User's Manual

Operation
RFI-148 & RFI-900 High Output Power Paging Transmitters User Manual Page 30 of 134
4.4.1 Modulation Formats
The RFI-148/900250 supports the
following modulation formats:
• POCSAG: Baud rates of 512, 1200 and 2400 bps (2-level FSK) are supported.
• FLEX-2: Baud rates of 1600 and 3200 (2-level FSK) are supported.
• FLEX-4: Baud rates of 3200 and 6400 bps (4-level FSK) are supported.
• Custom: A customizable deviation and FSK level at baud rates up to 6400 bps. See section 4.4.6.
2-level FSK protocol data may optionally be clocked into the paging transmitter using the external data clock
or may run asynchronously. 4-level FSK protocols must use the external data clock.
4.4.2 Inversion
The data that is input on the L-bit and H-bit pins can be inverted using the Data Invert field. The deviation
mapping produced by this described in the following sections.
4.4.3 2-Level Deviation Mapping
When using 2-level FSK i.e. when POCSAG, FLEX-2 or Custom 2-level is selected in Profiles -> Paging
Protocol, only data on either the H- or L-bit is transmitted and the deviation with respect to the H and L bits
is outlined in Table 9 below where N/C abbreviates Not Connected. N/C represents data 1 and Gnd represents
data 0.
L-bit
H-bit
Deviation from Carrier (Hz)
2-Level Data = L-bit
2-Level Data = H-bit
Normal
Inverted
Normal
Inverted
N/C
N/C
− 𝐹
𝑑
+ 𝐹
𝑑
− 𝐹
𝑑
+ 𝐹
𝑑
N/C
Gnd
− 𝐹
𝑑
+ 𝐹
𝑑
+ 𝐹
𝑑
− 𝐹
𝑑
Gnd
N/C
+ 𝐹
𝑑
−𝐹
𝑑
− 𝐹
𝑑
+ 𝐹
𝑑
Gnd
Gnd
+ 𝐹
𝑑
−𝐹
𝑑
+ 𝐹
𝑑
− 𝐹
𝑑
Table 9: 2-level deviation frequency offsets
Where 𝐹
𝑑
is the deviation frequency in Hz.
Paging Protocols -> Profiles-> Paging Protocol
Encoder Interface -> Data Invert