Abstract: A combination display window cover, tilt stand, and handle for a portable instrument, the unit serving each of these functions by virtue of an integrally formed appropriately shaped unit which can preferably be molded as a single piece of elastomeric material and does not introduce any substantial cost increase over and above a conventional handle. The invention is suited for use in conjunction with a portable instrument which includes a housing of generally parallelepiped configuration having relatively large area front and rear opposing surfaces and relatively small area top, bottom and opposing side surfaces, the housing having a display window extending across its front surface relatively near the top edge thereof and substantially parallel to the top edge.

Abstract: A moving coil instrument with a unique base of nonmagnetic sheet metal construction so arranged that sides of the base can flex to receive and clampingly retain a magnetic circuit, without causing movement of end portions of the base which support the moving coil for pivotal movement. Projections of a casing cooperate with circular mounting ears on the sides of the base to exert an inward force to assist the clamping action of the sides to securely hold the magnetic circuit against movement. A unique unitary sheet metal balance cross and a terminal plate assembly provide for connecting inner ends of taut bands which support the coil for movement. Cooperating tabs and slots on the coil, balance cross, and terminal assembly provide for securing the terminal plate and balance cross at opposite ends of the coil in predetermined locations with respect to the coil.

Abstract: A hub lighted indicator suitable for aircraft applications including one or more pointers, each capable of a full 360.degree. excursion over the dial face. The pointers include a portion which extends through a central circular aperture in the dial between the dial and the hub lighting member and are connected in a non-interfering manner to corresponding ring gears mounted for rotation coaxially with the dial aperture. The ring gears are driven in accordance with the quantities being measured to cause a corresponding excursion over the dial face of the connected pointer. Electrical connections are made to the hub lighting member from the rear portion of the indicator through the center portions of the ring gears.

Abstract: A panel meter having a unique casing with an adapter on the casing. The meter movement is in a compartment of the casing and the adapter is secured to the casing and cooperates with the casing to define a compartment separate from the meter compartment. Components such as calibrating resistors and rectifiers can be installed, if required, in the separate compartment after the meter movement is installed in the casing. In the preferred embodiment, the casing has a configuration generally in the form of a segment of a cylinder, and the adapter has a segment configuration so that the casing and adapter present a generally cylindrical profile when joined. This arrangement permits using the same basic meter movement and casing to produce meters of different operating characteristics. The meter either with or without the adapter can be inserted through the usual circular opening of a mounting panel. The casing has toothed sides to retain a quick connect panel nut used to secure the meter to the panel.

Abstract: A fully digital spectrum analyzer accepting as an input either an analog signal or a series of digital numbers and using time compression and DFT (Discrete Fourier Transform) techniques to provide the spectral component values of the input signal. Novel techniques and means are used in obtaining the power values for selected spectral lines and in averaging these power values. Statistically controlled noise is added to the input of the spectrum analyzer to enhance its resolution beyond the resolution which would be otherwise available. Advanced and efficient techniques are used for generating and applying trigonometric functions in the course of finding the real and imaginary part of Fourier transforms, and for providing running averages of the power spectra.

Abstract: A video system having a transmitter in which a composite signal is formed by combining digital information with scanlines of an analog video signal generated by a line scanning device, and a receiver in which the digital information is recovered. The digital information is combined with the analog video signal at predetermined locations along scanlines of the video signal, and these predetermined locations are varied in order to prevent visible deterioration of the video image. In the video receiver, the digital information is recovered by examining the composite signal at the predetermined locations to extract the digital information. Each bit of digital information to be conveyed is represented by a first pseudo-random digital pulse sequence (or its complement, depending on whether the data bit is 1 or 0) which is superimposed on a selected scanline of the analog video signal to form the composite signal.

Abstract: An electric meter particularly characterized by a small number of moving parts and simplified assembly. A coil assembly initially including integral support elements which permit connection of pivot bearings or taut bands is adapted to be accurately positioned for rotation on the supporting base by inserting the assembly into the base. Cooperating locating surfaces on the base and coil assembly provide for accurate positioning of the support elements so the axis of rotation of the coil is in a predetermined position relative to a magnetic circuit of the meter. After insertion of the coil assembly, the bridging elements are severed. A coil support form of unique construction includes motion limiting elements which cooperate with surfaces of the magnetic circuit to limit the permissible extent of movement of the coil, in the event of shock or impact, to positions well within the elastic limit of the supports which mount the coil for rotation.

Abstract: A measuring device such as a digital thermometer uses dual slope analog-to-digital converter techniques but elminates the usual need for a high precision voltage source. An input capacitor is connected through novel switching to the temperature responsive arm and the temperature insensitive arm of a resistance bridge, to the low precision voltage source and to the output of the integrator and detector amplifiers. The switching sequence is such that long term changes in the voltage source and in the amplifier offset and drift are cancelled out during measurement cycles, thereby providing highly accurate measurements without the usual need for an expensive high precision voltage source.

Abstract: A spectrum analyzer including a device for analyzing signals whose time duration is short as compared to the normal sampling rate of the spectrum analyzer. A transient signal, or a small portion of any analog signal, is sampled at a sampling rate which is substantially higher than the normal sampling rate of the spectrum analyzer, and the samples are stored in analog form in a storage device such as a charge coupled device acting as an analog delay line. The stores analog samples are then read out at the normal sampling rate of the spectrum analyzer, to form a longer duration signal which can be analyzed by the spectrum analyzer in a conventional manner.

Abstract: A dual slope analog-to-digital converter, which has an autozeroing circuit for cancelling out integrator and detector offset and drift, is additionally provided with a circuit for injecting a voltage of selected polarity and magnitude to offset the input voltage of the converter such that the input voltage can be measured with respect to a nonzero reference line.