Digital Modulations

Rician flat-fading simulation — line-of-sight plus scattered power

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Fading & Diversity — 6 lessons (same on every page in this path) 1. Rayleigh BER → 2. Clarke’s model (you are here) → 3. Young’s model → 4. SIMO models → 5. Selection combining → 6. MRC Tools: BER vs Eb/N0 · 3GPP TDL · CDL / Doppler Optional branch from Fading & Diversity. … Read more

Constellation diagram – investigate phase transitions

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The phase transition properties of the different variants of QPSK schemes and MSK, are easily investigated using constellation diagram. Let’s demonstrate how to plot the signal space constellations, for the various modulations used in the transmitter. Typically, in practical applications, the baseband modulated waveforms are passed through a pulse shaping filter for combating the phenomenon … Read more

Maximum Ratio Combining (MRC): Getting the Absolute Most from Your Antennas

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MRC weights each diversity branch by its channel gain to maximize post-combiner SNR — formula, intuition, and comparison to selection combining.

Understanding Selection Combining: The Simplest Way to Fight Fading

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MIMO — Diversity path 1. Intro → 2. Diversity vs mux → 3. SIMO → 4. Selection combining → 5. MRC Tools: Diversity & multiplexing demo Introduction Selection combining is the diversity scheme you can explain at a whiteboard in one minute: measure the SNR on each antenna, keep the best, ignore the rest. The … Read more

Differentially encoded BPSK: coherent detection

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In coherent detection, the receiver derives its demodulation frequency and phase references using a carrier synchronization loop. Such synchronization circuits may introduce phase ambiguity $latex \phi = \hat{\theta}-\theta $ in the detected phase, which could lead to erroneous decisions in the demodulated bits. For example, Costas loop exhibits phase ambiguity of integral multiples of $latex … Read more