Signal Processing for Communication Systems
Mathuranathan OFDM study path — 5 lessons (same on every page in this series) 1. Introduction → 2. Orthogonality → 3. IFFT modem → 4. Cyclic prefix (you are here) → 5. BER in AWGN Tools: OFDM CP overhead calculator · Eb/N0 ↔ SNR converter In one sentence: A cyclic prefix tricks a natural (linear) … Read more
How to get amplitude and phase from an FFT: |X[k]|, atan2, why phase looks noisy, the magnitude threshold fix, Matlab + Python, and links to bins/fftshift and the FFT calculator.
How DFT bins map to Hz, what negative frequencies mean, when to use fftshift/ifftshift, and how this pairs with magnitude/phase plots.
What RMS means for voltages and DSP signals, how it ties to average power, and the formulas for continuous and discrete waveforms.
Create AWGN manually: set noise variance from SNR or Eb/N0, generate real/complex noise, and verify power — links to BER tools.
How Gold codes are built from preferred m-sequence pairs, their three-valued cross-correlation, and why they are used in CDMA/GNSS spreading.
Auto-correlation, also called series correlation, is the correlation of a given sequence with itself as a function of time lag. Cross-correlation is a more generic term, which gives the correlation between two different sequences as a function of time lag. Given two sequences $latex x$ and $latex y$, the cross-correlation at times separated by lag … Read more
This article focused on constructing constellation for rectangular QAM modulation using Karnaugh-map walks. Exploit inherent property of Karnaugh-maps to construct Gray coded QAM constellation points. M-ary Quadrature Amplitude Modulation (M-QAM) In MQAM modulations, the information bits are encoded as variations in the amplitude and the phase of the signal. The M-QAM modulator transmits a series … Read more
MIMO — Capacity path 1. Intro → 2. Channel model → 3. SISO capacity → 4. Ergodic SISO → 5. MIMO capacity Tools: Shannon calculator Introduction Extend the scalar ergodic average to a matrix channel. With receiver CSI and equal power across transmit antennas, ergodic MIMO capacity is the expectation of a log-determinant—the expression Telatar … Read more
MIMO — Capacity path 1. Intro → 2. Channel model → 3. SISO capacity → 4. Ergodic SISO → 5. MIMO capacity Tools: Shannon calculator Introduction We already met ergodic capacity as an expectation. Now treat it as something you compute: how do you estimate it stably, and is there a closed form to check … Read more