spurious noises when batteries low

[eljay]

Have others found that when the batteries are getting low (but still showing 1/2 full on the screen), they get intermittent "Morse code" type interference? And the pinpointing function goes haywire?

 

[Digger]

I've not noticed any change in performance when the batteries are still 50%. Even less, for that matter. I use to think that having fresh batteries would increase the performance of the detector. But after understanding how the X-Terra is designed, I am confident that the "bottom half" will work just as well as the "top half". It is just a matter of having sufficient current flow to operate the electronics. Are you sure what you are hearing isn't some sort of interference? Next time it happens, try switching to a different Noise Cancel channel and see if it clears up. JMHO HH Randy

 

[khouse]

I used to change the batteries when they were half gone. But I now run them until the machine shuts down from the batteries being at the lowest. I don't notice any loss of depth or erratic operations when the batteries are less than 50%. This is on a XT-70

 

[Cliff KS]

This is kind of what I've been experiencing that I inquired about in my "Threshold Question" post. The threshold was stuttering a little -- kind of like morse code, but my battery level is OK. I thought it was interference so I tried the noice cancel procedure, but it didn't really make any difference. However ---- I did the noise cancel with my coil held close to the ground. I now remember some post that said noice cancel should be done with the coil held at waist height. Is that correct? Should I be holding my coil at waist height when I do the noise canceling?

 

[Digger]

Hold the coil up in the air, away from any targets. Waist high is fine. And hold it in the flat (horizontal) position, as you do when sweeping the ground. JMHO HH Randy

 

[Thumper III]

Maybe off the mark, but do you or anyone nearby (20-30 ft) have a cellphone turned on? Cell phone does not have to be in use - just turned on. Cell phones emit a "Here-I-Am" signal at least every few minutes anytime turned on. I can't turn my cell on if it's in the same room with my desktop computer or at work computer without the intermittent buzzy/beep sounds coming out of the speakers of the computer. Sounds like code when you have poor shortwave reception on a radio. And the computer doesn't have to be in active use, just on standby. The sensitivity of a metal detector that is searching for faint signals has to be much higher than a computer that's supposed to be shielded. Cell phones can even be tracked by the emissions they make in response to a network tower "Who-is-in-my-range" query signal when the phone is turned-off -- as long as the battery is installed. Even 'receive only' remote phone "beepers" emit the "Here-I-Am" signals.
The capability of the signal rejection circuitry of your detector may require a few hundredths of a volt higher minimum threshold voltage or may drop off performance at a faster rate than the detection circuirty performance when battery voltage is reduced by partial discharge. Just a thought.

Thumper III