GPF Bubble Level vs Ham Engineering

GPF Bubble Level is a minimal, high-contrast spirit level app for iPhone, built around real-time accelerometer data. It uses Core Motion to read device gravity and translates movement into a smooth on-screen bubble inside a circular level grid. The interface is intentionally clean: black background, white elements, Menlo typography, and a compact layout designed for quick visual alignment in everyday use. Key features: - Real-time level detection using accelerometer/device motion - Smooth bubble movement with light filtering for stability - Tilt angle readout in degrees - Live X/Y gravity values for reference - Dedicated Info screen with app icon, title, and version/build footer - Custom monochrome app icon (white on black) consistent with the app style Design goals: - Fast glanceability - No clutter - Strong visual contrast for indoor/outdoor visibility - Coherent monochrome identity across UI and iconography Technical notes: - SwiftUI-based UI - CoreMotion integration via observable motion manager - Motion privacy usage description configured - Build/version shown directly from bundle metadata This app is ideal for quick leveling checks on surfaces, shelves, frames, and small DIY tasks, with a focused UX that prioritizes readability and responsiveness.

Ham Engineering is the engineering bench for amateur radio — antenna and feedline maths, circuit design, propagation and a deep reference library, all completely offline. No account, no ads, no tracking, and not a single network call. ANTENNAS • Half-wave dipole with adjustable k (velocity) factor, quarter-wave and 5/8-wave verticals, ground-plane radials, end-fed half-wave, random wire, full-wave loop and a 3-element Yagi estimator • Matching: L-network, Pi-network, quarter-wave transformer, balun/unun ratios and stub matching • Antenna Lab — a live elevation radiation-pattern plot with directivity, realized gain, takeoff angle, beamwidth, front-to-back, mismatch loss, feedline loss and system gain, each explained • Grid Compass that rotates with your phone, showing beam bearing and distance from your grid to a target grid • Antenna gallery — every common type drawn as scalable vector art, with what it is, what it is for and what to watch out for FEEDLINES & RF • Coax loss by cable type, frequency and run length; velocity-factor electrical length • SWR from forward/reflected power, plus return loss and mismatch loss • Antenna A/B comparison and receiver noise-floor estimation • RF power conversions: dBm, watts, ERP and EIRP • Propagation: free-space path loss, radio horizon and Fresnel-zone clearance • NanoVNA and tinySA quick-start guides, and a coax + connector gallery CIRCUITS • Ohm's law, series/parallel resistance, voltage dividers, RC and RL time constants • Reactance, LC resonance, Q and bandwidth, stored energy • RC and LC filter cutoffs, a constant-k Pi/T filter designer, a bandpass/notch calculator and a Butterworth low-pass designer • Resistor, capacitor and inductor code decoders, an AWG wire table and a 555 timer calculator • A live RLC resonance lab and a 50-part component gallery REFERENCE & EXTRA • Filterable amateur band plan for ITU Regions 1, 2 and 3 • Unit converters including watts, dBm and microvolts • Comparison tables for coax, connectors, antennas and batteries • Tools-and-gear and rig-controls galleries — what every knob and button is called across manufacturers • Maidenhead grid tools and great-circle beam headings • 300+ searchable tips, 40+ formulas, a rich glossary and a constants reference • Curated external links to major retailers, brands and references BUILT FOR THE BENCH • Nearly 200 illustrations drawn as scalable vector art — nothing to download, everything sharp at any size • Works fully offline. The app makes no network calls at all • Export any panel or diagram as a theme-aware image to share or file • An (i) explanation on every panel — this is a tool and a guide, not a quiz • Light and dark themes, adjustable font size, weekly tips and in-app version history • Your callsign, grid and email stay on your device and are never transmitted PERFECT FOR • Licensed operators designing, building and tuning antennas • Anyone putting up a first dipole or vertical and wanting the numbers right • Homebrewers and kit builders working with filters, matching and components • SWLs and newcomers who want the reference material without the exam drill • Club elmers and anyone teaching antenna and RF fundamentals PRIVACY • Your callsign, grid and email are stored only on your device. • No account, no sign-up, no ads, no analytics SDKs, no advertising ID and no tracking of any kind. 73 de A41UX Yousuf AL Balushi — Unixeer, Oman