Signal Processing for Communication Systems
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Line code is the signaling scheme used to represent data on a communication line. There are several possible mapping schemes available for this purpose. Lets understand and demonstrate line code and PSD (power spectral density) in Matlab & Python. Line codes – requirements When transmitting binary data over long distances encoding the binary data using … Read more
Key focus: Euclidean & Hamming distances are used to measure similarity or dissimilarity between two sequences. Used in Soft & Hard decision decoding. Distance is a measure that indicates either similarity or dissimilarity between two words. Given a pair of words a=(a0,a1, … ,an-1) and b=(b0,b1,…,bn-1) , there are variety of ways one can characterize … Read more
Compare FFT windows by scalloping loss, sidelobe level, 3 dB bandwidth, and ENBW — and when to pick Hann vs Blackman-Harris vs flattop.
What ENBW means for FFT windows, the time-domain formula used in code, ENBW in bins for common windows, Python (SciPy), and how it shifts the noise floor.
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
Key focus: Discuss statistical measures for stochastic signals : mean, variance, skewness, kurtosis, histogram, scatterplot, cross-correlation and auto-correlation. Deterministic and stochastic signals A deterministic signal is exactly predictable for the given time span of interest. It could be expressed using analytic form (example: x(t) = sin (2 π fc t) ). Many of the signals … Read more
Simulate BPSK bit-error rate in Python and Matlab, compare Monte Carlo curves to the Q-function formula, and open the same points on the BER calculator.
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
Articles in this series Phased array antenna — an introduction Electronic scanning arrays Grating lobes in electronic scanning Array pattern multiplication (this article) Introduction So far the radiators were mathematical points. Real dipoles and patches have their own angular patterns. If the elements are identical and oriented the same way, the total far-field pattern factors … Read more
Articles in this series Phased array antenna — an introduction Electronic scanning arrays Grating lobes in electronic scanning (this article) Array pattern multiplication Introduction A uniform array samples the aperture field at equal intervals. Sample too coarsely and the far-field pattern aliases—the same idea as undersampling a time signal. The aliases show up as grating … Read more