VLF vs PI SHOOTOUT PROJECT

[moodz]

Roll your own VLF detector based on AD5933 chip vs cutting edge PI detector shootout challenge project for 2013.
More to follow soon.

[Aziz]

Yieeeepieeeee!, I like shootout projects.
I'm looking forward to it.
Aziz

[WM6]

Roll your own VLF detector based on AD5933 chip vs cutting edge PI detector shootout challenge project for 2013.
More to follow soon.

"We" are ready to patent
whatever you invent.

[Davor]

My new PLL driven balanced oscillator seem as a perfect candidate for the job.

[medj]

My new PLL driven balanced oscillator seem as a perfect candidate for the job.

We're here to help

[Altra]

I'm already on the AD5933. It's a fantastic little chip. I like
how you can calculate the phase and magitude from the Re and Im
for each frequency. I wish the adc was 24bit, nothing a preamp
won't fix

My application idea for this chip is similar to the Geophex GEM-2.
It scans a number of frequencies and then plots a composit based
on resistivity and phase. More info here
http://www.geophex.com/Publications/...uly-August.pdf

[Davor]

We're here to help

In what capacity?

[Ferric Toes]

Roll your own VLF detector based on AD5933 chip vs cutting edge PI detector shootout challenge project for 2013.
More to follow soon.

Could be like a shootout between an axe and a sledgehammer. Different tools for different jobs.

Eric.

[bklein]

Searching on this chip reveals an app note from AD for a speaker analyser:
http://www.analog.com/static/importe...7846AN_843.pdf
and also someone suggesting it for a power supply characterization tool. Would it be applicable for a coil characterization tool or would we need higher test frequency than this supports?
Diligent has a I2C board for $30 with this chip BTW.

[Altra]

Hi Bklein,
I have been experimenting with this chip. The DDS will only go up to 100khz. So probably not much

use for a P.I. coil analyser. For VLF it would make an excellent coil analyser. Connected to a PC it would

make a great automated production and QC tester. Programmed to test multible frequencies. Then compare phase

and magnitude readings against stored benchmark values.

I have designed a single frequency metal detector with this chip and will present the details soon.

It has been tested on a bread board and now finishing the pcb
.
The challange will be to make a broadband multi-frequency detector.

[moodz]

Hi Bklein,
I have been experimenting with this chip. The DDS will only go up to 100khz. So probably not much

use for a P.I. coil analyser. For VLF it would make an excellent coil analyser. Connected to a PC it would

make a great automated production and QC tester. Programmed to test multible frequencies. Then compare phase

and magnitude readings against stored benchmark values.

I have designed a single frequency metal detector with this chip and will present the details soon.

It has been tested on a bread board and now finishing the pcb
.
The challange will be to make a broadband multi-frequency detector.

maybe not such a big challenge ....read the data sheet for the chip very carefully ... it has an inbuilt programmable step freq sweep function so you just read in the data for each sweep and the multifrequency analysis is done.

[ODM]

And for expanding the frequency range of that IC, up/downconversion could be used - though at that point it's about the same hassle to go with a quadrature DDS and synchronous I/Q demodulation for the same effect.

[Altra]

maybe not such a big challenge ....read the data sheet for the chip very carefully ... it has an inbuilt programmable step freq sweep function so you just read in the data for each sweep and the multifrequency analysis is done.

Hi Moodz,

I am well aware of the sweep function. The challenge is to have TX and Rx stages with a flat response across sweep range.

Regards

[Carl-NC]

The challenge is to build a coil with a flat response.

[Davor]

Coils do have flat voltage response, and targets response directly proportional to the voltage. Also Rx coil is a voltage pickup, so all in all you have flat frequency response, provided you apply voltage source at Tx and high impedance preamp input at Rx. Resonance at Tx can serve as a partial energy conserving approach, but with voltage source applied across a tank the resonance is of little consequence to coil di/dt, because it is exactly the same as the applied voltage.

And for expanding the frequency range of that IC, up/downconversion could be used - though at that point it's about the same hassle to go with a quadrature DDS and synchronous I/Q demodulation for the same effect.

Or you simply generate 4x frequency and set the phases precisely by 2 flipflops connected in ring.