Composite Video Signal Research Articles

Computer peripheral for image data

A computer peripheral for the input of grey scale image data is described. Four versatile modes of operation provide flexibility in the collection of data sequentially or at random. A standard t.v. camera with an interlaced raster is used as the image transducer. The composite video signal produced by the camera provides all the information necessary for the peripheral interface circuitry. The peripheral described in the paper enables the collection of four bits of intensity on a 256 × 256 square grid.

Stationary television display of analog events — An aid in cardiovascular teaching

Summary This paper describes a device and its use to display heart sounds; murmurs; electrocardiograms; venous, arterial, or precordial pulses; either singly or simultaneously. The image is stored and displayed on one or more television monitors. Therefore, these events can be shown to small or large audiences. The principal component of this system is a scan converter that converts a conventional electrical signal into a composite video signal.

Photometric analyser for television cameras

A new, fairly inexpensive method of extracting information from a composite video signal is presented. By intensifying points of equal luminosity (i.e. points lying on the same isophote) which are normally indistinguishable, the details appear on the television screen. Applications are given covering the fields of photographic interpretations, mapping, surface and intensity measurements.

Discrete Analysis of a Composite Video Signal

In this paper the problem of representing the composite video signal for monochromatic T. V. transmission is examined and a method for computing the required spectral bandwidth is devised suitable for computer applications. The results obtained numerically are compared to measured results and to analytical solutions for a determinate signal for special cases. Comparison is made with some maximum horizontal resolution methods with a resulting decrease in bandwidth requirements for most applications.

A Simplified Television Color Encoder

A simplified NTSC-compatible encoder produces a signal which is subjectively equivalent to that of a full broadcast encoder but is simplified to the point of requiring only one 6- by 8-in. printed circuit card. The red, green and blue (R, G, B) signals are matrixed into the R–Y and B–Y chrominance signals. The bandwidths of both signal paths are identical, thereby eliminating the need for an additional video-delay line. Moreover, the burst-flag signal is added negatively to the B–Y signal before band limiting; therefore, no special delay is needed for the burst flag. The R–Y and B Y signals are modulated in balanced fashion with the color subcarrier 90° out of phase. The subcarrier is generated internally by a crystal oscillator. An external subcarrier from a crystal-controlled source can also be used. To create the Y signal, the R, G, B signals are matrixed in the normal manner after which the “combined” signal is amplified and inverted. The inverted Y signal is added directly to both the R and B signals simultaneously in correct proportions, thereby creating the R-Y and B-Y chrominance signals. A separate luminance channel has also been incorporated; this enables a separately derived luminance signal to be used directly as the Y signal. The output of the encoder is a composite color video signal completely compatible with receivers designed for the NTSC signal.

The Video Differential Planimeter

The video differential planimeter is an instrument which measures variations in the projected area of any remote object with the aid of a flying spot scanner or television camera system. The composite video signal, caused by the scanning of the object and its contrasting background, is shaped to yield a sequence of constant amplitude rectangular pulses that are negative going during a scan of the object, and positive going at all other times. The average of this sequence of pulses is obtained from a point on a bleeder resistance returned to the negative supply, and is fed into an integrator. The net integration voltage is read off and the integrator is returned to zero at the end of each field. If the object's projected area remains fixed, the sum of the positive and negative pulse areas entering the integrator will be constant. Hence, the change in integration voltage from field to field will be zero. If the object's projected area varies, the sum of the positive and negative pulses entering the integrator will change, and the readout voltage of the integrator will vary proportionately. The V.D.P. is applied here to the measurement of the vibration of a speaker cone, and to the measurement of the human respiration and plethysmogram.

Generation of NTSC Color Signals

The generation of compatible color signals according to NTSC specifications is covered in this paper. The equation for the composite signal is stated in terms of voltages existing in the red, green, and blue channels, and methods of calculating and measuring the composite video signal produced by a synthetic color bar chart generator are given. The development of the signal from the channel outputs of a color flying-spot scanner is illustrated with block diagrams, and the performance of a number of units in the chain is described. The signal specifications described in this article were used by the NTSC for field testing during the latter part of the year 1951 and also during the year 1952. On the basis of these tests certain modifications of signal specifications were made in January, 1953. These are listed at the conclusion.