TETRA End to End is a 14-part deep dive into the GopherTrunk TETRA stack — the whole path from a raw 25 kHz π/4-DQPSK carrier to clear voice in a WAV file. Where Protocol Decoders gave TETRA one survey episode, this series walks every layer at full depth: bursts and the slot grid, RCPC channel coding and the CRC that isn’t an LFSR, scrambling and colour codes, the traffic channel, a clean-room ACELP vocoder conformed bit-identical against the ETSI reference codec, the soft-decision and equalizer upgrades that roughly doubled marginal-signal yield, and the three-part Direct Mode (DMO) saga — including the “encrypted” verdict that turned out to be a descramble bug.

It is also a series about verification discipline. The recurring villain is the self-consistent synthetic test — the round-trip that validates its own bug — and the recurring hero is the reporter’s capture. Where Weak-Signal Engineering owns the cross-protocol theory of equalizers, soft decisions and diversity, this series is its flagship case study, protocol by protocol layer.

Every post reads three ways: a TL;DR + cheat-sheet for skimmers, bold headers, tables, and diagrams for the medium read, and full prose with real code for the deep read.

New here? Start with the Digital Trunking module for how a trunked system is laid out, then come back for the TETRA specifics.<p class="post-list__empty">No posts in this series yet — check back soon.</p><p class="blog-feed-link"> See all deep dives or subscribe via RSS. </p>