Fluke PM-3390B DBm 50Ω offset calculation, DBm 600Ω offset calculation, DBμV offset calculation

3 - 52 USING THE COMBISCOPE INSTRUMENTS

dBm - 50Ω offset calculation:

From the Vrms offset value the dBm-50Ωoffset value is calculated as follows:

dBm– 50Ω offset = 20 * 10log (Vrms offset ⁄0,2236068 )

Note: (P *R) = (1E-3 *50) = 0,2236068

Example for attenuator setting 0.5 V/div.:

dBm– 50Ω offset = 20 * 10log (1,118034 ⁄0,2236068 ) = 13,9794

dBm - 600Ω offset calculation:

From the Vrms offset value the dBm-600Ωoffset value is calculated as follows:

dBm– 600Ω offset = 20 * 10log (Vrms offset ⁄0,7745967 )

Note: (P *R) = (1E-3 *600) = 0,7745967

Example for attenuator setting 0.5 V/div.:

dBm– 600Ω offset = 20 * 10log (1,118034 ⁄0,7745967 ) = 3,1875874

dBμV offset calculation:

From the Vrms offset value the dBμV offset value is calculated as follows:

	dBμV offset = 20 *10log (Vrms offset ⁄ 1.0E-6)
Note:	0 dBμV = 1 μV (1.0E-6 V) at 50Ω impedance.

Example for attenuator setting 0.5 V/div.:

dBμV offset = 20 *10log (1,118034 ⁄ 1E-6)= 120,9691