Codan Radio P25 Training Guide - Manual (Page 74)

TRAINING GUIDE | P25 RADIO SYSTEMS
Chapter 5: Conventional Fixed Station Interface Page 66
E&M Specifi cations
Fixed Station audio input range: -30 dBm to +10 dBm (maximum modulation in analog or P25 digital
mode).
Fixed Station audio output range: -30 dBm to the maximum limit permitted by leased circuit compliance
(maximum modulation in analog mode).
The E-pair expects the host end to provide a dry contact closure for fi xed station transmission. The M-
pair provides a dry contact closure for fi xed station reception. The E & M pairs work over a range of 5
to 150 mA current with 50 ohm maximum contact resistance while the contacts are closed, and 10 to
60 Vdc with 5 megohm minimum resistance while the contacts are open. The E-pair limits its current
to this range.
Tone Remote Control Specifi cations
Figure 5-3 shows the Tone Remote Control sequence the host will send to control the Fixed Station.
The sequence begins with 120 ms of High Level Guard Tone (HLGT) at -30 to +10 dBm, followed by 40
ms of Function Tone, -10 dB relative to the HLGT, followed by the Low Level Guard Tone (LLGT) -30
dB relative to the HLGT. The LLGT is summed with the audio (average level of -6 to -18 dB relative to
the HLGT) for the duration of the transmission. All of these in-band tones are fi ltered out before being
transmitted. The Guard Tone will be 2100 Hz, 2325 Hz or the default tone 2175 Hz.
Figure 5-3: Tone Remote Control Sequence
HIGH LEVEL
GUARD TONE
(HLGT)
FUNCTION
TONE
LOW LEVEL GUARD TONE (LLGT)
AUDIO
120 ms 40 ms Length of Transmit
-30 to +10 dBm
-10 dB from HLGT
-30 dB from HLGT
-6 to -18 dB from HLGT