Method and device for inspecting spread spectrum signals

Abstract

A method and apparatus for detecting spectrum spread signals by reducing the correlation between the main information signal and the spread signal as much as possible, whereby the detection of a spectrum spread signal is made easier. From an input signal, in which a spectrum spread signal obtained by spectrum spreading an additional information signal has been superimposed on a main information signal, the spectrum spread signal is detected. Using a level adjusting circuit, the gain of the input signal, mainly the main information signal is controlled to reduce the change in the main information signal, or the input signal is sliced at a predetermined level by a slicing circuit to fetch a signal at a predetermined level or lower. A spectrum spread signal detecting unit performs an inverse spectrum spread on an input signal in which the change in the main information signal is reduced, or an input signal with the major portion of the main information signal removed to thereby detect the additional information spectrum spread signal.

Description

technical field [0001] The invention relates to a method and apparatus for detecting a spread spectrum signal in an additional information signal which has been spread and superimposed on a main information signal, such as a video signal. Background technique [0002] Digital information recording devices such as digital VTRs and MD (MiniDisk) recording and reproducing devices have been widely used, and DVD (Digital Video Disc or Digital Versatile Disk) devices each having a recording function have entered the market. In these digital information recording apparatuses, various additional information signals are allowed to be recorded after digital video signals, digital audio signals and other data for computers and the like which are main information signals. [0003] figure 1 is a diagram showing an example of the structure of a conventional recording apparatus suitable for adding an additional information signal to a recorded digital information signal. exist figure 1 ...

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Problems solved by technology

More specifically, if the main information signal is a flat signal with no change, the main information signal is uncorrelated with the spreading code, but since the general main information signal changes according to the information content, it cannot be said that the main information signal is uncorrelated with the PN code

[0021] Therefore, due to this correlation between the main information signal and the spread spectrum signal depending on the information content of the main information signal, it may be difficult to detect the spread spectrum signal obtained by spreading the additional information signal

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