Abstract: A method and apparatus to transform time to frequency or frequency to time of data signals is disclosed. A single processing element can be used recursively or can be use modularly to construct the apparatus. The processing element has two input digital data signals and generates to output digital data signals. The processing element also receives a coefficient signal and a plurality of status signals. The processing element computes its output signals in accordance with______________________________________ F=1, S=0 C = A+B D = K*(A-B) F=1, S=1 C = B D = K*(2*A-B) F=0, S=0 C = A+K*B D =A-K*B F=0, S=1 C = 2*K*B D = A-K*B ______________________________________The apparatus also has a storage means to store the coefficients and to store the output of the processing element. A sequencer which is connected to the output storage supplies the same as input to the processing element and controls the processing of the processing element to effectuate the FDCT operation or the IDCT operation.

Abstract: Described is an improved apparatus for joining the helical vending coil of a vending machine to its drive mechanism and which allows easy adjustment of the angular position of that coil. Rather than using conventional screws, washers and spacers to join a coil-engaging bracket to its gear-driven drive shaft, in accordance with the invention, a tension spring or other tensioning device operatively deployed between the vending coil coupling bracket and the drive shaft normally urges the bracket into engagement with the drive shaft but will permit the two to be pulled free of one another to allow rotational adjustment without requiring disassembly of many parts or any special tools.

Abstract: A decoder for recovering an analog signal from its digital representation produced by an encoder employing adaptive-delta-modulation first decodes audio bit-stream (17) in the digital domain with digital delta demodulation (15), to a pulse-code-modulation (PCM) format digital signal. Post-processing (35), complementary to encoder processing is performed digitally on the PCM signal. The output from post-processor (35) is up-sampled, and using delta modulation, a noise shaped single-bit highly oversampled output is produced by converter (14). Applying the single-bit output to lowpass filter (11) re-constructs the decoded analog signal, which is audio output (12). By fully exploiting digital signal processing techniques, the decoder can be manufactured at low cost and exceed the performance of existing analog implementations.

Abstract: This invention comprises two separate topologies for implementing a second order allpass function filter which is vital for equalization of the phase of other arbitrary response magnitude shaping filters. While the allpass response itself does not affect the frequency spectrum of the signal, these topologies have available outputs that have either bandpass or bandstop characteristics. Thus, two types of useful frequency characteristics formed by the filters that have exactly the same resonant frequency and Q (or Quality factor). Using the well known general two amplifier topology to implement a monolithic switched allpass filter with a high Q leads to very high capacitance ratios and hence excessive silicon area in manufacture. Both the topologies described here reduce the required silicon area by either reducing the required capacitance ratios or making the sensitivity to the smallest capacitor extremely small allowing it to violate otherwise necessary area-to-perimeter matching of the capacitor geometries.