User's Manual

Noggin 13-Survey & Map Mode
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interpret. Moving too slowly may result in over-sampling the data. This stretches the data image
making it more difficult to interpret. As well, maintaining a relatively uniform speed is important for
minimizing image distortion.
13.2.8.3 Determining Noggin Settings for a Desired Ground Speed
The time delay (13.3.2.2: p.98) and number of stacks (13.3.1.5: p.96) should be set to values that,
when combined with speed the Noggin is moving at, provide an appropriate station interval
(13.3.3.3: p.103).
Increasing the number of Stacks has the effect of slowing down the data collection speed of the
Noggin system. Decreasing the number of Stacks has the effect of speeding up the data
collection speed.
This may take a little experimenting to determine the optimal values for stacks, time delay and
the actual speed the Noggin is moving at.
To determine the towing speed to collect data, at approximately the desired station interval (13.3.3.3:
p.103), do the following calculation:
1) Set the Depth (13.3.1.1: p.94).
2) Set the Trigger Method to Free Run and the Trace Delay to zero (0.0) seconds (13.3.2.2:
p.98).
3) Set the number of Stacks to 32 (13.3.1.5: p.96).
4) Without moving the system, using a stopwatch, time the system to collect and save data in
Line Mode (13.1.1: p.75) for 120 seconds (2 minutes) and pause the data collection.
5) Record the number of traces that were collected in the 120 second time period. This will be
visible on the bottom of the data collection screen beside “Trace #”.
6) Divide the number of traces by the time in seconds to calculate the number of trace per
second (trcs/sec) that were recorded.
7) To calculate the towing speed necessary to collect traces at approximately the desired station
interval, perform the following calculation:
For kilometers/hour: trcs/sec * station Interval(m) * 3.6
For meters/sec: trcs/sec * station Interval
For miles/hour: trcs/sec * station interval(ft) * 0.68
For feet/sec: trc/sec * station interval (ft)
8) If the calculated towing speed is too fast, increase the number of stacks in Step 4 and repeat
the calculation.I f the calculated towing speed is too slow, decrease the number of stacks in
Step 4 and repeat the calculation.
9) Create a speed chart by doing this calculation at different numbers of stacks and different
time windows/depths.