Freequency Shift Keying in Digital to Analog Conversion
- 2. DIGITAL TO ANALOG CONVERSION DAC is the process of converting digital data (binary bits) into an analog signal. How DAC Works: The digital bitstream (0s and 1s) is mapped to variations in an analog waveform. These waveforms can be transmitted over different communication mediums such as copper wires, fiber optics, or wireless systems.
- 3. Digital Modulation Techniques • There are three primary digital modulation techniques: • Amplitude Shift Keying (ASK): Modulates the amplitude of the carrier signal. • Frequency Shift Keying (FSK): Modulates the frequency of the carrier signal. • Phase Shift Keying (PSK): Modulates the phase of the carrier signal. • Used in digital communication systems to encode digital data into analog signals. Purpose : Efficient transmission of digital data over analog channels like radio waves and optical fiber.
- 4. What is Shift keying? •A modulation technique where the digital signal alters a carrier wave’s properties (amplitude, frequency, or phase) to transmit data. •Used in digital communication systems to encode digital data into analog signals. Purpose : Efficient transmission of digital data over analog channels like radio waves and optical fiber.
- 6. Benefits: • Noise Resilience: Excellent resistance to signal degradation due to amplitude noise. • Simple Implementation: Easier to implement with basic hardware like oscillators. • Suitability for Low-Speed Data: Works well in systems where high data rates aren't required but robustness is important.
- 7. Drawbacks: • Bandwidth Consumption: Requires more bandwidth compared to ASK and PSK for the same data rate. • Data Rate Limitation: Less efficient for high-speed communications due to larger frequency separation requirements.
- 8. Applications 1. Radio Communication Systems 1. FM Transmission • Used for audio signals. • Efficient use of bandwidth and resistance to noise. 2. Walkie-Talkies • Portable two-way radios. • Common in military and emergency services. 2. Short-Range Wireless Technologies Bluetooth • Uses Gaussian FSK (GFSK). • Low power and good at avoiding interference. • RFID • FSK used in communication between tags and readers. • Effective in noisy environments and improves read range.
- 9. Applications 3. Low-Speed Data Transmission 1. Modems • Early telephone line modems used FSK. 2. Caller ID Systems • Transmit caller information on landlines. 3. Pagers • Use FSK for simple messaging. 4. Telemetry and Wireless Systems 1. Telemetry • Used for weather monitoring and wildlife tracking. 2. Wireless Sensor Networks • Employed in industrial and outdoor applications. 3. Satellite Communication • Certain systems use FSK for data transmission.
- 10. Comparison Feature FSK (Frequency Shift Keying) ASK (Amplitude Shift Keying) PSK (Phase Shift Keying) How It Works (Modulation) The signal’s frequency changes to show the data (1 for one frequency, 0 for another). The signal’s strength (amplitude) changes based on data. The signal’s phase (angle) changes to represent data (e.g., 0° for 1, 180° for 0). Modulated Signal One frequency for ‘1’, another frequency for ‘0’. High amplitude for ‘1’, low amplitude for ‘0’. Phase stays the same for ‘1’, phase shifts by 180° for ‘0’. Carrier Signal Uses two different frequencies for ‘1’ and ‘0’. Uses one frequency with different strengths (amplitudes). Uses one frequency but changes its phase(angle). Modulation Method ‘1’ is sent using higher frequency, ‘0’ using lower frequency. ‘1’ is sent by increasing signal strength, ‘0’ by lowering it. ‘1’ is sent by keeping phase same, ‘0’ by changing the phase. How It Works (Demodulation) Detects which frequency is received (higher or lower) to find out if it’s ‘1’ or ‘0’. Detects how strong the signal is (high or low) to decide if it’s a ‘1’ or ‘0’. Detects the phase of the signal (whether it changed or stayed the same) to read ‘1’ or ‘0’.
- 11. Feature FSK (Frequency Shift Keying) ASK (Amplitude Shift Keying) PSK (Phase Shift Keying) Demodulation Method Uses Bandpass Filters or a frequency detector to separate the two frequencies and decide if it’s ‘1’ or ‘0’. Uses Envelope Detection (checking signal strength) and a comparator to decide ‘1’ or ‘0’. Uses Coherent Demodulation (measuring phase) and a phase- locked loop (PLL) to track phase changes and read the data. Noise Sensitivity Less affected by noise (frequency changes are easier to detect in noisy environments). Sensitive to noise (noise easily affects signal strength). Least affected by noise (phase is not easily disturbed by noise). Bandwidth Usage Uses more bandwidth than ASK (because of the two frequencies). Uses less bandwidth (narrower signal). Moderate bandwidth use (more efficient than FSK but may need more than ASK depending on type). Complexity Moderate but Slightly more complex (requires generating and detecting two different frequencies). Easy to implement. Complex (requires phase synchronization and precise phase detection). Common Uses Radio modems, digital transmissions (e.g., modems, RFID applications). Low-speed data transmission (e.g.,, optical communication). High-speed digital communications (e.g., Wi-Fi, satellite, cellular networks). Comparison
- 12. THANKYOU…
Editor's Notes
- #2: Importance in Digital Communications:Analog channels cannot carry binary data directly, so a carrier signal (an analog wave) must be modulated using digital modulation techniques such as ASK, FSK, or PSK.