A method and apparatus for modulating/demodulating an FSK signal capable of overcoming a trade-off relationship between a modulation index and a spectral efficiency are disclosed. An apparatus for modulating/demodulating a frequency deviation keying (FSK) signal includes a channel selection-modulator, a phase locked loop, and an output unit. The channel selection-modulator modulates an FSK signal by setting a frequency channel to be used. The phase locked loop generates a desired output frequency ‘fout’ compared to a reference frequency ‘f.sub.REF’ by adjusting a frequency division ratio (N+n) with respect to a frequency of the modulated FSK signal. The output unit amplifies the FSK signal having the generated output frequency ‘fout’ and radiating the amplified FSK signal through an antenna. Here, each of the frequency channels is divided into two or more tones, and different frequency channels are allocated between the tones divided into two or more tones.

A transmission device includes a frequency detector configured to detect a frequency of an input signal to generate frequency information; a signal generator configured to generate a modulation wave signal with a frequency equivalent to the frequency of the input signal based on the frequency information; and a single side band modulator configured to modulate a carrier wave by the modulation wave signal.

A transmission device includes a frequency detector configured to detect a frequency of an input signal to generate frequency information; a signal generator configured to generate a modulation wave signal with a frequency equivalent to the frequency of the input signal based on the frequency information; and a single side band modulator configured to modulate a carrier wave by the modulation wave signal.

A unified mud-pulse (MP)-electromagnetic (EM) telemetry assembly and a downhole telemetry tool are provided including a downhole EM telemetry transmitter apparatus. The EM telemetry transmitter apparatus comprises a modulator configured to transmit at least one EM signal through transmission medium. The modulator comprises a first reactive circuit and a second reactive circuit, and a plurality of switches controlled by a controller to alternatingly switch the modulator between a first configuration and a second configuration. The EM signals are transmitted by passing one of the reactive circuits and bypassing the other reactive circuit.

A unified mud-pulse (MP)-electromagnetic (EM) telemetry assembly and a downhole telemetry tool are provided including a downhole EM telemetry transmitter apparatus. The EM telemetry transmitter apparatus comprises a modulator configured to transmit at least one EM signal through transmission medium. The modulator comprises a first reactive circuit and a second reactive circuit, and a plurality of switches controlled by a controller to alternatingly switch the modulator between a first configuration and a second configuration. The EM signals are transmitted by passing one of the reactive circuits and bypassing the other reactive circuit.

An audio data transmission method includes encapsulating, based on a physical layer frame header, a protocol data unit (PDU) including audio data, to obtain an audio data packet, where the physical layer frame header is modulated using a first digital modulation scheme, the PDU is modulated using a second digital modulation scheme, a value of a modulation rate of the first digital modulation scheme is equal to a value of a data transmission rate, and a value of a modulation rate of the second digital modulation scheme is less than the value of the data transmission rate, and sending the audio data packet on a BLUETOOTH low energy (BLE) physical channel at the data transmission rate.

An audio data transmission method includes encapsulating, based on a physical layer frame header, a protocol data unit (PDU) including audio data, to obtain an audio data packet, where the physical layer frame header is modulated using a first digital modulation scheme, the PDU is modulated using a second digital modulation scheme, a value of a modulation rate of the first digital modulation scheme is equal to a value of a data transmission rate, and a value of a modulation rate of the second digital modulation scheme is less than the value of the data transmission rate, and sending the audio data packet on a BLUETOOTH low energy (BLE) physical channel at the data transmission rate.

A vehicle control apparatus is mounted on a vehicle to perform wireless communication with a portable terminal. The vehicle control apparatus includes a first processor configured to execute a first process including a determination process that determines whether or not a received signal, which is a wireless signal received by an antenna mounted on the vehicle and encoded, is a regular wireless signal transmitted from the portable terminal by determining whether or not a counted number of short bits sandwiched by two long bits adjacent to each other in the received signal is an even number.

A signal specification identification apparatus includes processing circuitry that estimates the transmission rate of a received signal, performs sampling frequency conversion on the received signal, calculates a probability corresponding to each of a plurality of candidates for a specification of the received signal, selects a candidate using the respective probabilities, and calculates reliability corresponding to a selected candidate, determines whether to output the selected candidate as an identification result or perform the sampling frequency conversion again, based on the reliability, and changes a parameter indicating the ratio of the sampling frequency conversion when it is determined that the sampling frequency conversion is to be performed again. Processing is repeated until the processing circuitry determines that the selected candidate as the identification result is to be output.

The invention relates to the transmission and reception of non-binary error correcting code words. The transmission method includes a first modulation (56) which implements a set of q sequences comprising q-1 sequences of q-1 chips, each sequence being obtained by circular shifting of a basic pseudo-random sequence, and a partially invariant sequence, invariant to a predetermined subset of circular shifts. The first modulation (56) further implements an association between each code word symbol and a sequence of the set of sequences wherein said finite field GF.sub.q has a non-zero primitive element, the symbol zero being associated with said partially invariant sequence and a symbol equal to a power j of the primitive element, j being an integer comprised between 0 and q-2, being associated with a pseudo-random sequence determined by j circular shifts of the basic pseudo-random sequence.