© 2017 by Proceq SA
6
© 2017 by Proceq SA
7
3. System Settings
Select System Settings
Set:
- Transducer frequency
- Pulse width
- Calibration setting
- Averaging time/signal
Or scroll to next screen
Set:
- Excitation voltage
- Receiver gain
- Units (metric/imperial)
(Pundit Lab
+
only:
Compressive strength unit)
- Correction factor
Pundit Lab
+
only
Set:
Date and time
Compressive strength curve (Re-
bound value for SONREB method)
Parameter
Presets (Click on soft key to
scroll through)
Variable (Set with
navigation key; see 2.1)
Tx / Rx Frequency (kHz)
24, 37, 54, 82, 150, 200, 220, 250,
500
-
Pulse width
Automatic
1-100 µs
Calibration (See 2.1)
-
1-110 µs
Averaging
Time
Signal
Excitation voltage (V)
125, 250, 350, 500, AUTO
-
Rx Gain
Pundit Lab
Pundit Lab
+
1x, 10x, 100x, AUTO
1x, 2x, 5x, 10x, 20x, 50x, 100x,
200x, 500x, 1000x, AUTO
-
Units
Pundit Lab
Pundit Lab
+
ft / m
ft / m, MPa, N/mm2, psi, kg/cm2
-
Correction factor
-
0.07 – 1.3
Date and time (Pundit
Lab
+
)
Set time stamp.
Compressive strength
curve (Pundit Lab
+
)
Curves defined in PunditLink.
Enter a rebound value
for SONREB curves.
Automatic Gain and Voltage Setting
The excitation voltage and the receiver gain can both be set to automatic. In this mode the
Pundit Lab finds the optimum combination of the two parameters for a stable measurement.
Rx Gain 200x, 500x, 1000x
This feature is available in Pundit Lab
+
only and replaces the need for an external amplifier (325
40 059) when using long cables or exponential transducers. When such high gain stages are
selected it is highly recommended to use manual triggering with the waveform display.
Pulse Width
The pulse width is automatically set to the optimum value for the selected transducer frequency
and typically requires no adjustment. For certain applications, it may however be adjusted if
desired. (Refer to ASTM D 2845 - Standard Test Method for Laboratory Determination of Pulse
Velocities and Ultrasonic Elastic Constants of Rock.)
It also allows non-standard transducers up to 500 kHz to be used with Pundit Lab:
Pulse width “p” in microseconds (µs) to be entered here is calculated from the formula
p = 1'000/(2*f) , where f = transducer frequency in kHz
If a non standard value is set manually it is indicated
by an asterisk.
Averaging Time/Signal
A number of measurements are made and the resulting transmission times are
averaged. Time averaging provides the highest resolution of 0.1 µs.
Signal averaging provides greater stability for longer path measurements (e.g. several
metres). In this case a number of measurements are made and the waveforms are
averaged to determine the transmission time. The resolution in this mode is 0.5 µs.
Continuous/Burst Transmission
Continuous transmission continues transmitting until the “Stop” button is pressed.
Burst transmission sends out packets of pulses until a stable reading is obtained
then stops automatically.
Correction Factor
Pulse velocity measurements are affected by several factors. These are well described in BS
1881 : Part 203 and it is recommended that the user refers to this document. Two key factors
are the moisture content of the concrete and the temperature. The table below shows the
correction factor that should be keyed in based on the recommendations made in the above
standard.
Temperature
Dry concrete
Wet concrete
10°C – 30°C
1.0 (No correction)
1.0 (No correction)
60°C
1.05
1.04
40°C
1.02
1.02
0°C
0.99
0.99
-4°C
0.98
0.92
Units (Pundit Lab
+
only)
Selecting units opens a second screen where
the user may select a compressive strength unit
in addition to the imperial or metric units.
