Spare Tow Cable D-3
Use the formula
dB = 20 log (Vout /Vin)
For example, if at 15 MHz, you get a reading of 160 mv, then
dB = 20 log (0.16/1.0) = 15.9 dB loss.
D.2 Spare Tow Cable
Given the nature of high speed towing, cable problems can occur. For
troubleshooting purposes we suggest that you have on hand a lightweight Kevlar
reinforced 150-meter (minimum length) tow cable. This extra cable will allow you
to bypass your primary tow cable assembly and speed up fault isolation.
Figure D-2: Setup for Measuring Tow Cable Characteristics using a
Function Generator, Terminator and Oscilloscope
NOTE The whole cable assembly must not exceed an attenuation of greater
than 24 dB of insertion loss at 15 MHz. We suggest a working loss of 24 dB
at 15 MHz.
50 ohm terminator
Scope
Cable
Assembly
Function
Generator
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