Choosing, mounting and tuning a single-point laser rangefinder as a UAV altimeter: range, wavelength, update rate, interface and ArduPilot / PX4 setup

A practical guide to picking, mounting and tuning a single-point laser rangefinder as a UAV altimeter for terrain following, precision landing, obstacle avoidance and survey AGL hold. Covers why a range figure needs a target and conditions, 905 nm versus 1535 nm, update rate and latency, beam divergence, UART / I2C / CAN interfaces, mounting rules, ArduPilot and PX4 parameter starting points, a table of modules reaching at least 100 m with weight, interface and public price, and a first-flight checklist. Source repository: ErdiTech/drone-altimeter-laser-rangefinder-guide. Vendor values come from the open module database. Disclosure: published by ERDI TECH LTD (Chengdu, China), a manufacturer of laser rangefinder modules (erdilrf.com). Rows and sections about ERDI products are drawn from ERDI's own public product pages; every other manufacturer's values are copied from that manufacturer's public page with its source URL and capture date.