Series: Reading the Receiver: Peak and Null
by Allan Williams, Training Development Manager | GeoPoint Academy
One of the first things a locator learns is how to find the strongest response over a buried conductor. But learning where the signal peaks is only part of understanding what the receiver is telling you.
Peak and Null are two different ways of looking at the same electromagnetic field.
In Peak, the signal response increases as the receiver approaches the conductor and reaches its highest point over the target in a clean signal environment.
Null behaves differently. As the receiver approaches the conductor, the response drops and reaches a minimum over the target.
At first, Peak usually feels more natural. Follow the increasing response, find the highest point, and establish the path of the conductor.
So why bother with Null?
Because Null can tell us something Peak alone may not.
In a clean signal environment, the Peak and Null positions should closely agree. When they don’t, the receiver may be giving the technician an important clue that the electromagnetic field is distorted.
That doesn’t automatically tell us what caused the distortion. Nearby conductors, signal application, grounding, frequency selection and the surrounding environment can all play a part.
It does tell us something important:
Stop and investigate before trusting the locate.
Null also has value beyond simply checking Peak. In the right conditions, its sharp response can be useful for tracing and observing changes in the signal field. Like any receiver response, however, it has to be understood in context.
This is where training matters.
A technician who has only learned to chase the strongest number or follow an arrow may still be able to trace a utility when conditions are clean. The bigger test comes when the information on the receiver stops agreeing.
A trained technician notices that.
Peak is generally the primary locating response I teach. Null is an additional source of information that helps the technician verify what Peak is showing and recognize when the signal deserves a closer look.
Different manufacturers and receiver models present Peak, Null and directional information in different ways. That becomes especially important when arrows are added to the display.
We’ll get into that next.
This series is about helping technicians better understand what their receiver is actually showing them in the field.
That understanding matters when the signal is clean, and it matters even more when something doesn’t look quite right.
The receiver gives you information. Experience and training help you decide what to do with it.
One of the first things a locator learns is how to find the strongest response over a buried conductor. But learning where the signal peaks is only part of understanding what the receiver is telling you.
Peak and Null are two different ways of looking at the same electromagnetic field.
In Peak, the signal response increases as the receiver approaches the conductor and reaches its highest point over the target in a clean signal environment.
Null behaves differently. As the receiver approaches the conductor, the response drops and reaches a minimum over the target.
At first, Peak usually feels more natural. Follow the increasing response, find the highest point, and establish the path of the conductor.
So why bother with Null?
Because Null can tell us something Peak alone may not.
In a clean signal environment, the Peak and Null positions should closely agree. When they don’t, the receiver may be giving the technician an important clue that the electromagnetic field is distorted.
That doesn’t automatically tell us what caused the distortion. Nearby conductors, signal application, grounding, frequency selection and the surrounding environment can all play a part.
It does tell us something important:
Stop and investigate before trusting the locate.
Null also has value beyond simply checking Peak. In the right conditions, its sharp response can be useful for tracing and observing changes in the signal field. Like any receiver response, however, it has to be understood in context.
This is where training matters.
A technician who has only learned to chase the strongest number or follow an arrow may still be able to trace a utility when conditions are clean. The bigger test comes when the information on the receiver stops agreeing.
A trained technician notices that.
Peak is generally the primary locating response I teach. Null is an additional source of information that helps the technician verify what Peak is showing and recognize when the signal deserves a closer look.
Different manufacturers and receiver models present Peak, Null and directional information in different ways. That becomes especially important when arrows are added to the display.
We’ll get into that next.
This series is about helping technicians better understand what their receiver is actually showing them in the field.
That understanding matters when the signal is clean, and it matters even more when something doesn’t look quite right.
The receiver gives you information. Experience and training help you decide what to do with it.