The following example uses an S412E LMR Master to analyze the modulation quality and receiver sensitivity of a P25 handheld transceiver (HT) in simplex mode.
• Connect the MA25200A to the S412E RF In port, Signal Generator Out port, and USB port.
• Connect the HT RF output (antenna port) to the MA25200A Tx/Rx port.
Handheld Transceiver connected to LMR Master with a MA25200A High Power Tx/Rx Input Protection Module
Note
The MA25200A combines the S412E Signal Generator Out and RF In ports to the High Power Tx/Rx port of the module.
2. Set the HT to the desired simplex mode frequency (transmit and receive frequencies set to the same values) to receive a P25 1011 Hz test pattern.
3. From the S412E Frequency menu, set the following:
• Rx Freq: test frequency
• Tx Freq: test frequency
• Rx/Tx Coupling: On
• Coupling Offset: 0 Hz
• Span: 25 kHz
4. From the S412E Amplitude menu, set the following:
• Ref Level: –20 dBm
• Scale: 10 dB/div
• Rx Power Offset: 40 dB External Loss
• Auto Rx Range: On
• Tx Power Offset to 40 dB External Loss
• Tx Output Level: –120 dBm (initial setting)
From this point, the S412E signal generator and analyzer measurements are both referenced from the MA25200A Tx/Rx port.
5. Turn the S412E Signal Generator On and use the Setup menu to set the default 1011 Hz Rx Pattern and p25_1011 Tx Pattern.
6. Return to the Amplitude menu and adjust the Tx Output Level until the signal can no longer be distinguished from the measurement noise by the receiver.
7. Note the Tx Output Level is the receiver sensitivity value.
Measuring Transmitter Modulation
8. Turn off the S412E signal generator.
Note
The MA25200A has a small amount of signal leakage from the signal generator input to the analyzer output port (S412E RF In port). This leakage is mitigated by turning off the S412E signal generator.
9. Transmit the HT RF output test signal into the MA25200A Tx/Rx input and note the receiver summary data table on the S412E display.
