JP2832781B2 - Satellite broadcasting or satellite communication reception signal processing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reception signal processing circuit for satellite broadcasting or satellite communication, and more particularly to a satellite for generating a restored signal by removing a component of a dispersal signal mixed on a transmission side from a reception signal. The present invention relates to a reception signal processing circuit for broadcasting or satellite communication.

[0002]

2. Description of the Related Art In satellite broadcasting or satellite communication, which is also abbreviated as BS / CS, the transmitting side considers attenuation characteristics in a transmission path in addition to processing such as general FM modulation even in terrestrial broadcasting. Then, emphasis processing for emphasizing a predetermined frequency band to be particularly dealt with, and mixing processing of a dispersal signal for preventing energy from being unevenly distributed to a specific frequency band are also performed.

FIG. 5 shows the dispersal signal as:
FIG. 2 is a block diagram of a conventional reception signal processing circuit for restoring an original signal from a BS / CS reception signal modulated with a triangle wave synchronized with a synchronization signal included in a normal composite signal and mixed with a triangle wave. Here, 1 is a de-emphasis circuit that performs de-emphasis processing corresponding to inverse conversion of emphasis processing on the transmission side, 2 is a low-pass filter (LPF) that performs low-pass filtering, and 3 is a self-clamp that removes a triangular wave by a self-clamp method. Circuit.

[0004] BS demodulated with FM for FM modulation
The / CS reception signal is input to this reception processing circuit as an input signal A. Then, first, the emphasized portion is restored by the de-emphasis processing in the de-emphasis circuit 1 mainly composed of the CR circuit.
Next, a high-frequency noise component is removed by the low-pass filter 2 mainly composed of an LC circuit. Finally, the self-clamp circuit 3 removes the triangular wave component mixed on the transmission side, and restores the original signal. This is output as the restoration signal B.

[0005]

In such a conventional reception signal processing circuit for satellite broadcasting or satellite communication, low-pass filtering is performed before triangular wave removal. The level of the signal on which the triangular wave is superimposed has a wider variation range than the level of the signal not including the triangular wave by the signal level of the triangular wave. That is, the dynamic range is wide. Therefore, correspondingly, a low-pass filter having a wide dynamic range is required. In order to satisfy such a condition, the low-pass filter is constituted by an LC circuit composed of individual elements. However, if a filter is composed of individual elements, an IC
This is a problem because it is not possible to reduce the size or improve the productivity due to the miniaturization.

Further, although the triangular wave is removed by the self-clamp method to generate a restored signal, the self-clamp method has a disadvantage that the original signal cannot be completely restored because the triangular wave removing ability is low. The purpose of this invention is
In order to solve such problems of the prior art,
An object of the present invention is to realize a reception signal processing circuit for satellite broadcasting or satellite communication which is suitable for IC and has a high triangular wave removal capability.

[0007]

According to the present invention, there is provided a reception signal processing circuit for satellite broadcasting or satellite communication which achieves the above object, in which emphasis processing for emphasizing a predetermined frequency band is performed and the signal is used as a dispersal signal. Receiving a satellite broadcast signal or a satellite communication signal such as a BS or CS signal that has been subjected to a mixing process for mixing the triangular waves as an input signal, performs a predetermined restoration process on the input signal, and generates and outputs a restored signal. In the reception signal processing circuit of satellite broadcasting or satellite communication
Te, and it is applied de-emphasis processing and a low-pass filtering process which corresponds to the inverse transform pair Shi emphasis processing to the input signal
A sync separation circuit for separating the sync signal from the signal or from a low pass vortex filtered signal of the input signal;
Receives the signal and sync signal that have undergone de-emphasis processing.
A triangular-wave removing circuit that outputs a signal obtained by removing a signal component corresponding to a triangular wave in response to an input signal or a synchronization signal, and a triangular-wave removing circuit that has been subjected to de-emphasis processing.
Tei and a low pass filter for receiving an attitude signal of the road
Output a restored signal through a low-pass filter
It is.

[0008]

In the satellite broadcast or satellite communication reception signal processing circuit of the present invention having such a configuration, the synchronization signal is separated by the synchronization separation circuit and sent to the triangular wave removal circuit. This makes it possible to use a pulse clamp method which requires a synchronization signal but has a high triangular wave removal capability, instead of a self-clamp method which does not require a synchronization signal but has a low triangular wave removal capability for the triangular wave removal process. Therefore, the triangular wave can be sufficiently removed.

In addition, in this pulse clamp system, a synchronizing signal is also received in addition to an input signal to be processed, and a triangular wave removing process is performed according to the synchronizing signal. Therefore, even if noise is included in the input signal, it is hardly affected by the noise, and a low-pass filter for removing noise can be provided after the triangular wave removing circuit. Therefore, the low-pass filter receives a signal in which the triangular wave is removed and the fluctuation of the signal level is suppressed by that amount. Therefore, since the dynamic range is relatively narrow, a gyrator-based circuit or the like that does not require individual elements can be employed as the low-pass filter. Thereby, IC
The use of individual elements, which had been an obstacle to
Conversion rate can be increased.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reception signal processing circuit for satellite broadcasting (BS) or satellite communication (CS) according to the present invention will be described below with reference to the block diagram of FIG. Here, reference numeral 1 denotes a de-emphasis circuit that performs a de-emphasis process corresponding to the inverse conversion of the emphasis process on the transmission side;
Reference numerals 1 and 22 denote low-pass filters (LPFs) that perform low-pass filtering, 31 denotes a synchronization separation circuit that separates synchronization signals in which the phases of the triangular waves mixed on the transmission side are synchronized, and 32 denotes a triangular wave by a pulse clamp method. This is a triangular wave removing circuit for removing.

On the transmitting side, emphasis processing is performed in advance in consideration of attenuation during transmission and the like, and, for example, an audio signal modulated in a high frequency range, a so-called MUSE signal, and the like are particularly emphasized. The reverse process performed on the receiving side is the de-emphasis process. On the transmitting side, a triangular wave is mixed as a dispersal signal. This is a process for preventing energy from being unevenly distributed in a specific frequency band and effectively using the limited frequency band. While this advantage is obtained, the mixing of the triangular waves widens the level fluctuation of the BS / CS signal by, for example, about 15% in CS.

On the receiving side, the de-emphasis circuit 1 is mainly composed of a CR circuit which is relatively suitable for IC integration, receives a FM demodulated BS / CS reception signal as an input signal A, and A de-emphasis process is performed for this. By this processing, the specially emphasized portion of the BS / CS reception signal is returned to the original state. The synchronization separating circuit 31 separates the synchronizing signal in which the phases of the mixed triangular waves are synchronized from the signal after the de-emphasis, and sends the separated synchronizing signal C to the triangular wave removing circuit 32.

Although the low-pass filter 21 is provided before the synchronization separation circuit 31, the filtering characteristics need only be such that the synchronization signal can be separated thereafter, and a simple characteristic is sufficient. Therefore, as the low-pass filter 21, for example, a filter such as an active filter which has a simple configuration and is relatively suitable for IC can be adopted. The triangular wave removing circuit 32 outputs the BS after de-emphasis.
The / CS reception signal is input as a signal to be processed, the synchronization signal C is also received, and a triangular wave component is removed from the signal after de-emphasis by a so-called pulse clamp method according to the synchronization signal C.

Since the pulse clamp system has a high triangular wave removal capability, it is sufficiently possible to remove the triangular wave component and restore the original signal even from the signal before filtering for noise removal. Therefore, it is not necessary to provide a low-pass filter in front of the low-pass filter. Further, the BS / CS reception signal after the removal of the triangular wave has a wider range of signal level fluctuation than the signal before the removal of the triangular wave whose fluctuation range is widened. For example, by about 15%.

Since there is no need to provide a pre-position, the low-pass filter 22 can be disposed after the triangular wave removing circuit 32. In this case, the post-mounted low-pass filter 22 has a smaller range of level fluctuation of the input signal as compared with the case where the post-mounted low-pass filter 22 is provided, so that the dynamic range to be dealt with is smaller than in the related art. Therefore, low-pass filter 2
For example, a filter mainly composed of a gyrator or the like and suitable for integration into an IC can be used as the filter 2. The gyrator has restrictions on the dynamic range,
By using a capacitor and a resistor, a transistor, and the like having a small capacity, a large inductance can be equivalently realized, and thus, it is suitable for use in an IC.

Accordingly, since no individual element is required for the configuration of the low-pass filter 22, the low-pass filter can be integrated into an IC. Finally, the low-pass filter 22 formed as an IC removes high-frequency noise components, completely restores the original signal from the BS / CS received signal, and outputs the restored signal as a restored signal B to a subsequent circuit. Incidentally, in FIGS. 2 to 4, shows the block diagram of an embodiment of another configuration which corresponds to a modification of the above embodiment.
FIG. 2 shows that the de-emphasis circuit 1 is synchronized with the original circuit 1.
And the de-emphasis circuit 1
The side is disposed after the triangular wave removing circuit 32. Figure
3 further lowers the position of the de-emphasis circuit 1a.
It is arranged behind the filter 21. FIG.
The input signal to the low-pass filter 21 is de-emphasized.
The sampling is performed before the cis circuit 1.
You. The operation and effect are the same as those of the above-described embodiment, and are clear from the above description and each block diagram, and thus the detailed description is omitted.

[0017]

As can be understood from the above description, the reception signal processing circuit for satellite broadcasting or satellite communication of the present invention employs a pulse clamp type triangular wave removing circuit,
The circuit configuration is such that noise removal processing can be performed sufficiently even with a filter with a narrow dynamic range. As a result, it has become possible to configure a filter, which conventionally requires an individual element, mainly using a gyrator or the like that is easily integrated into an IC. As a result, there is an effect that the ability to remove the triangular wave is increased, the rate of IC conversion is increased, and the productivity is also improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of a reception signal processing circuit for satellite broadcasting or satellite communication having the configuration of the present invention.

FIG. 2 is a block diagram of a second embodiment of a reception signal processing circuit for satellite broadcasting or satellite communication having the configuration of the present invention.

FIG. 3 is a block diagram of a third embodiment of a reception signal processing circuit for satellite broadcasting or satellite communication having the configuration of the present invention.

FIG. 4 is a block diagram of a fourth embodiment of a reception signal processing circuit for satellite broadcasting or satellite communication having the configuration of the present invention.

FIG. 5 is an example of a conventional reception signal processing circuit for satellite broadcasting or satellite communication.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 De-emphasis circuit 2 Low-pass filter (LPF) 3 Self-clamp circuit 21 and 22 Low-pass filter (LPF) 31 Synchronization separation circuit 32 Triangular wave removal circuit

Claims (1)

(57) [Claims] 1. A reception signal of a satellite broadcast signal or a satellite communication signal of a BS, CS or the like, which has been subjected to emphasis processing for emphasizing a predetermined frequency range and subjected to mixing processing for mixing triangular waves as a dispersal signal, is input. Receiving signal as a signal, performing a predetermined restoration process on the input signal to generate and output a restoration signal, in a reception signal processing circuit for satellite broadcasting or satellite communication, wherein a de-emphasis process corresponding to the inverse conversion of the emphasis process is performed on the input signal; A sync separation circuit for separating a sync signal from a signal subjected to low-pass filtering or from a low-pass filtered signal of the input signal; and a signal obtained by subjecting the input signal to de-emphasis processing.
Signal and the synchronizing signal or the input signal and
And a triangular wave removing circuit that receives the synchronization signal and outputs a signal obtained by removing a signal component corresponding to the triangular wave, and a triangular wave removing circuit that has been subjected to de-emphasis processing.
And a low-pass filter for receiving the output signal, wherein the restored signal is output through the low-pass filter.
Reception signal processing circuit of satellite broadcasting or satellite communication, characterized in that it is force.