Abstract: A surface wave acoustic delay line is formed of a set of electrode assemblies disposed on the surface of a block of crystalline material propagative of a surface acoustic wave. In each of the assemblies, the electrodes are arranged in an interdigitated pattern. Reflected waves are cancelled by the construction of an additional electrode in each of an electrode assembly, the additional electrode extending only one-half the distance of the other electrodes and being spaced from an adjacent electrode by one-quarter wavelength. This introduces a 180.degree. phase shift between portions of relected waves which then cancel to remove the reflection. Also, in the case of closely spaced electrode assemblies, additional electrodes, equal in shape and size to the electrodes of the assemblies, are introduced between the assemblies in the form of a grid which propagates surface waves without reflection.

Abstract: A simplified stereo signal decoder is disclosed for use in an AM stereo receiver which receives composite AM stereo broadcast signals comprising a radio frequency carrier wave having amplitude modulation representing stereo sum (L+R information and phase modulation representing stereo difference (L-R) information. The decoder makes novel use of a common, commercially available integrated circuit (IC) that normally is used as a tone detector or a frequency-modulation (FM) detector. The decoder provides synchronous detection of the (L-R) information, combined two-mode phase-locked loop (PLL) recovery of the carrier component and enabling of the (L-R) signal output, and delayed enabling of the (L-R) signal output for a "stereo bloom" effect. The decoder is particularly useful for decoding independent sideband (ISB) AM stereo broadcast signals.

Abstract: Certain, but not all AM stereo radio broadcasting and reception systems suffer from a severe form of reception anomaly wherein the perceived stereo image moves from side to side, back and forth, which effect has come to be known as "Stereo Platform Motion" or simply "Platform Motion". A prior art patent proposed a method for sensing reception conditions conductive to Platform Motion and then switching the receiver from stereo to monophonic reception to avoid Platform Motion. The present invention enables the AM stereo receiver to maintain stereo operation under such reception conditions, and instead of switching the receiver to monophonic operation, it switches the receiver to a different method of stereo reception that does not suffer from Platform Motion.

Abstract: A stereo receiver is described which is capable of receiving any two or more of the five currently proposed AM stereo system broadcast signals. The multisystem receiver includes circuitry which is used in various configurations to demodulate the stereo signal components from broadcast signals of any one of two or more of the proposed systems. Selection of appropriate elements of the receiver's circuitry for demodulating any one of the received signals is performed automatically in response to the detection of the presence of a corresponding pilot signal which is unique for each of the five different AM stereo systems that have been proposed. The receiver includes apparatus which detects the presence of such pilot signals and controls the automatic switching of such receiver circuitry. Also described is the application of such apparatus for reliably detecting the presence of the desired pilot signal in a single system stereo receiver.

Abstract: An apparatus for generating a composite AM stereo broadcast signal wherein a carrier is angle modulated with stereo difference information contained in a first supplied signal and the angle-modulated carrier is then amplitude modulated with stereo sum information contained in a second supplied signal, an improvement wherein distortion is predicted by the use of a simulated transmitter and receiver to generate a correction signal having distortion representative components. Correction signals developed in this manner are used to modify the angle-modulated signal utilizing a feedback technique, a subtractive technique, or both, thereby reducing distortion in the output of the stereo difference signal channel of actual AM stereo receivers which receive said composite AM stereo signal.

Abstract: An apparatus for controlling a process machine, in accordance with control settings determined using a process simulating apparatus, makes use of a recorder associated with the simulating apparatus to record signals representative of the position of control elements on the simulating apparatus. The recorded signals are read and used to automatically set the controls of the process machine. The device is advantageously used in connection with a color scanner and a color previewer having a set of control elements corresponding to the control elements on the scanner.

Abstract: A stereo receiver is described which is capable of receiving any two or more of the five currently proposed AM stereo system broadcast signals. The multisystem receiver includes circuitry which is used in various configuration to demodulate the stereo signal components from broadcast signals of any one of two or more of the proposed systems. Selection of appropriate elements of the receiver's circuitry for demodulating any one of the received signals is performed automatically in response to the detection of the presence of a corresponding pilot signal which is unique for each of the five different AM stereo systems that have been proposed. The receiver includes apparatus which detects the presence of such pilot signals and controls the automatic switching of such receiver circuitry. Also described is the application of such apparatus for reliably detecting the presence of the desired pilot signal in a single system stereo receiver.