Dear Arduino community,
In our project we need to record intensity of signal from antenna on specific frequency. Chip like Philips TEA5767 would be great, but signal must not be demodulated. Anybody have any suggestions on which chip should be used?
Best wishes,
Dario
chip, chip, chip, chip, chip, chip, chip
chip
Always with the "chips"?\
How about an LC tank circuit and a FET front-end (RF amp)?
Sure, that's one option. Thing is that we are trying to do this as cheap as possible and buying own components, ordering/printing PCB and soldering might not be such solution. Or I am wrong?
What frequency?
Google "field strength meter circuit" for lots of ideas. Here is a very simple one for radio signals ranging from about 6-11 meters in wavelength, from the September 1960 issue of Popular Electronics http://www.rfcafe.com/references/popular-electronics/build-field-strength-meter-9-1960-popular-electronics.htm
Hi, if you are looking to measure signal strength, look at the radio receiver chip specs and look to see if it has a AGC or Automatic Gain Control. This pin will have a DC level on it either proportional or inversely proportional to the RF signal strength.
Tom..... 
PS..http://www.voti.nl/docs/TEA5767.pdf
page 22, pin 38 Tagc, this looks like it has the agc voltage you need.
"Specific frequency" would seem to imply that a complete selective receiver is required and if the signal is in any way remote, a Field Strength meter is not going to "cut it".
It definitely sounds as if the TEA5767 or similar is the way to go.
I'm talking about frequencies usually used by commercial FM radio stations (80-110 MHz).
Paul__B:
"Specific frequency" would seem to imply that a complete selective receiver is required and if the signal is in any way remote, a Field Strength meter is not going to "cut it".It definitely sounds as if the TEA5767 or similar is the way to go.
TomGeorge:
Hi, if you are looking to measure signal strength, look at the radio receiver chip specs and look to see if it has a AGC or Automatic Gain Control. This pin will have a DC level on it either proportional or inversely proportional to the RF signal strength.Tom.....
PS..http://www.voti.nl/docs/TEA5767.pdf
page 22, pin 38 Tagc, this looks like it has the agc voltage you need.
That could be it, I'll explore further. Thank you!
Hm. An RMS or RF Detector IC would be highly useful for this, but you need to have a way of only picking up one specific radio station. How accurate does this need to be? Is it only a relative measure?
The problem with FM receiver ICs is that they are build to drive the signal to clipping, so the AGC voltage may not be good for any but the most crude measure.
polymorph:
Hm. An RMS or RF Detector IC would be highly useful for this, but you need to have a way of only picking up one specific radio station. How accurate does this need to be? Is it only a relative measure?The problem with FM receiver ICs is that they are build to drive the signal to clipping, so the AGC voltage may not be good for any but the most crude measure.
LMH2110 data sheet, product information and support | TI.com
RF Power Detectors | Analog Devices
http://www.analog.com/en/rfif-components/detectors/products/index.html#RMS_Detectors
LMH2120 data sheet, product information and support | TI.com
We need to be sure to not have signal from any other station but the one we chosen.
Could you explain why AGC might not be good choice? We need accurate measurements of signal strength from that station.
When you say accurate measurements, what do you mean .
How accurate.
Measuring the signal strength of radio signals accurately is quite a hard thing to do , and theres no cheap way to do it.
You need a commercial field intensity receiver to do this type of thing accurately.
What exactly are you trying to measure?
Could you explain why AGC might not be good choice? We need accurate measurements of signal strength from that station.
Because you have no idea what curve the AGC voltage follows, or how stable it is with respect to time and temperature.
How would you pick only one station and have it's signal forwarded to other electronics? This is actually the core of my problem.
http://forum.arduino.cc/index.php?topic=236002.msg1697229#msg1697229
Runaway Pancake has already answered that question. I have a tunable field strength meter made for aiming TV antennas. That is basically what it is, calibrated.