Instruction In Order

[Mark-VA]

With all the discussions about the Equinox and the multi-frequency features. Many down right arguments about what is or is not transmitted. I'd like to be instructed as to how many frequencies are actually being transmitted. I circled each of the frequency peaks I captured from my Equinox 800.
The criteria that proves a frequency is transmitted or not.

[Skippy]

Mark, why have you started another pointless thread on the subject, when there are already two perfectly good ones in existence?

And if you don't understand what you're seeing on your Virtual Analyser screen, just ask , or read the user guide ( I assume there is one ..?)

Do you even know what 'frequency' is ? It has nothing to do with those heavily-rounded-off features that you have drawn circles around.
The bottom 'window' shows the frequency components.
The top 'window' attempts to show the actual waveform, albeit severely low-pass filtered. The 'Equinox Challenge' thread shows what it's supposed to look like if you read through it ... specifically Qiaozhi's Spice model, or my re-creation, showing one whole cycle of about 385 microseconds length:
.

[Mark-VA]

Thanks for the reply.
If the waveform was not important Carl would not have mentioned it so many times.


Ugh, the sample rate is just awful. Here is what you should see:

EqBeachPark.png

Top trace is Beach-MF and bottom trace is Park MF. Here is Prospecting-MF:

EqProsp.png

Note the 40kHz is slightly modulated at 5kHz.
Here is single-freq @ 5kHz:

Eq5kHz.png

The tau of the coil really starts to show up here. If Minelab bumped this up to 7.8kHz as some people claim, it was probably to improve battery life.

[Skippy]

He's 'complaining' about your sample rate because it's extremely poor at showing what the transmitted coil voltage/current/magnetic field ( take your pick) really looks like. However, you are (just) sampling at a rate that's higher than twice the maximum frequency that we are interested in. Maximum Nox frequency of relevance is 40kHz, you/Nino are sampling at 96000 samples/second, or greater. So provided you take enough samples ( eg. many thousand ) to do your frequency analysis maths on, you should get a faithful result produced.
And this seems to be the case, your spectrum results look good, your sampled waveform is awful. The main flaw in your spectrum result is the amplitude levels it shows. The '39kHz' should be stronger. It's lower because of the sound-card being designed for hifi/audio purposes , not laboratory instrumentation.

[Mark-VA]

thanks, I'll experiment with the different sample/second settings tonight
thanks for the added information.

[Skippy]

There's little point experimenting further with the settings, it's a PC sound card, that's all. You're lucky it can do what it does, maybe it's a 'HD' card ? many soundcards flat out ignore any frequency above 24kHz, as it's beyond audible, and also not reproducible with the highest 'standard' sample rate of 48k samples/sec ( DVD standard).
You need sample rates of 1 Megasamples/sec minimum to see the details of the Multi-Freq waveform, combined with a signal bandwidth of 500 kHz. And even then it will have some small flaws visible.

[ivconic]

There's little point experimenting further with the settings, it's a PC sound card, that's all. You're lucky it can do what it does, maybe it's a 'HD' card ? many soundcards flat out ignore any frequency above 24kHz, as it's beyond audible, and also not reproducible with the highest 'standard' sample rate of 48k samples/sec ( DVD standard).
You need sample rates of 1 Megasamples/sec minimum to see the details of the Multi-Freq waveform, combined with a signal bandwidth of 500 kHz. And even then it will have some small flaws visible.

That's quite discouraging! I was about to pick one digital 2 channel oscilloscope to buy soon. From lower price range (300 euros).
Although i don't intend to examine any ML products with it, not my final goal at all.
By your opinion (obviously you manage this problematic much more better than me); what man can expect from something like this one: https://www.siglent.eu/sds1052dl-50mhz.html

[EL NINO]

Skippy .... Thank you for explaining the problem ... ... actually, we can be glad to have such a simple equipping something quite well-orientationally measured .. If we want to be more ... we need better instruments-oscilloscopes-it will be another step for me...Meanwhile, I checked ....for practical tests and verification of certain theories similar to Liapor-Ceramic Mineralized Substrate-Test Box as colleague WM6 ..

[Skippy]

Ivconic:
I personally have no experience of Siglent products, but they do get good reviews in general, and the specification is certainly good enough for all 'hobbyist' level lab work.

[ivconic]

Ivconic:
I personally have no experience of Siglent products, but they do get good reviews in general, and the specification is certainly good enough for all 'hobbyist' level lab work.

Thanks!
I thought so.
I don't do complicated things anyway.
I just want to be able to catch and stabilize common type of signals when playing with various metal detector attempts.
PC USB oscilloscope that i have now is pretty alright... except for one thing; tiny signals just above the threshold (PC&USB hardware hum) are tough to stabilize and sometimes i feel desperate.
Cheers!

[green]

That's quite discouraging! I was about to pick one digital 2 channel oscilloscope to buy soon. From lower price range (300 euros).
Although i don't intend to examine any ML products with it, not my final goal at all.
By your opinion (obviously you manage this problematic much more better than me); what man can expect from something like this one: https://www.siglent.eu/sds1052dl-50mhz.html

I've been using a RIGOL 1052E. Looks like they might be the same scope. Works for what I've wanted to do.

[ivconic]

[nickel_n]

look at this
https://www.youtube.com/watch?v=LnhXfVYWYXE
turns your RIGOL 1052E 50mhz scope to 1102E 100mhz

[ivconic]

look at this
https://www.youtube.com/watch?v=LnhXfVYWYXE
turns your RIGOL 1052E 50mhz scope to 1102E 100mhz

Crazy!
Rigol dudes are indeed lazy!
Thanks God for that!

[EL NINO]

..I ordered the 4-channel Rigol DS1054Z... i also have possibility upgrade options to 100mhz...