The working engineer’s field guide to wireless communications
Structured lessons from your first decibel to the 5G NR physical layer, deep-dive topic hubs, honest platform and radio hardware references, and daily news written in plain English with sources linked.
All lessons are free to read until 31 Jan 2027. No account, no sign-up.
Learning tracks
All lessons →Start here
Full beginner track →What is a radio link
The parts of every radio link from bits to antenna and back, what the carrier frequency changes, why bandwidth matters, and a first working use of decibels
Complex baseband and IQ samples
Why radios represent signals as I and Q, how mixing moves a signal to and from the carrier, what sampling rate a complex signal needs, and what a negative frequency is
Decibels and link budgets
Decibel arithmetic in dB, dBm, dBW and dBi, the Friis transmission equation, free-space path loss checked against ITU-R P.525, and a link budget calculator in numpy
Noise, SNR and capacity
Where the −174 dBm/Hz thermal noise floor comes from, how noise figure and cascaded stages set receiver sensitivity, and what Shannon capacity says about bandwidth and power
Digital modulation and bit error rate
Map bits to BPSK, QPSK and 16-QAM symbols with Gray coding, detect them in noise, and measure bit error rate against Eb/N0 by Monte Carlo simulation compared with theory
Pulse shaping and matched filters
Why rectangular pulses waste spectrum, how raised-cosine and root-raised-cosine pulses avoid intersymbol interference, and why the receiver filter must match the transmit pulse
Topic hubs
All 20 topics →Wireless foundations
Radio links end to end, bands, bandwidth, SNR and the main system families
Signals and spectra
Complex baseband, IQ sampling, FFTs, filters, pulse shaping and dB arithmetic
Antennas and propagation
Antenna gain and arrays, path loss, Friis, fading, Doppler and channel models
Link budgets and noise
Thermal noise, noise figure, sensitivity, link margin, interference and capacity
Modulation
Keying a carrier, constellations, bit error rate and adaptive modulation
Channel coding
Block, convolutional, turbo, LDPC and polar codes, and HARQ in LTE and NR
OFDM and multicarrier
OFDM, cyclic prefix, NR numerology, OFDMA, DFT-s-OFDM and PAPR
MIMO and beamforming
Diversity, spatial multiplexing, precoding, massive MIMO and hybrid beamforming
Synchronisation and estimation
Timing and frequency recovery, channel estimation, equalisation and phase noise
RF front ends
LNAs, PAs, mixers, oscillators, data converters, linearity and DPD
Software-defined radio
SDR architectures, GNU Radio, UHD and SoapySDR, sample rates, IQ files
Cellular 4G LTE
E-UTRAN and EPC, frame structure, resource grid, physical channels
Platforms
Platform hubs →Build something
All projects →A QPSK modem with a measured BER curve
Build a QPSK transmitter and receiver in NumPy with root-raised-cosine pulse shaping, an AWGN channel and a matched filter, then measure the bit error rate from 0 to 10 dB Eb/N0 against theory.
A headless GNU Radio FM receiver tested on synthetic IQ
Generate an FM test signal in NumPy, save it as SigMF, demodulate it with a headless GNU Radio 3.10 flowgraph and check the recovered tone frequency, deviation and audio SNR in code.
A LoRaWAN link budget and coverage map calculator
Compute EU868 LoRaWAN uplink sensitivity, time on air, duty-cycle limits and range per spreading factor from Semtech, LoRa Alliance, ITU-R and 3GPP sources, then map coverage around one gateway in NumPy.