JPH0690455A - Satellite broadcasting or reception signal processing circuit of satellite communication - Google Patents

Abstract

PURPOSE:To realize satellite broadcasting or the reception signal processing circuit of satellite communication which is suitable to the making into IC and has high triangular wave removing capacity. CONSTITUTION:By providing a synchronizing separator circuit 31, a synchronizing signal C is separated from the signal after the de-emphasis of an input signal A. In a triangular wave removing circuit 32 removing the triangular wave components from the signal after the de-emphasis, a pulse clamp system having high removing capacity by utilizing the synchronizing signal C is adopted. As a result, because the back-end of a low-pass filter 22 for the triangular wave removing circuit 32 becomes possible and the narrow dynamic range is enough for the filter, the filter is mainly composed of a gyrator, etc. Thus, individual elements becomes unnecessary and the making into IC ratio of the circuit is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a received signal processing circuit for satellite broadcasting or satellite communication, and more specifically to a satellite for removing a component of a dispersal signal mixed at a transmitting side from a received signal to generate a restored signal. The present invention relates to a received 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, on the transmitting side, in addition to processing such as FM modulation that is generally used in terrestrial broadcasting, etc., attenuation characteristics in the transmission path are taken into consideration. Then, emphasis processing for emphasizing a predetermined frequency range to be dealt with in particular and mixing processing of dispersal signals for preventing uneven distribution of energy in a specific frequency range are also performed.

FIG. 5 shows this dispersal signal as
FIG. 1 is a block diagram of a conventional received signal processing circuit that restores an original signal from a BS / CS received signal that is modulated by a triangular wave that is synchronized with a sync signal normally included in a composite signal and mixed with the triangular wave. Here, 1 is a de-emphasis circuit that performs a de-emphasis process that is an inverse conversion of the emphasis process 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.

BS subjected to FM demodulation for FM modulation
The received signal of / CS is input to this reception processing circuit as the input signal A. Then, first, the emphasized portion is returned to the original state by the de-emphasis process in the de-emphasis circuit 1 mainly composed of the CR circuit.
Next, the low-pass filter 2 mainly composed of the LC circuit removes noise components in the high frequency range. Finally, the self-clamp circuit 3 removes the triangular wave component mixed on the transmitting side, and restores the original signal. This is output as the restoration signal B.

[0005]

In such a conventional received 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 fluctuation range than the level of the signal that does not include the triangular wave by the signal level of the triangular wave. That is, the dynamic range is wide. Therefore, a low-pass filter having a wide dynamic range is required correspondingly. In order to satisfy such a condition, the low pass filter is composed of an LC circuit composed of individual elements. However, if the filter is composed of individual elements, the IC
This is a problem because it cannot be miniaturized and productivity cannot be improved.

Further, although the triangular wave is removed by the self-clamp method to generate a restored signal, the self-clamp method has a drawback 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 the problems of the conventional technology,
It 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 removing capability.

[0007]

The structure of a received signal processing circuit for satellite broadcasting or satellite communication according to the present invention which achieves the above object is provided with emphasis processing for emphasizing a predetermined frequency range and as a dispersal signal. It receives as an input signal the received signal of a satellite broadcasting signal or satellite communication signal of BS, CS, etc. that has been subjected to a mixing process of mixing the triangular waves of, and performs a predetermined restoration process on this input signal to generate and output a restored signal In a reception signal processing circuit for satellite broadcasting or satellite communication, a signal after de-emphasis, which is a de-emphasis process and a low-pass filtering process, which are inverse transformations of the emphasis process, is applied to the input signal, or a low signal of the input signal. A sync separation circuit that separates a sync signal from the pass-pass filtered signal, and a pulse clamp method for synchronizing the sync signal with the sync signal. A triangular wave removing circuit that removes a signal component corresponding to the triangular wave from the signal after the emphasis (or the input signal) and outputs the signal component, and outputs the output signal of the triangular wave circuit (or the output signal of the triangular wave circuit to the output signal of the triangular wave circuit). The low-pass filtered signal of the signal subjected to the emphasis processing) is output as the restored signal.

[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. As a result, for the triangular wave removal processing, it is possible to use not the self-clamp system that does not require a sync signal but has a low triangular wave removal capability, but the pulse clamp system that requires a sync signal but has a high triangular wave removal capability. Therefore, the triangular wave can be sufficiently removed.

Moreover, in the pulse clamp method, a synchronizing signal is received in addition to the input signal to be processed, and the triangular wave removing process is performed according to the synchronizing signal. Therefore, even if noise is included in the input signal, it is not easily affected by the noise, and a low-pass filter for noise removal can be provided after the triangular wave removal circuit. Therefore, for the low-pass filter, a signal in which the triangular wave is removed and the fluctuation of the signal level is suppressed by that amount is input. Therefore, since the dynamic range is relatively narrow, a gyrator-based circuit that does not require individual elements can be used as the low-pass filter. This allows the IC
Eliminating the use of individual elements, which was an obstacle to integration,
The conversion rate can be increased.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a received signal processing circuit for satellite broadcasting (BS) or satellite communication (CS) having the structure of the present invention will be described below with reference to the block diagram of FIG. Here, 1 is a de-emphasis circuit that performs a de-emphasis process that is an inverse conversion of the emphasis process on the transmission side.
Reference numerals 1 and 22 are low-pass filters (LPFs) that perform low-pass filtering processing, 31 is a sync separation circuit that separates a synchronization signal in which the phases of the triangular waves mixed on the transmission side are synchronized, and 32 is a pulse clamp method that converts the triangular waves. It 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, for example, a voice signal modulated in a high frequency range, a so-called MUSE signal, etc. are particularly emphasized. The de-emphasis process is the opposite process performed on the receiving side. On the transmitting side, a triangular wave is mixed as a dispersal signal. This is a process for preventing uneven distribution of energy in a specific frequency band and effectively using a limited frequency band. While this advantage is obtained, the width of the level fluctuation of the BS / CS signal is widened by about 15% in CS, for example, due to the mixing of the triangular waves.

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

Although the low-pass filter 21 is placed before the sync separation circuit 31, this filtering characteristic is sufficient as long as it can separate the sync signal thereafter, and an easy characteristic is sufficient. Therefore, as the low-pass filter 21, for example, a filter such as an active filter having a simple configuration and relatively suitable for IC can be adopted. The triangular wave removing circuit 32 is a BS after de-emphasis.
The / CS received signal is input as a signal to be processed, the synchronizing signal C is also received, and a triangular wave component is removed from the de-emphasized signal by a so-called pulse clamp method according to the synchronizing signal C.

Since this pulse clamp system has a high triangular wave removing capability, it is sufficiently possible to restore the original signal by removing the triangular wave component even from the signal before filtering for noise removal. Therefore, there is no need to pre-position a low-pass filter, and the BS / CS reception signal after the triangular wave removal has a wider range of signal level fluctuation than the signal before the triangular wave removal in which the fluctuation range is widened. Is, for example, about 15% less.

Since there is no need for the pre-position in this way, the low-pass filter 22 can be installed after the triangular wave removing circuit 32. Then, the rear low-pass filter 22 has a narrower range of fluctuation in the level of the input signal than the front low-pass filter 22, and thus the dynamic range to be dealt with is narrower than in the conventional case. Therefore, the low pass filter 2
As the filter 2, a filter having a configuration mainly composed of a gyrator or the like and suitable for an IC can be adopted. The gyrator has a limited dynamic range,
Since a large inductance can be equivalently realized by using a capacitor, a resistor, a transistor, etc. having a small capacity, it is suitable for an IC.

Therefore, since the low-pass filter 22 does not require an individual element, the low-pass filter 22 can be integrated into an IC. Finally, the integrated low-pass filter 22 removes the noise component in the high frequency range and completely restores the original signal from the BS / CS received signal, which is output as the restored signal B to the circuit in the subsequent stage. 2 to 4 are block diagrams showing examples of other configurations corresponding to modified examples of the above-described example, the operation and effect thereof are the same as those of the above-described example, and the same as the above description. Since it is clear from each block diagram, its detailed description is omitted.

[0017]

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

[Brief description of drawings]

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

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

[Explanation of symbols]

 1 De-emphasis circuit 2 Low-pass filter (LPF) 3 Self-clamp circuit 21, 22 Low-pass filter (LPF) 31 Sync separation circuit 32 Triangular wave removal circuit

Claims (1)

[Claims] 1. A received signal of a satellite broadcast signal such as BS, CS or the like, which has been subjected to an emphasis process for emphasizing a predetermined frequency range and a mixing process for mixing a triangular wave as a dispersal signal, is input. In a received signal processing circuit for satellite broadcasting or satellite communication that receives a signal as a signal, performs a predetermined restoration process on the input signal to generate and outputs a restored signal, and a de-emphasis process that is a reverse conversion of the emphasis process to the input signal. A signal after de-emphasis that has been subjected to low-pass filtering, or a sync separation circuit that separates a sync signal from the low-pass filtered signal of the input signal, and a pulse clamp method in synchronization with the sync signal. A triangular wave that removes the signal component corresponding to the triangular wave from the de-emphasized signal (or the input signal) and outputs the triangular wave. And a low-pass filtered signal of the output signal of the triangular wave circuit (or a signal obtained by performing de-emphasis processing on the output signal of the triangular wave circuit) is output as the restored signal. A received signal processing circuit for satellite broadcasting or satellite communication characterized by the following.