Digital Modulation - Frequency Shift Keying(FSK)

[lorenzor]

Hello friends of Steemit, in this opportunity I share the experimental demonstration of one of the best known Digital modulation techniques, Frequency Shift Keying (FSK).

Definition of Frequency Shift Keying (FSK)

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The main features of the FSK are:

• High noise immunity.
• digital radio transmission, in the cellular telephone system.
• Applications in modems for data transmission.
• Likelihood of error less than ASK modulation.

Digital Modulation Methods

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Forms of modulated signals

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Schematic diagram used and materials (FSK Modulator)

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Datasheets

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Modulation Process

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Demonstration of the FSK modulation in the test laboratory

Objectives:

• Build an FSK modulator with the integrated XR2206.
• Transmit a digital information signal FSK

Process:

• The modulation is controlled by the capacitor placed on pins 5 and 6 and by the resistors R1 and R2 on pins 7 and 8 for which we have used a potentiometer as a variant of the circuit.
• The carrier signal is supplied by the integrated XR-2206 itself associated with the 200 resistance on pins 13 and 14.

General view of the assembly

Signal generator (frequency of the input signal f = 25.4KHz)

Power voltage of the function generator XR-2206 (V = 9.1 v)

Display of the output signal (FSK) on the oscilloscope.

Conclusions

• A sinusoidal signal of lower frequency is observed in the output signal when we have a binary 0 and a higher frequency for a binary 1. Which complies with the theory (see image shapes of modulated signals)
• Only changes in frequency and not amplitude are observed.

References

• Digital Signal Processing using MATLAB – John G. Proakis – 3ed
• Sistemas-de-comunicacion-digital-y-analogico-leon-w-couch-7ma-edicion
• Sistemas de Comunicación - 2da Edición - Ferrel G. Stremler
• https://www.sparkfun.com/datasheets/Kits/XR2206_104_020808.pdf
• https://es.slideshare.net/helbert15_1992/lab-de-modulacion-fsk-final

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I hope that this publication has given you knowledge about the subject. If you have any questions, please leave your comment and then I will gladly try to clarify them.

Thanks for reading my publication.

Comments

[yagoub]

this give me a nice knowledge about the subject.thank you @lorenzor

[lorenzor]

Thanks for reading and commenting. I hope it's useful.

[veeeenq]

Hello, could you please contact me with a private message? I just want to ask you some questions :)

[veeeenq]

Hello, could you please contact me with a private message? I just want to ask you some questions :) @lorenzor

[veeeenq]

Do you have maybe more photos of the circuit on breadboard? @lorenzor