Frequency detector circuit help required.

[jainu11]

Thanks for your reply

 

[JimB]

Never mind about fractal antennas, a long piece of wire or a multi-turn loop is a good start.

But, just saying "detect RF at various frequencies from 8kHz to 175kHz" does not really convey what you are trying to do.

What is generating the RF?
How much power is being radiated?
How far away is it?

A bit more information would help.

JimB

 

[dougy83]

I am a student at Wayne Kerr State University, developing a project to detect RF at various frequencies from 8kHz to 175kHz.

So you want to select a single frequency from within that range?

I need to identify the single frequencies.

Or do you want a spectral plot?

Can any one suggest me a circuit that picks up 175kHz frequency?

You can use a simple LC to remove all frequencies that you don't want. Then a simple amplifier to allow you to see the one you do want on an oscilloscope (or do something else with it).

 

[Nigel Goodwin]

As JimB said, you're far too vague - but it sounds like a spectrum analyser is what you're looking for?.

 

[jainu11]

Thanks for your reply

 

[jainu11]

Thanks for your reply

 

[JimB]

Removed duplicate post.

There is some weird science going on here this morning!

 

[JimB]

In a PM*, Jainu11 wrote:

Hey Jim,

I am Jainu, student at Wayne State University, designing an under-graduate class project which picks up signals from different pace - maker circuits and identify the frequency. I have found a similar paper: https://www.secure-medicine.org/icd-study/icd-study.pdf and using it as a reference. However, since I do not know much about the internal circuitry of the pace - maker, I am having tough time displaying the signal on the oscilloscope. If you could help me with a circuit that can be used to display 175Khz frequency picked up from that device at a distance of 15cm, using a pcb circuit.. it would be great.

Thanks for your help
-- Jainu

In the paper in the link, they state that they used a ferrite rod antenna from an AM radio, this can be clearly seen in the photo.

My initial thoughts were that a coil of wire would be a good solution.
Make the coil 3 inches diameter with 50 turns of 28 gauge wire.

I also thought that it would be a good idea to add a parallel capacitor to resonate the coil at 175khz, and thus increase to output voltage.
However, reading the paper, it appears that the signal from the pacemaker is two frequency FSK, centred on 175khz.
The two frequencies being 150 and 200khz.
To get a reasonable response from a single tuned coil under such conditions would result in such a low Q that the improvement would not be worthwhile.

Also, the paper tells us that it is necessary to trigger the pacemaker using a magnet before it will transmit data, otherwise, nothing.

JimB


*It is a good idea to keep information and correspondance within the forum, it increases your chances of a meaningfull reply.

Note that this is the second attempt at typing this, on the first attempt ETO threw a fit and declared a database error, losing my words in the process!