Abstract: An anti-theft system for a removable accessory has a transponder with a transponder security code located in the removable accessory. A remote sensing coil is operatively coupled to the transponder. A memory stores a security code corresponding to the transponder. A control module coupled to the remote sensing coil and the memory generates an interrogate signal and receives a response signal through the remote sensing coil. The transponder generating a response signal in the form of a transponder security code in response to the interrogate signal. The control module compares the transponder security code to the stored security code. If the transponder security code is not equal to the stored security code, a predetermined function is disabled. An output means is coupled to the control module for providing an indication to a vehicle operator of the disabled predetermined function.

Abstract: A security system utilizing a key-mounted transponder achieves fast and accurate charging of the transponder by using a frequency search and acquisition phase which attempts partial charging pulses at a plurality of spaced frequencies. After a successful partial charging, a frequency calibration signal is received from the transponder which provides a reference in the transceiver for producing a pulse for fully charging the transponder. Frequency search and acquisition allows robust system operation while using low cost and low tolerance parts.

Abstract: A portable, reprogrammable printer diagnostic controller comprising a microcontroller, an EPROM for storing operational programs, a "flash" memory for programmably storing data to be used in the diagnosis of the printer, and connectors for coupling the system to both a computer for the downloading of software into the system and to a printer for downloading the stored programs into a printer for diagnostic testing.

Abstract: A method and apparatus for storing compressed bit map images in a laser printer. Bit map images representing a page of data are divided into bands and compressed into the printer memory. Then, when needed by the interpreter/rasterizer, they are decompressed into another portion of that memory, or when desired to print those bands they are directly transmitted to a decompression engine. The bands of bit map image are compressed using a Lempel-Ziv algorithm that contains improvements allowing compression towards the end of the band and improves the compression speed at the beginning of the band by initializing a hash table. Further, the interpreter/rasterizer switches between compression routines depending on the available memory and the desired speed of compression. The compression routine requests supplemental destination buffers when it needs additional memory in which to compress data.

Abstract: A circuit and method of demodulating an FSK signal uses digital circuitry to convert the received signal into count values. For each reception an adaptive reference count value is determined by averaging the duration of received pulses during the preamble of the transmission. The adaptive reference count corresponds to a demodulated logic "1" or logic level "0". The counts from the coded portion of the transmission are compared to the adaptive reference count. If the count is within predetermined windows from the reference count, the count value is converted to the corresponding digital signal.

Abstract: A voltage comparator (10) includes two sampled input networks connected in arallel between an input reference voltage (Vref) and the inverting input (16) of an integrator (12,14), the other input (18) of which is grounded. The first input network has a first input capacitor (C1) which is through-switched at a first sampling frequency (F1). The second input network has a second input capacitor which is diagonally-switched at a second sampling frequency (F2), thus providing an output voltage to the integrator (12,14) which is of opposite polarity to that of the first network. For a given ratio between the capacitors (C1,C2), the output (15) of the integrator is determined by the relationship between the sampling frequencies (F1,F2), thus providing a comparator capability. Also disclosed is a frequency lock loop (34) in which the output (Vcontrol) of a frequency comparator (38) is filtered of the switching frequencies and utilized as the control voltage for a voltage controlled oscillator (42).