in this case, the FIR filter 34 is maintained in the immediately preceding setting state or the initial setting state by the tap coefficient initial value setting circuit 35.

Next, the operation of the embodiment configured as described above will be described.

The operation until the tap coefficient included in the downlink signal transmitted from the center device in the downlink signal receiving block 12 is extracted is the same as that of the embodiment of FIG.
In the present embodiment, the tap coefficients extracted by the downlink signal receiving block 12 are supplied to the band estimation circuit 51.

The band estimating circuit 51 estimates the bandwidth of the signal output from the FIR filter 34 when the tap coefficient transmitted from the center device is set in the FIR filter 34. This estimation result is provided to the coefficient verification circuit 52 together with the tap coefficient. The coefficient verification circuit 52 verifies whether the bandwidth indicated by the estimation result is wider than the bandwidth of the uplink transmission channel.

Now, it is assumed that the tap coefficient is correctly calculated by the center device. Then, the bandwidth indicated by the estimation result becomes narrower than the bandwidth of the uplink transmission channel. In this case, the coefficient verification circuit
The 52 outputs the tap coefficient transmitted from the center device to the tap coefficient control circuit 13 as it is. The tap coefficient control circuit 13 sets the tap coefficients in the FIR filter 34, and performs a filtering process using the tap coefficients transmitted from the center device in the subsequent communication.

Here, it is assumed that there is an error in the calculation of the tap coefficient by the center device. In this case, the bandwidth indicated by the estimation result may be wider than the bandwidth of the uplink transmission channel. Then, the coefficient verification circuit 52 does not output the tap coefficients transmitted from the center device to the tap coefficient control circuit 13. Therefore, the tap coefficient control circuit 13 does not set the tap coefficients in the FIR filter 34, and the FIR filter 34 performs the filtering process using the tap coefficients in the immediately preceding state. This prevents signals exceeding the allowable band from being sent to the cable network.

As described above, in the present embodiment, the same effects as in the embodiment of FIG. 4 can be obtained.

FIG. 6 is a block diagram showing another embodiment of the present invention. 6, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof will be omitted.

The present embodiment shows an example in which terminal apparatuses that perform pre-equalization processing and band-limiting processing using different filters and terminal apparatuses that perform pre-equalization processing and band limiting processing using a common filter coexist.

In FIG. 6, the center device 61 and the terminal device
63 and 64 are connected via the cable network 1. The terminal device 63 has the same configuration as the terminal device 33 in FIG. The terminal device 64 has the same configuration as the terminal device 28 in FIG. The center device 61 is the center device shown in FIGS.
The configuration is the same as that of the components 21 and 31. The configuration includes both the pre-equalization coefficient calculation circuit 7 and the pre-equalization and band limitation coefficient calculation circuit 32, and a coefficient calculation method selection circuit 62 is added.

The output of the server access circuit 23, the pre-equalization coefficient calculation circuit 7, and the pre-equalization and band limitation coefficient calculation circuit 32 is given to the coefficient calculation method selection circuit 62. Based on the filter configuration information from the server access circuit 23, the coefficient calculation method selection circuit 62 calculates tap coefficients from one of the pre-equalization coefficient calculation circuit 7 and the pre-equalization and band limiting coefficient calculation circuit 32. Selective tap coefficient sending circuit 9
To be supplied.

Next, the operation of the embodiment configured as described above will be described.

Now, it is assumed that the terminal device 63 performs pre-equalization setting. The terminal code generation circuit 29 of the terminal device 63 generates code number information unique to the terminal device. The upstream signal including the code number information is at least band-limited by the FIR filter 34, modulated by the modulation block 18, and transmitted from the duplexer 11 to the cable network 1.

The center device 61 takes in the test modulation signal from the terminal device 63 via the duplexer 5 and demodulates it in the upstream signal receiving block 6. The terminal code identification circuit 22 extracts the code number information included in the test modulation signal and outputs it to the server access circuit 23. Server access circuit 23
Accesses the server 25 via the network 24 and downloads the filter configuration information corresponding to the code number information from the database 26.

The server access circuit 23 recognizes from the downloaded filter configuration information that the terminal device 63 has an FIR filter for performing the pre-equalization processing and the band limitation processing. The pre-equalization and band limiting coefficient calculation circuit 32
In accordance with the filter configuration information from the server access circuit 23, a tap coefficient based on the waveform data from the upstream signal receiving block 6 and the bandwidth of the upstream channel of the cable network 1 is generated and output to the coefficient calculation method selection circuit 62.

The coefficient calculation method selection circuit 62 selects the output of the pre-equalization and band limitation coefficient calculation circuit 32 based on the filter configuration information from the server access circuit 23, and outputs it to the tap coefficient transmission circuit 9. In this way, the downlink modulation signal including the tap coefficient corresponding to the terminal device 63 is transmitted to the cable network 1 and received by the terminal device 63. The tap coefficient control circuit 13 of the terminal device 63 sets the tap coefficient transmitted from the center device 61 in the FIR filter 34.

Next, it is assumed that the terminal device 64 performs pre-equalization setting. The terminal code generation circuit 29 of the terminal device 64 generates code number information unique to the terminal device. The upstream signal including the code number information is band-limited by the band-limiting filter 16, modulated by the modulation block 18, and transmitted from the duplexer 11 to the cable network 1.

The center device 61 takes in the test modulation signal from the terminal device 64 via the duplexer 5 and demodulates it in the upstream signal receiving block 6. The terminal code identification circuit 22 extracts the code number information included in the test modulation signal and outputs it to the server access circuit 23. Server access circuit 23
Accesses the server 25 via the network 24 and downloads the filter configuration information corresponding to the code number information from the database 26.

The server access circuit 23 recognizes that the terminal device 64 has the pre-equalization filter 17 for performing only the pre-equalization processing based on the downloaded filter configuration information. The pre-equalization coefficient calculation circuit 7 includes a server access circuit 23
The tap coefficient corresponding to the waveform data from the uplink signal receiving block 6 is generated in accordance with the filter configuration information from the filter signal generator 6, and is output to the coefficient calculation method selection circuit 62.

The coefficient calculation method selection circuit 62 selects the output of the pre-equalization coefficient calculation circuit 7 based on the filter configuration information from the server access circuit 23, and
Output to In this way, the downlink modulation signal including the tap coefficient corresponding to the terminal device 64 is transmitted to the cable network 1 and received by the terminal device 64. The tap coefficient control circuit 13 of the terminal device 64 sets the tap coefficient transmitted from the center device 61 in the pre-equalization filter 17.

As described above, also in the present embodiment, FIG.
In addition, the same effect as the embodiment of FIG. 3 can be obtained.

In the embodiment of FIG. 6, it is clear that the terminal devices 40 and 50 shown in FIGS. 4 and 5 may be used as the terminal device. Also, an example is shown in which the center device accesses a server corresponding to one manufacturer. However, when a terminal device is manufactured by a plurality of manufacturers by adding a server for another manufacturer to the network. But it is possible.

As described above, in each embodiment, the center device may have a database for holding the filter configuration information inside the center device.
Even in this case, it is desirable that the database can be updated and added via a wide area network such as the Internet.

[0106]

As described above, according to the present invention, it is possible to obtain a sufficient filter characteristic in a terminal device by enabling a center device to transmit a coefficient corresponding to a filter configuration of the terminal device. In addition to this, there is an effect that a filter for pre-equalization and a filter for band limitation can be shared in the terminal device, and the circuit scale can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a data communication system according to the present invention.

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

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

FIG. 4 is a block diagram showing another embodiment of the present invention.

FIG. 5 is a block diagram showing another embodiment of the present invention.

FIG. 6 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cable network, 2 ... Center device, 3 ... Terminal device, 6 ... Up signal reception block, 7 ... Pre-equalization coefficient calculation circuit, 8 ... Terminal filter configuration identification circuit, 12 ... Down signal reception block, 13 ... Tap coefficient Control circuit, 14: test signal generation circuit, 15: upstream signal transmission block, 16: band limiting filter, 16: pre-equalization filter.

Claims (6)

[Claims] A filter that is provided in an upstream transmission system for transmitting an upstream signal to a center device to a predetermined transmission path and performs at least a pre-equalization process of a pre-equalization process and a band limiting process; Information transmitting means for transmitting, as the uplink signal, information that enables the center device to grasp the configuration of the filter; and a coefficient of a coefficient included in a downlink signal transmitted from the center device via the predetermined transmission path. A terminal device comprising: filter setting means for setting the filter using information. 2. Extracting information that allows a user to grasp the configuration of the filter included in an uplink signal transmitted via a predetermined transmission path from a terminal device having a predetermined filter, and extracts the extracted information. Filter configuration detection means for detecting the configuration of the filter provided in the terminal device based on the coefficient calculation means for calculating the coefficient of the filter provided in the terminal device based on the detection result of the filter configuration detection means, A center unit comprising: a transmitting unit that transmits information of the coefficient calculated by the coefficient calculating unit to the terminal device via the predetermined transmission path. 3. A terminal device, which is provided in an uplink transmission system for transmitting an uplink signal to a center device to a predetermined transmission line, and performs at least a pre-equalization process out of a pre-equalization process and a band limitation process. A filter, information transmitting means for transmitting, as the uplink signal, information enabling the center device to grasp the configuration of the filter, and a downlink signal transmitted from the center device via the predetermined transmission path. Filter setting means for setting the filter by using information of the included coefficient, wherein the center device comprises: a filter configured to be included in an uplink signal transmitted from the terminal device via the predetermined transmission path. A filter for extracting information that allows the user to grasp the information and detecting a configuration of the filter included in the terminal device based on the extracted information. Filter configuration detecting means, coefficient calculating means for calculating a coefficient of the filter provided in the terminal device based on a detection result of the filter configuration detecting means, and transmitting the information of the coefficient calculated by the coefficient calculating means to the predetermined transmission. And a transmitting means for transmitting the data to the terminal device via a path. 4. The data communication system according to claim 3, wherein the information enabling the configuration of the filter to be grasped is information indicating the configuration of the filter. 5. The information that enables the configuration of the filter to be grasped is information that specifies the terminal device, and the filter configuration detection unit holds or searches for information indicating a filter configuration for each terminal device. 4. The data communication system according to claim 3, further comprising: 6. The filter performs both a pre-equalization process and a band limiting process, and the terminal device sets the filter when the output band of the filter exceeds an allowable band. 4. The data communication system according to claim 3, further comprising a band confirmation unit for prohibiting setting of the filter by a unit.