Abstract: An analog to digital converter circuit includes an isolation circuit, an input circuit including a resistor chain, a plurality of fixed threshold comparators, and an encoder. The resistor chain includes a plurality of resistors connected in series, the isolation circuit being configured to isolate a device supplying the analog input signal from the input circuit. The isolation circuit is connected to the input circuit at a top node of the resistor chain, and wherein 2N values of the analog input voltage are connected to inputs of the fixed threshold comparators to produce corresponding output signals. Methods of converting an analog signal to a digital signal are also described.

Abstract: A system includes a database, a controller, and multiple nodes. The database is capable of storing information. The controller is capable of facilitating access to the database. The controller is also capable of detecting a new node in the network and, if necessary, communicating a network protocol to the new node to allow the new node to participate in the network. The information in the database could represent medical-related information. The nodes could include fixed nodes and portable nodes. The network could represent a mesh network.

Abstract: Source intelligence within a predetermined bandwidth is normally provided to a transmission channel having a bandwidth constraint of the predetermined bandwidth. For privacy transmission, a first pulse train indicative of the source intelligence is derived and is enciphered by addition of pseudo-random values to the pulses, either directly or modulo some specified constant. The enciphered pulse train is converted to first and second symbol pulse trains at subharmonic frequencies of the first pulse train. Energy within a selected spectrum is derived from each symbol pulse train, such as by filtering, and used to modulate first and second channels of a quadrature modulator having a carrier frequency centered within the predetermined bandwidth. A suppressed carrier quadrature modulated output is transmitted along with a carrier frequency component.

Abstract: An adaptive transmitter power control for use in satellite communications systems wherein at least two ground stations communicate serial streams of binary data via a satellite transponder whose power-output is functionally dependent upon received signal strength. At least one of the ground stations includes a quality monitor which makes a real-time determination of the quality of the received signal, and generates signal quality indications in accordance with this determination. These signal quality indications are continuously communicated back to the corresponding transmitting station along with the serial stream of binary data. An encoder multiplexes the normal binary data and the signal quality indications into single, combined signal for transmission over only a single communications channel. The normal binary data and the signal quality indications are reconstructed at the transmitting station, where the signal quality indications are used to control the power level of the transmitted signal.

Abstract: An equalizer-dependent timing recovery system monitors the equalizer weighting coefficient pattern over the entire time span of the equalizer, and differential changes at opposite ends of the pattern are used as a basis for adjusting the receiver symbol timing clock. The magnitudes of a plurality of equalizer weighting coefficients at the beginning of the equalizer are summed and the total is compared with the summed magnitudes of a plurality of equalizer weighting coefficients at the end of the equalizer. Depending upon the sign of the difference between the two totals, the phase (or frequency) of the receiver symbol clock will be adjusted so as to shift the equalizer weighting coefficient pattern in a direction such that the magnitude of the weights at both ends of the equalizers are approximately the same.Circuitry for implementing the above scheme includes a pair of adders coupled to sets or plural weighting coefficient stages for opposite ends of the equalizer.

Abstract: Non-linearities imparted by an acoustic coupling instrument for interfacing data signals from a modem to a telephone line are compensated. Both the output of the modem and that of the non-linearity introducing instrument are monitored. The two output signals therefrom are compared and an error signal representative of the degree of non-linearity of the line signal is generated, and this error signal is then appropriately scaled and stored in a memory as a correction signal. Stored correction signals are read out of the memory in response to address signals defined by the characteristics of the signals from the modem, and are added to the modem output signals before they are imparted to the non-linear coupling instrument. The added correction signals effectively compensate for the non-linearity of the acoustic coupler, thereby removing the unwanted distortion from the telephone line signal.

Abstract: In a pseudo-random number sequence generator, a random access memory is provided having a plurality of storage locations, each storage location having a number or bit pattern stored therein. A first number is accessed and read by a function generator. A second number is accessed, and an operation such as modulo two addition is performed on the first and second numbers, with a result being provided. Further numbers can be accessed and logically combined with one another, or with the previous result. The operations can all be identical, or may be mixed, so that, for example, some exclusive OR and some AND functions are performed. The result comprises an output digit and can also be written into the second storage location to replace the second number, or intermediate results can be loaded into this location. In successive cycles, the storage location having the most recently produced result comprises the first location, and a next storage location comprises the second storage location for that cycle.