2-14 Channel Power Measurement Spectrum Analyzer
2-18 PN: 10580-00349 Rev. H Spectrum Analyzer MG
2-14 Channel Power Measurement
Channel power measurement is one of most common measurements for a radio transmitter.
This test measures the output power, or channel power, of a transmitter over the frequency
range. Out-of-specification power measurements indicate system faults, which can be in the
power amplifiers or in filter circuits. Channel Power measurements can be used to validate
transmitter performance, comply with government regulations, or to keep overall system
interference at a minimum.
Frequency and span settings for many signal standards can be set.
1. Press the Freq main menu key.
2. Press the Signal Standard submenu key. Choose the desired standard and press Enter.
3. Press the Channel # submenu key to enter the channel number at which the
measurement is to take place and press Enter.
4. Press the Shift key then the Measure (4) key. Then press the Power and Bandwidth
submenu key, and press the Channel Power submenu key.
5. Press the On/Off submenu key to start and stop channel power measurements.
Channel Power Measurement for GSM
Global Systems for Mobile (GSM) communication is a globally accepted standard for digital
cellular communication. A number of frequency bands that are allocated to GSM mobile
phones use a combination of Frequency Division Multiple Access (FDMA) and Time Division
Multiple Access (TDMA). Within each band, are approximately one hundred available carrier
frequencies on 200 kHz spacing (FDMA), and each carrier is broken up into time-slots so as to
support eight separate conversations (TDMA). GSM uses the Gaussian Minimum Shift
Keying (GMSK) modulation method.
Required Equipment
• Test Port extension cable, Anritsu 15NNF50-1.5C
Procedure
1. Using the test port extension cable, connect the signal source to the RF In test port.
2. Press the Amplitude main menu key and press the Reference Level submenu key to set
the reference level to –20 dBm. Adjust the values given in this procedure to match your
measurement conditions.
3. Press the Scale submenu key and set the scale to 10 dB/div.
4. Press the BW main menu key and verify that Auto RBW and Auto VBW are On.
5. Press the Freq main menu key followed by the Signal Standard submenu key. Scroll
through the dialog box using the up or down arrow keys or the rotary knob to highlight
the GSM 900 - Downlink standard for the measurement and press Enter.
6. Press the Channel# submenu key and enter the channel number using the keypad, the
arrow keys, or the rotary knob. For this example, select Channel 60.
7. Press the Shift key then the Measure (4) key. Then press the Power and Bandwidth
submenu key, and press the Channel Power submenu key.
8. Verify that the center frequency is set to that of the GSM signal, in this case 947.0 MHz
by looking at the center frequency annotation on-screen.
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