Abstract: A parallel concatenated coder (20) outputs a sequence of data sets in which earlier data sets contain data bits (d) and non-interleaved parity bits (p) without interleaved parity bits (q), while later data sets include the interleaved parity bits (q). Each data set is modulated as one symbol. The output format partially overcomes the delay incurred by interleaving the parity bits (q), with a substantially even distribution of data and parity bits in the sequence of data sets. The delay may be reduced further by interleaving with an index constraint.

Abstract: Apparatus and methods usable for wavelength references and measurement of wavelength of a light beam. The apparatus comprise at least two wavelength reference or filter elements positioned in a light beam, each wavelength reference element having a different free spectral range and operable to define a joint free spectral range, and a detector positioned in the beam after the wavelength reference elements. The joint free spectral range provided by the multiple wavelength reference elements results in a joint transmission peak that is centered at a unique wavelength, and maximum optical power detectable from the beam by the detector occurs at the center wavelength of the joint transmission peak.

Abstract: A digitizing system for automatically recording data points representative of, for example, sheet metal templates having varying shapes is disclosed. A stylus connected to a tracing arm is guided along the edge of a template. As the arm moves, digital scales generate a stream of encoded electrical pulses which yield direction and distance information. These pulses are then decoded, counted, and stored. If the operator has selected the automatic digitize mode, a data point is automatically stored each time the stylus moves a predetermined distance in the X, Y, or Z direction. The present invention also provides an improved method of optimizing or compressing the stored set of data points.

Abstract: A video viewfinder system according to the preferred teachings of the present invention is shown for use with a camera of a standard design. The video viewfinder system includes video monitors for displaying derived images from a video camera of a primary image formed by the lens of the camera to allow the photographer to view the primary image formed by the camera lens at locations remote from the camera. Specifically, the video viewfinder system of the preferred form includes a viewfinder hood secured to the camera having a ground glass located at its first end for forming the primary image by the camera lens and with the video camera located at its second end and aimed at the primary image.