Stability and Self-Exchange in Alkanethiol Monolayers

A depth meter circuit which overcomes the usual necessity for manual adjustment of the sensitivity control to improve the signal-to-noise ratio and to prevent spurious meter response to wakes and debris at intermediate depths is achieved by a dynamically adjusted receiver attenuator circuit which is controlled by the combination of an automatic bottom tracking gate, a time varied sensitivity circuit and a transmission blanking circuit operating in conjunction with a meter indicating circuit which is activated only during the time of return echoes by means of a ramp voltage sampling circuit actuated only by the return echoes. The arrangement makes possible the use of maximum transmitted power for accurate measurement of deep bottoms and on the same nonlinear scale, provides accurate readings of shallow depths without manual adjustment.