Mike Hillis
Well-known member
The manual states:
SENSITIVITY This controls the signal gain, and is adjustable from 1 to 99. In the presence of electrical interference, high ground mineralization, or variable ground mineralization, operation will usually be too noisy (wobbly and erratic sound) if the sensitivity is set too high.
At settings above 90, the internal circuit noise of the machine will probably be audible. The sensitivity level setting is largely a matter of personal preference. However, if you cannot hear at least some noise, the smallest or deepest objects will not be detected.
The sensitivity system has two stages, 1-29 (low gain), and 30-99 (high gain). As you decrease sensitivity and cross the transition from 30 to 29, you may notice that the background noise increases. Despite this increase as you decrease sensitivity to the lower setting, 29, the sensitivity is in fact lower under 30, and the machine is less susceptible to overload from large targets, ground minerals, and saltwater. You may need to adjust to a setting of 29 or less to silence electrical interference, or to prevent overload on highly mineralized ground or in saltwater. You may also notice a shift in the ground balance setting over difficult ground conditions as you cross this transition.
What is Signal Gain?: The difference between the strength of the received signal and the strength of the signal after something has been done to increase the strength of the signal is called signal gain.
The reference to sensitivity setting of 1 to 29 as "low gain", and settings from "30 to 99" as high gain are making references to how much amplification is taking place on the received signal. It has a direct affect as to how much 'ground' noise you hear. As your FE304 bars increase, it is also likely that your ground noise will increase. When your ground noise becomes too much for you to properly identify deep. faint target responses, a drop into low gain sensitivity territory may be in order. This can also work in area's with lots of tiny ferrous responses. The main affect is less amplification of the ground signal.
Both Gain ranges have a basic level of signal amplification. That is why a low sensitivity setting, say 0, still supplies more depth potential than you might be accustomed to on other detectors at minimal settings. The same holds true with the higher settings. You will see less linear progression of the gain responses on the F75 due to these two types of amplification methods.
The key to their use is understanding what they do, and how and when to use them. Remember, the idea is to be able to clearly identify a metal response from both air and ground responses. Sensitivity settings within a "gain range" are for mitigating air (EMI) responses. Sensitivity settings between a "gain range" are for mitigating ground noise responses.
HH
Mike
SENSITIVITY This controls the signal gain, and is adjustable from 1 to 99. In the presence of electrical interference, high ground mineralization, or variable ground mineralization, operation will usually be too noisy (wobbly and erratic sound) if the sensitivity is set too high.
At settings above 90, the internal circuit noise of the machine will probably be audible. The sensitivity level setting is largely a matter of personal preference. However, if you cannot hear at least some noise, the smallest or deepest objects will not be detected.
The sensitivity system has two stages, 1-29 (low gain), and 30-99 (high gain). As you decrease sensitivity and cross the transition from 30 to 29, you may notice that the background noise increases. Despite this increase as you decrease sensitivity to the lower setting, 29, the sensitivity is in fact lower under 30, and the machine is less susceptible to overload from large targets, ground minerals, and saltwater. You may need to adjust to a setting of 29 or less to silence electrical interference, or to prevent overload on highly mineralized ground or in saltwater. You may also notice a shift in the ground balance setting over difficult ground conditions as you cross this transition.
What is Signal Gain?: The difference between the strength of the received signal and the strength of the signal after something has been done to increase the strength of the signal is called signal gain.
The reference to sensitivity setting of 1 to 29 as "low gain", and settings from "30 to 99" as high gain are making references to how much amplification is taking place on the received signal. It has a direct affect as to how much 'ground' noise you hear. As your FE304 bars increase, it is also likely that your ground noise will increase. When your ground noise becomes too much for you to properly identify deep. faint target responses, a drop into low gain sensitivity territory may be in order. This can also work in area's with lots of tiny ferrous responses. The main affect is less amplification of the ground signal.
Both Gain ranges have a basic level of signal amplification. That is why a low sensitivity setting, say 0, still supplies more depth potential than you might be accustomed to on other detectors at minimal settings. The same holds true with the higher settings. You will see less linear progression of the gain responses on the F75 due to these two types of amplification methods.
The key to their use is understanding what they do, and how and when to use them. Remember, the idea is to be able to clearly identify a metal response from both air and ground responses. Sensitivity settings within a "gain range" are for mitigating air (EMI) responses. Sensitivity settings between a "gain range" are for mitigating ground noise responses.
HH
Mike
