PORTFOLIO / SYSTEMS CASE STUDIES
These case studies focus on the engineering path: what failed, which boundaries mattered, how the system was isolated, and what made the result verifiable.
Embedded firmware / real-time audio / SIP-RTP
Building and debugging a real-time voice device across firmware, codecs, audio timing, packet transport, PBX integration and hardware behavior.
Linux / Docker / secure ingress / operations
An operations layer for a multi-service Linux environment where runtime state, health, dependencies, access and recovery need to be understood together.
Prometheus / Grafana / failure simulation
Testing whether monitoring detects real failure, including deliberately creating load and proving the complete alert path rather than trusting dashboards.
SIP signaling / RTP media / distributed debugging
Building and debugging signaling, routing, media, endpoints and infrastructure around real-time communications rather than treating the PBX as the whole system.
The four case studies above go deep. This index is intentionally broader: devices, firmware, telecom systems, infrastructure, sensing experiments, control planes and web/data tools. Derived systems are described as integrations rather than claimed as original upstream software.
Kotlin/Compose guardian app with pairing, QR scanning, device state, approved contacts, call history and the LOUP lifecycle model.
ESP device fleet service with unique device credentials, immutable firmware artifacts, compatibility gates, rollout state and authenticated operator control.
Browser infrastructure workspace built from a pinned Termix base with a custom Fimi brand layer, reproducible patch set, SSH agent integration and gateway access.
Self-hosted content operations platform for drafting, review, approval, scheduling, workspace isolation, audit history and durable AI generation workflows.
Dedicated publishing engine with scheduler, queue worker, PostgreSQL/Redis state, reproducible source pinning and restore-tested backups; external publishing remains deliberately disarmed until credentials are configured.
Custom ESP32-S3 voice device spanning codec bring-up, I2S audio, AEC, jitter/playout, SIP/RTP, e-paper UI, controls, provisioning and OTA.
A SIP registrar and PBX that runs on an ESP32-S3, with extension calling, peer-to-peer RTP, call features, web administration, optional LVGL UI and dual-OTA.
A 580K-parameter transformer trained from scratch to turn English and Spanish commands into GPIO, PWM and servo actions entirely on an ESP32-S3.
ESP32-S3 camera firmware with Wi-Fi bring-up, browser live view, MJPEG streaming and still-image capture for an OV2640-class camera board.
Central service, deployment, policy, storage and execution control plane with RBAC, audit events, read-only command views and guarded host execution.
Interactive topology and packet-path view that maps hosts, DNS, ingress, services and observed flows into drill-down network views.
Canonical L7 ingress joining Cloudflare Tunnel, Caddy, Authelia and Tailscale with per-service sessions, server-side credentials and private/public routes.
Metrics, logs, probes and alerting validated by controlled failures instead of dashboard appearance alone.
Two-tier OpenBao secret authority with Raft state, Transit auto-unseal, TLS, AppRole and a migration path away from filesystem secrets.
Encrypted backup and recovery system spanning local rsync, off-site object storage, checksums and disposable restore verification rather than backup-success alone.
Self-hosted ntfy alert path from Alertmanager to a private Tailscale HTTPS endpoint with isolated publisher/subscriber identities and no public push dependency.
Minimal capability-bounded packet capture path that parses a live tcpdump stream into bounded payload snapshots consumed by the operations UI.
Nomad-based compute path across multiple machines with deterministic build execution and fallback capacity rather than tying jobs to one workstation.
SIP/RTP infrastructure and debugging across endpoints, PBXs, routing, media, packet captures, NAT and service health.
Small end-to-end protocol implementation using custom TCP signaling, SDP offer/answer, direct RTP media and RTCP receiver reports.
SIP edge and FreeSWITCH load-balancing layer with ESL health checks, REGISTER/INVITE proxying, round-robin routing, config reload and Prometheus health surfaces.
Public RF and satellite observatory using SatNOGS, CelesTrak and NOAA data, with cache/failure isolation and bounded satellite decode tooling.
Live Khulna weather dashboard combining Himawari-9 South Asia imagery, local forecast data and a six-hour satellite animation.
First-party Flask/PostgreSQL publishing system powering the technical archive, case studies, admin workflow and public portfolio, with a parallel Tor v3 publishing path.
ESP32-S3 CSI telemetry firmware that streams channel-state data over UDP and supports persistent configuration plus signed A/B OTA through the fleet service.
ESP32 CSI collector, server-side signal processing and live dashboard for room calibration, motion and presence experiments using Wi-Fi channel-state changes.
Multi-node Reticulum setup with RNode radio interfaces, LAN TCP transport and ESP32/LR1121 experiments for resilient local messaging.
Repeatable serial/radio test workflow for E22 and EWM modules covering local configuration reads, temperature profiles, OTA initiator behavior and wired recovery tests.