Confused about Shutdown/Recovery time.

[harryhh]

This question is about the CTX 3030 of course.

I believe I understand one part of Shutdown/Recovery time because the things that I have read have been consistent. But the other half has been inconsistent and confusing.

This I think is correct:
When using the detector in a mode with discrimination, and the coil passes over a rejected target, the threshold will 'blank,' and the detector will go silent. Minelab calls this Shutdown time. There is a Recovery time in which the detector will not detect a nearby target. Neither an accepted target, nor rejected target. I think this is correct. If I've got it wrong let me know.

The confusion comes with detecting accepted targets. I've read different things. Suppose, in All Metal mode, the detector detects a target. Is there an associated Shutdown/Recovery time before the detector will detect a nearby target? And, if there is a Shutdown/Recovery time, is it the same as the threshold blank Recovery time?

 

[rjfjedi]

I Have found coins inches away from "blanked out objects"

 

[Digger]

Minelab calls this Shutdown time.

I'm not familiar with Minelab's use of the term "shutdown time". I'm familiar with rejection, blanking, nulling, overload and recovery time. But I don't recall their using the words "Shutdown time". Please let me know where you found (read) that and I'll see if I can help address your question. HH Randy

 

[harryhh]

Hi Randy,

I've taken a quick look for where I saw the term Shutdown time, but don't see it again. I believe it was someone writing about threshold and saying that Minelab calls this Shutdown time. It was one of the first references I saw on this subject and have been calling it Shutdown time since.

But what I am referring to is what I have most often seen referred to by most people as null, nulling, and in the CTX manual as threshold blank. I'm pretty sure I understand about the threshold blank. But, it's what happens when the detector detects an accepted target that I am confused about? Basically, after the CTX detects an accepted target, is there a short period where it won't detect another target.

As I'm writing this, I'm thinking that there may not be a null after detecting an accepted target. I'm thinking about Target Trace. You see many detections on the screen very quickly. That makes me think that after the detection of an accepted target there is no null, or wait, before the CTX will detect another target. Or at least nothing significant in any way. I can hear how long the threshold blank is. It must be a quarter of a second or something like that. A long time and distance of a moving coil.

I may have answered my own question here Randy, that there is no significant wait between accepted targets, but it would be good if you could confirm it.

 

[Digger]

Again, I'm not familiar with the term "shutdown time", nor do I remember seeing Minelab make reference to that term. That doesn't mean someone hasn't used it. It just means I can't address what it represents unless I see how it is being used. From my perspective, regardless of how much discrimination you are using, the CTX 3030 will detect anything metal. Just because you set a specific set of FE/CO values to be rejected, doesn't mean they won't be detected. They will. They just won't produce an audio response. Instead, rejected targets will produce "a burst of silence" that will over-ride the Threshold.........Nulling.........Target Blanking. The short period of time between hearing the audio response of two adjacent targets will depend on the magnitude of the audio response. e.g. larger targets will produce a longer audio response. It is also my belief that our ears interpret nulling (lack of sound) as "taking longer" than if we were to hear two distinct target responses. We've accustomed ourselves to hearing the Threshold in the background, so hearing "no sound" is more of a continuation of "there isn't a target here", compared to the audio responses made by accepted targets.

As to Target Trace and Target Trace Pinpoint....... they are visual indicators. We are still only going to hear one target at a time. But Target Trace and Target Trace Pinpoint allow the image of the target to remain on the SmartScreen for a longer period of time. This allows our ears and eyes to work in conjunction, recognizing that we have multiple targets under the coil, simultaneously. Again, we only hear one target tone at a time. But the images of each target "lingering on the screen" allow us to recognize there is more than one target. Target Trace does this while detecting.....in an the motion mode of the CTX 3030. And Target Trace Pinpoint does it in the non-motion Pinpoint mode, allowing us to separate and isolate each target.

There may be a very short period of time that it takes for a detector to "reset" between targets. But it is most noticed by the TID visual display than anything you're likely to hear. Although the Smart Coil technology reduces this period of time, you can make it more audibly noticeable with some of the Response settings. If you have your CTX 3030 set to Normal, you will hear short bursts of tone for each target. In addition, there is a slight break between the Threshold tone and the target signal. If you are using Long, Smooth or particularly Pitch Hold, it is virtually impossible to hear any break between Threshold or target tones. JMHO HH Randy