Showing papers by "Motorola published in 1984"

Efficient Modulation for Band-Limited Channels

Abstract: This paper attempts to present a comprehensive tutorial survey of the development of efficient modulation techniques for bandlimited channels, such as telephone channels. After a history of advances in commercial high-speed modems and a discussion of theoretical limits, it reviews efforts to optimize two-dimensional signal constellations and presents further elaborations of uncoded modulation. Its principal emphasis, however, is on coded modulation techniques, in which there is an explosion of current interest, both for research and for practical application. Both block-coded and trellis-coded modulation are covered, in a common framework. A few new techniques are presented.

ARQ Schemes for Data Transmission in Mobile Radio Systems

Abstract: An important problem in land mobile radio communications is how to provide reliable data communications to the largest number of users. To explore this problem, several existing ARQ protocols are examined which have application to the land mobile radio channel, as well as some new protocol combinations. All protocols are analyzed for several key system performance measures which are verified by experimental means for static as well as fading channels. Finally, a conclusion is reached regarding a new Protocol combination which is found to offer significant advantages over all other protocols explored.

Synthesized clock microcomputer with power saving

Abstract: A microcomputer (104) having predetermined clock pulse frequency requirements receives pulses from a multiplying type frequency synthesizer (200) which utilizes a reference frequency less than the largest of the predetermined requirements. The synthesizer (200) is responsive to program instructions to generate clock pulse frequencies sufficient to satisfy the requirement for immediate execution of programmed tasks. As the execution requirements change, the synthesizer (200) responds to provide only the frequency required. Thus, the power dissipated by the entire microcomputer system is minimized.

Temperature compensated automatic output control circuitry for RF signal power amplifiers with wide dynamic range

Abstract: Improved temperature compensated, automatic output control (AOC) circuitry for RF signal power amplifiers is described that maintains the output power within one-half dB of a selected one of eight power levels varying from nine milliwatts to five watts, a dynamic range of twenty-eight dB. The amplification of the RF signal amplifier is proportional to a drive current signal provided by a current amplifier. A half-wave rectifier is coupled to the output of final amplifiers for generating an output power signal that has a magnitude proportional to the output power. The half-wave rectifier is temperature compensated for and biased by a diode coupled to the rectifier by one resistor and coupled to supply voltage by another resistor. The output power voltage is further coupled to an amplifier having an amplification factor selected by level control signals. The amplified output power signal is coupled to a comparator which varies the drive current provided by the current amplifier in response to the voltage difference between the amplified output power signal and a reference voltage.

Method for communicating variable length messages between a primary station and remote stations of a data communications system.

Abstract: A data communications system (Fig. 1) in which variable length messages (Figs. 3, 4 and 5) are communicated between a general communications controller (GCC 104) and a plurality of portable and mobile radios (130, 132, 134, 136, 138). The variable length messages (Fig. 3) include a bit synchronization field (204), a message synchronization field (205) and a plurality of channel data blocks (203) for efficiently and reliably handling long strings of data or text. Each channel data block (Fig. 5) includes an information field (503), a parity field (505) for error-connecting the information field and a channel state field (507) indicating whether or not the radio channel is busy or free. The GCC (104) is coupled to a cellular arrangement of channel communications modules (CCM's 106, 108, 110, 112), which each include a radio transmitter (114, 120, 124) and/or radio receiver (116, 118, 122, 126, 128). The mobile and portable radios (130, 132, 134, 136, 138) communicate with the GCC (104) by way of the CCM's (106, 108, 110, 112).

Portable telephone id code transfer system.

Abstract: A wireless telephone communication system (10) in which a portable unit (12) communicates with a base unit (11) over a wireless (radio) communication link (15). Access to a telephone network (15b) by the portable unit (12), via the base unit (11), is permitted when the base and portable units have corresponding ID codes stored therein. The base ID code is hardwired into the base unit (11), and the portable unit (12) learns its ID code from the base unit in response to mechanically coupling the base and portable units together via plug (28) and socket (45) assemblies. The base and portable units each have associated microprocessors (22 and 40) which implement the transfer of an ID code to the portable unit from the base unit via conductors (24'-42') which are part of the plug and socket assemblies. The plug and socket assemblies, when mated, also provide a connection between a battery charging supply circuit (25) in the base unit (11) and a battery (46) in the portable unit (12). Reset circuits (29 and 50) are provided in the base and portable units and control the resetting of the microprocessors (22 and 40).

Dual band transceiver antenna

Abstract: A dual band antenna (11) for a radio transceiver includes a conductor of a predetermined length with a feedpoint (24) located substantially central of the conductor. Radiator elements (26, 28) terminate the ends of the conductor and ground plane (30) terminates the radiator elements. An impedance matching circuit (32) is coupled to the feed point whereby the high impedance part of the antenna is confined to the center. Dual banding elements (42, 44) coupled to the impedance matching circuit with a high Q resonant circuit element. Input/output circuits (46) are also coupled to the dual banding elements. The design minimizes the effect on the antenna by the proximity of user's hands, head and body.

Zoned data communications system for communicating message signals between portable radios and a host computer

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. Whenever the GCC transmits a message signal to a portable radio, the CCM transmitter is used that covers the zone having the largest adjusted signal strength for the last transmission from that portable radio. Since the GCC can be simultaneously transmitting message signals to portable radios in other zones using non-interfering CCM transmitters, information throughput is greatly enhanced.

Multi-user serial data bus

Abstract: A multiple device serial data bus and signalling scheme is described The serial data bus allows for inter-peripheral communication at a data rate established by a bus control unit Clocking information is extracted from data communicated from the bus controller to the peripheral devices Additional conductors for clock information are not required In addition an arbitration scheme is provided to eliminate bus contention if several units request service simultaneously The multiple device serial data bus is utilized on an as required basis and may communicate information at a variety of data rates

Current sensing circuit

Abstract: A current sensing circuit is disclosed wherein a small portion of a load current is sampled through a sensing resistor and a substantially larger portion of the load current is allowed to bypass the sensing resistor. A first high current vertical MOS transistor is coupled between the load and the ground terminal. A second vertical MOS transistor is coupled in series between the load and ground terminal. The transistors are constructed in a vertical MOS cellular construction whereby the first transistor comprises on the order of three-thousand cells and the second transistor comprises a single cell. A signal is taken across the sensing resistor and may be provided as feedback to a control means driving the first and second transistors for performing a current limiting or constant current function.

Cascaded pyroelectric energy converter

Abstract: A regenerative pyroelectric converter employing multiple staging has been constructed and tested. Operating between the temperatures of 150°C and 180°C the device converted heat into electrical energy. Measurements of the conversion efficiency and power density as functions of frequency (0.05 to 0.3 Hz) are reported. The converter's maximum power density was 33 Watts per liter of pyroelectric ceramic at 0.26 Hz.

Security for integrated circuit microcomputer with EEPROM

Abstract: An integrated circuit microcomputer with EEPROM has a limited number of modes for operation. In at least first and second modes, the inner workings of the microcomputer, including the contents of the EEPROM, can be read externally from the microcomputer. An EEPROM security bit, when set, prevents the first mode from being entered and causes the EEPROM to be erased when the second mode is entered. The EEPROM is also erased if the security bit is erased.

Universal paging device with power conservation

Abstract: A battery powered, adaptive signal decoder is disclosed which is capable of processing detected encoded signals in accordance with a plurality of decoding schemes. The decoder has an equivalent microcomputer implementation. Energy conservation means operating independently of the detected signals acts to conserve the energy of the battery.

MOSFET "H" Switch circuit for a DC motor

Abstract: A MOSFET "H" switch circuit for providing bidirectional control to a DC motor. The power MOSFET's employed have significant advantages over bipolar and darlington power transistors and allow for microcomputer interfacing for providing bidirectional rotational control as well as motor speed control by pulse width modulation.

Logarithmic arithmetic logic unit

Abstract: In a digital signal processing system, a logarithmic arithmetic logic unit is provided which selectively performs multiply/accumulate operations of operands in logarithmic number representation. Direct feed through of operands through an adder/subtractor circuit, even when an addition or subtraction is not effected, eliminates external bypass circuitry. A method for adding and subtracting operands in logarithmic number representation is provided. An adder/subtractor circuit which efficiently effects addition and subtraction of operands in logarithmic number representation over a wide dynamic range is provided.

Serial communication interface for a local network controller

Abstract: A serial communications interface for coupling a physical layer such as a modem to a media access control layer in a token bus network provides data and station management information therebetween on a plurality of bidirectional data lines providing management functions and a unique serial bus for control transfer in addition to communications data.

Telephone-radio interconnect system

Abstract: A telephone interconnect system for a two-way radio communications system is disclosed. A telephone patch interconnect unit accepts dialed digits from a telephone line, encodes them into a data packet, and couples the data packet to a fixed transceiver for transmission to remote units. A remote unit with a digit sequence identification matching the received and decoded dialed digit activates an alert. A remote unit may generate and store digits corresponding to a desired telephone number. The digits are subsequently encoded into a data packet and transmitted to the telephone patch interconnect unit. The interconnect unit accepts, acknowledges and decodes the data packet and couples the resulting digits to the telephone line.

Dynamic control of telephone traffic in a trunked radio system

Abstract: A method and means for controlling telephone interconnect traffic on a trunked radio system is described. The present invention continuously monitors all types of communication traffic on the system and in response to an increasing dispatch access delay, reserves certain repeaters for dispatch use only during a predetermined period. The present invention also contemplates a system in which the number of simultaneous telephone interconnect calls permitted on the system during a predetermined period is dynamically altered in response to system loading. In addition, the present invention establishes a variable, periodically updated, maximum interconnect call length based on the current system dispatch access delay.

A method and apparatus for coordinating execution of an instruction by a coprocessor

Abstract: A system for interfacing a Processor to a Coprocessor using standard bus cycles. The Processor, upon encountering in its instruction stream an instruction having a particular Operation word format, will transfer a Command word following the Operation word to a particular Coprocessor designated by a Coprocessor Identity field in the Operation word. Upon decoding the Command word, the Coprocessor will respond with any of a set of response primitives which define functions which the Coprocessor requires to Processor to perform in support of the Command by the Coprocessor. The interface provides for all functions which the Coprocessor may require, including selective vectoring to appropriate exception handlers.

Simultaneous voice and asynchronous data telephone

Abstract: A telephone which can receive and transmit voice and asynchronous data simultaneously is provided A signalling circuit provides signals indicating the request for a communication link or requesting a communication link to a predetermined location A transceiver circuit synchronously receives and transmits frames of digital data bits representing data, voice and signalling information A voice digitizer circuit converts the received frames of digital bits to an analog output and converts a received voice signal to a digital voice output An interface circuit is used to interface between an asynchronous data source and the synchronous transceiver circuit The telephone is line powered by utilizing DC isolating transformers to power both voice and data circuitry

Process for fabricating semiconductor device

Abstract: A process is disclosed for fabricating semiconductor devices, and especially for fabricating semiconductor devices having multiple levels of metallization separated by polyimide or other organic materials. The process avoids the sputter etching and redeposition of the lower metal layer during reactive ion etching of openings through the organic layer. Sequential layers overlying the first layer of metallization include a layer of oxide, a layer of organic material, and a second layer of oxide. The second layer of oxide functions as a hard mask for patterning the organic material. The first layer of oxide acts as an etch stop and protective layer to prevent attack of the underlying metal during reactive ion etching of the organic layer. The first layer of oxide is of limited areal extent to avoid subsequent problems with the organic layer. The oxide located at the bottom of the opening through the organic material as well as the second layer of oxide and any oxide which is sputtered and redeposited on the walls of the opening through the organic material are easily removed in a single etch step without adversely affecting the underlying metallization. After removing the oxide, a second layer of metallization is applied and patterned as required.

Circuit for adding and/or subtracting numbers in logarithmic representation

Abstract: In a digital signal processing system, a logarithmic arithmetic logic unit which selectively performs multiply/accumulate operations of operands in logarithmic number representation. Direct feed through of operands through an adder/subtractor circuit, even when an addition or subtraction is not effected, eliminates external bypass circuitry. A method for adding and subtracting operands in logarithmic number representation. An adder/subtractor circuit which efficiently effects addition and subtraction of operands in logarithmic number representation over a wide dynamic range.

Fully integratable superheterodyne radio receiver utilizing tunable filters

Abstract: A radio receiver from antenna to detector designed to be realized substantially on an integrated-circuit chip comprises a single tunable oscillator and a plurality of mixers. An input signal from an antenna is connected as an input to a first mixer and mixed with a signal derived from the oscillator. The signal may be taken directly, may be multiplied to a desired level or may be divided to a desired level. A particular output from the first mixer is selected by a first tunable filter. The output of the first tunable filter is taken as an input to a second mixer where it is mixed with a second signal derived from the oscillator. The process of mixing and application of the mixed signal to a tunable filter to select a desired frequency is continued as needed until the signal is reduced to a desired intermediate frequency range where it is amplified as needed to a level sufficient to drive a discriminator. Successive mixers receive, as inputs, signals that are derived by multiplication from the oscillator and that are in ratios to each other of integers of the order of two to eight. The center frequency of each of the tunable filters changes as different crystals or synthesized base frequencies are selected. This variation continues through the last intermediate frequency.

Inbound acknowledgement stack

Abstract: In a data message communication system, certain messages require a return acknowledgement signal. The present invention contemplates a method and means which are activated whenever an outbound message is received. Each portable unit which receives a message then monitors the outbound communication channel to determine if the inhibit signal is currently active. If the inhibit is not currently active, the particular unit will transmit its acknowledgement message immediately. If the inhibit signal is active, each portable unit will maintain a count of the number of outbound messages, addressed to other units requiring an acknowledgement, since that particular portable received its message. At the termination of the inhibit signal, each portable unit will pause for a period equivalent to the product of the acknowledgement message time slot multiplied by count of messages accumulated since the receipt of the particular portable units message. Each portable unit will then transmit an acknowledgement signal at the termination of its unique pause period.

Direct memory access controller supporting multiple input/output controllers and memory units

Abstract: A direct memory access controller (8, FIG. 1) is provided which can service a number of input/output controllers (24, 26) concurrently on a time-division multiplexed basis. The direct memory access controller 8 (DMAC) is capable of interconnecting more than one input/output device (64, 66, 69, 74, 76) with more than one system memory (2, 20). The DMAC 8 can also transfer data from one system memory (2) to a second system memory (20), or within one system memory.

Address encoding system for portable battery - operated devices

Abstract: A two-way radio communications system includes a battery-operated portable unit (12) and a base unit (11) having a receptacle (17) for receiving the portable unit when the portable unit is not in use. A security circuit (51, 52) in each unit allows communication with other units only upon the reception of an address code corresponding to an address code stored in the unit. When the portable unit is seated in the base unit receptacle, the batteries (38) of the portable unit are recharged by current supplied by the base unit. At the same time, the address code of the base unit is entered into the portable unit by encoding circuitry (55, 58, 62, 54) which modulates the battery charging current in accordance with the address code. Circuitry (44) within the portable unit demodulates the charging current to recover the address code for storage in the security circuit of the portable unit. The invention can also be used in systems where data other than address codes must be sent to a unit being charged.

Data communications system having overlapping receiver coverage zones

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 has at least one transmitter and receiver for covering at least one zone. Each CCM receiver has a coverage area overlapping the coverage area of at least two other CCM receivers and at least a predetermined minimum probability P of successful reception of a transmission from a data radio located in its coverage area, such that the joint probability P J of successful reception of the transmission from the portable radio by at least one of the CCM receivers is expressed by the equation, P J =1-(1-P) 3 . 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. Whenever the GCC transmits a message signal to a portable radio, the CCM transmitter is used that covers the zone having the largest adjusted signal strength for the last transmission from that portable radio.

Slope etch of polyimide

Abstract: A slope via through polyimide (13) between metal layers (111) is achieved by first sloping a hard mask (14) which overlies the polyimide. Sloped photoresist (15) overlying the hard mask (14) transfers the slope to the hard mask (14). The slope hard mask (14) is used to slope the polyimide (13). Oxide (12) underlying the polyimide (13) is also etched to expose the metal (11). The underlying oxide layer (12) can be subsequently slope etched.

Queued community repeater communications system

Abstract: A communication system which controls access to a single communications channel by a plurality of remote units arranged in predetermined groups is disclosed. Assignment of the channel is controlled by a central control station which provides time periods on the channel for remote units to request permission to transmit on the channel. As the channel becomes clear, the central control station transmits a grant of service to a requesting remote unit group permitting real time transmission of voice or data on the channel. At the conclusion of the transmission, the central control station detects an end-of-transmission condition and revokes the grant of service to the served remote unit group.

Reliability Implications of Nitrogen Contamination During Deposition of Sputtered Aluminum/Silicon Metal Films

Abstract: Aluminum/Silicon (Al/Si) sputtered metal films for MOS integrated circuit metalization deposited under conditions of nitrogen contamination coupled with a subsequent silicon nitride (Si3N4) passivation can seriously impact product relialility. The reliability implications of this sputtered metallization process will be discussed. The discussion will include film characteristics and structure, description f the failure mechanism, life modeling, accelerated testing, and electromigration behavior.