
WorkHorse H-ADCP Operation Manual
May
2015
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
Page 211
Converting ADC Channels
The ADC channels in the H-ADCP are defined as follows:
Channel
Signal
0
Transmit current
1
Transmit voltage
2
Ambient Temperature
3
Pressure High (+)
4
Pressure Low (-)
5
Attitude Temperature
6
Attitude Mux (X & Y tilts)
7
Contamination Sensor
Note that while each H-ADCP ADC channel is 16-bits, and the full 16-bit values are used for most
internal calculations (except for IXmt and VXmt), the raw counts that get output in the PD0 data
are truncated to just the upper 8-bits. It is not possible to get the exact value from the ADC
outputs.
XMT Voltage and Current Channels:
The H-ADCP uses a frequency-indexed table to set the scale factors for the Transmit voltage and Transmit
current ADC channels:
Transmit voltage
Transmit current
Frequency (kHz)
2092719
43838
76.8
592157
11451
153.6
592157
11451
307.2
380667
11451
614.4
253765
11451
1228.8
253765
11451
2457.6
The transmit voltage and current values are calculated for the built-in-test by multiplying the ADC upper
8-bit value by the scale factor (they are very rough values). However, the transmit voltage and current
measurements are not necessarily accurate, since the sampling is not synchronized to the phasing of the
inputs. The voltage and current tables are scaled by 1000000.
Examples (for a 600 kHz H-ADCP):
Transmit Voltage:
(90 counts * 380667) / 1000000
34.26 Volts
Transmit Current:
(103 counts * 11451) / 1000000
1.795 Amps
Temperature Channels:
The temperature values are produced by plugging the 16-bit raw ADC count value into a second-order
polynomial whose coefficients are hard-coded, plus an additional offset that is set via the &K command:
Temperature = ((a3*x + a2)*x + a1)*x + a0