Abstract: The invention relates to a lighting device, comprising a multi-layer carrier plate with a large number of through-openings, in each of which an LED is accommodated. According to the invention, it is provided that the through-holes, accommodating the LEDs have a circular cross-sectional face. Furthermore, the invention relates to the use of a carrier plate of this type.

Abstract: A digital signal processing apparatus is disclosed. The apparatus is particularly suited for detecting a digital signal containing a frequency component in a noisy environment. It uses a distributed arithmetic concept for hardware realization. The use of specific coefficients and hardware arrangement has resulted in a reduction of memory location requirement. The invention finds the main application in the area of telephony in which detection of a variety of signal tones is required for various operations of telephone functions.

Abstract: Digital FSK demodulators to be used in the telephone environment are disclosed. The demodulator according to one embodiment uses the sequential processing of a digital signal encoded in the fractional two's complement numeric representation. The use of multipliers is largely eliminated, thus enabling extensive use of simple shift registers and adders. Consequently the hardware complexity requirement is greatly reduced, thus resulting in very low cost products.

Abstract: Apparatus for use in a secure data communication system includes a microcomputer that controls a cipher process by which sensitive data is encrypted before transmission. When activated, the apparatus accepts either cleartext or ciphertext and transforms the text to its opposite form according to an algorithm that is past dependent and which is also dependent on a pseudo random cipher key. Ciphertext may then be stored in an information retrieval system or transmitted to a destination terminal where the text is deciphered in real time by a corresponding second apparatus that stores the same key. In either case, security of transmitted and stored data is maintained since the sensitive data is in encrypted form. A set of logical instructions according to the algorithm is stored in a read only memory of the microcomputer which includes an EPROM unit having a data field of predetermined characters.