Sidney T. Fisher has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
Abstract: A method for generating a compatible AM quadrature stereo wave by delivering a modulated carrier with in-phase sidebands generated by a first combination of two signals, and quadrature sidebands generated by a second combination of the signals, the in-phase and quadrature sidebands having substantially the same maximum amplitude. The carrier and both sets of sidebands are delivered to an envelope detector, which delivers only the first combination of signals, undistorted by the presence of the quadrature sidebands. The carrier and both sets of sidebands are also delivered to a synchronous detector, which delivers only the first combination of signals with predistortion. The output of the synchronous detector is subtracted from the output of the envelope detector to obtain as a result the predistortion of the first signal combination due to the presence of the quadrature sidebands.
Abstract: A keyboard in which, when one of the function keys is depressed simultaneously with one of the character keys, the signal generated by the depressed function key is transmitted during a first period of time following the key-stroke which depressed the keys, and the signal generated by the depressed character key is transmitted during a second period of time following the key-stroke which depressed the keys, the second period having an initial instant following the last instant of the first period. To achieve this result the character signal is delayed, so that an associated printer receives and is capable of performing the function commanded by the function signal before the printer is caused to print the character of the character signal which is subsequently received.
Abstract: The iron ores hematite, magnetite, limonite and siderite are reduced to iron by chemical reactions of the oxides in the ores with hydrocarbon gases in the absence of oxygen and oxygen compounds except carbon dioxide, in the input to the reaction chamber, other than the iron oxides. With certain ores and hydrocarbons the reactions are exothermic; other reactants require added heat. This method achieves the results of blast furnace techniques with more efficient utilization of fuel, lower cost fuel, lower cost of labor, an improved method of removing silica from the iron ores, and the use of readily available hydrocarbons in place of metallurgical coke which is often scarce.
Abstract: Recording apparatus which receives a signal, double-sideband amplitude modulates a carrier with at least three times the highest carrier frequency, with the signal, and records the modulated carrier on a recording medium. The reproducing apparatus reproduces the signal modulated carrier substantially free from superimposed noise and delivers it to an external circuit, where it may be recorded or may be demodulated and the signal recorded.
Abstract: Means and method for substantially eliminating a selected periodic wave from a frequency band-limited combined wave containing other waves. The combined wave is sampled in a sampling gate, opened by short gating pulses with a frequency equal to the selected frequency divided by an integer, and greater than the Nyquist frequency for the combined wave, timed from the selected periodic waves. The samples are reconstructed in a filter with the pass-band equal to the frequency band of the combined wave. The direct-current component in the output of the sampling gate, due to any error in the timing of the instants, is used in a negative-feedback circuit to adjust the sampling instants so that the periodic wave is substantially completely eliminated.
Abstract: In a gas compression system, heat rejected from the prime mover and the compressor is transferred from them to the loads driven by the compressed gas. This heat transfer reduces the energy required from the prime mover for delivery of a given amount of energy by the output load, and hence increases the efficiency of the gas compression system.
Abstract: A system and a receiver for transmission of signals by a double sideband amplitude modulated carrier with the carrier suppressed, known as a DSBSC wave, without reinsertion of the carrier at the receiver. In the receiver the DSBSC wave is amplified, demodulated by a full-wave rectifier, and the rectifier output reversed in polarity at instants of successive zero crossings of the signal, to produce the signal free from extraneous components.
Abstract: Receiving apparatus for a modified quadrature A-M dual-signal wave, which samples the input wave and separates and reconstructs the signals in analog form. Superimposed noise in the frequency band of the modulated wave may be substantially reduced in both signals. The signals may be separated adequately to permit reception of a single compatible stereo transmission, or of either one of two different non-compatible mono transmissions on a single carrier, by use of negative-feedback timing loops.
Abstract: Compatible AM quadrature stereo systems generating a carrier amplitude modulated by the signal sum, predistorted to cancel distortion in an envelope detector in a receiver caused by quadrature sidebands, and angle modulated by a pilot and the signal difference. The receiver separates the amplitude and angle modulation of the carrier, and delivers the signals separately. The transmitting apparatus may have multiple modulation circuits with linear amplifiers, may be an unequalized AM mono transmitter with auxiliary angle modulation apparatus, or may be an equalized AM mono transmitter. The signal sum received by a mono receiver with an envelope detector is substantially free from distortion. Noise-reduction circuits may be used in the stereo receiver, which delivers the signals separately without distortion.
Abstract: Drum-type brakes and band-type clutches which are activated by expansion or compression, or both, of one or more concentric magnetic members, with conducting windings carrying electric currents. Circular annular mating members carrying one or more conducting windings expand or contract in diameter, due to magnetic forces caused by currents in the winding or windings, and operate as a brake or a clutch.
Abstract: A dynamo with a stationary armature and with two rotors, with the frequency of the armature current the same as the frequency of the field excitation and independent of the speed of rotation of the rotors. The rotors have opposite instantaneous magnetic polarities, are magnetically connected and rotate in opposite directions on concentric shafts. Field excitation may be dc or single-phase ac. Disk or tubular rotor and stator structures may be used. Dynamos according to the invention may function as a d-c generator, an a-c generator, an amplifier, as a-c or d-c rotary transformers, and as a-c or d-c motors.
Abstract: The method of extracting hydrocarbons from an underground deposit of material containing hydrocarbons, which comprises injecting aqueous solutions of low resistivity into at least a portion of the deposit, heating a portion of the deposit underground by means of a varying magnetic field and controlling the flow of fluids from the heated portion of the deposit to the delivery point until the temperature of the heated portion of the deposit has reached a selected value at which substantial pyrolysis occurs of hydrocarbons released from the deposit. The value of temperature resulting is less than the break-out pressure of the overburden. When the selected temperature and the pressure have been reached the flow of fluids from the heated portion of the deposit is controlled by a pressure controller to maintain the pressure until heating stops. At this time the vapor pressure is reduced to atmospheric pressure.
Abstract: A first underground deposit of lignite or coal is heated by magnetic induction to recover hydrocarbon liquids and gases. The carbon remaining is combusted with air and steam to produce a gas which is combusted to generate electrical energy. The electrical energy is transmitted to second underground deposits of oil shale, tar sand or heavy oil, and is used to heat the second deposits in order to recover hydrocarbon liquids and gases.
Abstract: This invention provides means and method of eliminating a selected wave from a frequency band containing a plurality of waves, by sampling the plurality of waves at a rate greater than the nyquist rate for the frequency band in herz, at instants at which the selected wave has zero amplitude, and integrating the sequence of samples so obtained to produce a replica of the plurality of waves less the selected wave.The plurality of waves less the selected wave may be subtracted from the plurality of waves, after adjustment of relative amplitude and delay, so that the selected wave is obtained substantially free of other waves of the plurality of waves.
Abstract: A system which automatically corrects the wave-form of a signal of a given frequency passing over a transmission path, over which a carrier double-sideband amplitude-modulated by a complex tone and extending across the given signal-frequency band is transmitted in the signal-frequency band as a combined wave with the signal. At the receiving apparatus the reconstructed modulated carrier is used as a standard to correct the waveform of the signal from distortion caused by the transmission path, using sampling, reconstruction, comparison and gain-variation methods. The modulated carrier is eliminated from the corrected signal at the output of the receiving apparatus by sampling and reconstruction methods. Sampling and modulation frequencies and phases are derived from the carrier.
Abstract: A first stream of digits is converted to a second stream of alternating-current digits, each of the same amplitude and the same duration which may be different from the duration of the digits of the first stream, and which transmits at least the information in the first stream of digits at at least the same information rate. A number of alternating-current sources with different frequencies, the number at least as great as the greatest possible number of materially different groups of digits in the first stream, are connected one at a time to an output circuit in response to the first stream of digits to generate the second stream of alternating-current digits. The resultant wave may be limited at non-regenerative repeaters to remove amplitude noise, and may be regenerated in regenerative repeaters to remove substantially all noise and distortion.
Abstract: An acoustic transmission system for a gaseous or liquid transmission medium, in which the transmitting apparatus double-sideband amplitude modulates a carrier with the signal to be transmitted, the double-sideband amplitude modulated carrier is radiated acoustically over the transmission medium, and the receiving apparatus receives the modulated carrier plus noise introduced in the medium, rejects the superimposed noise by sampling and reconstruction means, and delivers the modulated carrier substantially free from superimposed noise.
Abstract: A double-sideband amplitude modulated (DSBAM) carrier passed through band-pass circuits wich are too narrow for the modulated carrier or are misaligned, may have one or both side-bands altered in relative amplitude, or in phase relative to the carrier. These effects result in amplitude modulation distortion and produce angle modulation of the carrier, with the same waveform as the amplitude distortion. In this invention the angle modulation is detected and applied to an amplitude modulator in the required phase and amplitude to substantially eliminate the distortion of the modulated carrier.
Abstract: Receiving apparatus for a message occupying a message frequency band which simultaneously may include noise, and includes one or more unmodulated or amplitude-modulated double-sideband constant-frequency carriers with or without carrier suppression as periodic signals, which uses sampling and reconstruction circuits to deliver the message substantially free from the periodic signals, and to deliver each periodic signal substantially free from noise, the message and any other periodic signal present in the message frequency band.
Abstract: A syllabic compandor using a pilot in the signal frequency band, with a compression ratio between approximately 2 and 20, including a frequency and delay equalizer in the negative-feedback loss-control circuits of the compressor and expandor, to permit high compression and expansion ratios without positive feedback at any frequency or signal level, the expansion ratio materially less than the compression ratio in some cases, and sampling at more than the Nyquist frequency for the signal band to remove any unwanted periodic wave such as the pilot wave, lying in the signal frequency band, from the output, without altering phase and amplitude of other waves in the signal frequency band.