| Parameter | AM (Amplitude Modulation) | FM (Frequency Modulation) | PM (Phase Modulation) |
|---|---|---|---|
| Carrier Parameter Varied | Amplitude | Frequency | Phase |
| Information Carried By | Amplitude changes | Frequency changes | Phase changes |
| Noise Immunity | Low | High | Better than AM |
| Bandwidth | Narrow | Wide | Depends on modulation |
| Power Efficiency | Low (carrier consumes power) | High | High |
| Major Advantage | Simple implementation | Excellent noise immunity | Good digital compatibility |
| Major Application | AM Radio Broadcasting | FM Radio Broadcasting | Digital communication systems |
| Frequency Deviation | Not applicable | Proportional to message amplitude | Proportional to message amplitude and frequency |
| Demodulation | Envelope Detector | FM Detector / PLL | Phase Detector |
| System | Frequency Range |
|---|---|
| FM Broadcast Band | 88 MHz – 108 MHz |
| Maximum FM Deviation (WBFM) | ±75 kHz |
| FM Audio Baseband | 15 kHz |
| FM Channel Allocation | 200 kHz per station |
| Parameter | DSB-SC | SSB-SC | VSB |
|---|---|---|---|
| Carrier | Suppressed | Suppressed | Partially present |
| Sidebands Transmitted | Both USB & LSB | Only one sideband | One sideband + vestige of other |
| Bandwidth Requirement | Higher | Minimum | Between DSB-SC and SSB |
| Power Efficiency | High | Highest | Moderate |
| Generation | Balanced/Ring Modulator | DSB-SC + Filtering | Partial Filtering |
| Additional Filtering Required | No | Yes | Partial |
| Demodulation | Synchronous Detection | Synchronous Detection | Product Modulator + LPF |
| Main Advantage | Carrier power saved | Maximum bandwidth & power efficiency | Reduced bandwidth with simple recovery |
| Application | Communication systems | HF, Military, Long-distance communication | Television Video Transmission |
| Modulation | USB | LSB | Carrier |
|---|---|---|---|
| Conventional AM | ✓ | ✓ | ✓ |
| DSB-SC | ✓ | ✓ | ✗ |
| SSB-SC | ✓ or LSB only | One only | ✗ |
| VSB | One complete | Partial | Partial |
| Parameter | BPSK | QPSK | DPSK | FSK |
|---|---|---|---|---|
| Full Form | Binary Phase Shift Keying | Quadrature Phase Shift Keying | Differential Phase Shift Keying | Frequency Shift Keying |
| Carrier Parameter Varied | Phase | Phase | Relative Phase | Frequency |
| Number of States | 2 | 4 | 2 (relative) | 2 frequencies |
| Phase Values | 0°, 180° | 0°, 90°, 180°, 270° | Relative to previous symbol | Mark & Space Frequency |
| Bits per Symbol | 1 | 2 | 1 | 1 |
| Spectral Efficiency | Good | Higher than BPSK | Similar to BPSK | Lower than PSK |
| Noise Performance | Good | Good | Good | Better than AM |
| Phase Reference Needed | Yes | Yes | No | |
| Main Advantage | Simple and reliable | Higher data rate | Eliminates phase ambiguity | Simple implementation |
| Applications | Digital communication | Wi-Fi, Cellular, Satellite | Digital communication | Data transmission |
| Technique | Key Point |
|---|---|
| BPSK | Uses 0° and 180° |
| QPSK | Uses 4 phase states and carries 2 bits/symbol |
| DPSK | No absolute phase reference required |
| FSK | Binary 1 → Higher Frequency, Binary 0 → Lower Frequency |
| PLL | Used for FSK Demodulation |
| Raised Cosine Filter | Minimizes ISI |
| Eye Diagram | Evaluates signal quality and ISI |
| Parameter | Value |
|---|---|
| FM Broadcast Band | 88–108 MHz |
| FM Maximum Deviation | 75 kHz |
| FM Audio Baseband | 15 kHz |
| FM Bandwidth (Carson Rule) | 180 kHz |
| FM Channel Spacing | 200 kHz |
| NBFM Deviation | ±5 kHz or less |
| BPSK Phases | 0°, 180° |
| QPSK Phases | 0°, 90°, 180°, 270° |
| Complete Phase Shift | 360° = One Time Period (T) |
| Topic | One-Liner |
|---|---|
| AM | Information carried by amplitude variation |
| FM | Information carried by frequency variation |
| PM | Information carried by phase variation |
| DSB-SC | Carrier suppressed, both sidebands transmitted |
| SSB-SC | Carrier suppressed, only one sideband transmitted |
| VSB | One sideband + partial other sideband |
| BPSK | Two phase states |
| QPSK | Four phase states, 2 bits/symbol |
| DPSK | Phase compared with previous symbol |
| FSK | Frequency changes according to binary data |
| PLL | Tracks frequency changes and demodulates FSK/FM |
| Raised Cosine Filter | Eliminates ISI |
| Eye Diagram | Measures digital communication quality |
This table set contains all comparison points explicitly mentioned in your provided notes and avoids adding outside information.