https://derek.engineer/series/aperture/ Recent content in aperture on derek.engineer https://derek.engineer/og-default.png https://derek.engineer/og-default.png Hugo en-us Mon, 28 Sep 2026 00:00:00 +0000 https://derek.engineer/posts/aperture-mystery-carrier-dc-spike/ Mon, 28 Sep 2026 00:00:00 +0000 https://derek.engineer/posts/aperture-mystery-carrier-dc-spike/ A 916.381 MHz 'carrier' that looked like LoRa turned out to be the RTL-SDR's own DC spike; plus the bursts that are really there, a 2-hour hopping decode of 902-928 MHz, and what PG&E publishes about its meters. https://derek.engineer/posts/aperture-whats-on-the-air/ Sat, 26 Sep 2026 00:00:00 +0000 https://derek.engineer/posts/aperture-whats-on-the-air/ A full-spectrum sweep, a test of whether strong FM stations overload the receiver, and an AM station I chased through four attempts that turned out to be an empty channel. https://derek.engineer/posts/aperture-ships-and-aircraft/ Wed, 09 Sep 2026 00:00:00 +0000 https://derek.engineer/posts/aperture-ships-and-aircraft/ Three AIS runs and an ADS-B run from one RTL-SDR in San Francisco, cross-checked against vessel-tracking sites and ADSBdb, with dates and times so anyone can look for themselves. Updated with a second ADS-B run in late September. https://derek.engineer/posts/aperture-433mhz-weather-sensors/ Sat, 22 Aug 2026 00:00:00 +0000 https://derek.engineer/posts/aperture-433mhz-weather-sensors/ Starting with a $25 RTL-SDR: fixing an antenna-length calculation, sweeping the tuner gain, walking the 433 MHz band for eight hours, and finding that a weather sensor's transmit clock drifts with its own temperature reading.