The sweep/setup menus include keys to set Run/Hold, Sweep Type, RF Immunity, Data Points, Averaging and Smoothing, and Output power.
Run/Hold
Controls if the instrument is actively sweeping the frequency range. When Sweep Type is set to Single, this key also provides a single sweep trigger.
1. Press the Sweep (3) main menu key.
2. Toggle the Run/Hold key.
Sweep Type Single and Continuous
This key toggles the sweep between Single and Continuous sweep. In single sweep mode, each sweep must be activated by the Run/Hold key.
1. Press the Sweep (3) main menu key.
2. Toggle the Sweep Type key.
RF Immunity High / Low
The instrument defaults to RF Immunity High. This setting protects the instrument from stray signals from nearby or co-located transmitters that can affect frequency and DTF measurements. The algorithm used to improve the instrument’s ability to reject unwanted signals slows down the sweep speed. If the instrument is used in an environment where immunity is not as issue, the RF Immunity key can be set to Low to optimize sweep speed. Use this feature with caution, as the introduction of an interfering signal might be mistaken for a problem with the antenna or cable run. If Immunity is set to Low during a normal RL or VSWR measurement, the instrument will be more susceptible to interfering signals. Interfering signals can make the measurement look better or worse than it really is.
1. Press the Sweep (3) main menu key.
2. Toggle the RF Immunity key.
Data Points
The number of data points can be set to 137, 275, or 551 data points. This can be changed before or after calibration regardless of the display setting. The default setting is 275. This is recommended for most measurements. Additional data points slow down the sweep speed but are helpful in DTF, as they enable increased distance coverage for the same distance resolution.
1. Press the Sweep (3) main menu key.
2. Press the Data Points key to select 137, 275, or 551 data points.
Averaging helps to average out the trace and minimize the effect of outliers. Trace averaging takes the running average of the number of traces indicated in the Averaging Factor. The Average Count in the status window turns on if Averaging is turned on. When the Average Count reaches the entered average count, a running average of the last set of sweeps is performed. Averaging Factor can be set between 1 and 65535.
1. Press the Sweep (3) main menu key.
2. Press the Averaging Smoothing submenu key.
3. Press Averaging Factor and enter the number of running averages using the arrow keys, rotary knob, or keypad and then press the Enter key.
4. Press the Averaging On/Off key and toggle Averaging to On.
5. Press the Restart key to start the averaging sequence from the beginning.
Smoothing %
Smoothing is a mathematical function that calculates a rolling average of the trace data. This provides a way to look at the general shape of a measurement while smoothing out smaller variations. The value is the amount of the display that is incorporated into the rolling average. Valid entries range from 0% (no smoothing) to 10% (maximum smoothing).
The display in Figure: Smoothing Reduces Ripple illustrates how smoothing can be used to reduce ripples when making 1-port cable loss measurements. The white trace shows the trace with no smoothing and the yellow trace shows the trace with 7% smoothing.
1. Press the Sweep (3) main menu key.
2. Press the Averaging Smoothing submenu key.
3. Select the Smoothing % key and enter the level of smoothing (1% to 10%).
Smoothing Reduces Ripple
Output Power (Low/High)
The power level defaults to High for all 1-port measurements (~ –7 dBm). It can be changed to Low (~ –40 dBm) if needed. All line sweep 1-port measurements should be performed with the output power High setting.
1. Press the Sweep (3) main menu key.
2. Select the Output Power submenu key and toggle Output Power between High and Low.
