CTX 3030 What is under the hood?

[Chrisdw]

Hi All, I/m a newbie to metal detecting but after talking about it, reading piles of magazines and watching too many episodes of oak island my wife put a CTX 3030 under the tree.
I did build a Heatkit BFO type detector back in the 60's but it never performed and I always wanted a serious detector.
I am an Electrical Engineer working on Electrical Power Quality Meter HW.
So I am very curious as to what is under the hood of this unit.
With some web searching I read that the core is a Freescale ARM9 running Linux OS.
What else can you tell me? Has anyone scanned the pcb ICs to see what stands out?
In particular I am curious about the TX drive and Receive circuits.
I'd envision a Differential front end up into a Delta Sigma converter to keep the common mode noise out and the SNR up.
Basically I was hoping to get a feel of the performance potential of this detector and then to compare with other designs.

Yes I understand that the design is a little dated and I may have wished I waited till the Equinox came out.
That will be a fun comparison.
What sort of cores are competitive machines using?
Any with dual ARMX and DSP?

Thanks - Chris

[Skippy]

There's not many people who would describe a 3030 as 'dated', it's only been out a few years, and is still in production.... it's pretty heavy, which some would consider a dated characteristic .... like 1970's machines.
And as you have observed, it's workings rely heavily on software in a microprocessor/microcontroller. Hence it's not possible to assess its design, nor compare to other current machines, most of which also use micro's to perform some/much of the work.
DSP micro's are a feature of some current machines, one of the first being the Teknetics T2, (and a short time later its cousin the Fisher F75), in 2007.
As for the 'front-end' , no-one's bothered reverse engineering it, but its likely to share most of its features with its predecessors such as the Safari, E-Trac. There's a low-noise pre-amp in the coil, probably single-ended, DC powered, from a wire in the search-coil cable, which also powers the other gubbins like the microcontroller, accelerometer.

If you're wanting some insight into what methods the 3030 uses, take a look on Minelab's website, where there's a few technical pdf's that
go into modest detail about the 'FBS' design. The KBA 00 & 01 are the most relevant ones:
https://www.minelab.com/usa/knowledg...-base-articles

[waltr]

Does not seem dated as the CTX is Lance's 'high end' detector in the British TV series "The Detectorist".

[Chrisdw]

Sorry to ruffle any feathers with that dated comment
I just got my CTX 3030 and the maturity did not phase me.
In Metal Detecting time the overall design may seem recent but in Micro Processor evolution time it has been ~ 8+ years since the ARM9 was released.
A lot has happened in that time, in particular some nice ARMX DSP dual cores.
In defense I am still designing with TI Sitara ARM9 on new projects.
Nice low power platform to run Linux on such as found in beagle bone black/blue.

[Skippy]

I guess you don't realise that it's perfectly possible to design/manufacture an excellent metal detector without a single microprocessor. And there's plenty of machines that are largely analogue, with just a modest micro, like a mid-range MicroChip PIC, to take care of the 'human interface' ( LCD drive, reading buttons/switches, audio tone generation) and general housekeeping.
Fast cpu's aren't needed for the majority of signal processing. After demodulation (hardware or software), the raw signals have a bandwidth less than 50 Hz.

[WM6]

It is clear (after touching reality), that CTX3030 should be named EPX3030.

[Davor]

It is merely a hype cycle that marketing people in OZ do not seem to understand: ageing detectors become vintage, not garbage.

[Carl-NC]

Sorry to ruffle any feathers with that dated comment
I just got my CTX 3030 and the maturity did not phase me.
In Metal Detecting time the overall design may seem recent but in Micro Processor evolution time it has been ~ 8+ years since the ARM9 was released.
A lot has happened in that time, in particular some nice ARMX DSP dual cores.
In defense I am still designing with TI Sitara ARM9 on new projects.
Nice low power platform to run Linux on such as found in beagle bone black/blue.

Detector designs don't tend to ride the cutting edge of processors, or anything else for that matter. I've had a CTX apart and probably have pics somewhere but can't find them, and I don't recall the processor(s) used. I do know the White's V3 used an ARM9 as the main processor, plus a couple of MSP430s for auxiliary tasks. The Minelab GPZ uses a SmartFusion2 which is fairly new but still uses a Cortex M3 core. Way back when, Garrett was pretty cutting-edge in using a Blackfin DSP chip in their GTI design.

Most current detector designs use 8-bit PIC/Atmel, PIC24, MSP430, or Cortex processors. For a while I liked the dsPIC but they're power hogs. My current preference is Cortex. An M0+ has enough horsepower for a damn good detector, I used one in the new Fisher pinpointer and it doesn't even break a sweat. Another design I'm working on uses an M7 just because I can, but likely will back off to an M4 near the end.

[keith777]

CTX 3030 What is under the hood?

i stumbled across this thread today on another forum. it may be of interest to you.

Hacking the CTX. Link.... http://www.findmall.com/read.php?86,2208946,2330557

[Davor]

... An M0+ has enough horsepower for a damn good detector...

... provided you know what you are doing. Otherwise you need a shovel of those, and a big battery. And an *** to carry it all.

[Carl-NC]

i stumbled across this thread today on another forum. it may be of interest to you.

Says the CTX uses an iMX25 processor (ARM926). V3 uses a slightly older version, the iMXL (ARM920). Key elements in these designs are the need to drive a QVGA display and do multifrequency DSP. A drawback of the iMX chips is lack of on-board flash, so the firmware resides in external memory where it is quite easy to extract.

... provided you know what you are doing. Otherwise you need a shovel of those, and a big battery. And an *** to carry it all.

Most detectors are single frequency VLF with a segmented LCD. Not a whole lot to them, and many will run (and do run) on an 8-bit PIC. The M0+ will run rings around an 8-bit PIC and provided you don't get too carried away you could probably do a modest multi-frequency design with the M0+. A key is to get as much autonomy in the peripherals as possible, such as cascaded timer/PWMs and DMA. At 90uA/MHz (core) you'll be hard-pressed to find something with lower power; in my pinpointer I measured the total micro consumption to be around 4.2mA @ 3V, and I'm sure there was room to dial back the clock speed.

[Chrisdw]

Yes M4s should make a nice platform. In my work I use both the STM32L4XX series for low power and STMF4XX for higher performance Cortex M4 processors in recent projects. ST Micro provides some power saving modes that I suspect could make a difference on battery life. I've also used the MSP430 which is a low power MCU for sure. I just started to read up on MD theory and hope to understand more about the various drive and receive circuits and overall architecture. Ordered the book "Inside Metal Detecting" to get some clues. As others have pointed out it appears that the CTX core is an i.MX25X ARM9 processor from NXP/Freescale and is running 2.6 Kernel of Linux OS. The higher performance platform helping out with the wireless and GPS functions of the CTX. Perhaps the OS has evolved in the recent releases. Mostly I just want to understand what is under the hood for now. I have much to learn as a MD newbie.

[Carl-NC]

ST is my go-to processor company, they have powerful PWMs with DMA timers that my code guru Jeff is using to do autonomous on-the-fly complex timing pulses. I used the STM32L072 in the pinpointer (overkill, actually) and now using the STM32L496 in a walk-thru design. In a super-secret R&D design I'm starting with the STM32F767 simply because I want to.

George & I wrote "Inside the Metal Detector" which focuses solely on circuits & technology. Hope that's the one you meant.

[Chrisdw]

Carl - I'm using the STM32L476 now in a power protection design.
We need the low power because we power up from the current we are measuring.

I also work on electrical power quality meters where the focus is on accurately reading voltage and current off the mains.
We have to measure current over a wide range and still be accurate down low so we tend to use differential delta sigma type converters.
This helps eliminate a lot of the common mode noise.

Yes your book! Should come tomorrow so I have lots to read.
It will be interesting to see what the challenges are on MD platforms.

Chris

[bklein]

I just commented on the other thread and might as well here... how difficult does it seem to replicate the chip in the CTX coil?
Anyone yet determine what chip it is?