HP E1429A Setting Measurement Range, Setting the Input Impedance, Enabling the 10 MHz Filter

Setting the Input Impedance

The impedance of the single-ended inputs can be set to 50Ω or 75Ω. At power-on or following a reset, the impedance is set to 50Ω. The impedance is changed using the following bits of the A/D shift register.

Bit	Name			Setting
Position
6	TERM75 1	0 - Ch1		50Ω input imedance selected
		1	- Ch1	75Ω input impedance select
11	TERM75 2	0	- Ch2	50Ω input imedance selected
		1	- Ch2	75Ω input impedance select

Procedure

Enabling the 10 MHz Filter

With the bit position known, set the input impedance as required using the procedure for reading and writing to the shift register.

At power-on or following a reset, the 10 MHz filter is switched out of the signal path (disabled) of the single-ended and differential inputs. The filter can be switched into the path (enabled) using the following bits of the A/D shift register.

Bit	Name			Setting
Position
9	FILTER1	0 - Ch1 10		MHz filter disabled
		1	- Ch1 10	MHz filter enabled
14	FILTER 2	0	- Ch2 10	MHz filter disabled
		1	- Ch2 10	MHz filter enabled

Procedure

Setting the

Measurement

Range

Note

With the bit position known, disable/enable the filter as required using the procedure for reading and writing to the shift register.

The digitizer measurement range is set using a series of attenuators (Figure 3-3). Table C-1 shows the attenuator settings used to select the corresponding measurement range.

There is a 3 ms relay settling time following each range change. Samples cannot be taken during the settling time.

370 Register Programming Appendix C