Field Guide

GopherTrunk Field Guide — the RF, SDR & software-development reference

The GopherTrunk Field Guide is a plain-language reference covering the terms, technologies, algorithms, people, hardware, organizations, and software behind radio, software-defined radio, and the craft of building software itself. Each article is a standalone, long-form definition — no lesson order, no exercises, just information — cross-linked to related entries and to the learning paths. Browse by domain and category, or jump to the A–Z index.

951 entries · A–Z index · Learning path · Glossary

Looking for a quick definition? The glossary has one-line entries. Want to learn in order? Start a learning path — RF & SDR or intro to software development. This Field Guide is the long-form, neutral reference: each article defines and explains one topic in depth, cites its sources, and links to everything related. Entries are grouped into domains — RF & SDR and Software Development — each with its own categories.

RF & SDR

Radio, signals, SDR, DSP, the protocols GopherTrunk decodes, and the people and bodies behind them.

RF & signal fundamentals

The physical quantities and units that describe radio waves and signal power.

Receiver performance & metrics

The figures of merit that quantify receiver performance and signal quality — noise, linearity, and error.

Antennas

The radiators that turn current into radio waves, and the parameters that describe how they do it.

Propagation

How radio energy travels from transmitter to receiver — the paths, losses, and impairments.

Modulation

The schemes that put information onto a carrier — analog and digital — and the terms that describe them.

SDR & DSP

Software-defined radio and the digital signal processing between IQ and bits.

Filtering & multirate DSP

The digital filters and rate-changing structures that isolate a channel and hand clean samples to the demodulator.

Synchronization, carrier & timing

The feedback loops and estimators that lock onto a signal's carrier and symbol clock.

Equalization

The adaptive filters that undo multipath and channel distortion so symbols can be sliced.

Transforms & spectral analysis

The Fourier machinery and spectral-estimation methods behind every waterfall, filter, and OFDM link.

Error-correcting codes

The forward-error-correction codes and their decoders that recover bits from a noisy channel.

Spread spectrum & multiple access

The spreading codes and multi-carrier schemes that share spectrum and resist interference.

Estimation, detection & array processing

The algorithms that track parameters, decide whether a signal is present, and locate emitters in space.

Cryptography & cryptanalysis

Ciphers, keys, and the techniques used to analyze and break them — including trunked-radio metadata obfuscation.

Trunked radio

The concepts that let many users share a pool of channels.

Land mobile & trunking

The professional and public-safety land-mobile and trunked-radio systems GopherTrunk targets.

Cellular

The mobile-phone air interfaces, from GSM to 5G NR.

Wireless data & IoT

Short-range and low-power wireless data links — Wi-Fi, Bluetooth, and the IoT/LPWAN protocols.

Satellite & GNSS

Satellite communications and the global navigation systems that ride the same spectrum.

Broadcast

Digital and analog broadcasting — radio and television.

Aviation & marine

The datalinks and navaids of aircraft and ships.

Paging & data

One-way paging and packet data links.

Amateur digital modes

The weak-signal and keyboard digital modes of amateur radio.

Voice coding

The vocoders and speech-coding algorithms that compress voice into a few kilobits per second.

SDR devices

SDR dongles, transceivers, and the tuner chips inside them.

RF front-end & components

The components between the antenna and the receiver — amplifiers, filters, mixers, connectors, and references.

Test & measurement

The instruments used to measure and characterize RF signals and hardware.

SDR software

The software that drives SDR hardware and decodes what it hears.

SDR frameworks & libraries

The toolkits, driver libraries, and DSP libraries you build SDR software on.

SDR programming & DSP engineering

The streaming-DSP programming model and the engineering concerns of real-time signal processing in software.

SDR data & streaming

How IQ samples are represented, recorded, and moved between processes and machines.

Building SDR applications

The building blocks and practices of a working SDR application — from the software receiver chain to testing without a radio.

People

Scientists and engineers whose work underpins radio and SDR.

Organizations & standards bodies

The bodies that allocate spectrum and write the standards.

Software Development

Programming languages and the concepts, paradigms, and practices of building software — the craft behind GopherTrunk itself.

Programming languages

The languages used to build software, from systems languages to scripting and the historical pioneers.

Language internals & execution

How source code becomes a running program — compilation, interpretation, memory, and types.

Concurrency & execution models

How programs do more than one thing at a time.

Paradigms & design patterns

Styles of organizing code and reusable solutions to recurring problems.

Principles & code quality

The guidelines that separate maintainable software from a mess.

Testing, tooling & delivery

Verifying that software works and getting it into users' hands.

Hardware (computers & devices)

The computing hardware a developer chooses between — from cloud servers down to the microcontroller — what each is for, what runs on it, and its trade-offs.

Hardware foundations

The parts inside every computer and the ideas that span the whole spectrum from cloud to chip.

Servers & hosting

Where software runs for other people — shared hosting, VPSes, dedicated and home servers, and the cloud behind them.

Personal computers

The machines you build software on — the desktop-vs-laptop trade and what each is for.

Mobile devices

The computers in everyone's pocket and bag, and what it takes to build software for them.

Single-board computers

A complete Linux computer on one small board — the Raspberry Pi and its rivals, and the GPIO header that touches the physical world.

Microcontrollers

The tiny, cheap, low-power chips that run the physical world — no OS, the Arduino, and the wireless ESP32.

Networking & connectivity

How computers reach each other and the internet — the cards, boxes, links, and addresses that move bytes between machines.

Storage & memory

Where bytes live — the drives, chips, and cards that hold data, and the memory hierarchy that ranks them by speed and cost.

GPUs, FPGAs & accelerators

Chips that do specialized work faster than a general CPU — graphics, AI, signal processing, and reconfigurable logic.

People

The engineers and founders who built the computing-hardware world — from the first transistors and CPUs to the boards and chips developers use today.

Organizations & makers

The companies and bodies that design and make computing hardware — chip makers, board vendors, foundries, and the standards groups behind them.

A–Z index