Fluke CombiScope PM3370B - Page 71

3 - 52 USING THE COMBISCOPE INSTRUMENTS
dBm - 50Ω offset calculation:
From the Vrms offset value the dBm-50Ω offset value is calculated as follows:
Example for attenuator setting 0.5 V/div.:
dBm - 600Ω offset calculation:
From the Vrms offset value the dBm-600Ω offset value is calculated as follows:
Example for attenuator setting 0.5 V/div.:
dBµV offset calculation:
From the Vrms offset value the dBµV offset value is calculated as follows:
Example for attenuator setting 0.5 V/div.:
dBm 50Ω offset– 20 * Vrms offset 0,2236068⁄()log
10
=
P *R() 1E-3 *50()0,2236068==
Note:
dBm 50Ω offset– 20 * 1,118034 0,2236068⁄()log
10
13,9794==
dBm 600Ω offset– 20 * Vrms offset 0,7745967⁄()log
10
=
P *R() 1E-3 *600()0,7745967==
Note:
dBm 600Ω offset– 20 * 1,118034 0,7745967⁄()log
10
3,1875874==
dBµV offset 20 * Vrms offset 1.0E-6⁄()log
10
=
Note: 0 dBµV = 1 µV (1.0E-6 V) at 50Ω impedance.
dBµV offset 20 * 1,118034 1E-6⁄()log
10
120,9691==