Frequency-related parameters are set using the FREQ SPAN Menu. Pulse measurements are conducted in zero span so only the center frequency needs to be entered. Additionally, a frequency offset can be used, depending on what makes the most sense, either for the user or for the measurement.
Entering a Center Frequency
1. Press FREQ SPAN on the main menu.
2. Press CENTER FREQUENCY to open the center frequency parameter entry keypad.
3. Enter the desired center frequency. When entering a frequency with the keypad, available frequency units (GHz, MHz, kHz, and Hz) will be displayed along the left and right edge of the menu.
4. Press the appropriate frequency unit to terminate the entry or press ACCEPT to terminate the entry with the current frequency unit.
Note
To quickly move the center frequency value up or down, press the + or - slider controls to increment the center frequency by the set FREQUENCY STEP. You can also drag the center frequency using the slider or by dragging the trace directly.
A user‑defined frequency offset can be entered to adjust the frequency that is displayed on the instrument from the actual swept frequency. For example, if the DUT is an antenna system receiving signals in the 10 GHz range and offsetting the signals to the 1 GHz range, you can set a frequency offset in the spectrum analyzer in order to display the actual received antenna frequency in the sweep window.
Both positive and negative offset values are allowed. Negative offsets can be useful for seeing differences from expected values. Enter a negative offset of the expected value, and the received antenna frequency should display in the 0 Hz range.
When enabled, the offset value is displayed at the left of the screen in the status panel (see Status Panel). To remove a frequency offset, open the FREQ SPAN menu and set FREQUENCY OFFSET to 0 Hz. You can also access this parameter directly from the left side status panel.
Note
Offset frequency apply to start, stop, center, and marker frequencies.
FREQ SPAN Menu
FREQ / SPAN Menu
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CENTER FREQUENCY
Sets the center frequency of the sweep range.
FREQUENCY STEP
Sets the frequency step value used for the plus (+) or minus (–) control.
FREQUENCY OFFSET
The frequency offset value accounts for frequency conversions outside of the analyzer. The offset frequency value is added to the start, stop, center, fixed marker, and normal marker frequencies. Pressing the plus (+) or minus (–) control moves the offset frequency in steps defined by the FREQUENCY STEP value.
