Difference between average and CW power

[countmybones]

Hi all,

When measuring RF power using a power meter and power sensor, what is the difference between average power and CW power?
For a sine wave type of signal, is the average power and CW power the same thing?
What about for a pulsed signal like GSM, which I suppose there will be no CW power?

Thanks.

 

[biff44]

Well, you can only measure "CW Power" if in fact your signal is a CW one.

If your signal has a varying amplitude, then your power meater is measuring Average power.

If you use a power meter to measure a CW signal, then the reading is also the cw signal's average power.

 

[vfone]

GSM with GMSK has constant envelope (like FM modulation).
So, the continuous power in GMSK mode would be almost equal with CW power.

To find the power of the bursty GMSK you have to trigger and gate the power meter to measure the power in the middle of the burst, ignoring the rise and fall portions.

 

[shiv_chandan]

For measurement with the power meter, average & CW power will be same.
Also in a pulsed signal, CW component will be there.

 

[rghrob]

CW power will be about 3 db higher than avg. power for a modulated signal. Ex:
DCS(static, no bursting): CW=30 dBm and PRBS9=27 dBm (ACP w/ Ch. BW=200kHz).