Author Topic: RF lab set up ...  (Read 2236 times)

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Offline NateDuong

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RF lab set up ...
« on: July 04, 2015, 04:34:09 am »
Dear everyone...

I am trying to set up a RF lab at home to help me do DSP projects with very low frequency, as low as possible.

Anyone who has experiences about RF lab, please give me some ideals and what machines from basic to advance will be needed for the lab?

Thank you,

Nate Duong.
 

Offline mazurov

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Re: RF lab set up ...
« Reply #1 on: July 04, 2015, 04:40:22 am »
You meant 'high' frequency, not 'low', correct? You can detect RF with a diode, it will be very cheap. The oscilloscope/probes need to be rated for 10x the frequency of interest if you want to see well in time domain.
 

Offline NateDuong

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Re: RF lab set up ...
« Reply #2 on: July 04, 2015, 05:36:50 am »

I meant "low" frequency such as heart beat...so there is no way to measure it?
 

Offline T3sl4co1l

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Re: RF lab set up ...
« Reply #3 on: July 04, 2015, 05:40:31 am »
"RF" broadly means electromagnetic radiation, at frequencies able to be carried in wires and radiated through space; very loosely, 100kHz to 100GHz or so.

You can do "RF" at ELF (< 10kHz), but it's considerably more difficult.

Heartbeats have nothing to do with RF; perhaps you're confusing abbreviations?

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Offline JoeN

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Re: RF lab set up ...
« Reply #4 on: July 05, 2015, 05:26:20 pm »
Heartbeats have nothing to do with RF; perhaps you're confusing abbreviations?

Perhaps he will be the first person to be able to detect heartbeats from radiated EMF rather than electrodes.  Now how cool would that be?    :P
Have You Been Triggered Today?
 

Offline evb149

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Re: RF lab set up ...
« Reply #5 on: July 05, 2015, 05:46:32 pm »
For low frequency electric field measurements you could start off with some kind of electrometer instrument with a digitizing system attached to it or a DIY electrometer input op-amp buffer system in front of some kind of 24 bit ADC.  You'd want a lot of gain optionally and the ability to use less as desired.  You may also want some good filtering in analog as well as what can be done in DSP.

For low frequency magnetic field measurements you could start with a loop of wire (air core) going into a low noise pre-amplifier and several gain stages (and possibly filter stages) after that before digitization.  You could also look at the possibility of buying something like a SQUID detector and appropriate cryogenic cooling setup.  There are other possibilities like spin exchange magnetometers that aren't cryogenic but which are still pretty specialized.  You could get inexpensive (relatively) GMR sensors as well but they're not nearly as sensitive or suitable for larger detection areas.  You may want some kind of multi-axis Helmholtz coil system to help control external fields if they will disrupt whatever you are trying to measure.

If you clarify what exactly you're trying to measure in terms of the actual application and origin of the signals and constraints on the measurement apparatus / environment you'd get more specific answers.

It is possible to measure some pretty tiny electric or magnetic fields but even if you have the apparatus to do so, you'll need the right kind of isolation or shielding or signal characteristics to permit the isolation of the faint signal from the extremely abundant electric and magnetic noise fields in most populated areas of the planet.
 

Offline hendorog

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Re: RF lab set up ...
« Reply #6 on: July 07, 2015, 04:17:43 pm »
Quote
Perhaps he will be the first person to be able to detect heartbeats from radiated EMF rather than electrodes.  Now how cool would that be?    :P

He won't be the first. I remember reading a few years ago about a trial of a system which could detect people trapped under rubble after an earthquake. It detected respiration and heartbeat - RF goes all the way to DC :)
Apparently it was used for real in Nepal after the recent quake there.

Google found all these:
http://www.academia.edu/5382185/Contactless_Detection_and_Analysis_of_Human_Vital_Signs_Using_Concurrent_Dual-Band_RF_System

http://www.ncbi.nlm.nih.gov/pubmed/19964829
http://nyuwireless.com/ThePulse/03/Heart-Rate-Measurement-Utilizing-Non-Contact-RF-Detection-From-Within-The-Mouth.php
http://fox41blogs.typepad.com/wdrb_weather/2015/05/nasas-radar-found-4-men-trapped-under-rubble-in-nepal-by-their-heartbeats.html

 

Offline Alexei.Polkhanov

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Re: RF lab set up ...
« Reply #7 on: July 07, 2015, 04:26:40 pm »
I think I got it. He is talking about Doppler radar systems that are used by police for example to detect if there is anyone in a room behind a wall etc. Those are 3GHz as far as I know and yes they can sense heart bit of human or even small animal.

http://www.range-r.com/tech/theory.htm
This one?



 


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