SignalWatch: Real Signal Test

The "4G" indicator on your phone reports radio signal strength. It does not report whether anything is actually loading. On a train, in a car, on a bus, those two things come apart constantly: four bars and nothing moves, or one bar and video plays fine. SignalWatch measures the second thing. Press Start once and put the phone in your pocket. You get a notification the moment the connection becomes good enough for what you're waiting for — and another the moment it dies. "Connection is back — 6.2 Mbps. YouTube 1080p, video calls, everything works." "No data is getting through. LTE is showing, but nothing is loading." WHAT IT ACTUALLY MEASURES Every check asks three independent services — Cloudflare, Google and Apple's own connectivity endpoints — whether they answer. If two of the three stay silent, the connection is dead, whatever the radio claims. That is the whole point: it is the case the signal bars can never tell you about. When something does answer, SignalWatch times a real download and measures round-trip delay and its variation. A LEVEL, NOT A NUMBER Speed alone tells you nothing. A cell edge gives you 3 Mbps at 900 ms: video buffers happily, a call is unusable. So every level requires both speed and latency: • Messages & email • Voice calls & voice notes • Web & social feeds • TikTok, YouTube 360p • YouTube 720p, video calls • YouTube 1080p You pick which one you're waiting for. Notifications fire on crossing that level and nothing else. IT DOESN'T SHOUT On a train the signal changes every thirty seconds. SignalWatch only tells you the connection is back after it holds for two checks in a row, only calls it dead after three, and never repeats itself inside five minutes. IT WATCHES YOUR DATA Checking whether anything is reachable costs about 2 KB. Measuring actual speed downloads 256 KB, at most once every two minutes, and never at all on a dead connection. Intervals stretch out when nothing is changing. A four-hour journey comes to roughly 40 MB, and there is a hard limit per session you can set. If you'd rather spend almost nothing, Frugal mode skips the speed measurement entirely. If you're on an unlimited plan and want a live speedometer, Continuous mode measures constantly instead. WHILE YOU'RE LOOKING, AND WHILE YOU'RE NOT On the Lock Screen and in the Dynamic Island: the current level, the speed, elapsed time. On the Home Screen: a widget with the same. Afterwards: charts of speed and latency, a list of what happened ("Connection lost for 6 minutes"), and a map of your route coloured by what worked where. Export any session as CSV. IT REMEMBERS WHERE IT FAILED Every journey adds to one map. Where the connection keeps dying, SignalWatch remembers — and on a route you've travelled before, it warns you a couple of minutes ahead: "Dead zone in about 2 min. Send anything that needs sending now." NOTHING LEAVES YOUR PHONE No account. No server. No analytics. Measurements, locations and history are stored on the device and deleted automatically after 30 days. The only network traffic SignalWatch creates is the probes themselves. WHY IT ASKS FOR BACKGROUND LOCATION Because iOS only lets an app keep running in the background if it is receiving location updates — and because SignalWatch uses where you are. Every measurement is pinned to the map, and warning you before a dead zone means knowing which way you are heading towards it. Accuracy is set to about a kilometre — enough to know you're moving, far too coarse to follow you, and much easier on the battery. If you say no, SignalWatch still works, but only while it's on screen — and it tells you that on the main screen instead of pretending otherwise. HONEST LIMITS iOS can still suspend the app; no app can promise otherwise. Notifications arrive at the next scheduled check after the connection returns, not at the exact instant. Lock Screen indicators end after eight hours, which is an iOS limit. Measuring costs real data.