Codan Radio P25 Training Guide - Manual (Page 52)

TRAINING GUIDE | P25 RADIO SYSTEMS
Chapter 3: P25 Technical Information Page 44
P25 RADIO SYSTEM PERFORMANCE TESTING
Testing a P25 radio system is very similar to testing an analog system for the majority of tests to be
performed. In many cases, the radio system can be tuned in analog mode, and then the accuracy of
the digital mode can be tested to ensure compliance.
The following are some radio system tests that can be performed on P25 radio systems in analog or
digital mode:
Analog Receiver Reference Sensitivity
Analog Receiver Reference Sensitivity is a measure of the amount of minimum RF signal level that is
required to produce an intelligible audio signal when an FM signal is demodulated. Analog Reference
Sensitivity measurements can be made with any P25 receiver in analog mode.
The measurement device used in analog systems is typically the SINAD meter which shows a ratio in
dB of:
Signal + Noise + Distortion
Noise + Distortion.
Digital Receiver Sensitivity (BER)
Digital Receiver Sensitivity is a measure of the amount of RF signal level that is required to produce an
intelligible audio signal when a C4FM signal is demodulated. Digital Sensitivity measurements can be
made with any P25 receiver in digital mode.
Sensitivity in a digital radio system is expressed in terms of Bit Error Rate (BER). BER is the percentage
of received bits in error to the total number of bits transmitted. The Digital Sensitivity test must be
conducted with a known test signal such as the Standard 1011 pattern. The radio is typically placed into
a special test mode for this test and radio specifi c software and a computer may be required to evaluate
a decoded 1011 patterns Bit Error Rate.
Audio Levels and Distortion
Audio Level and Audio Distortion readings can be performed in both analog mode and digital mode.
The measurements are made using the same procedure as for conventional analog equipment. In
digital mode, the audio level readings are performed before vocoding in the transmitter, and the audio
level and distortion readings are performed after de-vocoding in the receiver.