MAINTENANCE
Section 17, Page 5 May 2002
External Monitoring - The ADC convert command (sample rate) can be monitored on
bus connector J1 pin A30, and EOC (end of convert) on pin A31.
Duty Cycle (Duty)
Changing this parameter allows the operator to select a duty cycle of 100% to
generate a frequency-domain waveform, or a duty cycle of 50% to generate a time-
domain waveform.
External Monitoring - The Duty Cycle can be observed on connector J3 pin 10 on the
timing card, connector J1 (DIN bus connector) pin 8, and on pin K of the transmitter
I/O connector.
NOTE: The low or ground level voltage state produced by the frequency domain duty
cycle places the transmitter in a continual "on" state. The time-domain duty cycle rate
is exactly twice that of the period waveform and produces a transmitter output
waveform as shown in Figure 17.1.
Automatic Transmitter Control (Auto Tx, used for TEM and NanoTEM)
The TEM program provides for the control of battery powered transmitters to extend
battery life. To turn the transmitter off, the Duty Cycle line is set high (OFF).
It may be necessary to change Timing Board parameters while controlling an external
lab or field transmitter in addition to doing GDP board level tests. See Figure 16.6 (a)
for timing board parameters.
Analog Board Diagnostic Fields
Analog Board fields are shown on the right-hand side of the display in Figure 17.2 (a). In the
following discussion, the default field parameters are used. Refer to Figure 17.2 (a) for details of
the analog board.
Ch 1 SN 177
The channel number and serial number displayed indicates the selected channel. The
parameters for this channel are then displayed on the screen. If a new channel is
selected using the Cursor Control Keys or entering the number from the keypad, the
screen is updated and the new parameters are displayed.
Power OFF Notch 50,3-5,9
OFF indicates the position of the individual channel power supply relay that provides
power to the board. OFF can be toggled between ON and OFF. Notch 50,3-5,9
indicates the type of powerline notch filter installed. In this case it is a
50/150/250/450 Hz powerline notch filter. Other standard options are
60/180/300/540 Hz and 50/150/60/180 Hz.
Cal IN
Indicates that the calibrate relay is IN, which connects the analog input to the
calibrate card and disconnects it from external inputs. See Figure 16.6 (a). The other
option is OUT, which connects the analog card inputs to the external inputs.
Ohm OUT
Sets the Ohm (contact resistance) relay to IN or OUT. See Figure 8.11(b).
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