AudioSpeedGun for Tennis Serve
Audio-based tennis radar gun. No extra hardware needed.
What it does
AudioSpeedGun: Smart Tennis Serve RadarMeasure your serve speed using just your smartphone! It analyzes audio to calculate the time between racket impact and wall hit.Using physics-based air resistance, it estimates both Muzzle Velocity ($V_0$) and Terminal Velocity ($V_{end}$). No expensive radar guns—just your phone.Core measurement is free. Upgrade to the paid version for data saving, history logs, and manual waveform analysis. Perfect for tracking progress during solo wall-practice!
Does the same job
all alternatives →- IMI made a free app to calibrate your turntable by simply playing a song2024 · grooved.okat.best · ▲452
Hey there! I made a little app that lets you to calibrate your turntable by putting on any record and tapping a button. It's called Grooved and it uses your phone's microphone to see how fast your platter is going, almost like magic. You can see what it looks like in action here: https://twitter.com/OKatBest/status/1795453042994680148 The app itself is free without ads, subscriptions, or trackers. It's a tool I built for myself, and I just thought someone else might want to use it too. I have never seen this technology being used before, all other apps require you to…
- RMRacketmeter – Measure Badminton String Tension Using Sound Frequency2025 · racketmeter.com · ▲44
Racketmeter lets badminton players measure string tension using the sound frequency produced when tapping the racket strings. It's 100% free, works in your browser on mobile and desktop, and requires no sign-up or installation. I built it to solve a personal problem. I started playing badminton regularly in 2016 and quickly learned that players often ask stringers to string rackets at specific tensions (like 22 or 26 lbs). But after a few stringing jobs, I began to feel like the tension was inconsistent. Other players told me they just tap the strings and go by ear where "sharper sound meant…
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Launched alongside, May 2026
the whole month →
Parallel agents, diff reviewer, and multi-model comparisons
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- NW
Hey HN, Henry here from Cactus. We open-sourced Needle, a 26M parameter function-calling (tool use) model. It runs at 6000 tok/s prefill and 1200 tok/s decode on consumer devices. We were always frustrated by the little effort made towards building agentic models that run on budget phones, so we conducted investigations that led to an observation: agentic experiences are built upon tool calling, and massive models are overkill for it. Tool calling is fundamentally retrieval-and-assembly (match query to tool name, extract argument values, emit JSON), not reasoning. Cross-attention…
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- FM
Dev tools · May 2026 · github.com