S820E Microwave Site Master™ User Guide : Cable and Antenna Measurements : Measurement Setup : Sweep
The Sweep menu include keys to set Data Points, Run/Hold, Sweep Type, RF Immunity, RF Pwr In Hold, Source Power, IFBW, Smoothing, and Sweep Averaging.
Data Points
The number of data points can be set to 130, 259, 517, 1033, or 2065 data points. This can be changed before or after calibration, with one exception (refer to the Note). The default setting is 259. This is recommended for most measurements. Additional data points slow down the sweep speed but are helpful in DTF, because they enable increased distance coverage for the same distance resolution.
1. Press the Sweep (3) menu key then press Data Points.
2. Select 130, 259, 517, 1033, or 2065 data points.
Refer to Sweep Menu for additional information about the Sweep menu and submenus.
Setting Data Points to 2065 can invalidate an active Standard Cal correction that was performed with a lower number of data points. If this occurs, then a new calibration is recommended before making measurements.
To prevent this from occurring, set the number of data points to 2065 before performing any calibration. If this step is done before calibrating, then you may freely switch between any number of data points after calibrating.
Controls if the instrument is actively sweeping the frequency range. When Sweep Trigger Type is set to Single mode, this key also provides a single sweep trigger.
1. Press the Sweep (3) menu key.
2. Toggle the Run/Hold key.
Sweep Trigger Type
The Sweep Trigger submenu key sets the type of trigger that initiates a sweep. The trigger can be internal (single or continuous) or external. Continuous is the default setting.
In continuous sweep mode, a new sweep is triggered automatically at the end of each sweep. In single sweep mode, each sweep is activated by the Run/Hold key. In external trigger mode, each sweep is activated by a TTL signal at the External Trigger In connector.
1. Press the Sweep (3) menu key.
2. Toggle the Sweep Trigger key through Single, Continuous, and External Trigger.
RF Immunity
The instrument defaults to RF Immunity Low. When set to High, RF Immunity protects the instrument from stray signals generated by nearby or co‑located transmitters that can affect frequency and DTF measurements. The algorithm that is used to improve instrument ability to reject unwanted signals may slow down the sweep speed if interferers are detected. If the instrument is used in an environment where immunity is not an issue, then the RF Immunity key can be set to Low to optimize sweep speed. Use this feature with caution, because 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 Return Loss or VSWR measurement, then 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) menu key.
2. Toggle RF Immunity between High and Low.
RF Pwr In Hold
This setting determines if the RF output power at the RF Out/Reflect In port stays On or is turned Off when the instrument Run/Hold setting is toggled to Hold. When RF Pwr In Hold is set to Off, the power at the port is turned off when the instrument is placed in Hold mode and is not sweeping. Power at the port is resumed when the Run/Hold setting is toggled back to Run. This is useful when you may not want a signal radiating out of the port at all times.
This function sets the level of smoothing applied to a frequency domain measurement trace. A level of 0 % turns smoothing OFF. Levels 1 % through 20 % turn smoothing ON and set the smoothing percentage (the higher the level, the higher the percentage of smoothing applied to the trace). Smoothing is a trace averaging process that reduces or removes ripples from frequency swept data. This is especially useful when making 1‑port cable loss measurements with a short at the other end of the cable. The ripple that is usually present in this kind of measurement can be removed with smoothing, thereby resulting in a more accurate average cable loss frequency response trace. Care should be taken when applying smoothing in order to not remove ripples that are inherent parts of the data (as opposed to measurement artifacts).
Sweep Averaging
This function sets the trace averaging process to use the measurement values of the same point in a set number of sweeps (refer to Data Points). For settings greater than 1, the Measurement Information displays the current sweep number (since entering the setting) followed by the setting value. For example, if you set the averaging value to 100, then you would see the first number counting from 1 up to 100 as the sweeps are completed. Thereafter, the values would be displayed continuously as 100/100.
A Sweep Averaging setting of 1 means that only one point is used in the averaging calculation, which means that no averaging is being done. The Averaging value that is displayed in the Measurement Information area (item 14 in Figure: Site Master Display Overview) is “--” when Sweep Averaging is set to 1.
Source Power
The RF power radiated from Port 1 or Port 2 can be adjusted to be either High (nominally –3 dBm) or Low (nominally –20 dBm). The High power setting (default) is optimized in order to maximize the dynamic range of the measurement. The Low power setting must be used whenever the device under test cannot be operated with high power input signals, such as with high gain amplifiers. Care must be taken when making a transmission measurement on an amplifier in order to prevent damage or excessive distortion in the amplifier under test. Take extra caution to ensure that the output of the amplifier under test does not exceed the maximum rated input to the ports on the S820E analyzer.
The Intermediate Frequency Bandwidth (IFBW) setting allows users to optimize instrument measurement speed versus dynamic range performance. Lower IFBW values provide higher dynamic range at the expense of measurement speed. Higher IFBW settings provide faster measurement speed at the expense of dynamic range. The default setting is 1 kHz, maximum is 100 kHz, and minimum is 10 Hz.