Converting Adc Channels - Teledyne WORKHORSE Operation Manual

WorkHorse H-ADCP Operation Manual

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
2092719 43838
592157 11451
592157 11451
380667 11451
253765 11451
253765 11451
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:
Frequency (kHz)
76.8
153.6
307.2
614.4
1228.8
2457.6
Temperature = offset + ((a3*x + a2)*x + a1)*x + a0
EAR-Controlled Technology Subject to Restrictions Contained on the Cover Page.
May 2015
Page 211