U.S. Geological Survey Open File Report OF-93-722

Appendix A. Other Signals of Interest

The switching power regulator produces a 50 kHz, 20 mv ripple on the regulated line. The maximun expacted drop is 7 mv due to charging. The regulated power level is changed by adjusting potentiometer R7 on the right side of the microcomputer board (looking down on the top of the board).

A/D Reference Voltage
Input to CH1: 5 v reference voltage for the A/D, (pin 13 on the 32 pin connector to the Tattletale 4, pin 32 is nearest the backplane) on the microcomputer board.
Input to CH2: none
Current probe: n/a
Sweep: 100 ns/div
CH1 setting: 20 mv/div
CH2 setting: n/a
Trigger: CH1, normal
Trigger slope: positive
Trigger level: 4.79 v
Current Probe setting: n/a
Averaging or store: on
Delay: none

Expect a 20 mv ripple and 20 mv spikes 400 ns apart.

A/D Input (CH0)
Input to CH1: output from xmit/rec board for respective axes A: pins 22 or 25, B: pins 18 or 21, C: pins 14 or 17, D: pins 10 or 13
Input to CH2: A/D input signal, pin 17 of the microcomputer board
Current probe: n/a
Sweep: 200 us/div
CH1 setting: 2 v/div
CH2 setting: 50 mv/div
Trigger: CH1, normal
Trigger slope: positive
Trigger level: 2 v
Current Probe setting: n/a
Averaging or store: on
Delay: none

The two peaks are the foreward and reverse measurement for the axis, the difference between them is the final current measurement value recorded or output by the BASS system. These peaks will be very mall and hard to see for a BASS pod sitting in a bucket of still water. This image was made using the BASS delay input test set, simulating a large current velocity signal.