crtdrops ยท Noteshttps://crtdrops.mx/notas/Technical notes with measured dataenThe lab's ofrenda: what didn't survive Octoberhttps://crtdrops.mx/notas/the-lab-ofrenda.htmlhttps://crtdrops.mx/notas/the-lab-ofrenda.htmlFri, 30 Oct 2026 09:00:00 -0600Six of the lab's departed in October 2026, and a Raspberry Pi that came back from a power outage. Each with its certificate: date, technical cause of death, what it leaves us, and its calaverita.Ghosts in the frame: my 2001 robot-vision tricks against two local vision modelshttps://crtdrops.mx/notas/ghosts-in-the-frame.htmlhttps://crtdrops.mx/notas/ghosts-in-the-frame.htmlWed, 28 Oct 2026 09:00:00 -0600A disk in haunted frames with analog TV's echo, noise and bars. The 2001 eye, in C, against Qwen2.5-VL 3B and Gemma 3 4B on an N100: 0.1 px in 37.5 ms against 1.3 px in 146 s where Qwen gave a box, and Gemma answered the center.The bytes that are not yourshttps://crtdrops.mx/notas/the-bytes-that-are-not-yours.htmlhttps://crtdrops.mx/notas/the-bytes-that-are-not-yours.htmlFri, 23 Oct 2026 09:00:00 -0600A 60-byte report can cost 209 or 4,653 bytes on the network, depending on how the device connects. Where a fleet's data goes, why shrinking the report barely helps and what does change the math.Night shift: a local Gemma writes my 7 a.m. lab report, and I measured where it makes things uphttps://crtdrops.mx/notas/night-shift.htmlhttps://crtdrops.mx/notas/night-shift.htmlSat, 24 Oct 2026 09:00:00 -0600An N100 and a Raspberry Pi 5 watch each other overnight; fixed rules detect and Gemma 3 4B, offline, writes. With injected faults, detection got all of them; the model invented on a quiet night and explained against the evidence.The query that took too longhttps://crtdrops.mx/notas/the-query-that-took-too-long.htmlhttps://crtdrops.mx/notas/the-query-that-took-too-long.htmlSun, 18 Oct 2026 09:00:00 -0600An eight-million-row table, a 504 and a plan that estimated few rows and did a lot of work. How it was read with EXPLAIN and EXPLAIN ANALYZE, what an index on operation and date changed, and what was not measured.An open socket is not a connected devicehttps://crtdrops.mx/notas/an-open-socket-is-not-a-connected-device.htmlhttps://crtdrops.mx/notas/an-open-socket-is-not-a-connected-device.htmlSat, 17 Oct 2026 09:00:00 -0600A TCP connection can die without the server knowing. How long each mechanism takes to find out, what happens to a command written to a dead socket, and the reconnection after a restart.Four versions of the same top-uphttps://crtdrops.mx/notas/four-versions-of-the-same-top-up.htmlhttps://crtdrops.mx/notas/four-versions-of-the-same-top-up.htmlSat, 17 Oct 2026 09:00:00 -0600What was requested, delivered, recorded and charged have to be the same operation. What reconciling costs without a shared identifier, and why a match does not authorize moving money.The average that never happenedhttps://crtdrops.mx/notas/the-average-that-never-happened.htmlhttps://crtdrops.mx/notas/the-average-that-never-happened.htmlSat, 17 Oct 2026 09:00:00 -0600Together, the 25,898 inferences of a Raspberry Pi 5 average 347 ms, and none took that long. Why latency should be asked for per condition, in percentiles and without discarding timeouts.The right position at the wrong timehttps://crtdrops.mx/notas/the-right-position-at-the-wrong-time.htmlhttps://crtdrops.mx/notas/the-right-position-at-the-wrong-time.htmlSat, 17 Oct 2026 09:00:00 -0600A device gets its signal back and sends its history while it keeps sending the present. If the platform cannot tell them apart, a correct position leads to a wrong decision.The geofence computed on the flyhttps://crtdrops.mx/notas/the-geofence-on-the-fly.htmlhttps://crtdrops.mx/notas/the-geofence-on-the-fly.htmlThu, 15 Oct 2026 09:00:00 -0600Positions that jump, arrive late or never arrive: geofences fail because of that, not the geometry. And computed on the fly, changing a value rewrites the history.The throttling your system does not show youhttps://crtdrops.mx/notas/the-throttling-you-do-not-see.htmlhttps://crtdrops.mx/notas/the-throttling-you-do-not-see.htmlWed, 07 Oct 2026 09:00:00 -0600Seventy minutes of YOLO26n non-stop on a Raspberry Pi 5 and an N100. The Pi throttles after ten minutes, and Linux keeps reporting 2,400 MHz.The top-up nobody knows went throughhttps://crtdrops.mx/notas/the-top-up-nobody-knows.htmlhttps://crtdrops.mx/notas/the-top-up-nobody-knows.htmlMon, 05 Oct 2026 09:00:00 -0600The carrier does not answer and the system has already debited. With money, a timeout is not an error: it is a third state, and it has to be designed.The parked truck that kept racking up kilometershttps://crtdrops.mx/notas/the-parked-truck.htmlhttps://crtdrops.mx/notas/the-parked-truck.htmlSun, 04 Oct 2026 09:00:00 -0600A GPS at rest jumps around, and adding up points never gave the distance. The filter everyone adds cleans up the dashboard, but hides real movement.The ten-year battery that would not make fivehttps://crtdrops.mx/notas/the-ten-year-battery.htmlhttps://crtdrops.mx/notas/the-ten-year-battery.htmlSun, 04 Oct 2026 09:00:00 -0600A water meter designed for ten years on a 19 Ah cell. The spreadsheet said fourteen; measured in the lab, the GPRS version would not make five.On the N100, OpenVINO was not faster. And I almost measured it wronghttps://crtdrops.mx/notas/openvino-was-not-faster.htmlhttps://crtdrops.mx/notas/openvino-was-not-faster.htmlSat, 03 Oct 2026 09:00:00 -0600I measured ONNX Runtime against OpenVINO on an Intel N100. With precision pinned to f32, OpenVINO was slower. Earlier, in a rehearsal, it had dropped to FP16 on its own, and validation did not notice.Why your telemetry platform loses frames and nobody noticeshttps://crtdrops.mx/notas/a-read-is-not-a-frame.htmlhttps://crtdrops.mx/notas/a-read-is-not-a-frame.htmlFri, 02 Oct 2026 09:00:00 -0600Almost every backend receiving devices over TCP assumes each socket read brings exactly one frame. It is false by definition of the transport.