Abstract: A low battery voltage indicator is for use with remote control keyboards which are not linked by a cable to a power supply. Such keyboards contain their own power and are widely used. Remote keyboards that are infra red linked to personal computers are widely available. Similarly, remote control TV channel selectors utilizing infra red links are extensively used and sold. A majority of these devices utilize a battery to power the transmitter for the infra red communication link from the remote unit to the base unit. This is an improved low voltage indicator circuit and technique that utilizes the infra red link and the key encoding circuits of the keyboard to transmit to the base station a key code indicative of the fact that low battery voltage exists. At the base station, the key code is received and is looked up in a table that identifies the key code as a low battery voltage indication. This causes the base station to flash a low battery voltage warning message on the display screen.

Abstract: Disclosed are a method and apparatus for exchanging information between a data terminal equipment (DTE) and data circuit terminating equipment (DCE) or controller connected to the data terminal equipment over a communications line. The specific information to be exchanged is the information indicating the delay period between a request to send received at the DCE and a clear to send condition occurring sometime later in response to the request to send. This function is normally handled by separate signalling lines, but for the so-called mini interface, no clear to send communication line exists. A method and apparatus employed in the present invention utilizes the transmitter signal element timing or clock line to convey the information from the DCE to the DTE. In response to receipt at the DCE of a request to send signal from the DTE, the DCE temporarily stops the transmitter signal timing clock, thus preventing the DTE from transmitting data.

Abstract: An improved method and apparatus are disclosed for the reading (or sensing) and decoding of two frequency "bar coded" or transition coded sensible data. The data may take the form of indicia recorded on various media or it may be transmitted on a communications channel. The method and apparatus include means for simultaneously or separately accommodating both variable velocity scan (or distorted reception) conditions and non-uniform bar widths in the coded data or other variations in the spacing of transition signals in the recorded indicia. Frequency variations in transmitted data signals can also be accommodated. Hand held sensor or "wand" scanning of coded tangible indicia-bearing media is facilitated for either optically or magnetically recorded data indicia. Correct interpretion of frequency-distorted transmitted data is also made possible.

Abstract: A digital-to-analog converter method and apparatus is disclosed which utilizes a hybrid technique of combined pulse width and pulse rate modulation to achieve improved performance with reduced logic and circuitry requirements. Lower order bits of an N-bit digital data input for conversion to a corresponding analog output voltage level are treated in a manner similar to pulse rate modulation approaches utilized previously. High order bits are handled together in a variant form of pulse width (duration) modulation in which the pulse width required to generate the given analog voltage level corresponding to the high order digital bit inputs is divided into a fixed number of slices in a given sample time, each slice having a width or duration of pulse output which is variable in itself in correspondence to a function of both the high and low order bit value inputs. A low pass filter or integrator combines all of the pulses in a given sample to produce the analog voltage level output.

Abstract: A toggling type of switch actuator is described in which a pivotable coupling plate is caused to snap away from electrical contact members which it couples together. Action is caused by the depression of an actuator which compresses a spring and moves the line of action of compressive force over center to cause a snap-action motion. Pushbutton actuation is achieved in a very low profile apparatus providing good tactile feel and a self-biased, self-returning, snap-action. The device has only three moving parts.

Abstract: The invention covers an amplifier circuit in which the output is limited in either polarity. Normally, a part of the output voltage is fed back to the input to maintain linearity but when the output reaches a maximum or minimum value, any further departure is amplified and fed back to the input circuit to neutralize the part of input signals which is outside of the range to be amplified. The feedback amplifier can be designed to initiate limiting at any desired output voltages and the positive and negative output limit voltages can be asymmetric with respect to the quiescent output voltage.