Chirp Detectors?

[Flipperfla]

Has any Company or Engineers researched chirp technology with metal detectors? Instead of specific frequencies the machine would do a “sweep” of frequencies through a specific range. This technology is popular with marine sonar. I assume this would require a coil designed for multiple frequencies to be matched for impedance issues or could be “tuned” by the machine like a HF Ham radio would have a tuner for matching different bands (frequencies) with the antenna, or the coil could be designed with a frequency range instead of a specific one.

 

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[Carl-NC]

The idea has been bounced around. For general hunting it would not provide any real benefit and would probably have poor depth. Once you detect a target, it might be possible to hover the coil over the target and initiate a chirp-based analysis. But even this would not be substantially better than a 2 or 3 discrete frequency detector. In any case, the coil design is not difficult.

 

[Flipperfla]

The idea has been bounced around. For general hunting it would not provide any real benefit and would probably have poor depth. Once you detect a target, it might be possible to hover the coil over the target and initiate a chirp-based analysis. But even this would not be substantially better than a 2 or 3 discrete frequency detector. In any case, the coil design is not difficult.

Thanks for the reply. Never considered depth with frequency, which frequencies go deeper high or low? How does the shape of the wave effect depth? Sine, square, triangular, modified sine? What is the normal output range of detectors? Thanks again!

 

[Carl-NC]

Single freq detectors are almost universally sine waves. Multi-freq detectors are almost universally square-wave driven. You could chirp-drive either with sine or square. Detectors normally rely on repetitive responses from a target as the coil is swept over to build up a stronger signal for better depth. A chirp system would still result in multiple responses but those responses would vary with the frequency due to phase shifting, resulting in an overall weaker build-up. It's not a matter of whether high or low frequency goes deeper, it's a matter of not hitting the target with a consistent frequency.

 

[Flipperfla]

Single freq detectors are almost universally sine waves. Multi-freq detectors are almost universally square-wave driven. You could chirp-drive either with sine or square. Detectors normally rely on repetitive responses from a target as the coil is swept over to build up a stronger signal for better depth. A chirp system would still result in multiple responses but those responses would vary with the frequency due to phase shifting, resulting in an overall weaker build-up. It's not a matter of whether high or low frequency goes deeper, it's a matter of not hitting the target with a consistent frequency.

Got it. Thanks again! You are THE Man!