WCDMA Analyzer Measurement Guide : WCDMA Analyzer (Option 871) : WCDMA Adjacent Channel Power
 
WCDMA Adjacent Channel Power
Adjacent Channel Power (ACP) measurements are set up using the SETUP Menu (ACP). Adjacent channel power is a measure of the power that leaks into adjacent transmit channels. The ACP measurement measures the power present in the transmit channel (refer to WCDMA Channel Power) along with the adjacent transmit channels that have been configured in the SETUP menu.
WCDMA Adjacent Channel Power Ratio Measurement
1. The status panel provides quick access to common spectrum analyzer settings. See STATUS PANEL (ACP).
2. Green integration bandwidth edge of lower alternate channels.
3. Red integration bandwidth edge of lower adjacent and alternate channels.
4. Blue integration bandwidth edge of lower main and adjacent channels.
5. All adjacent channel power measurement parameters are set via the SETUP men. See SETUP Menu (ACP).
Frequency and span settings for many signal standards can be set as follows:
1. Select MEASURE on the main menu.
2. Select ACP from the MEASUREMENT button.
3. Select SETUP and choose appropriate parameters for the following:
• Channel spacing
• Main integration bandwidth
• Adjacent integration bandwidth
• Alternate integration bandwidth
• Limit Type
• Main channel limit
• Adjacent channel limit
• Alternate channel limit
Adjacent channel power is a constant measurement; after it is turned on, it remains on until a different measurement is selected or the sweep is paused. ACP is calculated at the end of each sweep.
SETUP Menu (ACP)
The Adjacent Channel Power SETUP menu is available in MEASURE > MEASUREMENT > ACP > SETUP. Once the ACP measurement is selected, the SETUP menu can be quickly accessed by tapping on the summary display area below the spectrum window.
SETUP Menu (ACP)
 
CHANNEL SPACING
Sets the channel frequency spacing (center channel to center channel).
MAIN INTEG BW
Sets the range of integration used in calculating the power within the channel. The integration bandwidth (IBW) is displayed as two vertical dashed lines for each channel.
ADJ INTEG BW
Sets the range of integration bandwidth used in calculating the power in the adjacent channel.
ALT INTEG BW
Sets the range of integration used in calculating the power in the alternate channel.
LIMIT TYPE
Selects Absolute or Relative for the limit evaluation.
LIMITS
Turns on or off the use of ACP limits.
MAIN CH LIMIT
Sets the main channel limit.
ADJ CH LIMIT
Sets the adjacent channel limit.
ALT CH LIMIT
Sets the alternate channel limit.
PRESET SETUP
Sets all ACP setup parameters to default. Turns off limits.
 
 
 
STATUS PANEL (ACP)
Below is the status panel with the corresponding minimized status panel icons for adjacent channel power measurement.
Status Panel and Minimized Status Panel Icons (ACP) 
 
SWEEP: Toggles the current sweep setting between continuously or sweep once.
SWEEP ONCE
When sweep is set to single sweep, SWEEP ONCE updates the measurement display. Data continues to be captured in the background.
REF LEVEL
Sets the reference level of the top graticule line in the selected units. If the reference level offset is not zero, OFFSET REF LEVEL is displayed at this location. Refer to Setting Amplitude.
SCALE/DIV
Sets the graticule scale/division for log-based units. This setting does not apply to linear units.
FREQ OFFSET
Accounts for frequency conversions outside of the analyzer.
ATTEN LEVEL
When auto attenuation is off, sets input attenuation.
CENTER FREQUENCY
Sets the center frequency of the sweep range. The current span setting will remain constant or will be adjusted to accommodate the start and stop frequency range of the instrument. The center frequency can also be dragged on the display when gestures are not toggled off.
PRE AMP
Turns the low-noise front-end preamplifier on or off. To ensure accurate measurement results, the largest signal into the instrument input when the preamplifier is turned on should be less than –40 dBm. The preamplifier cannot be turned on if auto attenuation is on and the reference level is above –40 dBm.
TRACES
Displays the current status of up to six traces in a quick-view summary. The summary information includes the trace number, type, mode, and detector type. The active trace will show a highlighted background with the mode and detector type restated under the table. Pressing a trace in the summary panel activates the pressed trace and opens the TRACE menu, which allows you to select and set up an individual trace as desired. Refer to Setting Trace Parameters.
FREQ REFERENCE
Indicates the current frequency reference source of Internal, External, or GNSS (GPS) Hi Accuracy (requires GPS). The instrument automatically selects the frequency reference in the following order of priority: external, GNSS (GPS), then the internal time base.