JPH0458620A - Receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a receiving apparatus capable of removing random noise components having a smaller amplitude than signal components in wired and wireless digital transmission systems.

BACKGROUND OF THE INVENTION Conventionally, as shown in FIG. 2, this type of digital receiving apparatus has a receiving input terminal 1, a receiving filter 2, a sampler 3, a determiner 4, and an output terminal 5. When a received signal is input from the receiving input terminal 1, this received signal is band-limited by the receiving filter 2 in order to improve the S/N ratio, and this band-limited filter 41
The digital signal is sampled by a sampler 3, and a digital signal is decoded by a decider 4 according to the sample value and outputted from an output terminal 5.

In this way, even in the conventional receiving apparatus described above, a digital signal with improved transmission errors can be obtained by band-limiting the received signal on the frequency axis using the receiving filter 2.

Problems to be Solved by the Invention However, in the above-mentioned conventional receiving device, when the band of the receiving filter 2 is narrowed, the signal component is distorted, and when the band is widened, the S/N ratio is not sufficiently improved. There was a problem that it could not be lowered.

The present invention solves these conventional problems, and provides an excellent receiving device that sufficiently reduces transmission errors by removing only the noise component without adding distortion to the received signal. The purpose is to provide

Means for Solving the Problems In order to achieve the above object, the present invention uses, as a reception filter, a signal component and superimposition on this, focusing on the spectral fine structure on the time axis of the reception signal, in addition to a normal linear filter. ε−, which can separate small-amplitude random noise components
By using a separating nonlinear filter, only noise components are removed without adding distortion to signal components, and transmission errors are reduced.

Effects The present invention has the following effects due to the above structure. In other words, when a received signal in which a relatively small amplitude random noise component is superimposed on the signal component is input to the receiving device, the ε-separating nonlinear filter makes sure that the difference in amplitude value between the input signal and the output signal is equal to or less than ε. Under such conditions, it acts to smooth the received signal, so only the noise component can be removed without adding large distortion to the signal component. Embodiment that has the effect of reducing data transmission errors as a result FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, l is an analog input terminal, into which a received signal is input. Reference numeral 2 denotes a low-pass filter, a so-called linear filter on the frequency axis, which removes aliasing noise components contained in the received signal. 3 is an A/D converter which converts the input signal from which aliasing noise components have been removed into a digital signal. Reference numeral 4 denotes an ε-separated nonlinear filter (hereinafter referred to as ε-filter), which processes the digital signal on the time axis. 5 is a determiner, ε−
The received signal processed by the filter 4 is decoded. A digital output terminal 6 outputs a decoded digital signal.

Next, the operation of the above embodiment will be explained. In FIG. 1, a received signal on which a noise component is superimposed input from an analog reception input fil is band-limited by a low-pass filter 2 to remove aliasing distortion components, and then converted into a digital signal by an A/D converter 3. is converted into ε-filter 4. The ε-filter 4 executes processing based on the following equations (1) to (3).

Here, X is the filter input, y is the filter output, a
, are coefficients of an even symmetric non-recursive low-pass filter normalized so that the DC gain becomes O dB, as shown in equation (3).

Equation (1) is the same arithmetic expression as that of a normal linear low-pass filter, but the tap X to be multiplied by the coefficient ak, -
As shown in equation (2), the value of 3 is the filter manual power
, the difference between them is ε. The above values are replaced by filter manual power X. Therefore, large amplitude changes that are signal components are distinguished by equation (2), and only small amplitude random noise components are removed by the low-pass filter action shown in equation (1). As a result, only random components with small amplitudes are removed without distortion occurring in signal components with large amplitudes compared to noise components. In this way,
The received signal from which the small amplitude random component has been removed is decoded by a determiner 5, and the decoded digital signal is output to a digital output terminal 6.

In this case, according to the above embodiment, the ε-filter 4 focuses on the difference in the spectral fine structure on the time axis between the signal component of the received signal and the superimposed random component, and removes only the noise component without greatly distorting the signal component. Therefore, transmission errors can be further reduced compared to processing using a normal linear filter as a reception filter.

In addition. For details on the ε-separating nonlinear digital filter, see, for example, IEICE Theory, April 1982, Vol. J6.
5-A, No. 4 rε-separation nonlinear digital filter and its applications] (Harashima).

It is described in Odajima, Shikakumi, and Miyayo).

Effects of the Invention As is clear from the above-mentioned embodiments, the present invention uses an ε-separating nonlinear filter in place of the conventional linear low-pass filter as the receiving filter, so that the signal components are thickened (distorted). The effect is that only the noise component can be removed without any interference, and the transmission error rate can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a receiving device according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a conventional receiving device. l...Analog receiving end, 2...Low pass filter,
3... A/D converter, 4... ε-separation nonlinear filter, 5... Judgment device, 6... Digital output end agent Patent attorney Shigetaka Awano Haka 1 person

Claims (1)

[Scope of Claims] An A/D converter that converts a received signal into a digital signal, and an ε-separating nonlinear digital filter that removes a noise component with a small amplitude compared to the amplitude of the signal component from this digital signal. Receiving device.