Active Interference Versus Passive Interference: What’s the Difference?

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When we talk about passive interference and active interference, what we are referring to are magnetic fields. Magnetic fields matter a great deal as it relates to how well tools work if you’re in the midst of a project. Some tracking and locating tools from Digitrak and other companies work well regardless of interference that is being created by the environment around them, while others are severely impacted. To understand more about why that is, it’s important to know about the difference between the passive form of magnetic interference and the active version.

Active Interference

Active interference is caused by a magnetic field that is generated by a source other than the beacon corresponding to it. That could mean a diesel generator nearby, phone lines, traffic loops, cable TV signals, power lines, or something else of this nature. The equipment being used may respond badly to active interference because it will distort the signals coming from the beacon or the other tracking and locating tools in the network. To solve this problem, you must figure out the best frequencies to use where this form of interference will not be an issue.

Passive Interference

Things like large metal objects most often cause passive interference that generates a magnetic field. Likely culprits are fences, culverts, vehicles, pipe, rebar, buried utility vaults, etc. If you are using locating and tracking tools in places where these sorts of things are present, it may present a bit of a challenge. In most cases, the solution is going to be to use lower frequencies. If you are using tools that come with a beacon, you can also increase its power level to overcome this form of resistance, though this will lower battery life.

It Is Difficult to Avoid All Forms of Resistance

In essence, then, active resistance is what comes from objects that are actively working to create magnetic fields. Passive resistance is from objects that are sitting there but because their composition is interfering with the tools you are trying to use. What you have to understand, though, is that there are going to be very few worksites, unless they are extremely remote locations, where you won’t be dealing with some degree of both active and passive magnetic interference. It’s out there in the world, but if the tracking and locating tools you are using are powerful enough, you should still be able to use them effectively.

If you’re going to be doing something that requires a great deal of precision, like drilling, for instance, and you’re using tracking and locating tools, exercise caution. You don’t want to allow any form of magnetic interference, whether active or passive, to cause you to misread any signals the instruments are giving you. Make sure that the crew who you are using are trained in the use of these tools, and that they also know all about the different forms of interference and how to account for them. If they make a mistake, property damage, explosions, electrocution, blindness, or burns could be the results.