BNC 630 - Manual (Page 17)

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4.4 Offset key
The Offset key is used to specify a DC offset voltage to be added to the output signal. When this key is pressed, the LCD display
is cleared and the cursor is placed in a numeric field to enter the offset voltage. Both positive and negative voltages can be entered.
To exit the offset entry screen and return to the current mode, press the Offset key again.
The offset voltage value can be entered in the same manner as any other numeric value. You can also use the wheel to modify a
particular digit in the value. Any voltage within the range of -6.0 to +6.0 can be entered.
NOTE: The offset voltage specified is a 50 ohm LOADED value. This is the voltage that will appear across a 50 ohm load
connected to the SIG Out connector. If you are connecting the output to a high impedance load, the output voltage will be twice that
entered.
NOTE: Care must be taken when specifying an output offset voltage and level such that the output does not clip. The loaded
output cannot swing higher than +6.0V or lower than -6.0V. Therefore:
Offset voltage + 1/2 * Vp-p < 6.0
The 630 can be used as a variable voltage source by setting the output frequency to 0.0 Hz while in Sinewave mode. Then set the
offset voltage to the desired output voltage. Remember, the output impedance is 50 ohms. Up to +/- 70 mA can be drawn from the
output under these conditions.
This key is also used to select the RS232 baud rate after the Mode key is pressed once. By pressing Mode then Offset , a menu
of baud rates for the 630 is presented. For more information, refer to the chapter on Remote Mode.
4.5 Trigger key
The Trigger key is used in modes that require a trigger event to begin a process. Triggered Sweep mode uses this key to begin a
sweep. Triggered Burst and Data Modulation modes also use this key to begin the generation of a burst signals. Arbitrary Waveform,
Function Generator and Pulse Generator modes use this key to begin the generation of a waveform in Triggered mode.
In modes that require a trigger, the trigger can come from three sources:
1. Pressing the Trigger key
2. Applying a low-to-high transition on the Ext Trigger In connector
3. Sending an ASCII "T" to the RS232 port
The 630 will simultaneously accept a trigger from all of the above sources.
4.6 Numeric keys ( 0 to 9, - and . )
The 0 to 9 ,
-
and
.
keys are used to enter a numeric value. These keys are used in the same manner as those on a calculator.
The
-
key is only accepted when entering numeric values that can be negative, i.e. dBm or offset values. The keypress is ignored
otherwise.
In DTMF Generation mode, the
.
key is used to generate the star ("*") DTMF digit and the
-
key is used to generate the pound
("#") DTMF digit.
These keys are also used to select a mode after the Mode key is pressed once. These keys are then used to select a mode indicated
by the blue text written beneath these keys.