Minelab 4901 - 0059 quick start 2HOW DETECTORS WORK, Coil, Control Box, Analog Signal

2HOW DETECTORS WORK

3

Metal detectors create an electro- magnetic field, which penetrates the ground. Because metal is conductive it causes a change in this field. The

The X-Terra 70 uses a single frequency (7.5kHz) as it’s standard operating frequency. This frequency has the ability to penetrate deep into the ground and is the most

The X-Terra 70 has two basic coil configurations, each with its own benefits.

detector senses this change and sends a signal back to the control box, alerting the operator.

Metal detectors can determine the size, shape and composition of metallic objects beneath the coil. Typically, the larger the object, the easier it is

to detect.

The frequency of a detector is the number of times a signal is transmitted into the ground, per second (measured in Hertz - Hz). 1000Hz = 1kHz.

suitable for general purpose detecting.

Being the the top model in the X-Terra product range, the X-Terra 70 is capable of operating at frequencies of 3kHz and 18.75kHz, depending upon the selection of appropriate accessory coils (pg. 48, 51).

The X-Terra 70 has two main detecting modes: Coin & Treasure Mode (pg.18) for general purpose detecting and Prospecting Mode (pg. 19) for detecting gold nuggets and relics.

The specialised Prospecting Mode has improved Sensitivity and adjustable Iron Mask Discrimination. It is the ideal mode when searching for gold nuggets, small relics, and some types of jewellery.

A Concentric coil is the standard coil supplied with the X-Terra 70 and is an all purpose coil with excellent pinpointing capabilities.

Double D coils are available as accessories. They provide improved ground rejection and have a different detection profile.

The X-Terra detectors are Minelab’s first products to incorporate VFLEX Technology.

VFLEX uses state of the art digital and mixed-signal components to enhance standard single frequency technology by replacing most of the analogue circuitry with digital signal processing. The small amount of analogue circuitry still employed has been very carefully designed and calibrated to obtain the outstanding sensitivity, stability and repeatability required to match the performance of the digital processing.

This radical departure from traditional approaches to metal detector design has been made possible by advances in electronics that power personal digital assistants, cell (mobile) phones and high-fidelity portable audio equipment.

Power Audio Transmit

Supply

Analog Signal

PRIMARY MICRO

(IN CONTROL BOX)

DIGITAL SIGNAL PROCESSING (DSP)

CODEC SIGNAL CONVERSION

Keypad LCD Receive

Control Box

Transmit

SECONDARY MICRO (IN COIL)

SENSING + TRANSMITTING COIL TYPE, SIZE, FREQUENCY

Analog Signal

Receive

Coil

Standard VLF Signal	Precision VFLEX Signal
(Without VFLEX)

For the X-Terra user, this precision means dependable performance and improved immunity to environmental conditions such as ground mineralisation, electromagnetic interference and temperature variations.

VFLEX requires coils that are accurately constructed and calibrated. Every time the detector starts up, the micro-controllers in the control box and the coil establish communication through a digital data link.

Information about the coil is sent to the control box, so the detector ‘knows’ what type of coil is attached and can set the appropriate operating parameters.

This optimizes performance, and also makes the detector ‘future proof’, in that it will be capable of operating

at different frequencies depending on the electronic properties of the coil.