FSK modulation and demodulation

Experiment Objectives:

This paper dives into the topic of using the frequency-shift keying method of modulation in a digital communications system. When using a communications system, to transmit a signal through long distances efficiently is by modulating the signal. In digital communications, there are three shift keying techniques; amplitude, phase, and frequency. This research focuses on the implementation of frequency-shift keying in modulating and demodulating a signal using MATLAB.

Experiment # (8) FSK Demodulator Experiment Objectives: 1. To understand the operation theory of FSK demodulator. 2. To implement the FSK detector circuit by using PLL. 3. To understand the operation theory of comparator by using operational amplifier as voltage level converter. Experiment theory: In experiment 7 we use FSK modulator for long distance communication, which the volatfe level of digital signal has been converted to frequency. Therefore, at the receiver, we have to recover the FSK signal to digital signal, that means the frequency should be converted back to voltage. We use phase locked loop (PLL) as FSK demodulator. PLL is a kind of automatic tracking system, which is able to detect the input signal frequency and phase. PLL is widely used in wireless applications, such as AM demodulator, FM demodulator, frequency selector and so on. In the digital communications, various types of digital PLLs are developed. Digital PLL is very useful in carrier synchronization, bit synchronization and digital demodulation.

FSK Demodulator, one of the applications of PLL has been implemented using both hardware and software. Results are found to be similar and based on these results it is believed that this will contribute for the improvement in performance and reliability for future communication systems. Hence this will also contribute to the development of higher reliability of the systems.

International Journal of Advanced Computer Science and Applications, 2016

This paper presents the design of low power modulator and demodulator circuits dedicated to a BFSK transceiver, operating in the 863-870 MHZ ISM band. The two circuits were designed using ams 0.35µm technology with 3V dc voltage supply. Simulation results of the new Direct Digital Frequency Synthesizer in the modulation have shown good performances of the designed system as the Spurious Free Dynamic Range SFDR reached-88 dBc while the circuit consumes only 47.7 µW @ 43.3MHz. The demodulator has also presented a good BER of 10-3 @10.9 EbtoN0 and a sensitivity of about-115 dBm.

IEEE Signal Processing Magazine, 2000

Ieice Transactions, 2008

In this letter, a simple binary Fast Frequency Shift Keying (FFSK) modulator and its coherent demodulator is proposed. The performance of the proposed modem is in between a coherently detected and a non-coherently detected binary FSK, but its bandwidth requirement is the same as for the Minimum Shift Keying (MSK) modulation.

Frequency shift keying (FSK) is the most common form of digital modulation in the high-frequency radio spectrum. The demodulation of Binary FSK involves complex operations on the modulated signal like reconstruction of carrier signal and multiplication of carrier signal with the modulated signal. In this paper, BFSK is realized as two separate ASKs and a much simpler incoherent method is proposed for demodulation of BFSK modulated signal. Since power consumption is one of the main factors in electronic devices, low power devices are always demanding. Power Consumption could be minimized by reducing the actual block diagram of the system by opting an alternative approach to achieve the same output signal. The same BFSK demodulator can be used to demodulate an ASK modulated signal if it follow certain criteria's.