JP3945508B2 - Receiver - Google Patents

Description

  The present invention relates to a direct modulation wave demodulator and an input evaluation method in a digital broadcast receiver such as CATV [Community Antenna TV (Cable TV)].

  Currently, digitalization of broadcasting is proceeding at a rapid pace, and CS digital broadcasting using a communication satellite [Communication Satellite] has already been put into practical use. In addition, the development of digital transceivers for CATV, BS broadcasting [Broadcasting Satellite], and terrestrial broadcasting is also ongoing.

  However, when digitized, unlike current analog broadcast receivers, it is difficult to determine the state of the transmission path and the state of the receiver from the video on the screen. This is because in digital broadcasting, error correction is performed, so if the signal reception quality is above a certain level, it is displayed with exactly the same image quality, and if it is lower than that, it is not displayed at all. For this reason, it cannot be judged whether or not there is a signal just because nothing is reflected. In order to solve these problems, it is necessary to make a judgment based on the data error rate. However, it is difficult to introduce a large amount of expensive measuring instruments into a store or a maintenance center such as CATV, and the receiver itself. A method for determining the state is desired.

In order to solve the above problems, in a receiving apparatus, a receiving unit that receives a digital modulation signal, a demodulation unit that demodulates the digital modulation signal received by the receiving unit, and a signal of a signal demodulated by the demodulation unit Signal level detection means for detecting the level, constellation evaluation means for evaluating the distribution state of the signal output by the demodulation means, and distortion added to the transmission path included in the signal output by the demodulation means. Waveform equalization means for controlling and outputting control information relating to the control, and waveform equalization evaluation means for evaluating the state of the input signal to the waveform equalization means based on the control information output by the waveform equalization means An S / N evaluation unit for evaluating a signal-to-noise ratio of the signal output by the demodulation unit, and an error correction process for data output from the demodulation adjustment unit Error rate evaluation means for obtaining an error rate, and the signal level detection means permits no signal output, and any one of the S / N evaluation means, the signal level detection means, and the constellation evaluation means is no signal. Output state evaluation means that evaluates that there is no signal, otherwise input state evaluation means that evaluates that there is a signal, the signal level detection means, the constellation evaluation means, Displaying a combination of at least two of the signals output by the waveform equalization evaluation means, the S / N evaluation means, and the error rate evaluation means, and the signal quality based on the evaluation result of the input state evaluation means And a display means for displaying the evaluation of the state.

According to the present invention, it is possible to provide a receiving apparatus suitable for easily performing inspection and maintenance.

  FIG. 1 is a block diagram showing an embodiment of the present invention. 101 is variable gain means, 102 is quadrature demodulation means, 103 is waveform equalization means, 104 is code identification means, 105 is data conversion means, 106 is error correction means, 107 is signal level detection means, 108 is waveform equalization evaluation 109, constellation evaluation means, 110 S / N evaluation means, 111 error rate evaluation means, 112 input state evaluation means, and 113 evaluation result display means.

  The variable gain means 101 inputs an IF input, adjusts the amplitude of the IF input so that it falls within a certain range, and outputs the result. The orthogonal demodulator 102 demodulates the IF signal output from the variable gain unit 101 and outputs an I signal and a Q signal. The waveform equalization means 103 receives the I signal and the Q signal, removes distortion added to the signal in the transmission path, and outputs it. The code identifying unit 104 identifies the I signal and the Q signal output from the waveform equalizing unit 103 and outputs digital data. The data conversion unit 105 converts the digital data output from the code identification unit 104 into a series of data at the time of transmission. The error correction unit 106 performs error correction processing on the output of the data conversion unit 105.

  The signal level detection means 107 receives the output of the quadrature demodulation means 102 and generates a signal for controlling the variable gain means 101 so that the amplitude is within a certain range.

  The waveform equalization evaluation means 108 receives the control data of the waveform equalization means 103 and determines the state of the waveform equalization means.

  The constellation evaluation means 109 receives the output of the waveform equalization means 103 and evaluates the signal distribution on a plane with the I signal as the horizontal axis and the Q signal as the vertical axis.

  The S / N evaluation unit 110 receives the output of the code identification unit 104 and evaluates the S / N of the signal.

  The error rate evaluation unit 111 simply calculates the error rate by dividing the number of data corrected in unit time by the error correction unit by the number of data transmitted in unit time.

  The input state evaluation means 112 includes a signal for controlling the variable gain means 101 output from the signal level detection means 107, a state of an input signal to the waveform equalization means output from the waveform equalization evaluation means 108, and a constellation evaluation means. From the evaluation of the signal distribution output from 109, the evaluation of S / N output from the S / N evaluation means 110, and the evaluation result of the error rate evaluation means 111, the state of the input signal is evaluated, and the no-signal state and the signal A certain state is detected, and the result and the input evaluation result are output.

  The evaluation result display means 113 outputs the signal level detection result, the waveform equalization evaluation result, the constellation evaluation result, the S / N evaluation result, the error rate evaluation result, and the presence / absence of the input signal output from the input state evaluation means. Display some or all of the results.

  As described above, in the embodiment of the present invention, it is possible to easily know information and data error rate such as whether there is an input signal, whether the S / N is good or bad, and whether the level of the input signal is high or low. , Inspection and maintenance can be performed without using expensive measuring instruments.

  FIG. 2 is a diagram illustrating a configuration example of the waveform equalization evaluation unit 108 of FIG. 201 is a main tap evaluating means, 202 is a tap coefficient sum calculating means excluding the main tap, 203 is an adding means, 204 and 205 are judging means, and 206 is a state judging means.

  The main tap evaluation unit 201 evaluates whether the size of the main tap of the waveform equalization unit is in a normal range. The tap coefficient sum calculating means 202 excluding the main tap calculates the sum of tap coefficients other than the main tap. The adding means 203 adds the calculation result of the tap coefficient sum calculating means 202 excluding the main tap and the tap coefficient of the main tap. The determining means 204 and 205 respectively determine whether the output of the adding means 203 and the output of the tap coefficient sum calculating means excluding the main tap are within a certain range. The state determination unit 206 determines the signal state from the output of the main tap evaluation unit 201 and the outputs of the determination units 204 and 205.

  As described above, the waveform equalization evaluation means constituting a part of the embodiment of the present invention can know the state of the input signal from the control information of the waveform equalization means.

  FIG. 3 is a diagram illustrating a configuration example of the constellation evaluation unit 109 of FIG. Reference numeral 301 denotes storage means, 302 denotes reference value storage means, and 303 denotes comparison means.

  The storage unit 301 stores the output of the waveform equalization unit 103. The reference value storage means 302 stores all the patterns for which the signal distribution during no signal is calculated in advance. The comparison unit 303 compares the signal distribution stored in the storage unit 301 with all signal patterns stored in the reference value storage unit 302, and determines that there is no signal if there is a matching pattern.

  As described above, the no-signal state can be completely detected by the constellation evaluation means constituting a part of the embodiment of the present invention.

  FIG. 4 is a diagram showing a configuration example different from FIG. 3 of the constellation evaluation means 109 of FIG. 401 is storage means, 402, 404 and 407 are comparison means, 403 is a counter, 405 and 408 are references, 406 is a frequency distribution creation means, and 409 is a condition determination means.

  401 stores the output of the waveform equalization means. The comparison unit 402 compares the output of the waveform equalization unit with the data stored in the storage unit, and outputs the result to the counter 403 when the values match. The counter 403 counts the number of times the input value is matched by the comparison unit 402. The comparison unit 404 compares the value of the reference 405 with the count value of the counter 403, and outputs whether the value is larger or smaller than the value of the reference 405.

  The frequency distribution creating unit 406 changes the data distribution stored in the storage unit 401 to a frequency distribution. The comparison unit 407 compares the distribution of the frequency distribution creation unit 406 and the reference 408 to detect whether the number of signal points is equal to or less than a certain value or the existence range of signal points is within a certain range.

  The condition judgment means 409 inputs the outputs of the comparison means 404 and 407, and when the output of the comparison means 404 has a counter value larger than the reference 405, or the output of the comparison means 407 has a number of signal points below a certain value or , It is determined that there is no signal when the signal point exists within a certain range.

  As described above, in this configuration example, no signal detection can be performed with a small circuit without using a large amount of reference patterns as in the configuration example of FIG.

  FIG. 5 is a diagram illustrating a configuration example of the input state evaluation unit 112 of FIG. Reference numeral 501 denotes a logical sum means, and 502 denotes a logical product means.

  When the output of the signal level detection means 107 is a signal that amplifies the input signal to the maximum, and the evaluation result of the error rate evaluation means 111 cannot be corrected, the logical product means 502 permits no signal output.

  The logical sum means 501 outputs a no signal when any of the outputs of the S / N evaluation means 110, the waveform equalization evaluation means 108, and the constellation evaluation means 109 outputs a no signal.

  The logical product means 502 determines that there is no signal when the output of the signal level detection means 107 permits no signal output and the logical sum means 501 outputs no signal. Otherwise, it is determined that there is a signal.

  As described above, in this configuration example, it is possible to distinguish whether there is really no signal or whether the signal quality is bad by comprehensively judging a plurality of no-signal detection results.

  FIG. 6 shows another embodiment of the present invention. Reference numeral 601 denotes an evaluation means.

In the embodiment of FIG. 1, the blocks 108 to 112 configured by hardware are illustrated in FIG. In the sixth embodiment, the evaluation unit 601 implements software.

  As described above, in this embodiment, it is possible to add flexibility to the evaluation method addition and the output of the evaluation result.

  FIG. 7 is a diagram illustrating a configuration example of the evaluation result display unit 113 of FIG. Reference numeral 701 denotes request detection means, reference numeral 702 denotes abnormality detection means, reference numeral 703 denotes display switching means, and reference numeral 704 denotes display means.

  The request detection unit 701 detects a request to display or hide the state of the input signal from the inputs from the remote controller or the operation unit of the main body, and outputs a control output according to the request. The abnormality detection unit detects an abnormality of the input signal from the evaluation result output from the input state evaluation unit 112 or the evaluation unit 601, and outputs a control output so that the evaluation result is automatically displayed in the abnormal state. The display switching unit 703 switches whether the evaluation result of the input signal is output to the display unit or not based on the control output from the request detection unit 701 or the abnormality detection unit 702. The display unit 704 displays the evaluation result of the input signal output from the display switching unit 703.

  As described above, in this configuration example, the evaluation state of the input signal can be known as necessary during inspection and maintenance. In addition, when an abnormality occurs, work can be efficiently performed to automatically notify the abnormality.

  FIG. 8 is a diagram showing a configuration example of the display unit 704 in FIG. Reference numeral 801 denotes a display device (hereinafter abbreviated as a display device) such as a fluorescent display tube, an LED, or a liquid crystal display, and 802 denotes a video composition device.

  The display device 801 displays the output of the display switching unit 703. The video composition device 802 synthesizes the output of the display switching means 703 and the received broadcast video signal, outputs the synthesized video signal, and displays the evaluation result of the input signal on the screen of a display device such as a television. To do.

  As described above, if an abnormality occurs while viewing the broadcast, the status is displayed on the screen, and it is easy to explain the status when contacting the maintenance center or the like. Further, even when an abnormality occurs in the part displaying the video after the quadrature demodulator, since the display device 801 provided separately in the main body is provided, it is easy to identify the site where the abnormality has occurred.

  FIG. 9 is a diagram showing a flow of processing executed by the evaluation unit 601 in FIG.

  Step 901 calculates the error rate from the number of errors corrected by the error correction means 106.

  Step 902 determines from the error rate calculated in step 901 whether or not error correction is possible. If it cannot be corrected, the process proceeds to step 903. , Go to Step 911.

  In step 903, it is determined whether or not the control value output from the signal level detecting means 107 is the maximum value. If it is maximum, the process proceeds to step 904, and if not, the process proceeds to step 911.

  In step 904, the S / N value of the signal is obtained from the output of the code identifying means 104, and the process proceeds to step 905. In step 905, if the S / N value obtained in step 904 is within a certain range, the process proceeds to step 910, and if it is out of the range, the process proceeds to step 906.

  In step 906, the signal point distribution of the constellation is obtained from the output of the waveform equalizing means 103.

  In step 907, it is determined whether the distribution of the signal points obtained in step 906 is within a certain range. If it is within the certain range, the process proceeds to step 910. If it is out of the range, the process proceeds to step 908.

  Step 908 performs processing to evaluate the control information of the waveform equalizing means 103.

  In step 909, it is determined whether the control information processed in step 908 is within a certain range. If it is within the certain range, the process proceeds to step 910. If it is out of the range, the process proceeds to step 911. .

  Step 910 outputs a determination result indicating no signal.

  Step 911 outputs a determination result with a signal.

  FIG. 10 is a diagram showing the flow of the waveform equalization evaluation method in step 908 in the processing of the evaluation means of FIG.

  Step 1001 determines whether the value of the center tap is within a certain range in the control information of the waveform equalizing means 103. If there is no signal, the waveform equalization may run away and become an extremely small value. In this case, the process proceeds to step 1004. Otherwise, go to Step 1002.

  In step 1002, all the tap coefficient values of the control information of the waveform equalizing means 103 are added, and it is determined whether or not the sum is within a certain range. In the normal state, the total sum of the tap coefficients, which is the total gain of the waveform equalization means, does not become extremely large or small. Therefore, it is determined that the sum is within a certain range as normal, and the process proceeds to Step 1003. If it is out of range, the process proceeds to step 1004 as an abnormality.

  In step 1003, it is determined whether the ratio of the sum of tap coefficients other than the center tap and the tap coefficient of the center tap is within a certain range. Since it is impossible that the total sum of taps other than the tap coefficient value of the center tap becomes extremely large under normal conditions, the process proceeds to step 1005 with the normal case being within a certain range. If it is out of range, the process proceeds to step 1004 as an abnormality.

  Step 1004 outputs a determination result indicating no signal.

  Step 1005 outputs a determination result with a signal.

  FIG. 11 is a diagram showing the flow of the constellation evaluation method in step 906 in the processing of the evaluation means in FIG.

  Step 1101 takes in the I signal and Q signal output from the waveform equalizing means 103.

  Step 1102 counts the number of continuous data having the same value acquired in Step 1101. If a certain number or more continues, it is determined that there is no signal and the process proceeds to Step 1105. If the number is less than a certain number, the process proceeds to step 1103.

  In step 1103, the number of the data fetched in step 1101 is counted for each identification value to create a frequency distribution.

  In step 1104, it is determined whether the data distribution is biased in the frequency distribution created in step 1103. If it is biased to only a part of the values, it is determined that the input is abnormal, and the process proceeds to step 1105. If it is distributed over a wide range, it is determined as normal and the process proceeds to step 1106.

  Step 1105 outputs that there is no signal.

  Step 1106 outputs that there is a signal.

It is a block diagram which shows one embodiment of this invention. It is a block diagram which shows the structural example of the waveform equalization evaluation means of FIG. It is a block diagram which shows the structural example of the constellation evaluation means of FIG. It is a block diagram which shows the structural example different from FIG. 3 of the constellation evaluation means of FIG. It is a block diagram which shows the structural example of the input state evaluation means of FIG. It is a block diagram which shows other embodiment of this invention. It is a block diagram which shows the structural example of the evaluation result display means of FIG. It is a block diagram which shows the structural example of the display means of FIG. It is a figure which shows the flow of a process of the evaluation means of FIG. It is a figure which shows the flow of the method of the waveform equalization evaluation in the process of the evaluation means of FIG. It is a figure which shows the flow of the constellation evaluation in the process of the evaluation means of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Variable gain means 102 ... Orthogonal demodulation means 103 Waveform equalization means 104 ... Code identification means 105 ... Data conversion means 106 ... Error correction means 107 ... Signal level detection means 108 ... Waveform equalization evaluation means 109 ... Constellation evaluation means 110 ... S / N evaluation means 111 ... Error rate evaluation means 112 ... Input state evaluation means 113 ... Evaluation result display means 201 ... Main tap evaluation means 202 ... Excluding main tap Tap coefficient sum calculation means, 203... Addition means, 204, 205... Determination means, 206... State determination means, 301, 401 ... Storage means, 302 ... Reference value storage means, 303, 402, 404, 407 ... Comparison means, 403 ... counter, 405, 408 ... reference, 406 ... frequency distribution creating means, 409 ... condition judging means, 501 ... logical sum means 502 ... logical product means, 601 ... evaluation unit, 701 ... request detecting means, 702 ... abnormality detecting means, 703 ... display switching means 704 ... display unit, 801 ... display unit, 802 ... video synthesizer.

Claims (7)

Receiving means for receiving a digitally modulated signal;
Demodulation means for demodulating the digitally modulated signal received by the receiving means;
Signal level detection means for detecting the signal level of the signal demodulated by the demodulation means;
Constellation evaluation means for evaluating the distribution state of the signal output by the demodulation means;
Waveform equalization means for controlling distortion applied to the transmission path included in the signal output by the demodulation means and outputting control information related to the control;
Waveform equalization evaluation means for evaluating the state of an input signal to the waveform equalization means based on the control information output by the waveform equalization means;
S / N evaluation means for evaluating the signal-to-noise ratio of the signal output by the demodulation means;
Error rate evaluation means for obtaining an error rate in error correction processing of data output from the demodulation control means;
When the signal level detection means permits no signal output and any one of the S / N evaluation means, the signal level detection means, and the constellation evaluation means outputs no signal, no signal is output. An input state evaluation means for evaluating that there is a signal in other cases,
Said signal level detecting means, the constellation evaluation unit, the waveform equalization evaluation unit, and displays a combination of at least two or more of the signals output by the S / N evaluation means and the error rate evaluating means, And a display unit for displaying an evaluation of a signal quality state based on an evaluation result of the input state evaluation unit . The receiving device according to claim 1,
The receiving device displays the result of presence / absence of the input signal and a part or all of the result output by the output device. The receiving device according to claim 1 or 2,
The waveform equalization evaluation means calculates main tap evaluation means for evaluating the tap coefficient of the main tap representing the gain of the main signal, and the sum of tap coefficients of taps excluding the main tap, among the control information of the waveform equalization means. A tap coefficient sum calculating means excluding the main tap; an adding means for adding a calculation result of the tap coefficient sum calculating means excluding the main tap and a tap coefficient of the main tap to obtain a sum of tap coefficients of all taps; First determination means for evaluating the calculation result of the means, second determination means for evaluating the calculation result of the tap coefficient sum calculation means excluding the main tap, evaluation result of the main tap evaluation means, and the first A state determination unit that evaluates a state of an input signal to the waveform equalization unit from the evaluation result of the determination unit and the evaluation result of the second determination unit Receiving apparatus according to claim. In the receiving device according to any one of claims 1 to 3,
The constellation evaluation means includes a storage means for storing a signal and a change pattern of the signal, and a reference for storing a change pattern of a signal that may be output from the waveform equalization means when no signal is input. A receiving apparatus comprising: a value storage unit; and a comparison unit that determines whether there is a match between the change pattern stored in the storage unit and the change pattern stored in the reference value storage unit. . In the receiving device according to any one of claims 1 to 4,
The error rate evaluation means obtains an error rate by dividing the number of error occurrences by the number of passing data in a data error correction process. Input means for inputting a digitized IF signal;
Demodulation means for demodulating the IF signal input by the input means;
Signal level detection means for detecting the signal level of the signal demodulated by the demodulation means;
Constellation evaluation means for evaluating the distribution state of the signal output by the demodulation means;
Waveform equalization means for removing distortion included in the signal output by the demodulation means and outputting control data relating to the removal;
Waveform equalization evaluation means for evaluating the state of the input signal to the waveform equalization means based on the control data output by the waveform equalization means;
S / N evaluation means for evaluating the signal-to-noise ratio of the signal output by the demodulation means;
Error rate evaluation means for obtaining an error rate in error correction processing of data output from the demodulation control means;
When the signal output from the error rate evaluation unit and the signal level detection unit is a signal to be amplified to the maximum, and the evaluation result of the error rate evaluation unit is uncorrectable, it is determined that there is no signal, Otherwise, input state evaluation means for evaluating that there is a signal,
The signal level detection means, the constellation evaluation means, the waveform equalization evaluation means, the S / N evaluation means, and the signal output by the error rate evaluation means are extracted and displayed, and the input A receiving device comprising: display means for displaying an evaluation of a signal quality state based on an evaluation result of the state evaluation means. Receiving means for receiving a digitally modulated signal;
Demodulation means for demodulating the digitally modulated signal received by the receiving means;
Signal level detection means for detecting the signal level of the signal demodulated by the demodulation means;
S / N evaluation means for evaluating the signal-to-noise ratio of the signal output by the demodulation means;
Error rate evaluation means for obtaining an error rate in error correction processing of data output from the demodulation control means;
When the signal level detection means permits no signal output and any one of the S / N evaluation means, the signal level detection means, and the constellation evaluation means outputs no signal, no signal is output. An input state evaluation means for evaluating that there is a signal in other cases,
The signals output by the signal level detection means, the S / N evaluation means, and the error rate evaluation means are displayed on the same screen, and the evaluation of the signal quality state based on the evaluation result of the input state evaluation means is displayed. A receiving device.

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