I am a graduating ECE student and we are currently making our project study. Our group would like to make a proximity indicator. Initially, we planned to use Radio Frequency for this. The idea was to measure the signal strength of the output signal in terms of voltage. We were to use AD8313 to be able to convert the db output signal to voltage. Unfortunately, our component has not yet arrived and we are forced to look for alternative ways. Could you please suggest other ways on how to accomplish this?
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asked Jan 29, 2014 at 10:37
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2\$\begingroup\$ Without a circuit diagram (and antenna description/type) it is guesswork to tell you what the signal level means in terms of RF power received. What do you want - rf power received by the antenna? \$\endgroup\$– Andy akaCommented Jan 29, 2014 at 10:46
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\$\begingroup\$ What do you mean by, "in terms of voltage"? Of all the ways RF signal strength is commonly measured, none of them are in just volts. Common units are volts per meter, or watts, though these measure actually two different things: field strength, and power received by something in that field, respectively. \$\endgroup\$– Phil FrostCommented Jan 29, 2014 at 13:15
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\$\begingroup\$ For a very simple way to qualitatively measure signal strength, see How can I tell if an RF transmitter is transmitting?. Quantitative measurements are going to require that you more completely specify just what you want to measure. \$\endgroup\$– Phil FrostCommented Jan 29, 2014 at 13:35
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Andy is correct - we really need to know the details about frequency, power out etc. to give a precise answer but as a general solution you will require a pick-up/tuned circuit (LC), a sensitive detector (diode) and some sort of buffer/amplifier (possibly a FET/mosfet/op amp) and a meter to indicate the field strength.
Accurate calibration of what the meter reading actually means is of course a different matter but if you just want to detect a particular field strength for proximity you could always use a comparator to set the point at which the field strength will exceed a certain value of voltage output.
