Abstract: A system is provided which transmits either analog or digital data signals over the air. The system includes including a transmitter and a receiver. The transmitter and receiver are arranged to transmit signals using a carrier signal having a high frequency such as in the range of 902-928 MHz. The transmitter and receiver are configured to provide for the transmission of two channels of stereophonic signals while maintaining high signal-to-noise ratios, good frequency response, and low distortion. To provide for the proper transmission of signals between transmitter 10 and receiver 12, these devices include oscillating circuits having ceramic resonators which provide a base frequency which is readily modulated to facilitate proper transmission of either analog or digital signals between the transmitter and receiver.

Abstract: A discrete parallel path modulation multiplexer for use in generating a composite baseband signal from separate left and right input signals. The composite baseband signal includes the sum of the left and right input signals and the product of the difference between the left and right input signals and a subcarrier. The composite baseband signal may also include a pilot subcarrier at one-half the frequency of the subcarrier. In one signal path, the multiplexer multiplies the right input signal by the function (1+sin (wt)) and in a second signal path the multiplexer multiplies the left input signal by the function (1-sin (wt)). The products are then combined to obtain the composite baseband signal. A pilot subcarrier may also be generated and included as part of the composite baseband signal.

Abstract: Apparatus and methods are disclosed for broadcasting auxiliary data in an FM stereo broadcasting system. The auxiliary data is broadcast in addition to regular audio broadcast programs including musical selections, and includes data which identifies the musical selections. Embodiments are disclosed for broadcasting the auxiliary data during, immediately prior to and immediately following the broadcast of musical selections, without the need to use the SCA portion of the broadcast band.

Abstract: A system which enables transmission of a standard composite stereo sound signal, made up of baseband, subcarrier band and pilot signals, from a first location to a second location while requiring only a relatively low bit rate for the transmission link. The standard composite stereo signal is synchronously sampled at a first location at rate F.sub.s twice the subcarrier frequency F.sub.c (four times the pilot frequency F.sub.p), and the sampled signal transmitted over the link along with appropriate synchronizing signals. At the second location, a signal processor separates the received signal into a first signal related to one stereo channel signal (e.g. R) and a second signal representative of the other stereo channel (e.g. L), determines the proper scale for the pilot signal, and regenerates the original standard composite stereo sound signal by combining the L-related and R-related signals with the pilot scale signals in appropriate proportions and with appropriate filtering.

Abstract: A stereo FM radio transmission system with FMX transmission and reception capability includes a transmitter that transmits a pilot-coherent FMX-tone indicator signal at a frequency of an exact integer submultiple of the pilot frequency. The system also includes a receiver for dividing the frequency of the received pilot signal by various submultiples, nearly equal to the exact submultiple, toward quickly finding a match in phase of the received tone and the received pilot and finally dividing the pilot by the exact submultiple to establish an operational lock mode of the receiver tone detector to keep-on an FMX-indicator lamp, to change the receiver decoder to an FMX-reception operating mode and to stand by to quickly recapture the pilot and FMX-tone in the event of multipath or other interfering signals.

Abstract: A signal conditioning circuit for use in broadcasting a composite stereo signal in the 50 hertz to 53 kilohertz range. The signal conditioning circuit includes a filter for attenuating signals above the 53 kilohertz range, a delay circuit to reduce frequency dependent distortion caused by the filter, and an amplitude limiting circuit to reduce filter introduced amplitude distortion. Use of the signal conditioning circuit results in better utilization of the radio station's allocated transmission frequency and allows subchannel carrier authorization (SCA) use of the modulation frequency range above 53 kilohertz.

Abstract: An improved transmitter having protection from undesired out-of-band radiation caused by high frequency components in a supplied signal to be transmitted uses means for determining when the supplied signal is such as to cause out-of-band radiation. A resulting control signal then reduces the amplitude of the higher frequency components of the supplied signal relative to the remainder of the signal, thereby preventing out-of-band radiation.

Abstract: A multichannel FM subcarrier broadcast system is disclosed which enables the transmission of multiple independent signals by generating independent sidebands of suppressed carriers in the subcarrier band of an FM transmitting station. Transmitting and receiving apparatus is disclosed which employs phase shift networks to minimize interchannel distortion, thus allowing close spacing of adjacent sidebands.

Abstract: A video signal processing apparatus has an input terminal for receiving an input video signal and a delay line for delaying the input video signal. A first transmission circuit processes the video signal which has been delayed by the delay line and a first timer reversal circuit reverses the time sequence of the input video signal during a predetermined time period. A second transmission circuit processes the time reversed signal from the first time reversal circuit and a second time reversal circuit reverses the time sequence of the signal processed by the second transmission circuit. An adder circuit adds the signal processed by the first transmission circuit and the time reversed signal from the second time reversed circuit. A control pulse generator produces a control pulse sequence which inverts its level every predetermined period so as to control the first and second time reversal circuits. The output of the adder circuit serves as the output signal processing apparatus.

Abstract: A signaling system for FM transmission systems is disclosed that utilizes one or more so-called quadrature subcarriers for transmitting at least one data signal, including signaling tones, digital data, program material, or the like. The signal is modulated on outer edges of the quadrature channel so as to minimize crosstalk interference with the conventional FM stereo difference channel subcarrier and to place the signals in regions of low hearing acuity. Use of a quadrature subchannel also enables a signal to be modulated onto the quadrature subcarrier to provide the capability of modulating a noise compressed difference signal in a manner so as to minimize degrading crosstalk with the adjacent difference channel subcarrier. A receiving apparatus is disclosed for decoding the quadrature subcarrier data independently of standard FM stereo demodulation.

Abstract: An FM broadcasting system comprises an FM transmitter for transmitting a multiplex signal which is frequency-modulated on a main carrier wave and an FM receiver for cooperation with said FM transmitter. The multiplex signal comprises: an audio-frequency first information signal and, in the case of a stereo transmission, a second information signal modulated on a suppressed stereo subcarrier, a stereo pilot signal whose frequency (f.sub.p) is situated between the frequency spectra of the two information signals, a first binary-code signal (f.sub.p -f.sub.c) which is phase-modulated on a first code subcarrier situated outside the frequency spectra, which code subcarrier is a harmonic of a subharmonic of the stereo pilot (f.sub.p) which harmonic does not coincide with a harmonic of said pilot (f.sub.p), the multiplex signal, in order to extend the transmission capacity, comprising a second binary-code signal which is phase-modulated on a second code subcarrier (f.sub.p +f.sub.c).

Abstract: An FM stereophonic radio broadcasting system in which stereophonically related audio frequency source signals L and R are matrixed to obtain stereophonic sum and difference signals M and S, respectively. At the transmitter, the difference signal, is compressed, and the conventional difference signal and the compressed difference signal modulate respective quadrature-related sub-carriers of the same frequency to develop two double-sideband, suppressed-carrier signals, the frequency of the sub-carriers being sufficiently high as to assure a frequency gap between the lower sidebands of the modulated sub-carrier signals and the sum signal M. The M signal, the aforementioned suppressed-carrier signals, and a pilot signal having a frequency which lies within the frequency gap, are combined and frequency-modulated onto a high frequency carrier for the purpose of transmitting the same to one or more remote receivers.

Abstract: FM-broadcasting system comprising a FM-transmitter (1-16, 32-34) and a receiver (14-31, 35, 36) cooperating therewith, the transmission signal of which comprises a multiplex signal which is frequency-modulated on a main carrier wave, which multiplex signal comprises an audio-frequency information signal (L+R) and, in the case of a stereo transmission, a stereo information signal (L-R) modulated on a (38 kC) suppressed stereo subcarrier wave, also comprising a (19 kC) stereo pilot which is situated between the frequency spectra of the two information signals and a binary, differentially coded code signal which is phase-modulated on a (16.625 kC) code subcarrier wave which is situated outside the frequency spectra, and does not coincide with the (19 kC) stereo pilot, the receiver (14-31, 35, 36) comprising a pilot regeneration circuit (22-25) for regenerating the (19 kC) stereo pilot, the code signal having a bit repetition period which is an integral number of times the period of the (19 kC) stereo pilot.

Abstract: Two parallel signal paths carry a composite signal having a narrow-band component such as an FM station's composite signal. The first path includes a notch filter that removes the narrow-band component, such as the FM stereo pilot tone, from the composite signal and also includes a reciprocal clipper coupled to the output of the notch filter that selects peaks beyond given maximum and minimum limits from the remainder of the composite signal. These peaks are then effectively subtracted from the corresponding peaks of the composite signal in the second path and the resultant signal is used to modulate the station's carrier frequency. The resultant signal is an amplitude limited composite signal in which the narrow-band component is substantially unimpaired even though the composite signal has been amplitude limited.