I generated a 50 MHz, -10 dBm sine-wave
using a Rohde & Schwarz RF signal generator.
I checked this using an Agilent spectrum analyser
and, as you'd expect, I get my tone at 50 MHz with
peak amplitude of -10 dBm. However, when I input
my RF signal to a TDS 210 Tecktronix Digital Oscilloscope,
the peak-to-peak voltage is 336 mV and the Cyc RMS
voltage is 117 mV. Now, on the TDS210, Cyc RMS calculates
the RMS voltage over one complete cycle of the waveform.
When I tried to calculate this I got a different
P = -10 dBm, which is equivalent
to 100 uW
Now, P = V^2 / R
I've taken R =
Therefore Vrms = sqrt(P x R)
is: Vrms = sqrt(100 uW x 50 ohms)
= 70.7 mV
This is different to the 117 mV
measured on the oscilloscope??