A Decametric Long Baseline Interferometer System

A relatively simple long baseline interferometer (LBI) system, which uses analog tape recorders, is described; it operates at decametric wavelength (26.3 MHz). A base station at Boulder with an array of 76 full‐wave dipoles is used in conjunction with a small, readily portable antenna of sixteen full‐wave dipoles that can be set up at various outlying field sites by two men in less than three hours. Commercial rubidium clocks are employed for timing and for local oscillator signals at each station. Tapes are aligned and data are correlated by an analog multiplier after each run at the base station. The use of pseudo‐random code generators which can be reset and started on a given clock pulse at each station greatly simplifies tape alignment and system calibration.