Teledyne 440, System Manual, Page: 121 / 256

6 – Operating Procedure
DPN 402196 Issue 4.1 © Teledyne TSS 6- 17
It is important that you should possess a full understanding of the information presented on this screen
so that you may interpret its displayed information correctly.
Signal Strength
The two information boxes in the bottom left and right-hand corners of the Run Display screen show
the signal strength received from each of the search-coils. Digital information appears in the left-hand
box, while vertical bar graphs show the same information in the right-hand panel.
Once you have completed the background compensation correctly, both panels should indicate a value
of zero ±5µV when there is no target near the coils. This can be verified by using the Background
Noise Profile facility allowing for a permanent log to be made of spurious signals in the area. This data
can also be replayed to assist survey/ post survey analysis.
As the ROV moves towards the target, the signal strength measured by one of the outer search-coils
will increase. Signals on the other coils will then increase in strength until all three search-coils return a
signal.
As the signal strength from each channel increases and the signal differences exceed the threshold
setting, the red bars will change to yellow and the ‘Target Out of Range’ warning will be switched off.
The logarithmic scale used for the vertical bar graphs reacts clearly to weak signals while
simultaneously displaying strong signals. An experienced operator will be able to detect the presence
of a target and guide the ROV towards it using this graphical display, even when there is no target
visible on the main region of the Run Display screen.
Target Track
The main region of the Run Display screen shows the track of the target relative to the centre of the coil
array. This clear and simple graphical display style helps you to manoeuvre the ROV over and along
the target.
On the bottom region of the screen, a thick line represents the track of the target relative to the centre-
line of the coil array. The top of this line moves from side to side and scrolls downward to create a
‘waterfall’ display showing the relative position of the target over the previous 200 updates.The colour
of the target line changes according to the nature of the received signal:
Light grey Good signals supplied by the coils. The target is covered.
Dark grey Good signals supplied by the coils. The target is exposed.
If the System receives no altitude information, a good target signal will always appears
as a light grey line.
Blue The quality control flag is set. The display will not show VRT, COV or LAT
measurements in these circumstances. This could be for any of the following reasons:
❐ The System is receiving signals from one coil only.
❐ The lateral offset is greater than ±0.9m. See section 6.4.1.1 "External Logging
Format" on page 6-23 for more information on quality control.
If you have connected an altimeter to the System, the SDC determines the state of target burial by
performing the simple calculation:
COV = VRT – ALT
A positive value for COV indicates that the target is covered.