Abstract: A helical filter is disclosed which includes a ground plane having microstrip transmission line segments to which a respective helical resonator coil is connected at the high impedance end thereof. A discrete capacitor is connected in parallel with each transmission line. A housing is provided with individual resonator compartments which effect associated distributed capacitance with the resonators themselves, which capacitance may be adjusted by included tuning screws. Conductors are connected to and form an integral part of a given two of said transmission lines and serve as the input and output for the helical filter. The transmission line and discrete capacitor pair provides the necessary impedance match, while the capacitor itself facilitates temperature compensation and frequency range selection.

Abstract: A correction control circuit for use in compatible AM stereophonic receivers of the type utilizing a cosine correction signal to remove inherent distortion from the received and detected signals. During periods of weak or noisy signals or when co-channel interference is present, excess cosine correction signal causes a reduction in the amount of stereo difference signal component in the output signals, and in the amount of correction provided. In a worst case signal situation, there will be no difference signal component in the output and the monophonic output not be corrected.

Abstract: A method within adjusting values of a passive temperature compensation network for use in an oscillator includes the steps of determining the frequency variation of the oscillator from nominal over a specified temperature range, determining the maximum frequency variation over the temperature range, and recalculating the performance of the circuit over the temperature range utilizing reduced values for the temperature compensation components therein. The oscillation frequency can be utilized as the controlled parameter to a laser based component trimming system. Power is applied to the oscillator and the compensation component is trimmed until the circuit oscillates at the specified target frequency.

Abstract: The system requires the use of the permanent ID of the requesting unit in every channel request made on a control channel before every transmission. The channel grant will include the ID along with the channel number and these may be recorded for possible later reference. A channel assignment is retained for a brief period after each transmission, allowing a conversation to be continued on the same channel without a break. Units can access the control channel with a channel request and be assigned a channel even while the dispatcher is using the voice channel. In the case of a need for communication with a larger group, a dispatcher can form a temporary "patch" group of all involved units, with a temporary ID assigned to that group. A channel request from a member of the larger group must then include, not only the permanent ID of the requesting unit, but the temporary ID of the "patch" group.

Abstract: Increased efficiency in the use of a communications channel between a Control Unit and a multiplicity of terminal or satellite units by utilizing the combinations of the unit address code words and their complements as coded commands and automatically returned responses. At least one combination of the Control Unit address code words and word complements can be manually entered at any one of the satellite units to serve as a special response to one combination of the respective satellite address code words and word complements, to cause a change of function or operation at the Control Unit. The system may be coupled to a Host Computer and normally the information received by the Control Unit would be encoded for transmission to the computer, in which case the change of function could be the disenabling of transmission to the Host Computer.

Abstract: In accordance with the present invention, there is provided a register-modelled radio system comprising a plurality of register-modelled processors having addressable registers for modelling the virtual state of the processor; a serial bus, interconnecting the register-modelled processors for communicating between the addressable registers; and a communications protocol for passing information to or from the addressable registers, whereby the virtual state of a radio portion may be determined or altered by, respectively, communicating information from or to the addressable registers. The communications protocol further comprises an information packet having an address, an operation code, optional data, and an error detection device, such as a cyclical redundancy check packet. The operation code is chosed from the group of primitive operation codes reset, read, write, bit set, bit clear, acknowledge, and negative acknowledge.

Abstract: An analog divider circuit as for use in AM stereophonic receivers provides minimum phase variation with control voltage level change, by means of a feedback circuit. The division process is performed by subtracting logarithms of currents produced by the dividend and divisor voltages, then deriving the antilog of the difference or remainder. At the critical point in the process, where junction capacitances do not accurately track the change in the control level, cross-coupled capacitors stabilize the circuit by feeding back a signal from the circuit output to minimize any undesired phase changes.

Abstract: A missing pulse detector is disclosed in which the absence of a pulse in a variable frequency periodic pulse train is detected and distinguished from a reduction in the pulse repetition rate. Between successive pulse train pulses a first counter counts clock pulses at a first rate and develops a maximum count related to the time duration between successive pulses. This maximum count is maintained by a latch circuit during the next time duration between successive pulses and is compared with the count of a second pulse counter which counts clock pulses during successive pulse train pulses at a second rate normally less than the first incrementing rate. When the count of the second counter exceeds by a predetermined amount the latched count of the first counter, this indicates the occurrence of longer time duration and a count comparator and logic circuit provides an arming output signal.

Abstract: A frequency control circuit for a single sideband receiver is disclosed wherein the local oscillator is swept at a first rate to enable the acquisition of a transmitted signal. When the signal is acquired, the local oscillator is swept at a second rate in an indicated direction in order to center the signal. Upon centering, the local oscillator is maintained at a frequency which centers the signal in response to the activation of a squelch detector.

Abstract: Three possible types of "faults" may be detected in the ignition system of a vehicle, using simple combinational logic to provide an essentially error-free activation of an indicator when a true fault is present. "Fault" signals which mean non-rotation of the alternator, broken cables or short circuits and the like are distinguished from transient and less significant conditions. The latter conditions are prevented from activating the indicator. A single indicator lamp serves to alert the user to a serious fault requiring service.

Abstract: The tone detector provides accurate detection of a single predetermined tone frequency within a mixture of frequencies, utilizing a carrier signal source at a relatively high frequency. The high frequency signal is divided down to two frequencies, one just above and one just below the tone. The divider output is then maintained at the frequency of the tone by continuously adjusting the divisor number between the two divisor values. Multiplying the received signal or a portion thereof by the divider output provides a detect signal when the tone is present in the received signal with sufficient amplitude.

Abstract: Disclosed, herein, is an Automatic Gain Control (AGC) signal processor and a method for generating an AGC signal in a phase-locked receiver. An incoming signal, exhibiting both coherent and incoherent characteristics, is filtered to obtain the desired bandwidth. The filtered signals are amplified to maintain an amplitude relationship between the coherent and incoherent signals. The incoherent signals are conditioned in the same circuit, but in a different manner, than coherent signals are conditioned. The conditioned signals are utilized to generate an AGC signal such that an AGC signal is generated in a single circuit for both coherent and incoherent signals, although by differing circuit responses, depending upon the conditioning of the incoming signal.The preferred embodiment of the novel AGC processing contemplates a full wave rectifier as its signal conditioner. Another embodiment contemplates negative peak detection as its conditioner.

Abstract: In accordance with the present invention there is provided a bandpass T filter and power splitter for electromagnetic energy. It is composed of a plurality of resonant elements serially arranged to form a plurality of forward multi-pole bandpass filters. At least one resonant element is common to both signal paths. The common resonant element transfers energy from the common path to the independent signal paths to effect a power split. The two signal output paths are isolated from one another by a multi-pole bandpass filter. The resonant elements may be composed of either resonant waveguide cavities or dielectric resonators.

Abstract: In a stereophonic broadcasting receiver, a single indicator with two levels of illumination serves to provide indication of both accurate tuning and the presence of stereophonic signals. One signal or a combination of signals related to the tuning circuits of the receiver cause the indicator to be illuminated to a perceptible level. When, by use of a pilot tone detector, it is certain that stereophonic signals are being received, additional current is caused to flow through the indicator, raising the illumination to the maximum allowable level. The circuit has particular application to manually tuned receivers.

Abstract: A switched-capacitor high pass filter is disclosed and in which a switched capacitor approximation of an inductor is inserted in the direct coefficient loop to prevent instability. The value of the inductor is selected to compensate for the filter termination phase error.

Abstract: A processing circuit for efficiently amplifying radio frequency signals while generating minimal splatter includes a first channel having an envelope detector for generating a rectified envelope signal from a modulated radio frequency input signal provided thereto. The first channel includes a peak clipping circuit which clips portions of the rectified envelope signal having an instantaneous voltage less than a first selected threshold level. A second channel includes a symmetric clipping circuit for symmetrically clipping portions of the modulated radio frequency input signal which exceed a second voltage threshold level.

Abstract: In accordance with the present invention, there is provided a Loran C cycle slip reduction technique that consists of sensing the signal to noise ratio and narrowing the phase locked loop bandwidth when a predetermined signal-to-noise threshold is exceeded.

Abstract: There is provided a method and a corresponding apparatus for establishing the proper bandwidth at one frequency in a microwave, dielectric resonator waveguide filter.Bandwidth is determined by the product of the resonant center frequency and the interresonator coupling coefficient. The interresonator coupling coefficient has been found to vary depending upon the interresonator spacing as well as the position at which the resonators intercept the electromagnetic field distributed across the waveguide.This method establishes the proper combination of field-intercepting position and interresonator spacing such that the proper bandwidth is established at one frequency.