User's Manual

Internal Encoding
RFI-148 & RFI-900 High Output Power Paging Transmitters User Manual Page 38 of 134
6. Internal Encoding
6.1 Overview
The RFI PTX supports both internal and external page message encoding:
• External Encoding: The historical and most common way of interfacing to the RFI PTX is by clocking
in pre-encoded paging data using the TTL inputs on the LIU. The RFI PTX will typically interface
with a Base Station Controller (BSC) that provides the encoded data.
• Internal Encoding: The RFI PTX supports internal encoding of the POCSAG paging standard for
generating messages when submitted through the serial or Ethernet ports. Messages can be submitted
using the industry standard TNPP, TAP, or PET protocols. A custom protocol developed by STI
Engineering also provides an additional simple datagram protocol for submitting pages: “Page
Datagram”.
This section provides an overview of the internal encoding functionality.
When internal encoding is in use, the Hardware PTT and Auto PTT functions are disabled.
6.2 POCSAG Settings
The RFI PTX has several options for the POCSAG protocol in order to support differing networks:
• Preamble Length: The POCSAG preamble is used to wake up paging receivers and allow them to lock
to the incoming signal. A default value of 576 bits is used which is the de facto standard for POCSAG.
• Function Override: Allows the function bits in a POCSAG address codeword to be overridden to this
value. By default the function bits will follow the message encoding (00: Numeric, 01: Tone-only, 11:
Alpha-numeric). The function bits have also been known as the “Group Code”.
• Purge Timeout: The RFI PTX waits up until the purge timer in order to collate incoming page
submissions into a single large transmission. This saves on overhead of having to repeat the preamble.
Shorter Purge Timeouts will produce lower latency on page submission to transmission, at the possible
expense of lower throughput when sending many page messages.
6.2.1 Page Repeating
The RFI PTX supports a set of rules that trigger the repetition of a submitted page messages. When a rule is
enabled any messages which match the cap code will be repeated Count number of times every Delay seconds.
6.2.2 Tx Delay
The RFI PTX supports a configurable delay on internally encoded messages. When Tx Delay is not zero then
messages will be held for “Tx Delay” seconds before transmit. If repeats are configured then they will occur
the configured repeat time after the Tx Delay.
Paging Protocols -> Encoding Mode
Paging Protocols -> POCSAG
Paging Protocols -> POCSAG -> Page Repeat Rules
Paging Protocols -> POCSAG -> Tx Delay