Abstract: An audio FM transmitter is disclosed that may achieve high-precision frequency control as well as compact size and low cost by enabling FM modulation using a fractional-N type PLL circuit.

Abstract: [Problem to be Solved] To provide an audio FM transmitter that achieves high-precision frequency control as well as compact size and low cost by enabling FM modulation using a fractional-N type PLL circuit. [Solution] An audio FM transmitter 1 that analog FM-modulates an audio signal using a PLL modulator 8 and transmits the FM-modulated audio signal includes: the PLL modulator 8; and a controller 11 for outputting a frequency divider setting signal to the PLL modulator 8.

Abstract: There is provided a wireless measuring apparatus that efficiently measures the frequency characteristics of a sensor unit mounted on an object to be measured. The wireless measuring apparatus is a wireless measuring apparatus that measures the frequency characteristics of a sensor unit (10) mounted on an object (40) to be measured, including the sensor unit (10) having a piezo-resonator (11), an antenna (20) that forms a circuitry with the sensor unit (10), and a measuring element (30) that supplies high frequency electricity changed in different frequency to the circuitry and measures the frequency characteristics of the reflected electricity strength received from the circuitry.

Abstract: An FM transmitter device having an audio signal processing compression unit for logarithmically compressing an audio signal, an FM broadband transmission single chip IC receiving as inputs a modulated signal from the audio signal processing compression unit and a channel frequency setting signal C, operating upon receipt of a reference clock, and transmitting an FM high frequency wave, a SAW resonator configuring a locally oscillator, a 700 MHz band SAW oscillation circuit, a mixing circuit for mixing the non-modulated high frequency wave from this oscillation circuit and the FM high frequency wave from the FM broadband transmission single chip IC and converting the frequency, and a SAW filter for eliminating an unrequired frequency among mixed waves from the mixing circuit and extracting a high frequency component in the 200 MHz band or the 800 MHz band, whereby an FM transmitter device which is small in size and lower in power consumption and can obtain a high S/N ratio is provided.

Abstract: A compact and lightweight wireless microphone and transmitter. The transmitter is connected to the microphone using a standard connector. The transmitter includes a low-frequency amplifier for amplifying a received voice signal and a surface acoustic wave oscillator providing a high-frequency oscillation signal. A modulator combines the amplified voice signal and the high frequency oscillation signal into a modulated signal. The modulated signal is amplified using a high-frequency amplifier to create a high-frequency modulated signal. The high-frequency modulated signal is output as radio waves through an antenna. A power supply is included for powering the transmitter. To improve sound quality, the transmitter additionally includes a compander circuit for improving signal-to-noise ratio and increasing a dynamic range through a logarithmic compression algorithm.

Abstract: A compact and lightweight wireless microphone and transmitter. The transmitter is connected to the microphone using a standard connector. The transmitter includes a low-frequency amplifier for amplifying a received voice signal and a surface acoustic wave oscillator providing a high-frequency oscillation signal. A modulator combines the amplified voice signal and the high frequency oscillation signal into a modulated signal. The modulated signal is amplified using a high-frequency amplifier to create a high-frequency modulated signal. The high-frequency modulated signal is output as radio waves through an antenna. A power supply is included for powering the transmitter. To improve sound quality, the transmitter additionally includes a compander circuit for improving signal-to-noise ratio and increasing a dynamic range through a logarithmic compression algorithm.

Abstract: A wireless microphone use UHF band carrier FM transmitter adopting a PLL system, which has a voltage controlled crystal oscillation type modulator (VCXO) for performing FM modulation on an oscillation frequency of a crystal oscillation circuit by an input of a modulation signal AF of an acoustic signal and which uses an FM modulated signal fr obtained from the VCXO as a reference signal Vr to be input to an analog phase comparator (PC) of a PLL circuit 60. The PC performs a phase comparison operation at a high speed (10 MHz or more), therefore a cutoff frequency of a loop filter (62) may be a high band frequency of about 100 KHz to 1 MHz so that the cutoff frequency considerably higher than the highest audible frequency 20 KHz can be selected. The filter output moves at an inaudible frequency and therefore there is no audible noise generated even due to vibration, feedback, etc.

Abstract: A diversity FM receiver of the antenna switching system type which includes first and second antennas, an antenna switching circuit, an FM receiving unit and a sample hold circuit. The receiving unit functions to demodulate the wave signal input thereto and to output a wave detection signal. The switching circuit switches the signal received from one antenna or the other antenna to the receiving unit in accordance with the amplitude of the wave detection signal. The sample hold circuit maintains the voltage of the wave detection signal during switching at the value of the signal immediately before switching.

Abstract: A frequency modulated (FM) transmitter for use in the 100 to 300 megacycle band is described having a low parts count topology. The disclosed topology requires the use of five tank circuits tuned to various frequency multiples of a crystal oscillator to achieve a twelve fold multiplication of the natural frequency of the crystal oscillator.