摘要:
A hybrid of controlled access and random access schemes using frequency hopping spread spectrum communication techniques is implemented in an indoor digital data radio communication system between mobile stations and a computer system. A hop in the frequency hopping spread spectrum communication system is subdivided into two intervals so that different media-access protocols can be used in each interval. The protocol uses a centralized control scheme in one interval and a decentralized scheme in the other, and the intervals may be varied depending on the load of the system.
摘要:
A system for sensing paper on a paper roll includes an ultrasonic transducer positioned to be in contact with an outer surface of the paper roll; a transmitter circuit in communication with the ultrasonic transducer, the transmitter circuit providing a transmit signal to the ultrasonic transducer, the ultrasonic transducer generating an ultrasonic signal in response to the transmit signal; a receiver circuit in communication with the ultrasonic transducer, the receiver circuit providing a received signal indicative of an ultrasonic return echo from the paper roll, the ultrasonic return echo resulting from the ultrasonic signal interacting with the paper roll; and a processor circuit, in communication with the transmitter circuit and the receiver circuit, that determines an amount of paper remaining on the paper roll in response to the transmit signal and the receive signal, the processor providing an output signal when the amount of paper remaining falls below a threshold.
摘要:
A system for sensing paper on a paper roll includes an ultrasonic transducer positioned to be in contact with an outer surface of the paper roll; a transmitter circuit in communication with the ultrasonic transducer, the transmitter circuit providing a transmit signal to the ultrasonic transducer, the ultrasonic transducer generating an ultrasonic signal in response to the transmit signal; a receiver circuit in communication with the ultrasonic transducer, the receiver circuit providing a received signal indicative of an ultrasonic return echo from the paper roll, the ultrasonic return echo resulting from the ultrasonic signal interacting with the paper roll; and a processor circuit, in communication with the transmitter circuit and the receiver circuit, that determines an amount of paper remaining on the paper roll in response to the transmit signal and the receive signal, the processor providing an output signal when the amount of paper remaining falls below a threshold.
摘要:
A method for controlling a display device, such as, for example, the display device mounted on a shopping cart, the shopping cart having a wheeled base and a basket portion in connection with the wheeled base and a handle in connection with the wheeled base, the method comprising: allowing a user to enter information at and obtain information from the display device; and providing a locking mechanism located on or implemented within the device for permitting the user to activate or deactivate the display device in order to prevent unauthorized access.
摘要:
A method for sensing paper on a paper roll is disclosed. The method comprises transmitting an ultrasonic signal into the paper roll and detecting an ultrasonic return echo transmit signal from the paper roll, the ultrasonic return echo transmit signal resulting from the ultrasonic signal interacting with the paper roll. Moreover, the method comprises determining an amount of paper remaining on the paper roll in response to the ultrasonic return echo transmit signal. Furthermore, the method may comprise indicating that the paper roll needs to be replaced in response to determining the amount of paper remaining on the paper roll.
摘要:
A system includes an ultrasonic transducer positioned to be in contact with the outer surface of a paper roll. The system further includes a transmitter circuit and a receiver circuit in communication with the ultrasonic transducer. The transmitter circuit provides a transmit signal to the ultrasonic transducer for generating an ultrasonic signal, which is transmitted into the paper roll. The receiver circuit provides a received signal indicative of an ultrasonic return echo from the paper roll. The ultrasonic return echo resulting from the ultrasonic signal interacting with the paper roll. The system also includes a processor circuit for determining an amount (length or diameter of roll) of paper remaining on the paper roll in response to the transmit signal and the receive signal. The processor provides an output signal when the amount of paper remaining falls below a threshold. A method of sensing paper on a paper roll is also presented. The method includes transmitting an ultrasonic signal into a paper roll and detecting an ultrasonic return echo from the paper roll. The ultrasonic return echo resulting from the ultrasonic signal interacting with the paper roll. The method further includes determining an amount of paper remaining on the paper roll in response to the ultrasonic return echo transmit signal.
摘要:
Apparatus and method are disclosed for communicating between a central location and a plurality of identification tags or labels located in a container or in a space without separately passing each tag or labeled product through a read station. The disclosure includes use of hashing to reduce the amount of time needed to read the possible tags in the space. Reading is accomplished using radio communication with a combination of broadcast and time division multiplex architectures.
摘要:
A data source on a main local area network (LAN) transmits broadcast messages via bridges to remote stations. A ring buffer in a bridge on the main LAN buffers a selected number of packets received from the data source. When the main bridge on the main LAN receives a "Lost Frame Message" from a remote bridge, not on the main LAN, the main bridge backs up to the address of the lost packet in the ring buffer, and retransmits the lost packet and then continues sequential transmission of subsequent packets. If buffer is, filled above a pre-set criteria, retransmission is slowed or stopped until buffer is mostly emptied.
摘要:
A free space laser communication system operates at two power levels. The system includes a microprocessor to control the laser output beam to a safety level when the input beam indicates that the output beam is not being received at the remotely positioned terminal. If the output beam is not being received by the remotely positioned terminal, a blockage or misalignment of the beam is indicated. During normal operation when a blockage or misalignment of the beam is not detected, the output beam may be operated at a level higher than a safety limit to thereby provide enhanced communication performance.
摘要:
An optical scanner uses frequency modulation and detection techniques to produce and utilize multiple, simultaneous scan patterns in which corresponding scan lines have different focal lengths. Two or more solid state lasers are modulated at unique frequencies. The frequency modulated output beams pass through different combinations of focusing lenses and are deflected by a single beam deflecting apparatus. Light reflected from any scanned object is detected. The resulting multi-frequency signal is applied to a plurality of bandpass filters to separate the returned signal into a plurality of separately decodable signals.