Testing The Minelab PRO-SONIC Response Time

[Chet]

On 12/29/2016 at 4:58 PM, canslawhero said:

the <50ms spec doesn't look good.....

on the Minelab site, knowledge base....I see this...

"Wi-Stream uses efficient low-power digital audio transmission to achieve no perceivable audio time lag (<10 ms) from the CTX 3030 / GPZ 7000 to the WM 10 / WM 12. With multiple channel capability, this wireless technology provides reliable communication with maximum sound quality."

notice the <10ms......

if these use different technology than "wi-stream", ie Deteknix 'like' chinese tech you'd see the poor response time...I'm really hoping this is NOT the case....I had a CTX and was amazed at how good the wireless audio was.

Can someone (who can) verify with Minelab that the pro-sonic tech IS Wi-Stream AND delay is <10ms

and not <50ms, which btw IS noticeable....and the chinese versions simply suck in use on my G2+ (it's fast)

cheers

    I couldn’t find a wireless delay specification for the GPZ 7000 WM 12.  So I tested it.  The attached oscilloscope display is the audio waveform envelopes from a US nickel passing over the GPZ-19 coil at approximately 40 inches per/sec.

    The upper yellow waveform is from the earphone jack on the back of the GPZ 7000.  The lower green waveform is from the earphone jack of the wireless WM 12 receiver.

     The waveforms are sweeping in time from the left side to the right side.  The entire display is divided into 10 horizontal increments of 50 milliseconds (0.050 sec.) each.  The audio (wah-wee sound) created by the nickel is spread across 9 divisions (450 milliseconds) with the nickel crossing the center of the coil at approximately 4.5 divisions (225 milliseconds).  Close measurement of the green trace displacement to the right indicates that the wireless WM 12 receiver audio is delayed by 20 milliseconds.

     The nickel speed of 40 inches per second is equal to 1 second divided by 40 = 0.025 sec. = 25 milliseconds to move 1 inch.  So a delay of 20 milliseconds is less than a 1 inch position error which would be imperceptible during normal searching.  When slowed down to pinpointing speed it would be a minuscule error.

     A 50 ms delay would result in an approximate 2 inch position error which at sweep speed is probably not that noticeable to most of us. Again at pinpointing speed it should not be a problem.   

      For information; the scattered positive and negative spikes are noise spikes from the GPZ 7000 transmitter pulses. The wide bandwidth / fidelity of the oscilloscope allow it to capture these spikes. The spikes are too high in frequency for the human ear to hear.  Electromagnetic Interference (EMI) that we randomly hear resembles the waveform envelopes shown in this display.
 
This is somewhat technical so I hope I have made it understandable to some.

Have a good day,
Chet

[Norvic]

Top info.

[Rege-PA]

It`s nice to have some one with the equipment and knowledge to explain this!

[fredmason]

that seems to clarify that no person would/could notice any lag in the sound-signal...

neat toy you have there!

fred

[Steve Herschbach]

Wow, that is an amazing post Chet! Thanks for taking the time and effort to test and post the information!!

[mn90403]

Steve,

That is post of the year or maybe decade.  It should have a separate thread.

Scientific proof like this is rare among 'believers and promoters' of one product vs another.

Mitchel

[Steve Herschbach]

I agree - done!

[cabelafella]

Great post Chet , Ive been looking to go wireless but I'm a little on the frugal side ,so if you have some spare time and could compare the Garrett z-link  to the  Pro Sonic wm , I will gladly buy you breakfast at Katrina's.

Greg

[canslawhero]

thanks Chet, very cool (I actually have an EE from CalPoly)....I really appreciate the time you spent on it..

now wish I could see the same analysis for their new version (and Garretts (they state 17ms delay)).

cheers

[Nevada Brian]

On ‎1‎/‎7‎/‎2017 at 11:16 PM, Chet said:

 

Hello Chet, thank you for taking the time to perform this test.  Would I be correct in saying that the nickel is giving off a high/low sound based on the oscilloscope display or is there a double signal?

Brian.