Abstract: An improved fuse and mounting arrangement is disclosed especially suited for mounting on a printed circuit board or the like. The fuse device itself is of the two-bladed type for reinserting in an individual fuse holder. The holder is formed of a thermo setting plastic with a high resistance to heat. End positioned cavities in the holder are dimensioned to receive conductive terminals which accommodate the fuse blades and which holder further includes leg portions extending downwardly for appropriate attachment to the associated printed circuit board, such as by soldering or the like.

Abstract: A system and method for use in a network of the type including a bus which carries a plurality of digital, multiple bit time divided channels of information including audio information provides for the decoding of digital audio within one of the channels to analog audio signals, the coding of analog audio to digital audio and the placing of the digital audio onto the bus within one of the channels, and the generation of internal or localized analog tones in an improved and efficient manner. A decoding means is provided for converting a digital multiple bit word to analog form. A control means which includes tone generating means adapted for providing digital multiple bit tone words controls a select means which selectively couples the decoding means to the bus to enable decoding of the digital audio or to the tone generating means for providing the analog tones in response to digital data received from the bus within a preselected channel.

Abstract: A decoder for receiving and decoding a coded signal includes a particular frequency f.sub.o with a first and second amplitude. The first amplitude of the frequency f.sub.o is associated with the end of a first coded message while the second amplitude of the frequency f.sub.o is associated with the beginning of a second coded message. The decoder includes a receiver for receiving the coded signal, a tone detector circuit for detecting the frequency f.sub.o, a level sensor responsive to the receiver output, a function block for performing a command and a control unit responsive to the tone detector circuit and the sensor means. The tone detector and control unit operate in one of at least two possible states. In the first state the control unit causes the tone detector to respond to the first amplitude of the frequency f.sub.o. When the level sensor senses the second amplitude of the frequency f.sub.o the control unit responds by placing the tone detector circuit into its second state.

Abstract: An improved multifrequency trunked, two-way communications system is provided in which a plurality of conventional single channel radio units are provided access. The system includes a predetermined number of information channels that are shared by a plurality of trunked stations. A trunked controller assigns one of the information channels to a requesting trunked mobile unit. The requesting trunked mobile unit is enabled to operate on the assigned channel in response thereto.The improved communications system includes a radio access link which enables the single channel radio units to operate on an assigned information channel in the same manner as the trunked remote stations. The radio access link provides the plurality of conventional remote stations automatic access to the trunked system without requiring any modification of the conventional remote stations, and likewise without modification of the trunked remote stations and trunked controller.

Abstract: An interdigital microstrip transmission line filter (100) includes three electrically conductive strips (104, 106 and 108) each coupled to grounded portions (110 and 120) on one end and coupled to respective capacitive loading pads (112, 116 and 114) on the other end. Input and output pads (130 and 140) may be coupled to signals from other circuitry located off or on the same substrate (150). Grounded portion (110) extends between capacitive loading pads (112 and 114) for minimizing undesired coupling between non-adjacent strips (104 and 108). As a result, the unique microstrip filter (100) has a frequency response that is substantially devoid of passband transmission zeros.

Abstract: A modular transducer mounting arrangement includes a substantially planar support plate. An aperture having an angular bevel is provided in the support plate such that a loudspeaker may be positioned in the bevel to allow sound to exit from the loudspeaker in a manner which is substantially unobstructed acoustically. An adhesive shock absorbing pad is attached to the rear of the support plate for isolating the loudspeaker microphone and support plate from mechanical shock. This creates a free floating and reliable transducer mounting assembly which provides shock isolation and easy serviceability.

Abstract: The remote digital volume control system (10) as used in an audio control apparatus comprising at least one multidigital/audio slot bus (12) which is coupled to base stations through interfaces (21-24). Console interfacing circuits (38) are coupled to the bus (12) and a plurality of remote consoles (30) each with channel control panels (32) coupled to the interfacing circuits (38). The system (10) comprises channel control modules (102) and shared A/D circuitry (150) including two comparators (152, 153) and an up/down counter (154) for generating a four-bit word for each volume control setting of each channel control module (102). The remoted interfacing circuits (38) coupled to said bus include a RAM (180) for storing volume level information for each channel control module (102) and routing information, and a timing control circuit (182) for routing information from the respective digital/audio slots on the bus (12) to audio line driver circuits (71-74) in the consoles (30).

Abstract: An improved adaptive loop filter for modulatable frequency synthesizers containing digital phase comparators is described. The unique adaptive loop filter provides a wide bandwidth during a signal acquisition mode and a narrow bandwidth during a signal tracking mode. The adaptive loop filter includes a current limiter coupled to the error signal from the digital phase comparator for generating a current-limited output signal; a filter coupled by a resistor to the current limiter output signal and including a series-coupled resistor and capacitor for filtering the current limiter output signal to provide a steering line voltage; an amplifier coupled to the junction between the filter resistor and capacitor for generating a feedback signal; a resistor for coupling the feedback signal to the current limiter output signal for substantially reducing the duration of voltage transients; and a reference filter for coupling the steering line voltage to the steering input of a voltage-controlled oscillator.

Abstract: An electrical contact assembly is provided which is capable of accommodating batteries for other electrical devices exhibiting a plurality of different physical sizes. A V-shaped contact arm having a hook-shaped member at one end thereof and a double torsion spring at the remaining end thereof is mounted to a battery housing surface. The double torsion spring end of the V-shaped member is mounted on a support post and is fixedly held in position such that the torsion spring does not freely rotate. The hook-shaped end of the V-shaped member is engaged by a second post adjacent to the first post so as to place the contact arm under tension. The tip of the V-shaped member thus forms an elbow which deflects to a greater or lesser degree depending upon the size of the electrical device to be contacted.

Abstract: A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal.

Abstract: A synthesizer radio frequency (RF) signal receiver (FIG. 1) for single sideband radios is described that can eliminate interference due to internally generated spurious signals, commonly referred to as "whistler spurs". The unique receiver includes first and second mixers (102 and 106), which are intercoupled by a 75 mHz crystal filter (104) having a 20 kHz passband, and which are each coupled to signals from voltage controlled oscillators (120 and 140). The first IF frequency provided by the first mixer (102) varies about 75 mHz, and the second IF frequency provided by the second mixer (106) is fixed at 11.4 mHz. The second mixer (106) is coupled to 11.4 mHz stages (108) which have a 2.7 kHz passband. The 11.4 mHz stages (108) are followed by another mixer (110) and audio stages (112) for demodulating audio signals from the received RF signal, which are then applied to a speaker (114).

Abstract: An improved method and means of determining reflection coefficients that characterize an electrical signal that obtains characteristics of an all-zero inverse lattice filter. The reflection coefficients are obtained by filtering the signal, sample the filtered signal, obtaining the elements of a correlation array from the samples, initializing values of arrays forward residuals, backward residuals, and cross correlation of residuals, combining array elements to obtain a first reflection coefficient, removing from the forward, backward and cross-correlation arrays the effect of the first reflection coefficient, calculating from the revised arrays a second coefficient, and repeating the calculations to the desired order. In a second embodiment of the present invention, samples are selected from the digitized signal and multiplied by a windowing function.

Abstract: A shock absorbing insert for protecting a fragile quartz crystal includes a Teflon carrier with sloping walls which carries a number of dimple or rib shaped springs. These springs have varying spring rates increasing as they get farther from the base. The carrier is supported by a cushion spring system having a lower spring rate than that of the dimple or rib springs. This structure allows the force of mechanical shock to be distributed across the entire surface of the crystal rather than being concentrated at isolated areas of high stress.

Abstract: Improved method and apparatus in the form of coherent demodulators for MSK signal or other angle-modulated carrier signals of substantially constant amplitude and continuous phase are provided. The coherent demodulators include a frequency doubler, a first mixer for multiplying the frequency doubled signal with a half clock signal to produce a carrier term signal, a bandpass filter for filtering the carrier term signal and a divider coupled to the carrier bandpass filter to produce a coherent carrier signal. The half clock signal is generated by multiplying the frequency doubled signal with the filtered ouput signal of the carrier bandpass filter by a second mixer, and bandpass filtering the output signal of the second mixer to produce the half clock signal. The received binary data modulated signal and the generated coherent carrier signal are input to a quadrature detector for recovering the binary data.