I am an engineering co-op tasked with measuring the output power of an avionics WiFi unit. I want to measure the maximum conducted power at the coax port to then calculate max EIRP.

The challenge is measuring the WiFi signal itself. I am using a Tektronix RSA306B and SignalVu (Not the full subscription, so I don't have the WLAN measurement tools).

I decided to go with the MAX value shown on the Amplitude-vs-time measurement as it was the closest to the datasheet for the WLAN chip that is in the unit. Is this right?

For clarification the mode(s) measured are 802.11b/g.

On another Avionics unit, I tried measuring the integrated power as I read somewhere that that's the power you want to measure, but I kept getting outrageous values that exceed the WLAN chips datasheet values.

I obviously have no idea what I am doing here, so any help with pointing out the best way to measure the maximum conducted power of a WiFi signal would be fantastic. Additionally, if possible, I would like to know what exactly the Amplitude-vs-time measurement is measuring if the peak of the spread spectrum signal is at -20dBm and the A-vs-T measurement is measuring 13.33dBm.

The measurements I made on Avionics Unit A (one screenshot of many similar shots): SignalVu Screenshot WLAN Measurement

The measurements I made on Avionics Unit B (one screenshot of many similar shots): enter image description here


  • I am aware of the two different RBW values.
  • Unit A and Unit B have two different WLAN chips.
  • The setup was calibrated and cable loss is accounted for.
  • \$\begingroup\$ 1st, calibrate your setup. Use an RF signal generator, with a known attenuator and measure it. 2nd, use the same RBW across all measurements. One of your measurements uses 10KHz, the other 5KHz. It can affect the amplitude measurement. \$\endgroup\$
    – Lior Bilia
    Nov 21, 2023 at 18:23
  • \$\begingroup\$ @LiorBilia The setup was calibrated and cable loss was accounted (should probably mention that, thanks!). I am aware of the change in amplitude based on RBW, the two units have different WLAN chips in them. But you are right, RBW is one issue here. There is a bit more to my question then that unfortunately. \$\endgroup\$
    – Pxl
    Nov 21, 2023 at 18:27

1 Answer 1


I have asked some knowledgeable co-workers, and the answer they provided is as follows:

  • Amplitude vs. time is fine for measuring the peak conducted output power.
  • Integrated power (or channel power) will be greater than your peak as the total power is spread across the signal (channel bandwidth).
  • Amplitude vs. frequency will give power over the spectrum.
  • The RSA is an FFT device, amplitude vs. time will sum all the spectral components in the time domain, which is the same as a Zero Span measurement over the spectrum analyzers set capture bandwidth.

So for those wondering, to make a Zero Span measurement on the Tektronix RSA306B and SignalVu software, make an Amplitude vs. time measurement and set the Span (capture bandwidth) as your desired signal bandwidth.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.