Stanford Research Systems DS335, Руководство пользователя

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Calibration 4-15
DS335 Synthesized Function Generator
CALIBRATION
Introduction The calibration of the DS335 is composed of two parts: adjustment and
calibration. Adjustments are actual physical adjustments to variable resistors
and capacitors to correct the DS335's filters, and output amplifier response.
Calibration is the process of determining the calibration constants
("calbytes") that the DS335 firmware uses to correct the output amplitude,
etc..
The settings of the adjustments are, in general, very stable and should rarely
require change. If the adjustments are changed the corresponding
calibrations must be performed. However, the DS335 rarely requires
complete recalibration to maintain its performance. It is recommended that
the unit be sent back to the manufacturer in the case where a full
recalibration is required.
Calibration Enable The DS335 is shipped with calibration byte editing disabled. When
calibration is disabled, direct access to the calbytes is prevented. The
internal calibration enable jumper must be set to enable calibration. To set
the jumper remove the DS335's top cover by removing its four retaining
screws (this will break the calibration seal). In the center of the bottom circuit
board is a three pin jumper labeled JP200. Setting JP200 between pins 1
and 2 enables calibration, setting it between pins 2 and 3 disables
calibration.
Calbytes The DS335's calibration is controlled by calibration constants ("calbytes") that
the firmware uses to adjust the various output parameters. These calbytes
are stored in the DS335's RAM. Recalibration of the DS335 involves
determining the values of the calbytes and storing the new values in RAM.
The calbyte values at the time of the DS335's production are also stored in
ROM and may be recalled at any time.
Direct access to the DS335's calbytes is allowed from both the front panel
and computer interfaces after calibration is enabled. From the front panel
press [SHIFT][9] once to display the calbyte menu line. There are two
displayed parameters: on the left is the calbyte number, and on the right is
the calbyte value. The calbyte number and value may be modified with
either the keypad or the UP/DOWN ARROW keys. To select an item use the
[SHIFT][DOWN ARROW] and [SHIFT][UP ARROW] keys. The calbyte
number may be set between 0 and 554. The calbyte value may be set
between -127 and 65536. The complete set of factory calbyte values may be
recalled by pressing [SHIFT][9] twice to bring up the Clear Cal menu and
then pressing any of the unit keys. The tables on the following pages lists
the DS335 calbytes. Shown is the calbyte number, name, and meaning.