Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
Distance to Fault
On Nov 2, 11:22*pm, ashwanthh
wrote: Hi all, For my project, I want to perform Distance to fault measurement in the cable connecting the antenna. The principle is that a signal should be sent to the cable and using the forward and reflected voltage VSWR should be calculated and should be viewed in a spectrum analyzer. My question is 1. *What transducer is used to detect the transmitted/reflected signals from the cable? 2. Should the transducer be connected in series or parallel? Anyone, Please help -- ashwanthh Forward and reverse power are normally resolved using a "directional coupler." Such a coupler can also be thought of as a bridge circuit. Directional couplers can be built in various ways. For example, the free-ware RFSim99 program, under tools--component--coupler shows five different ways to build a directional coupler. That program doesn't show the Wheatstone bridge form of directional coupler, but those are also common, especially where a wide range of frequencies is to be covered. Wheatstone bridges are generally used with equal (e.g. 50 ohm) arms in test and measurement equipment that runs low RF power (because such a bridge must dissipate most of the RF power fed to it), and with very unequal arms when high power is to be handled (resulting in a low coupling factor; -40dB is common). Please note that directional couplers must be designed for the impedance line they are used with (and ideally, the calibration should be verified). In your project to locate faults, you may wish to consider not only the ratio of forward and reverse power (e.g., SWR), but also the phase relationship between the two. The rate of change of phase as frequency is changed should tell you how far away a single fault is; multiple faults are more complicated. Cheers, Tom |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Bushes Fault | Shortwave | |||
Help with TS711 fault | General | |||
FT 480R fault - 147.000 MHz on TX | Homebrew | |||
RA17 Fault-Help Please | Shortwave | |||
RA17-FAULT, Help please | Boatanchors |