User's Manual

Analogue Paging
RFI-148 & RFI-900 High Output Power Paging Transmitters User Manual Page 51 of 134
8. Analogue Paging
RFI-148 units offering Analogue Paging support allow a tone or audio signal (from e.g. a microphone) to be
injected into the PTX via the LIU. Once configured and calibrated, the PTX will frequency modulate the
carrier according to changes in the audio amplitude.
Dedicated, configurable Deviation (“ATM28”) and Carrier Offset (“ATM27”) values are provided for
Analogue Paging, as distinct from their existing digital paging counterparts. While analogue mode is engaged,
a “Current Deviation” diagnostic is also provided (“ATM29”).
All parameters and behaviours that support configuration and/or diagnostics can be done so either via AT
command (refer to Appendix D) or Cruise Control. Attempts to configure invalid or inconsistent values will
return an error.
Refer to Table 16 for the relevant performance specifications.
Note that alternate use of the existing digital paging (i.e. POCSAG, FLEX-2, FLEX-4 etc.) and analogue
paging can be achieved simply by controlling LIU Pin 13. That is, the Analogue Paging feature itself can
remain enabled permanently.
Is strongly advised to ensure that the configured Deviation setting does not exceed 85% of the configured
Deviation Limiter value, to ensure minimal audio distortion.
8.1 Compatibility
Analogue Paging operation requires firmware support, specifically firmware 4.3-B and above, and additional
hardware within the transmitter (nominated during purchase with the ‘A’ order code character – see Appendix
F).
8.2 Features
Analogue Paging offers several configurable features:
8.2.1 Signal format
The LIU will accept the signal modes given in Table 12.
Signal Mode
LIU Connections
Pin 5
Pin 6
Fully-differential
Audio+
Audio-
Pseudo-differential
Audio+
DC Voltage
Single-ended
Audio+
GND
Table 12: LIU configuration for supported audio signal modes
Paging Protocols -> Analogue