I sent them an email and this is the answer. It includes my questions with the answers. Also they included "a short document" re: the 12 ferrous question.
So... here it is. ( I will post the "document" in a follow up post)
Hi Julien,
Thanks for purchasing the E-Trac, and I'm happy to hear you are enjoying it.
I have copied and pasted your questions below so that my answers are easier to follow.
Q: What is the order of the signal processing in the ET? Particularly the sensitivity and the gain?
A: Sensitivity comes first. The Volume Gain simply amplifies the audio response of weak detections. By having a high Volume Gain will not
detect a signal that is being missed due to a Sensitivity that is too low. Basically the Volume Gain is set depending on how much of a
difference the user wants between weak and strong detections, and will rarely require adjustment.
The Sensitivity setting is the most critical, and may need constant adjustment, depending on the ground and environmental
conditions. When these are variable, Auto is better, as it will adjust for you as required (explained further in your last question)
Q: Which adjustment combination will be more likely to lose a deep target? Lowering the sensitivity or lowering the gain?
A: Lowering the Gain will make a medium stregth signal sound quieter. A target that is on the edge of it's detection depth, can be
lost if the sensitivity is reduced too much.
Q: In other words will a higher gain do no good if a lower sensitivity has already filtered out a signal?
A: Exactly right, but "filtered" is not the right word. The Sensitivity adjusts the detection threshold (not to be confused with audio threshold).
So if the Sensitivity is too low (high detection threshold), then a faint response is just ignored by the detector.
Q: What about the order of other filtering?
A: Depends on what other filtering you are talking about, but most other information is patented.
Q: Many people would love to understand the thinking behind the grouping of targets into the ferrous 12 area. Personally, I have no problem with it but I wonder what the thinking was behind the ferrous remapping on the ET? Was the change in the ferrous mapping done to help reduce falsing on iron, to help to unmask good targets in iron, or what? Or... is it a secert. Just curious.
A: I have attached a short document, which explains how and why the Smartfind screen was changed on the E-trac. It is pretty self explanatory, but if you need any clarification, let me know.
Q: What are the three sensitivity channels? Are they three frequencies?
A: They are not frequencies. As described in the Instruction Manual (page 54), the E-Trac has three dedicated sensitivity channels for small, medium, and large signals. These channels are essentially seperate hardware circuits. During operation, when the Auto sensitivity mode is selected, the E-Trac algorithms calculate the "optimal" sensitivity value that guarantees optimal detection of all three signal types. This "optimal" sensitivity is presented to you as the "Suggested Sensitivity". By default, the value of the Suggested Sensitivity will ensure stable operation. The user has a choice to make the Suggested Sensitivity more "aggressive" by selecting +1, +2, or +3 options.
Manual Sensitivity on the other hand, sets detection thresholds for all three target channels to your chosen value and is locked.
Q: I notice a definate loss of targets in Auto. I usually run manual 25 or higher. I get some falsing but I am learning to decipher it. Many times I will switch to auto when I get a target. The shallow ones are still there, the deeper ones are not.
A: Yes Auto is designed to err on the side of caution, giving you a stable detector with consistent ID's. You can run it more cautious, or slightly hotter using the offset control. However, Auto can have its advantages. For example, assume that after you power up E-Trac determines the optimal Auto Sensitivity (suggested value) to be 25. Now lets consider two scenarios.
1. If ground conditions change and you start detecting in "difficult" grounds, E-Trac may reduce its Auto Sensitivity, say, to 22. Which means that if you use Auto Sensitivity mode, E-Trac may increase its detection threshold to ignore false signals.
2. If ground conditions "improve", E-Trac may increase its Auto Sensitivity, say to 28. In this case, if you had selected Manual sensitivity 25, you would have been running at less than optimal performance.
For the above two examples, Auto sensitivity provides an advantage in retaining stable operation when going over "difficult" ground and increased depth when going over "mild' ground.
In most scenarios, as you've discovered, you can achieve better depth by slightly pushing the manual sensitivity. Be very careful though, as pushing it too high can cause targets to be masked particularly in high trash concentrations. In these instances, a lower sensitivity can in fact provide a cleaner signal to the detector, improving the discrimination accuracy. I guess the key thing here is that if you want to run in Manual, keep a close eye on the Suggested scale.
Hope this information is of use.
Kind regards,
Nenad Lonic
CUSTOMER & TECHNICAL
SUPPORT OFFICER
Minelab Electronics Pty Ltd
118 Hayward Avenue
Torrensville, SA 5031
So... here it is. ( I will post the "document" in a follow up post)
Hi Julien,
Thanks for purchasing the E-Trac, and I'm happy to hear you are enjoying it.
I have copied and pasted your questions below so that my answers are easier to follow.
Q: What is the order of the signal processing in the ET? Particularly the sensitivity and the gain?
A: Sensitivity comes first. The Volume Gain simply amplifies the audio response of weak detections. By having a high Volume Gain will not
detect a signal that is being missed due to a Sensitivity that is too low. Basically the Volume Gain is set depending on how much of a
difference the user wants between weak and strong detections, and will rarely require adjustment.
The Sensitivity setting is the most critical, and may need constant adjustment, depending on the ground and environmental
conditions. When these are variable, Auto is better, as it will adjust for you as required (explained further in your last question)
Q: Which adjustment combination will be more likely to lose a deep target? Lowering the sensitivity or lowering the gain?
A: Lowering the Gain will make a medium stregth signal sound quieter. A target that is on the edge of it's detection depth, can be
lost if the sensitivity is reduced too much.
Q: In other words will a higher gain do no good if a lower sensitivity has already filtered out a signal?
A: Exactly right, but "filtered" is not the right word. The Sensitivity adjusts the detection threshold (not to be confused with audio threshold).
So if the Sensitivity is too low (high detection threshold), then a faint response is just ignored by the detector.
Q: What about the order of other filtering?
A: Depends on what other filtering you are talking about, but most other information is patented.
Q: Many people would love to understand the thinking behind the grouping of targets into the ferrous 12 area. Personally, I have no problem with it but I wonder what the thinking was behind the ferrous remapping on the ET? Was the change in the ferrous mapping done to help reduce falsing on iron, to help to unmask good targets in iron, or what? Or... is it a secert. Just curious.
A: I have attached a short document, which explains how and why the Smartfind screen was changed on the E-trac. It is pretty self explanatory, but if you need any clarification, let me know.
Q: What are the three sensitivity channels? Are they three frequencies?
A: They are not frequencies. As described in the Instruction Manual (page 54), the E-Trac has three dedicated sensitivity channels for small, medium, and large signals. These channels are essentially seperate hardware circuits. During operation, when the Auto sensitivity mode is selected, the E-Trac algorithms calculate the "optimal" sensitivity value that guarantees optimal detection of all three signal types. This "optimal" sensitivity is presented to you as the "Suggested Sensitivity". By default, the value of the Suggested Sensitivity will ensure stable operation. The user has a choice to make the Suggested Sensitivity more "aggressive" by selecting +1, +2, or +3 options.
Manual Sensitivity on the other hand, sets detection thresholds for all three target channels to your chosen value and is locked.
Q: I notice a definate loss of targets in Auto. I usually run manual 25 or higher. I get some falsing but I am learning to decipher it. Many times I will switch to auto when I get a target. The shallow ones are still there, the deeper ones are not.
A: Yes Auto is designed to err on the side of caution, giving you a stable detector with consistent ID's. You can run it more cautious, or slightly hotter using the offset control. However, Auto can have its advantages. For example, assume that after you power up E-Trac determines the optimal Auto Sensitivity (suggested value) to be 25. Now lets consider two scenarios.
1. If ground conditions change and you start detecting in "difficult" grounds, E-Trac may reduce its Auto Sensitivity, say, to 22. Which means that if you use Auto Sensitivity mode, E-Trac may increase its detection threshold to ignore false signals.
2. If ground conditions "improve", E-Trac may increase its Auto Sensitivity, say to 28. In this case, if you had selected Manual sensitivity 25, you would have been running at less than optimal performance.
For the above two examples, Auto sensitivity provides an advantage in retaining stable operation when going over "difficult" ground and increased depth when going over "mild' ground.
In most scenarios, as you've discovered, you can achieve better depth by slightly pushing the manual sensitivity. Be very careful though, as pushing it too high can cause targets to be masked particularly in high trash concentrations. In these instances, a lower sensitivity can in fact provide a cleaner signal to the detector, improving the discrimination accuracy. I guess the key thing here is that if you want to run in Manual, keep a close eye on the Suggested scale.
Hope this information is of use.
Kind regards,
Nenad Lonic
CUSTOMER & TECHNICAL
SUPPORT OFFICER
Minelab Electronics Pty Ltd
118 Hayward Avenue
Torrensville, SA 5031
Did he say when they will come out with an Ex-Trac?