Abstract: A fractional N synthesizer is disclosed. The synthesizer includes a phase detector that receives first and second input signals and generates a pulse width modulated (PWM) output signal having a pulse width indicative of the phase relationship between the input signals. A pulse-width-to-amplitude (PW/A) conversion circuit connected to a loop filter where the conversion circuit receives the phase detector output signal and generates a PW/A output signal having an amplitude indicative of the phase detector output signal pulse width. The phase detector output signal may comprise a periodic series of pulses having varying pulse widths and the PW/A output signal amplitude changes at the end of each pulse to reflect the corresponding pulse width. The conversion circuit may include a current circuit connected to a capacitor, where the current signal receives the phase detector output and sources a constant current during a charging phase of the phase detector output signal.

Abstract: A fractional N synthesizer is disclosed. The synthesizer includes a phase detector that receives first and second input signals and generates a pulse width modulated (PWM) output signal having a pulse width indicative of the phase relationship between the input signals. A pulse-width-to-amplitude (PW/A) conversion circuit connected to a loop filter where the conversion circuit receives the phase detector output signal and generates a PW/A output signal having an amplitude indicative of the phase detector output signal pulse width. The phase detector output signal may comprise a periodic series of pulses having varying pulse widths and the PW/A output signal amplitude changes at the end of each pulse to reflect the corresponding pulse width. The conversion circuit may include a current circuit connected to a capacitor, where the current signal receives the phase detector output and sources a constant current during a charging phase of the phase detector output signal.

Abstract: A direct digital synthesis (DDS) clock generation circuit (100) produces a digital clock signal having low phase jitter. A N/M digital divider circuit (103) produces an output signal having a frequency of N/M times an input clock frequency. The N/M digital divider (103) generates a control signal that is used to alternately charge and discharge a capacitor (122) through a current source (118) and a current sink (116) to produce a linear sawtooth waveform having rising and falling rates which are proportional to the N and M−N values, respectively. A voltage sensor and current controller (120) automatically adjust the current sink (116) and current source (188) to maintain waveform amplitude at a relatively constant magnitude and average DC level. A voltage comparator (126) compares the instantaneous voltage on the capacitor (122) to a bias voltage and produces the digital clock signal having low phase jitter without the use of a sine look-up table, a digital-to-analog converter, or an analog filter.

Abstract: A radio which can operate in two separate frequency bands, with size, weight, and cost that is comparable with a conventional unit that can operate in only one frequency band. The radio includes two local oscillators which respectively produce signals at substantially the same frequencies for operation in both frequency bands. By appropriately choosing the frequency of the oscillators' signals, the radio can produce an intermediate signal which has the same frequency when the radio is operating in either band.

Abstract: A system for generating a short-range wireless data communication link through an over-the-air channel on a predetermined radio frequency (RF) carrier. The system integrates conventional RF techniques into a low-power and low-cost system for establishing short-range wireless data communication. The system generates short-range wireless data communication links between a transmitting unit (500) that transmits an operating signal carrying data, and a receiver unit (1000) that receives the operating signal without a synthesizer or a heterodyne scheme.

Abstract: A narrow band RF carrier acquisition method suitable for Demand Assigned Multiple Access (DAMA) networks having multiple narrow band carriers operating with channel frequency spacing that may be less than the frequency uncertainty on the link. The present invention uses a variable database of active narrow band carrier frequency assignments for the ground stations in the system, which, together with a knowledge of the approximate magnitude of the frequency errors, can be exploited to allow a receiving ground station to optimize the process of narrow band carrier frequency acquisition. The optimization employs alternative procedures depending upon different acquisition circumstances, thereby allowing the receiving ground station to utilize the optimal acquisition method under any given set of circumstances, where the circumstances are individual and changing for each ground station in the system but are known and communicated from a system database.

Abstract: A space and power efficient digitally controlled, all solid state, DC to AC converter powered by low voltage DC, typically found in logic circuits, that generate a high voltage low frequency AC output with a low slew rate waveform, suitable for activation of an electro-mechanical bell or electronic ringer in a telephone. The present invention is particularly suited for application in small, wireless terminals used to provide telephone services via satellite or terrestrial radio to single users or a small number of users as found in a PBX. The present invention is also particularly suited for battery or solar powered equipment where power efficiency is of significant value.

Abstract: A distributed, demand access local loop telephone system is disclosed. An optical fiber, or fibers, connect a central office and a plurality of remote units which are located near subscriber populations. Communications on the fiber is by high speed digital data stream which is comprised of a plurality of bit multiplexed PCM channels, each of bandwidth equivalent to a VF channel or greater. The remote units are connected to the subscriber equipment (e.g. telephones or other data sources/sinks) by subscriber dedicated links (e.g. wire pairs or other cabling), and the remote units may be added, subtracted, or moved along the fiber path to reconfigure the overall system. Because of the demand access nature, the fiber bandwidth can be dynamically redistributed among the remote access units at high speed and controlled at the central office. The topology of the system can also be reconfigured, within limits, from a central site.

Abstract: A TDMA multiplexer-demultiplexer includes a plurality of input/output ports and common control equipment. Each input port is capable of accepting information asynchronous to the TDMA clock and at typical terrestrial clock rates. The input/output ports perform all the necessary signal processing for a TDMA terminal including pulse stuffing, changing continuous asynchronous low rate information to high bit rate burst form as well as forward acting error correcting encoding, if desirable. By incorporating all the signal processing in the multiplexer-demultiplexer, much equipment duplication is eliminated along with eliminating a requirement for multiple high frequency control and timing signal line drivers and buffers. More particularly, the transmit side of each port includes a separate elastic buffer to raise the input rate to a synchronous common higher rate. In addition, on the receive side, clocking on the low speed side of the expansion buffer is derived from the station's transmit clock.