Author Topic: RF detector help  (Read 1164 times)

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Offline Cacao

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RF detector help
« on: July 13, 2017, 01:35:27 AM »
Just gonna ask question about detecting RF signal. Will this certain IC will be effective on detecting any signal?? and will connecting an open ended coaxial probe as an antenna in the RF input work??
Thanks in advance.
LTC5535 datasheet:
http://cds.linear.com/docs/en/datasheet/5535f.pdf
 

Offline ChristofferB

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Re: RF detector help
« Reply #1 on: July 13, 2017, 03:04:11 AM »
"Any" signal is a pretty broad concept. It will detect signals in the range and freq. given in the datasheet. It will probably detect something with just a bit of wire sticking out, but it all depends on what you want to see. I've had a similar log. detector chip on a small board with a little dipole on for relative measurements, and that did pick up some signals, but depending on what it is, you may want to put a LNA in front of it.
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Online Ian.M

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Re: RF detector help
« Reply #2 on: July 13, 2017, 03:09:26 AM »
Also its an AM detector.  Don't expect any joy with a weaker FM or FSK signal.

It also may misbehave if you try to operate it a long way below its lower specified frequency limit of 600MHz, so unless your only interest is UHF upwards, its either the wrong chip for the job, or for a one-off project you'll need to test and calibrate it for lower frequencies.
« Last Edit: July 13, 2017, 03:11:37 AM by Ian.M »
 
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Offline Cacao

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Re: RF detector help
« Reply #3 on: July 15, 2017, 01:36:33 AM »
"Any" signal is a pretty broad concept. It will detect signals in the range and freq. given in the datasheet. It will probably detect something with just a bit of wire sticking out, but it all depends on what you want to see. I've had a similar log. detector chip on a small board with a little dipole on for relative measurements, and that did pick up some signals, but depending on what it is, you may want to put a LNA in front of it.

I plan to detect microwave signals that has been transmitted thru an open ended coaxial cable. Will it work?
 

Offline MikeLogix

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Re: RF detector help
« Reply #4 on: July 16, 2017, 09:20:56 AM »
Also its an AM detector.  Don't expect any joy with a weaker FM or FSK signal.

It also may misbehave if you try to operate it a long way below its lower specified frequency limit of 600MHz, so unless your only interest is UHF upwards, its either the wrong chip for the job, or for a one-off project you'll need to test and calibrate it for lower frequencies.

It is just a power detector. It does not matter what the modulation type is.
 
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Online CJay

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Re: RF detector help
« Reply #5 on: July 17, 2017, 09:10:10 PM »
Umm, seems 'detector' is a confusing term to use but I have a suspicion the log detector ICs could function as a demodulator for AM/SSB signals. They would of course be useless for demodulating FM/PSK and of course their primary purpose is for power measurement
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Offline Cacao

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Re: RF detector help
« Reply #6 on: August 14, 2017, 03:31:14 AM »
Also its an AM detector.  Don't expect any joy with a weaker FM or FSK signal.

It also may misbehave if you try to operate it a long way below its lower specified frequency limit of 600MHz, so unless your only interest is UHF upwards, its either the wrong chip for the job, or for a one-off project you'll need to test and calibrate it for lower frequencies.

It is just a power detector. It does not matter what the modulation type is.

Even if it is just a simple microwave signal that has not been modulated and just travel along copper?
 

Offline retrolefty

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Re: RF detector help
« Reply #7 on: August 14, 2017, 07:39:37 AM »
Also its an AM detector.  Don't expect any joy with a weaker FM or FSK signal.

It also may misbehave if you try to operate it a long way below its lower specified frequency limit of 600MHz, so unless your only interest is UHF upwards, its either the wrong chip for the job, or for a one-off project you'll need to test and calibrate it for lower frequencies.

It is just a power detector. It does not matter what the modulation type is.

Even if it is just a simple microwave signal that has not been modulated and just travel along copper?

Yes, it will detect unmodulated RF signals within it's dynamic and frequency range. Note that this will not provide a 'power' measurement but rather a voltage level measurement. There are log amp type RF power detectors with larger dynamic range and dbm linear DC output. Review your desired frequency range and min and max signal level requirement, you might find a better chip
for your requirements.

 
 
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Offline Cacao

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Re: RF detector help
« Reply #8 on: August 14, 2017, 11:30:30 AM »
Also its an AM detector.  Don't expect any joy with a weaker FM or FSK signal.

It also may misbehave if you try to operate it a long way below its lower specified frequency limit of 600MHz, so unless your only interest is UHF upwards, its either the wrong chip for the job, or for a one-off project you'll need to test and calibrate it for lower frequencies.

It is just a power detector. It does not matter what the modulation type is.

Even if it is just a simple microwave signal that has not been modulated and just travel along copper?

Yes, it will detect unmodulated RF signals within it's dynamic and frequency range. Note that this will not provide a 'power' measurement but rather a voltage level measurement. There are log amp type RF power detectors with larger dynamic range and dbm linear DC output. Review your desired frequency range and min and max signal level requirement, you might find a better chip
for your requirements.
thank you very much :)
 


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