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RF Front End, Part 12: The SDR Pool & USB Hotplug Watchdog
How GopherTrunk manages a fleet of opened dongles behind one pool — assigning control, voice, and wideband roles, running a USB watchdog that re-enumerates every 30 seconds to catch hotplug, and reacquiring a device after the kernel hands it a new bus address. Plus the re-open race that taught us to serialize retune behind stream teardown.
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RF Front End, Part 11: HackRF One — Signed 8-Bit IQ End to End
The HackRF One driver end to end — the simplest IQ format of the three, signed 8-bit interleaved I,Q scaled to complex64; enumeration across One/Jawbreaker/Rad1o PIDs; and the open-time board-ID readback that fixed empty probe gains by establishing identity and the gain ladder before streaming.
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RF Front End, Part 10: Airspy R2/Mini & HF+ — Real Samples to Complex Baseband
How GopherTrunk turns the Airspy R2/Mini's bare real ADC stream into complex baseband entirely on the host — a leaky DC blocker, a multiplier-free Fs/4 mix, and a stateful half-band Hilbert pair — then folds in the Airspy HF+, whose native int16 IQ needs none of it.
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RF Front End, Part 9: RTL-SDR III — IQ Streaming & the GC-Churn Bug
Sustained IQ streaming from the RTL2832U in pure Go — 32 async USB buffers, a deep consumer channel, and a bit-identical U8-to-complex64 lookup table. Plus the headline bug: per-chunk allocations whose GC churn shed a quarter of the control channel's live IQ, and the zero-allocation reuse ring that fixed it.
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RF Front End, Part 8: RTL-SDR II — The R82xx Tuner & the Blog V4 Deafness
GopherTrunk's pure-Go R820T/R828D tuner driver — PLL tuning, a shadow-register cache that makes read-modify-write free, and tuner auto-detection. Plus the headline bug: why the RTL-SDR Blog V4 came up deaf and mistuned by 1.8×, and how a manual override plus per-band input switching fixed it.
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RF Front End, Part 7: RTL-SDR I — Bringing Up the RTL2832U
How GopherTrunk brings up the RTL2832U demodulator in pure Go — the order-sensitive init sequence captured verbatim from librtlsdr, the I2C bridge to the tuner, GPIO and bias-tee, and the USB register transport underneath it all.
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RF Front End, Part 6: USB on macOS & Windows
How GopherTrunk reaches the same Transport contract through macOS IOKit (via purego, with OS-thread-pinned reader goroutines) and Windows WinUSB (with overlapped I/O), and why macOS forced us to own the calling thread.
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RF Front End, Part 5: USB on Linux — USBDEVFS & Async URBs
How GopherTrunk's Linux USB backend hand-rolls USBDEVFS ioctl encoding, submits a ring of async URBs, and reaps them in a single goroutine for sustained IQ throughput — all in pure Go behind a safe Transport API.
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RF Front End, Part 4: Talking to USB Without libusb
How GopherTrunk speaks to RTL-SDR hardware over raw kernel USB interfaces instead of linking libusb, and the single Transport contract that lets one driver run on three wildly different OS USB stacks.
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Rebuilding GopherTrunk from Source: Update to the Latest Version with Git and GitHub
A copy-paste guide to rebuilding GopherTrunk from source with the Git CLI and GitHub — clone the repo, check out the latest version or a specific branch, build the pure-Go binary, verify it, and keep an existing clone up to date.
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RF Front End, Part 3: The Driver Registry & Enumeration
How GopherTrunk's self-registering driver registry keeps the core hardware-agnostic — drivers register at init(), the binary's import set chooses the hardware, and EnumerateAll walks every backend to list attached dongles while staying resilient when one driver fails.
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RF Front End, Part 2: The Device Contract
A method-by-method tour of GopherTrunk's Device interface — the one abstraction four very different radios hide behind — and the optional, type-asserted extension interfaces that expose RTL-SDR-only quirks without polluting the universal contract.
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RF Front End, Part 1: Why Drive Radios in Pure Go?
The opening post of RF Front End, a 14-part deep dive into GopherTrunk's RF source layer — the pure-Go USB drivers that turn RTL-SDR, Airspy, and HackRF hardware into IQ samples without libusb, librtlsdr, or any C dependency.
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SDR in Pure Go, Part 14: APIs, Testing & the Pure-Go Story
How GopherTrunk exposes the engine through gRPC, REST, WebSocket and a TUI, observes it with Prometheus and SQLite, and proves it works with synthesized-IQ integration tests — a ports-and-adapters finale.
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SDR in Pure Go, Part 13: Recording, Composition & Streaming
How GopherTrunk records calls to WAV, drives a per-call demodulation chain with the composer, and streams audio to Broadcastify and RdioScanner — all from optional, config-driven subsystems.
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SDR in Pure Go, Part 12: Voice Coding — IMBE, AMBE+2 & MBE
How GopherTrunk turns digital voice frames into audio with pure-Go IMBE and AMBE+2 vocoders sharing one MBE synthesis core, all behind a pluggable Vocoder registry.
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SDR in Pure Go, Part 11: The Trunking Engine & Event Bus
How GopherTrunk's trunking engine turns channel grants into recorded calls, and how an in-process pub/sub event bus decouples the core from the API, storage, and streaming subsystems.
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SDR in Pure Go, Part 10: Protocol Decoders as State Machines
How GopherTrunk decodes P25, DMR, NXDN, TETRA and a dozen more trunking protocols in pure Go — each a stateful receiver behind a uniform Grant contract, an adapter pattern that keeps the engine protocol-agnostic.
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SDR in Pure Go, Part 9: Framing & Forward Error Correction
How GopherTrunk recovers clean data from noisy symbols using pure-Go forward error correction — Golay, BCH, Hamming, Reed-Solomon, BPTC, trellis, and Viterbi — built as deterministic, table-driven codecs.
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SDR in Pure Go, Part 8: Equalization, Diversity & the FFT
How GopherTrunk fights simulcast distortion with adaptive equalizers, combines multiple receivers with diversity, and drives the live waterfall with a rate-limited FFT — all in pure Go.
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SDR in Pure Go, Part 7: Symbol Timing & Sync Recovery
How GopherTrunk recovers the symbol clock from oversampled signals with a Mueller-Muller timing loop and finds frame boundaries with a sync correlator — feedback state machines implemented in pure Go.
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SDR in Pure Go, Part 6: Demodulation — FM, C4FM, GFSK & More
How GopherTrunk turns baseband IQ into symbols with pure-Go demodulators for FM, C4FM, GFSK, FFSK, and π/4-DQPSK — each a focused, single-responsibility type composed from DSP primitives.
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SDR in Pure Go, Part 5: Tuning & Channelization — DDC vs. Polyphase
How GopherTrunk extracts many narrowband channels from one wideband SDR capture using a digital down-converter or a polyphase channelizer, selected at runtime through a Go Strategy interface.
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SDR in Pure Go, Part 4: DSP Foundations — Filters, NCO & AGC
The building blocks of GopherTrunk's signal chain in Go — FIR/CIC filters, a numerically-controlled oscillator, automatic gain control, and resamplers — and the zero-allocation streaming design behind them.
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SDR in Pure Go, Part 3: The SDR Pool & Streaming Concurrency
How GopherTrunk streams IQ samples through Go channels and goroutines, manages a fleet of SDR dongles with a device pool, and fans one stream to many consumers without blocking the decode path.
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SDR in Pure Go, Part 2: SDR Devices & the Driver Registry
How GopherTrunk talks to RTL-SDR, HackRF, and Airspy hardware in pure Go behind one Device interface, and how a self-registering driver registry keeps the core hardware-agnostic.
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SDR in Pure Go, Part 1: What Is Software-Defined Radio?
A pure-Go tour of software-defined radio — what SDR is, the GopherTrunk signal pipeline from RF to audio, and the layered architecture behind a single static binary.