Description of conversion of an EGG VMCM into a MVMS (multi-variable moored sensor)

摘要

A standard EG&G VMCM (vector measuring current meter) has been modified to acquire data from external sensors. The external sensors are mounted on a compact backpack which attaches to the VMCM's cage. Some simple changes to the VMCM's A/D (analog/digital) board opened up eight analog voltage channels. Changes to the VMCM's firmware were made to allow control over the period of time between toggling external power on and the A/D sampling cycle. Some sensors with low power consumption were powered continuously and their signals passed through a low-pass filter to match time constants and minimize aliasing. Sixteen VMCMs were modified and three deployments of these MVMSs (multivariable moored sensors) were made in 1987 with durations of three to four months.