Subelement L: L – Installation, Maintenance & Repair— Topic 78: Measurement Procedures
Question 3-78L1
Element 3 (GROL)Can a P25 radio system be monitored with a scanner?
Explanation
P25 (Project 25) is a digital radio communication standard. Unlike analog signals, where audio directly modulates the carrier wave, P25 systems encode voice into a digital data stream. A conventional analog scanner can tune to the frequency of a P25 system, but without the appropriate digital signal processing (DSP) hardware and software, it will only produce an unintelligible noise or "digital hash."
To monitor a P25 system and hear the actual voice communications, a scanner must have built-in P25 decoding capabilities. This allows the scanner to receive the digital bitstream, process it, and convert it back into audible speech.
Therefore, option C is correct. Option A is incorrect because a scanner without P25 decoding cannot convert the digital signal into voice. Option B is incorrect because scanners *can* monitor P25 if equipped. Option D introduces "P26 decoding," which is not a relevant or existing standard for this context.
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