The ornithodolite: An instrument for collecting large samples of bird speed measurements

An instrument is described in which a rangefinder is mounted on an alt-azimuth mount, and readings of azimuth, elevation and range are obtained by means of digital photoelectric angular encoders. The readings are passed as eight-bit numbers to a miciocomputer, which logs them together with the time. A series of timed position observations (or ‘run’), is acquired and then recorded on cassette tape together with details of the species, its behaviour, and the wind. The tape is later read back into the computer, and the data are printed out. The instrument is battery powered, fully portable, and requires only one operator.