Fluke PM-3394B, PM-3380B, PM-3390B For 8-bit sample traces, Ps = Ts / 25600 * 100 = Ts

3 - 34 USING THE COMBISCOPE INSTRUMENTS

3.4.3.3Conversion to voltage values

Screen positions correspond to voltage values. This relation is shown in the figure below, and is determined by the settings that are programmed by the SENSe:VOLTage:RANGe:PTPeak and SENSe:VOLTage:RANGe:OFFSet commands.

PTPeak

	Amplitude		Screen		Trace sample
	value (Vs)		position (Ps)		value (Ts)
0 Volt					32767 (127)
		-OFFSet+PTPeak/2	top 100%
					25600	(100)
OFFSet
		-OFFSet	mid	0%	0	(0)
		-OFFSet-PTPeak/2		-100%	-25600	(-100)
			bottom
					-32768	(-128)
						ST7188

Figure 3.12 Relation between screen position and amplitude value

The relation between the screen position Ps and the corresponding voltage amplitude Vs is expressed by the equations:

Vs = (Ps * PTPeak) / 200 - OFFSet	(for 8-bit sample traces)
Vs = (Ps * PTPeak) / 51200 - OFFSet	(for 16-bit sample traces)

As explained in section 3.4.3, there is also a relation between the screen position Ps and the value Ts of a trace sample. This relation is expressed by the equations:

Ps = Ts	(for 8-bit sample traces)
Ps = (Ts / 25600) * 100 = Ts / 256	(for 16-bit sample traces)

Eliminating Ps from the preceding equations results in a relation that can be used to calculate the voltage value Vs from a trace sample Ts. This relation is expressed by the equations:

Vs = (Ts / 200) * PTPeak - OFFSet	(for 8-bit sample traces)
Vs = (Ts / 51200) * PTPeak - OFFSet	(for 16-bit sample traces)