I am trying to check how electric devices such as Sunroof could affect the remote key performance range (meter) for cars. I am thinking of measuring relative antenna gain of RF receiver of one test vehicle at various test condition with below method.

  1. Disconnect and put off the RF receiver(RFR) in the car
  2. Soldering shield wire at LNF Output pin of the RFR chip and connect the wire to spectrum analyzer. (Please refer to below measurement point.)
  3. Put the RFR to the original location in the vehicle
  4. Tx Signal is sent by pushing button of the original key fob for the car
  5. Compare the RFR gain value [dBm] at different test condition.
    • Test site is widely open space.
    • Spectrum analyzer is in vehicle. One person send Tx by Key Fob outside the car. The other check the dBm gain in the car.
    • Test condition is to turn on and off radio, sunroof or blower electric devices.

#1 Measurement point: LNO pin 6 of Infineon RFR, TDA 5211

I add wire without disconnecting any of the RFR circuit to visibly check if the car operates Lock or Unlock function when the key fob sends Tx signal. I prefer vehicle level test, not component level. I know the gain measurement is not accurate because of other RFR elements, but i think that i could compare the gain value with different test condition. My goal is to find best test condition for relatively higher gain that leads to best remote key range(meter).

TDA 5211 Block Diagram

[#2 Measurement result]:

-69.3 dBm is measured even without key fob operation. Should I think it as base noise level? Please kindly review if my test approach has any problems.

enter image description here

  • \$\begingroup\$ You could edit this to make the actual question stand out more - otherwise people might miss it. \$\endgroup\$ – David Sep 30 '14 at 21:06
  • \$\begingroup\$ Not really base noise level. Those spikes are other transmitters. The spectrum analysers I used would let you manually sweep, and listen to them! Don't know if that's possible with yours. \$\endgroup\$ – Brian Drummond Oct 1 '14 at 11:30

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