T&M Amplitude Modulation vs. Angle Modulation: A Detailed Comparison
Modulation is a crucial technique used to transmit information, such as voice, data, and video, over long distances. It works by changing the parameters of a carrier signal based on the information we want to send. This helps combat interference, noise, and fading, ensuring a clearer signal. Any modulation process involves two inputs: the baseband or modulating signal (the information) and the carrier signal. The result is a single output known as the modulated signal.
Here, we’ll explore the differences between two major types of modulation: amplitude modulation and angle modulation.
Understanding Amplitude and Angle Modulation
The core difference lies in what aspect of the carrier signal is modified:
- Amplitude Modulation (AM): The amplitude of the carrier signal is varied in proportion to the modulating signal.
- Angle Modulation: Either the frequency or the phase of the carrier signal is varied in response to the modulating signal. When the frequency is varied, it’s called Frequency Modulation (FM), and when the phase is varied, it’s called Phase Modulation (PM).
Let’s break down the key differences further:
Amplitude Modulation vs. Angle Modulation: A Comparison
| Feature | Amplitude Modulation | Angle Modulation |
|---|---|---|
| Definition | The amplitude of the carrier signal is varied according to the modulating signal. | The frequency or phase of the carrier signal is varied according to the modulating signal. |
| Modulated Carrier | The amplitude of the modulated carrier varies. | The amplitude of the modulated carrier remains constant. |
| Noise & Interference | Offers poor discrimination against noise and interference. | Offers better discrimination against noise and interference. |
| Examples | Includes Pulse Amplitude Modulation (PAM) and Quadrature Amplitude Modulation (QAM). | Includes Phase Modulation types (PSK, DPSK, QPSK), Frequency Modulation type (FSK), constant phase modulation types (GMSK, MSK, CPFSK), trellis coded modulation types (PSK, QAM) etc. |
Applications
Both AM and angle modulation techniques are widely used in various communication systems, including:
- TV sound transmission
- Mobile radio
- Radio broadcasting
- Microwave/Satellite communication
- Cellular radio
Key Takeaways
- AM is simpler to implement but more susceptible to noise.
- Angle modulation (FM and PM) offers better noise immunity but is more complex.
- The choice between AM and angle modulation depends on the specific application and its requirements, balancing simplicity and noise performance.
