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.
- Disconnect and put off the RF receiver(RFR) in the car
- Soldering shield wire at LNF Output pin of the RFR chip and connect the wire to spectrum analyzer. (Please refer to below measurement point.)
- Put the RFR to the original location in the vehicle
- Tx Signal is sent by pushing button of the original key fob for the car
- 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).
[#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.