JP2577379Y2 - Satellite receiver - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a satellite that determines the reception status of satellite radio waves based on the bit error rate of PCM voice and AGC output or C / N ratio detection output. Regarding the receiver.

[Prior art] Satellite broadcasting and commercial communication performed using a broadcasting satellite or a communication satellite over the equator have completely different signal transmission formats and occupied radio wave bands from terrestrial broadcasting. Requires antenna and receiver. That is, as shown in FIG. 5, a satellite-dedicated antenna 1 was installed toward a satellite at a place where the sky could be seen and captured by the antenna 1.
Converter 2 attached to antenna 1 for 12GHz band radio wave
, Temporarily converts the signal into an intermediate frequency signal in the 1 GHz band, and then leads the signal to the indoor satellite receiver 3 via a dedicated connection cable.

The satellite receiver 3 selects a signal of a desired channel from an output of the converter 2 and performs FM demodulation. A video signal which extracts and processes a video signal from an FM demodulated output of the channel selection demodulator 4 is processed. It is roughly composed of three blocks of a processing unit 5 and an audio signal processing unit 6 for demodulating and outputting PCM audio transmitted by the four-phase DPSK wave. The tuning demodulator 4 converts the desired channel signal into a second intermediate frequency signal by mixing the input first intermediate frequency signal with the second local oscillation signal, amplifies the second intermediate frequency signal, and then amplifies the amplitude. It comprises a tuning circuit 7 for limiting and an FM demodulation circuit 8 for FM demodulating the output of the tuning circuit 7. The output of the tuning circuit 7 is output from an internal AGC circuit (not shown).
And is supplied to the automatic gain control while being externally output through an AGC output terminal.

The FM demodulation output includes a video signal to which an energy spread signal is added and a four-phase DPSK audio subcarrier. For this reason, the video signal processing unit 5 extracts only the video signal component in the low-pass filtering circuit 9 having a filtering band of 4.5 MHz, and restores the pre-emphasized video signal to the original waveform in the de-emphasis circuit 10. Next, the subsequent energy spread signal removing circuit 11 removes the energy spread signal, and finally outputs the video signal to the outside via the video amplification circuit 12.

On the other hand, in the audio signal processing unit 6, first, the center frequency is 5.73.
An audio subcarrier is extracted in a MHz band filtering circuit 13. Since the extracted audio subcarrier has four-phase components, it is demodulated by the four-phase DPSK demodulation circuit 14 to obtain a two-series digital signal. The PCM demodulation circuit 15 performs PCM demodulation of these two series of digital signals and extracts a 16-bit digital audio signal. The extracted digital audio signal is
Finally, the signal is converted to an analog signal by the DA converter 16, and after removing unnecessary components in the high frequency range, the signal is output to the outside.

By the way, in order to receive satellite broadcasts and satellite communications properly, the antenna 1 must be accurately pointed at the satellite, but since a satellite stationary above the equator cannot be seen from the ground, the antenna 1 In this example, the AG of the tuning and demodulating unit 4
The AGC output voltage obtained from the C output terminal is supplied to the received radio wave intensity display circuit 17 as a measure of the received radio wave intensity.
The attitude of the antenna 1 can be adjusted with reference to the numerical value displayed on the received signal strength display circuit 17 corresponding to the output voltage.

[Problem to be Solved by the Invention] The conventional satellite receiver 3 has a configuration in which the AGC output voltage of the channel selection demodulator 4 is used as a measure of the received radio wave intensity. When there is no obstacle such as a tree, and the antenna 1 is almost facing the satellite, the received radio wave intensity display circuit 17 displays the signal in accordance with the angle deviation of the antenna 1 from the ideal attitude angle. Value gradually decreases. However, once the angle deviation of the antenna 1 exceeds a certain angle, the numerical value displayed on the received radio wave intensity display circuit 17 immediately decreases,
There was a problem that it was difficult to grasp how much the angle shift occurred. On the other hand, even when the antenna 1 is driven to a state where only a small angle correction is required, only a low numerical value is displayed on the received radio wave intensity display circuit 17, and thereafter, adjustment is performed until it is convinced that only fine adjustment is required. There was also a problem that it took a considerable amount of time. Furthermore, trees that have grown after the antenna 1 has been installed gradually erode the space connecting the antenna 1 and the satellite, or the reception environment gradually deteriorates as building construction progresses. AGC output voltage does not show a remarkable change when a situation beyond
The received radio wave intensity display circuit 17 continues to display the same numerical value as immediately after the antenna is installed, so that while actually feeling discomfort that the image has increased noise or the sound quality has deteriorated, There was also a problem that the investigation of the cause and the subsequent measures were delayed.

On the other hand, as an alternative to the AGC output voltage, the antenna 1
C /
For example, in the satellite receiver 21 shown in FIG. 6, a specific band excluding the video signal band and the audio signal band is output to the satellite receiver 21 shown in FIG.
The C / N ratio detection circuit 23 detects the ratio of the noise component and the carrier component included in the extracted specific band as a C / N ratio, and receives the signal corresponding to the detected C / N ratio. The sensitivity is displayed on the display circuit 24. However, the C / N ratio detection circuit 23 detects the C / N ratio by analog signal processing.
Since the configuration is to detect the / N ratio, there is a problem that there is a lot of variation between sets, and it takes time for the inspection process before shipping.

In addition, the PCM broadcast receiver of No. 60-101844 has a PC
There is disclosed a satellite receiver that can display reception quality by generating and displaying an output corresponding to an error rate of a reception code of an M broadcast. However, this system displays the reception quality based on a block error rate detected by an error rate detection circuit in a decoding process of a BCH (63, 56) SEC / DEC encoded audio signal included in satellite television broadcasting. For example, a decrease in the reception quality due to the angle deviation of the receiving antenna with respect to the satellite means that the block error rate increases linearly as the angle of deviation of the receiving antenna increases, so that the receiving antenna is largely deviated from the satellite. This is very effective in the case, but when the direction of the receiving antenna is very close to the target angle and the angle is small, the rate of change of the block error rate with respect to the angle change, that is, the rate of change of the receiving sensitivity is not remarkable. When fine-tuning the receiving antenna near the target angle, there is a problem that it cannot be as effective a decisive factor as AGC output or C detection output. It was the.

In addition, in Japanese Utility Model Laid-Open No. 2-53639, "BS antenna input level display device", the reception state is not normal, and in the reception state with much noise, the AGC voltage component based on the noise is canceled in the form of the AGC voltage component based on the noise. Is disclosed. However, when the receiving antenna is largely off the satellite, the antenna input level display is set to the minimum value “0” based on the out-of-sync signal output for muting the sound when the receiving antenna is largely off the satellite.
Even if the angle deviation from the satellite is large, there is no bit error rate that is effective in knowing the receiving sensitivity, so relying on intuition without knowing the antenna input level In this case, the angle of the receiving antenna must be adjusted in advance, so that it takes a very long time to make a coarse adjustment until reaching the fine adjustment stage.

[Means for Solving the Problems] The present invention solves the above problems, and includes a tuning demodulator for tuning and demodulating radio waves arriving from a satellite, and a tuning demodulation output of the tuning demodulation unit. An audio signal processing unit that performs PCM demodulation of an audio subcarrier to be transmitted, and C / C in a specific band excluding a video signal band and an audio signal band among outputs of the channel selection demodulation unit.
A C / N ratio detection circuit for detecting an N ratio;
The bit error rate found in the PCM demodulation process and the C / N ratio detection output of the C / N ratio detection circuit are supplied, and the bit error rate is set in advance to provide a reception sensitivity selection standard for the C / N ratio detection output. The threshold value is determined based on the reference value, and when only a bit error rate equal to or less than the reference value has occurred, the reception sensitivity corresponding to the C / N ratio detection output is selected and displayed, and the reference value is displayed. When a bit error rate exceeding the bit error rate occurs, a reception state discriminating and displaying means for selecting and displaying the reception sensitivity corresponding to the bit error rate is provided.

Further, the present invention provides a tuning demodulator for tuning and demodulating radio waves coming from a satellite, a voice signal processing unit for PCM demodulating a voice subcarrier included in a tuning demodulation output of the tuning demodulator,
A bit error rate determined in the PCM demodulation process of the audio signal processing unit and an AGC output used for automatic gain control in the channel selection demodulation unit are supplied, and the reception sensitivity of the AGC output in which the bit error rate is set in advance is adopted. A threshold is determined based on a reference value that gives a reference, and when only a bit error rate equal to or less than the reference value has occurred, a reception sensitivity corresponding to the AGC output is selected and displayed, and the threshold is set. When a bit error rate exceeding the bit error rate occurs, a reception state discriminating and displaying means for selecting and displaying the reception sensitivity corresponding to the bit error rate is provided.

[Operation] The present invention provides a bit error rate which is determined when PCM demodulating an audio subcarrier included in a channel demodulation output of a satellite radio wave to a reception state discriminating and displaying means, and determines a threshold value of the bit error rate. Depending on the bit error rate or the C / N ratio detection output or the reception sensitivity corresponding to the AGC output is selectively displayed, so that the most suitable information for the optimal reception of satellite broadcasting or satellite communication can be obtained. .

[Embodiment] FIGS. 1 to 4 show an embodiment of the present invention.
This will be described with reference to the drawings. FIG. 1 is a schematic circuit diagram showing an embodiment of the satellite receiver of the present invention, and FIG.
FIG. 3 is a diagram showing the relationship between the C / N ratio of the M signal and the bit error rate, and FIG. 3 is a diagram showing the relationship between the deviation of the attitude angle of the antenna and the receiving sensitivity based on the bit error rate.

The satellite receiver 31 shown in FIG.
The waveform shaping circuit 3 is connected to the error flag output terminal of the M demodulation circuit 15.
2 and a receiving state discrimination display circuit 34 connected via an AD converter 33. As is well known, the PCM demodulation circuit 15
The two-phase digital signal obtained by the phase DPSK demodulation circuit 14 is subjected to signal processing such as descrambling, deinterleaving, error correction, channel switching, mode switching, and interpolation. And in the current error correction, PCM
For the audio signal in the code string, error correction is performed with 63 bits as one block, and a 1-bit code error is corrected.
A 2-bit code error is only detected.

In this case, the error correction capability such as 1-bit error correction and 2-bit error detection indicates the limit of the error correction capability of the BCH, SEC, DED (63, 56) system. When an error of more than bits exists, the PCM demodulation circuit 15 always outputs an error flag indicating the limit of error correction capability. Therefore, in this embodiment, in order to use the error flag as a measure of the reception sensitivity, the waveform is first shaped by the waveform shaping circuit 32, and then converted into digital data by the AD converter 33, and then taken into the reception state determination display circuit 34. Like that. In parallel with the reception of the error flag, the reception state determination display circuit 34 displays the C / N ratio in a specific band excluding the video signal band and the audio signal band in the output of the channel selection demodulation unit 4 as the reception sensitivity. Captured for display, it enables reception status display based on dual information.

Specifically, the center frequency of a signal in a specific band excluding the video signal band and the audio signal band in the output of the channel selection demodulation unit 4 is 8.
The 5 MHz band filtering circuit 22 extracts the ratio of the noise component and the carrier component contained in the extracted specific band as a C / N ratio in a C / N ratio detecting circuit 23, and this C / N ratio is determined by AD. converter
At 35, the data is converted into digital data and supplied to the reception state determination circuit 34. The reception state determination circuit 34 has a built-in microcomputer, calculates the bit error rate by summing up the frequency of occurrence of the error flag at regular intervals, and detects the obtained bit error rate with a preset C / N ratio detection. Threshold discrimination based on the reference value that gives the output reception sensitivity selection standard.If only a bit error rate below the reference value occurs, select and display the reception sensitivity corresponding to the C / N ratio detection output. When a bit error rate exceeding the reference value occurs, an operation program is defined so that the reception sensitivity corresponding to the bit error rate is selected and displayed. As a reference value for providing a reception sensitivity selection criterion for the C / N ratio detection output, an optimal value obtained from experience is used.

The bit error rate is generally the number of bits N of the code transmitted.
Is represented by the ratio n / N of the number of erroneous bits n to the C / N ratio of the voice PCM signal of the satellite receiver 31 and the bit error rate,
The relationship shown in FIG. 2 exists. Generally, the bit error rate when a bit error causes noise to start to be heard is:
Although it depends on the individual difference, it is said to be about 1 × 10 −8, and the C / N ratio of the voice PCM signal decreases as the bit error rate increases. For this reason, the bit error rate can be used as a measure of the reception sensitivity of satellite radio waves without detecting the C / N ratio of a specific band as in the related art.
Focusing on the fact that the bit error rate works effectively when the N ratio is low, if the bit error rate exceeds the reference value that gives the reception sensitivity selection criteria for the C / N ratio detection output, the bit error rate is supported Is displayed, and if only a bit error rate equal to or less than the above reference value occurs, the C / N ratio detection circuit 2
The receiving sensitivity corresponding to the output C / N ratio of 3 was displayed.

Therefore, even if the signal input to the satellite receiver 31 is reduced and the C / N ratio is deteriorated, no bit error rate exceeding the reference value that gives the reception sensitivity adoption standard of the C / N ratio detection output is generated. Shows the reception sensitivity according to the C / N ratio detection output, rather than the bit error rate that increases in response to the decrease in the S / N ratio of the voice subcarrier signal. When a state where a bit error rate exceeding a reference value giving an acceptance criterion is reached is reached, the reception sensitivity corresponding to the bit error rate that works effectively when the C / N ratio is low is displayed.

As described above, the satellite receiver 31 determines the threshold based on the reference value that provides the reception sensitivity selection criterion for the C / N ratio detection output, which is set in advance, and determines only the bit error rate equal to or less than the reference value. If not, select and display the reception sensitivity corresponding to the C / N ratio detection output.If a bit error rate exceeding the reference value occurs, select the reception sensitivity corresponding to this bit error rate. Since the configuration is such that the bit error rate and the C / N ratio detection output can be used for the display of the reception sensitivity in the respective optimum coverage ranges, the coverage range in consideration of the accuracy, resolution or linearity of the reception sensitivity Even if the antenna attitude deviates from the ideal angle to some extent, the receiving sensitivity can be determined linearly over a fairly wide angle range even if the antenna attitude deviates from the ideal angle. High order, the how much angular deviation occurs can be accurately grasped.
Also, just looking at the reception sensitivity display does not reveal the substance,
The coarse adjustment of the attitude of the antenna based on the bit error rate and the fine adjustment of the attitude of the antenna based on the C / N ratio can be executed in the respective optimum ranges.
Trees that have grown after the installation have gradually exceeded the attention range of the viewer, such as the erosion of the space between the antenna 1 and the satellite or the deterioration of the reception environment as the building construction progresses. Even if the situation progresses, even if the C / N ratio detection output does not change much, by judging the receiving sensitivity based on the bit error rate, it is possible to show a clear difference from immediately after the antenna installation. It is possible for the viewer to investigate the cause and take corrective action as soon as possible.In practice, it is possible that the noise is increased in the image or the sound quality is degraded, but the root cause is not left. Absent. Also, unlike a conventional satellite receiver in which only the AGC output voltage in the channel selection demodulation unit 4 is displayed as the received radio wave intensity, by monitoring the C / N ratio of the voice PCM signal and the corresponding bit error rate, It is possible to accurately determine the reception state in the digital domain, thereby eliminating variations in the determination accuracy between sets and promising to enjoy high quality video and audio inherent in satellite broadcasting or satellite communication. .

The satellite receiver 31 is configured to display the reception sensitivity by integrating the bit error rate and the C / N ratio detection output.
The AGC output of the channel selection demodulation unit 4 can be used instead of the N ratio detection output. This is because, as shown in FIG. 3, the reception sensitivity based on the bit error rate shows a linear downward slope over a wide angle range with respect to the attitude angle deviation of the antenna 1. Since the AGC output shows a sharp change with a slight angle deviation from the target angle, in the fine adjustment region where the angle deviation is small, the rate of change of the reception sensitivity with respect to the unit angle deviation, that is, the resolution of the reception sensitivity is excellent. That's why.

In view of this, the satellite receiver 41 shown in FIG. 4 adopts a configuration in which the reception state is determined by integrating the bit error rate and the AGC output.
The C output is taken in through the AD converter 43, and the reception sensitivity is displayed by integrating the C output with the bit error rate taken in through the AD converter 33. Specifically, a threshold value is determined based on a reference value that provides a reception sensitivity selection criterion for an AGC output whose bit error rate is set in advance, and when only a bit error rate equal to or less than the reference value occurs, the AGC output is output. The corresponding reception sensitivity is selected and displayed, and when a bit error rate exceeding the threshold occurs, the reception sensitivity corresponding to the bit error rate is selected and displayed. For this reason, coarse adjustment of the antenna attitude is based on the reception sensitivity based on the bit error rate, and fine adjustment is based on the reception sensitivity based on the AGC output. It can be executed by referring to the value in the optimal defense range, and the extraction of the AGC output is simpler than the extraction of the C / N ratio in a specific band excluding the video signal band and the audio signal band. It is possible to accurately determine the reception state at low cost without complicating the operation.

In the above description, the embodiment in which the reception state is determined by combining the bit error rate and the C / N ratio detection output and the embodiment in which the reception state is determined by combining the bit error rate and the AGC output have been described. Alternatively, the reception state may be determined by integrating all of the bit error rate, the AGC voltage, and the C / N ratio detection output. In this case, areas where the resolution of the receiving sensitivity (the rate of change of the receiving sensitivity with respect to the unit angle shift of the antenna attitude) is remarkable may be set as the respective defense ranges.

[Effects of the Invention] As described above, in the present invention, the bit error rate is determined based on a reference value that provides a reception sensitivity adoption criterion for the C / N ratio detection output that is set in advance, and the threshold value is determined. When only the bit error rate has occurred, the reception sensitivity corresponding to the C / N ratio detection output is selected and displayed, and when a bit error rate exceeding the reference value occurs, the reception sensitivity corresponding to the bit error rate is determined. Since the receiver sensitivity is selected and displayed, the bit error rate and the C / N ratio detection output can be adopted for the display of the receiver sensitivity within the optimal coverage range, respectively, and the accuracy, resolution or linearity of the receiver sensitivity can be improved. Because the defensive range can be divided into considerations, even if the antenna attitude deviates from the ideal angle to some extent, the receiving sensitivity according to this deviation can be determined linearly over a fairly wide angle range. Because of the high linearity of the other content, it is possible to accurately grasp the degree of angular deviation that has occurred.Also, by looking at the display of the reception sensitivity, the substance cannot be determined, but the antenna error based on the bit error rate The coarse adjustment of the attitude and the fine adjustment of the attitude of the antenna based on the C / N ratio can be performed in the respective optimum ranges, so that the trees that have grown after installing the antenna gradually occupy the space connecting the antenna and the satellite. C / N ratio detection output does not change much even when the situation that exceeds the daily attention range of the viewer progresses, such as erosion of the sound or the reception environment gradually deteriorates as the building construction progresses. Even if you don't see it, the receiver sensitivity can be determined based on the bit error rate, which can clearly show the difference immediately after installation of the antenna. This allows the viewer to immediately investigate the cause and take corrective measures. It is possible, and in practice, the root cause is not neglected while feeling that the noise has increased in the image or the quality of the sound has deteriorated, and only the AGC output voltage in the channel selection demodulator is used. Unlike conventional satellite receivers that displayed as received signal strength,
By monitoring the C / N ratio of the audio PCM signal and the corresponding bit error rate, it is possible to accurately determine the reception status in the digital domain, thereby eliminating variations in determination accuracy between sets and enabling satellite broadcasting. Alternatively, an excellent effect such as promising viewing of high quality video and audio inherent in satellite communication can be achieved.

In addition, the present invention provides a method in which the bit error rate is set in advance.
A threshold is determined based on a reference value that provides the reception sensitivity selection standard for the AGC output.If only a bit error rate equal to or less than the reference value has occurred, the reception sensitivity corresponding to the AGC output is selected and displayed. When a bit error rate exceeding the threshold occurs, the reception sensitivity corresponding to the bit error rate is selected and displayed. Therefore, the coarse adjustment of the antenna attitude reduces the reception sensitivity based on the bit error rate. While watching and fine-tuning the receiver sensitivity based on the AGC output, the accuracy, resolution, and linearity can be performed by referring to the values in the respective optimal coverage ranges of the bit error rate and the AGC output. Extracting the output is easier than extracting the C / N ratio in a specific band excluding the video signal band and the audio signal band, so it is possible to accurately and accurately determine the reception status at low cost without complicating the device configuration. Possible Excellent effects and the like.

[Brief description of the drawings]

FIG. 1 is a schematic circuit diagram showing an embodiment of the satellite receiver of the present invention, FIG. 2 is a diagram showing a relationship between a C / N ratio of a voice PCM signal and a bit error rate, and FIG. Diagram showing the relationship between the deviation of the attitude angle of the antenna and the receiving sensitivity based on the bit error rate,
FIG. 4 is a schematic circuit configuration diagram showing another embodiment of the satellite receiver of the present invention, and FIGS. 5 and 6 are schematic circuit configuration diagrams each showing an example of a conventional satellite receiver. 4: Tuning demodulation unit 6: Audio signal processing unit 15: PCM demodulation circuit 22: Bandpass filtering circuit 23: C / N ratio detection circuit 31, 41: Satellite receivers 34, 42: Reception state Discrimination display circuit 35,43 …… AD converter

Claims (2)

(57) [Scope of request for utility model registration] 1. A tuning demodulator for tuning and demodulating radio waves arriving from a satellite, an audio signal processing unit for PCM demodulating an audio subcarrier included in a tuning demodulation output of the tuning demodulator, and the tuning. A C / N ratio detection circuit that detects a C / N ratio in a specific band excluding a video signal band and an audio signal band among outputs of the demodulation unit, and a bit error rate and a bit error rate that are determined in a PCM demodulation process of the audio signal processing unit. The C / N ratio detection output of the C / N ratio detection circuit is supplied,
A threshold value is determined based on a reference value that provides the reception sensitivity adoption reference of the C / N ratio detection output, wherein the bit error rate is set in advance, and when only a bit error rate equal to or less than the reference value occurs, the A reception sensitivity corresponding to the C / N ratio detection output is selected and displayed, and when a bit error rate exceeding the reference value occurs, a reception sensitivity corresponding to the bit error rate is selected and displayed. A satellite receiver, comprising: display means. 2. A tuning demodulator for tuning and demodulating a radio wave arriving from a satellite, an audio signal processing unit for performing PCM demodulation of an audio subcarrier included in a tuning demodulation output of the tuning demodulator, and an audio signal The bit error rate found in the PCM demodulation process of the processing unit and the AGC output used for automatic gain control in the channel selection demodulation unit are supplied, and the AG in which the bit error rate is set in advance
A threshold is determined based on a reference value that provides a reception sensitivity selection standard for the C output.If only a bit error rate equal to or lower than the reference value has occurred, the reception sensitivity corresponding to the AGC output is selected and displayed. And a receiving state discriminating means for selecting and displaying a receiving sensitivity corresponding to the bit error rate when the bit error rate exceeds the threshold value.