MS20xxA VNA Master UG 10580-00166 Rev. C 9-1
Chapter 9 — Interference
Analyzer, Option 25
9-1 Introduction
Many wireless networks operate in complicated signal environments. Three or four base
station antennas may be located onto the same tower and can create interference problems,
which can affect system capacity and coverage.
The Interference Analyzer option adds three measurement capabilities to the VNA Master:
• Spectrogram
• Signal Strength
• RSSI (Received Signal Strength Indicator)
The instrument also has a spectrum mode which displays signals in a traditional Spectrum
Analyzer view.
The following menus are available in Interference Analyzer (Option 25) mode.
9-2 Spectrogram Measurement
A Spectrogram is a three dimensional representation of frequency, time and power useful for
identifying intermittent interference. Color is used to represent power levels. Figure 9-1
shows a sample spectrogram display in a Field measurement menu.
Procedure
The following procedure demonstrates one example of an Interference Analyzer Spectrogram
setup.
1. Select the
Shift key, then the Mode (9) key, using rotary knob or Up/Down arrow keys
select
Interference Analyzer and press the Enter key to select.
2. Press the
Freq function hard key.
3. Select the
Signal Standard soft key and select the desired air interface standard from the
dialog box displayed. Alternatively, choose the appropriate soft keys and enter the
center, start and stop frequencies and the span.
4. For the most effective spectrogram display, press the
Amplitude key, select the Reference
Level
soft key and set the reference level such that the largest signal to be displayed will
be near the top of the Spectrum Analyzer area of the screen. The reference value
required can be determined by observing the color of the highest signal and changing
the reference level to place that value near the top of the Spectrum Analyzer area.
5. Select the
Scale soft key and set the scale value to place the lowest signal near the
bottom of the screen. In general, 4 or 5 dB/division will be good starting values.
6. Select the
BW function hard key and set Auto RBW and Auto VBW On, or set the applicable
RBW and VBW values by selecting the
RBW and VBW soft keys.
10580-00166C.book Page 1 Thursday, February 21, 2008 12:52 PM
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