FSK Demodulator/Tone Decoder with RC2211N

A monolithic phase locked loop for data communications. The IC contains a basic phase locked loop for tracking an input signal within the pass band, a quadrature phase detector which provided carrier detector and an FSK voltage comparator which provides FSK demodulation. In the circuit shown, the IC is used as an FSK demodulator such as would be found in the receiver circuit of a modem. More: The table below shows the component values required for a modem demodulator using standard European tones on the public switched network.

The described integrated circuit (IC) implements a monolithic phase locked loop (PLL) specifically designed for data communication applications. Its primary function is to maintain synchronization with an input signal by utilizing a basic PLL architecture. This PLL is adept at tracking signals within a specified pass band, which is crucial for effective data transmission and reception.

The IC incorporates a quadrature phase detector, which plays a vital role in carrier detection. This component enables the PLL to accurately determine the phase relationship between the incoming signal and a reference signal, facilitating the extraction of the carrier frequency. The quadrature detection method enhances the performance of the demodulator by allowing it to operate effectively even in the presence of noise and signal distortions.

In addition to the phase detection capabilities, the IC features an FSK (Frequency Shift Keying) voltage comparator. This comparator is integral for performing FSK demodulation, a common technique used in modem circuits for digital data transmission. The FSK demodulator interprets the frequency shifts of the incoming signal to recover the original data, making it essential for modem applications.

The circuit configuration illustrated indicates that this IC is employed as an FSK demodulator, typically found within the receiver section of a modem. This setup is particularly relevant for modems operating on standard European tones in the public switched telephone network (PSTN), where specific component values are required to ensure optimal performance and compatibility with the network specifications.

For practical implementation, a detailed table of component values is necessary to facilitate the design of the modem demodulator. These values are critical to achieving the desired operating characteristics and ensuring reliable communication over the network.A monolithic phase locked loop for data communications. The IC contains a basic phase locked loop for tracking an input signal within the pass band, a quadrature phase detector which provided carrier detector and an FSK voltage comparator which provides FSK demodulation. In the circuit shown, the IC is used as an FSK demodulator such as would be found in the receiver circuit of a modem.

The table below shows the component values required for a modem demodulator using standard European tones on the public switched network.