ACLR (Adjacent Channel Leakage Ratio) is defined as the ratio of the amount of leakage power in an adjacent channel to the total transmitted power in the main channel and is displayed in table format under the bar graph. The 3GPP standard specifies one main channel and two adjacent channels. The ACLR screen displays the main channel power and the power of two adjacent channels on each side as a bar graph.
The channel spacing is – 10 MHz, – 5 MHz, + 5 MHz and + 10 MHz and the channels are color coded. The 3GPP standard requires the adjacent channel power leakage ratio to be better than 45 dB at 5 MHz offset and 50 dB at 10 MHz offset.
ACLR measurements can be made for multi‑channel systems by measuring the main channels and the adjacent channels, from one to four channels. The ACLR screen can display up to 12 channels total.
In the ACLR measurement mode the filtered channel power is used to determine ACLR values and is listed as filtered on the display.
The following procedure is for one main channel two adjacent channels.
ACLR Measurement Procedure
1. Set the measurement frequency using one of the methods listed in the User Guide.
2. Press the Measurements main menu key.
3. Press the RF Measurements submenu key.
Note
The ACLR measurement uses the filtered channel power to determine the ACLR values and it is listed as filtered on the display. In all other screens the unfiltered channel power is displayed as channel power.
4. Press the ACLR submenu key to activate the ACLR measurement.
Note
Using the Band Spectrum cursor, select the required channel and press the ACLR submenu key. The measurement will be displayed.
5. Press the ACLR submenu key again and select one main channel and two adjacent channels (Figure: ACLR Measurement).
ACLR Measurement
ACLR Multi‑channel ACLR Procedure
1. Press the Measurements main menu key.
2. Press the RF Measurements submenu key.
3. Press the ACLR submenu key to activate the ACLR measurement.
4. Press the ACLR submenu key again to open the ACLR menu.
5. Press Select # of Main Channels to open the Num of Main Channels list box. Highlight the desired number of channels and press Enter. In Figure: ACLR Multi‑channel Measurement, four channels were selected.
