RF glossary¶

This glossary keeps the course terminology consistent across Russian and English pages. It focuses on terms that appear repeatedly in SDR, DSP, FPGA, RF and IQ recording labs.

Core SDR terms¶

Term	Meaning	Course context
SDR	Software-Defined Radio. A radio system where signal processing and control are largely implemented in software or programmable logic.	Main course subject.
RF	Radio frequency. The physical high-frequency signal domain before or after mixing.	Used in AD9363, RTL-SDR and hardware labs.
Baseband	Signal representation around 0 Hz after frequency translation.	Most DSP algorithms operate here.
Complex baseband	IQ representation where a signal is represented by in-phase and quadrature components.	Used for modulation, recording and analysis.
IQ	In-phase and quadrature samples.	Main data format for SDR recordings.
LO	Local oscillator. Frequency source used for mixing between RF and baseband/intermediate frequency.	Used in frequency planning.
Sample rate	Number of samples per second.	Defines frequency axis and bandwidth in DSP labs.
Bandwidth	Frequency span occupied or processed by a system.	Used in filters, SDR configuration and measurement.

DSP terms¶

Term	Meaning	Course context
FFT	Fast Fourier Transform. Efficient algorithm for spectrum estimation and frequency-domain processing.	Used in spectrum and lab plots.
PSD	Power spectral density. Signal power distribution over frequency.	Used for noise floor and spectrum analysis.
FIR	Finite impulse response filter.	Used for filtering, interpolation and decimation.
Window	Weighting function applied before FFT or FIR design.	Used to control sidelobes and leakage.
Decimation	Reducing sample rate after filtering.	Used in receiver chains and analysis.
Interpolation	Increasing sample rate, usually before filtering or transmission.	Used in transmitter chains.
DDC	Digital downconverter. Translates and filters a signal to lower frequency or baseband.	Used in RX chains.
DUC	Digital upconverter. Translates and filters a signal toward a higher sample rate or carrier offset.	Used in TX chains.
NCO	Numerically controlled oscillator. Digital oscillator used for mixing.	Used in FPGA and DSP labs.
Quantization	Mapping continuous or high-precision values to finite precision.	Used in fixed-point analysis.
Fixed-point	Numeric format with a fixed number of integer and fractional bits.	Bridge from model to HDL/FPGA.

Modulation and synchronization terms¶

Term	Meaning	Course context
AM	Amplitude modulation.	Early spectrum examples.
FM	Frequency modulation.	Early spectrum examples.
BPSK	Binary phase-shift keying. One bit is represented by one of two carrier phases.	Used in frame-sync, BER and hardware bring-up labs.
QPSK	Quadrature phase-shift keying. Two bits are represented by one of four constellation points.	Constellation, EVM and synchronization labs.
OFDM	Orthogonal frequency-division multiplexing.	Advanced mini-link and final project path.
CFO	Carrier frequency offset. Frequency mismatch between transmitter and receiver.	Synchronization labs.
Coarse CFO	Coarse carrier-frequency-offset estimation/correction. A first, wide-range correction before a fine carrier loop.	Used before Costas/PLL-style tracking in practical receivers.
Phase offset	Constant phase rotation between expected and received symbols.	Constellation correction.
Timing recovery	Estimating correct symbol sampling instants.	Receiver synchronization.
TED	Timing error detector. A block that estimates whether the receiver samples symbols too early or too late.	Gardner timing recovery and symbol-clock labs.
Preamble	Known sequence used for detection, synchronization or channel estimation.	Packet receiver labs.
Costas loop	A carrier-recovery PLL variant for suppressed-carrier modulations such as BPSK and QPSK.	Used to remove residual carrier phase/frequency error before bit decisions.
BER	Bit error rate. Ratio of incorrect bits to total received bits.	End-to-end link quality metric.
BER floor	Error-rate floor below which BER does not improve even when SNR is increased. It usually indicates a systematic issue rather than simple noise.	Used to diagnose CFO, timing error, clipping, phase ambiguity or frame-sync failure.
FER	Frame error rate. Ratio of incorrectly received frames to total received frames.	Useful when packet framing and CRC are available.
EVM	Error vector magnitude. Distance between ideal and measured constellation points.	Modulation quality metric.
SNR	Signal-to-noise ratio. Ratio between signal power and noise power.	Used in measurement and link analysis.
SNR vs BER	SNR says whether a signal is visible above noise; BER says whether the receiver recovered the correct bits.	Core acceptance rule for digital-link labs: SNR alone is not sufficient.

FPGA / HDL terms¶

Term	Meaning	Course context
HDL	Hardware description language, such as Verilog or VHDL.	FPGA implementation blocks.
RTL	Register-transfer level hardware description.	Used for Verilog modules and testbenches.
Testbench	Simulation environment that drives and checks an HDL module.	Used in Block 5.
AXI-Stream	Streaming interface commonly used in FPGA signal processing chains.	Used for DSP block integration.
Latency	Delay between input and corresponding output.	Important for streaming DSP and synchronization.
Throughput	Amount of data processed per unit time.	Used for FPGA and system-level evaluation.
Resource usage	LUT, FF, BRAM, DSP slice consumption.	Used for implementation trade-offs.

RF and measurement terms¶

Term	Meaning	Course context
Attenuator	Passive component that reduces signal power by a known amount.	Required for safe conducted RF experiments.
Digital attenuator	Electronically controlled attenuator with discrete dB steps.	Used for repeatable attenuation sweeps and BER/SNR threshold measurements.
Gain staging	Choosing gains across TX, RF path and RX to avoid overload and poor SNR.	Used in AD9363 and RTL-SDR labs.
Noise floor	Baseline noise level visible in spectrum.	Used for receiver and capture quality.
Clipping	Signal amplitude exceeding ADC or numeric range.	Indicates overload or wrong scaling.
DC offset	Unwanted constant component at zero frequency.	Common in IQ receivers.
IQ imbalance	Amplitude or phase mismatch between I and Q paths.	Advanced receiver quality metric.
Loopback	Feeding transmitter output back to receiver through a controlled path.	Used in board-level validation.
OTA	Over-the-air. Wireless path through antennas.	Use carefully and legally.
VNA	Vector network analyzer. Measures complex reflection and transmission parameters over frequency.	Used in NanoVNA labs before SDR RF loopback.
NanoVNA	Low-cost handheld VNA.	Used as a practical instrument for cable, filter, attenuator and matching checks.
DUT	Device under test.	The measured cable, filter, attenuator, antenna or RF Demo Kit element.
S11	Input reflection coefficient.	Used to check matching, return loss, VSWR and Smith-chart position.
S21	Forward transmission coefficient.	Used to measure filter response, cable loss and attenuation.
VSWR / КСВН	Voltage standing-wave ratio. A scalar indicator of mismatch derived from reflection.	Used as a quick matching metric, but should be interpreted together with frequency and Smith chart.
Smith chart	Graphical representation of complex impedance/reflection coefficient.	Used to see whether a DUT looks resistive, inductive or capacitive across frequency.
SOLT calibration	Short-Open-Load-Thru calibration.	Required before meaningful NanoVNA S11/S21 measurements.
Return loss	Reflection magnitude usually expressed in dB. Larger positive return-loss numbers mean lower reflection.	Used when judging loads, antennas and input matching.
Insertion loss	Loss through a two-port device, usually measured from S21.	Used for cables, filters and attenuators.
TDR	Time-domain reflectometry. Estimates cable length and discontinuities from reflections.	Optional NanoVNA-Saver extension for cable validation.
Touchstone	Common text file format for S-parameter data, such as `.s1p` or `.s2p`.	Used for preserving VNA measurements and comparing them with simulations.

IQ file formats¶

Format	Meaning	Notes
CI16	Complex signed 16-bit integer IQ samples, usually interleaved I,Q.	Good for efficient recordings.
CU8	Complex unsigned 8-bit integer IQ samples.	Common for RTL-SDR raw data.
CF32	Complex 32-bit floating-point IQ samples.	Convenient for analysis, larger files.
WAV IQ	IQ samples stored in a WAV container.	Useful when software exports audio-like IQ files.

Recommended translation consistency¶

English	Russian recommendation
sample rate	частота дискретизации
bandwidth	полоса
complex baseband	комплексная baseband-модель / комплексная низкочастотная модель
fixed-point	fixed-point / фиксированная точка
testbench	testbench / тестовое окружение
RF frontend	радиотракт / RF frontend
measurement report	измерительный отчёт
reproducibility	воспроизводимость
dataset manifest	manifest набора данных / dataset manifest
BER floor	нижняя граница BER / пол BER
SNR vs BER	SNR против BER / почему SNR недостаточен
VNA	векторный анализатор цепей / VNA
S11	коэффициент отражения от входа / S11
S21	коэффициент прямой передачи / S21
VSWR	КСВН / коэффициент стоячей волны по напряжению
Smith chart	диаграмма Смита
SOLT calibration	SOLT-калибровка: Short, Open, Load, Thru
TDR	рефлектометрия во временной области / TDR
insertion loss	вносимые потери
return loss	обратные потери / return loss

Style rule¶

Prefer the English acronym when it is standard in SDR literature, and explain it once in Russian text. Examples: CFO, EVM, BER, IQ, DDC, DUC, NCO, HDL, RTL, VNA, S11, S21, TDR.