DE3034839A1 - Circuit measuring amplitude and phase distortions - uses signals separated into sections with non-modulating sine square pulses - Google Patents

Abstract

The network measures amplitude and phase distortions in an electrical transmission system such as in television transmission. A measuring signal with two or more sine squared pulses are transmitted and the amplitudes of the received sine squared pulse answers are measured at the receiving end. Each measuring signal contains a first signal section with a number of non-modulating sine squared pulses varied at half their bandwidth. They have the same amplitude and start from a common signal level. The first signal section is linked to a second signal section with a number of non-modulated pulses varied at half their bandwidths.

Description

METHOD OF MEASURING AMPLITUDES AND / OR

PHASE DISTORTION OF AN ELECTRICAL TRANSMISSION SYSTEM.

The invention relates to a method according to the preamble of claim 1, as it is known from the.

For measuring the transmission quality of television transmission systems one usually uses so-called test line signals according to the CCIR standard, which including two sin2 pulses of different half-widths, namely a 2 T pulse and contain a 20 T pulse, where T = 100 ns. These check line signals are suitable However, only for high-quality transmission systems that cover the entire bandwidth of the video signal of 5 MHz. Transmission systems with smaller Band limit than 5 MHz, such as Hetm video recorders, show when transmitting the Check line signals delays which do not provide exact information about the transmission behavior LIn <I allow the achievable dild (ualitäl. Furthermore, the test line signals Even with high-quality transmission systems, no precise detection of non-linear ones Distortions too.

In contrast, the object of the invention is to provide a method of the type mentioned above, which also applies to transmission below the Bandwidth, systems with an exact bandwidth / transmitted signal Statement about amplitude and / or phase errors as well as about non-linear distortions enables.

According to the invention, the object is achieved by the characterizing features of claim 1 solved.

Advantageous further developments and refinements of the method according to Claim 1 results from the subclaims.

The inventive method uses a measurement signal from a unsupported. . Large number of / sinZ pulses of the same amplitude and varying There is a half-value width, which the frequency band to be measured is relatively finely graduated cover and therefore a high resolution accuracy as well as an exact localization of the frequency range of a transmission error allowed. Furthermore, the sin2 impulses go in a first Signal portion from a lower level, e.g. Black level of a video signal, and in a second signal portion of one upper level, e.g. the white level of the video signal, so that by comparing sin2 pulses of the same half-width in the two signal sections are non-linear Distortions can be measured.

The variation of the half-widths within each signal section preferably takes place according to a geometric sequence; e.g. in each signal section eight pulses with half widths of 20 T, 10 T, 6 T, 4 T, 3 T, 2 T, 1.4 T and 1 T are provided.

The invention is explained in more detail with reference to the drawings: It shows: 1A is a timing diagram of a preferred embodiment of the one according to the invention Method used measurement signal; FIG. 1B shows an enlarged representation of an in the measuring signal according to FIG. 1A existing sin2 pulse, and FIG. 2 the spectral Course of the measurement signal according to FIG. 1.

The measurement signal 10 illustrated in FIG. 1A comprises two superimposed the following signal areas 11 and 12 each with eight / sin2 pulses varying Half width is, of which a pulse 20 is shown enlarged in FIG. 1B. The pulses of the first signal range 11 go from the lower level 13 and the Pulses of the second signal range 12 from the upper level 14. All impulses both signal areas 11, 12 have the same amplitude A, which is the difference between the level 14 and 13 corresponds. The half widths of the eight pulses each Signal range 11, 12 change according to a geometric sequence and amount for example 20 T, 10 T, 6 T, 4 T, 3 T, 2 T, 1.4 T and 1 T, where T in the case of a Use of the measurement signal 10 for television transmission systems is equal to 100 ns. the The time between adjacent pulses is constant and can be selected as required will. Furthermore, the transitions between levels 13 and 14 can be in the range between the last pulse of the first signal range 11 and the first pulse of the signal area 12 and in the area after the last pulse of the signal area 12 can be chosen at will.

unsupported The variation of the half-widths of the / sin2 pulses each signal range 11, 12 is shown in FIG. 2 on the basis of a spectral distribution for illustrates the case of a measurement signal suitable for television transmission systems. The chosen variation according to a geometric sequence, starting with the larger half-width, results in a relatively large spectral density of the measurement signal in the low-frequency range and a decreasing spectral density in the higher-frequency range. This density distribution corresponds to the importance of the corresponding frequency components for the measurement result.

To measure a transmission system, the impulse response of the in the measurement signal fed into the transmission system according to the amplitude differences of the individual pulses as well as any harmonics with respect to a reference value (which can be chosen to be equal to the amplitude of the first incoming pulse). Furthermore, the amplitudes of pulses are the same half-width in the two Signal sections 11, 12 compared with one another, resulting in non-linear distortions are recognizable.

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Claims (5)

PATENT CLAIMS Method for measuring amplitude and / or phase distortion an electrical transmission system, in particular a television transmission system, in which a measurement signal with at least two sin2 pulses is transmitted and at the receiving location the amplitudes of the received sin2 impulse responses are measured, d a d u r c h e k e n n n n z e i c h n e t that each measurement signal has a first signal section a multitude of unsupported sin2 pulses with varying half-width which have the same amplitude and a common first Signal level assume that the first signal section is a second signal section with a large number of non-carrier sin2 pulses with varied half-width connected, their amplitudes with each other and with respect to the Amplitudes of the sin2 impulses of the first section are the same and which of a common one second signal level, that of the difference or the Sunxne from the first signal level and corresponds to the pulse amplitude. 2. The method according to claim 1, characterized in that the number of the sin2 pulses in the first signal section of the measurement signal is equal to the number of sin2 pulses in the second signal section of the measurement signal. 3. The method according to claim 1 or 2, characterized in that the Half-widths of the sin2 impulses of each signal section according to a geometrical one Increase or decrease in consequence. 4. The method according to any one of claims t to 3, for measuring amplitude and / or phase distortions of a television transmission system, characterized in that that the first signal level is the black level and the second signal level is the white level of a video signal. 5. The method according to claim 4, characterized in that in each Signal segment eight sin2 pulses with the following graduation of their half-widths are: 20 T, 10 T, 6 T, 4 T, 3 T, 2 T, 1.4 T and 1 T, where T = 100 ns are.