RWOP is the short title for the "RW Open Protocol V1.1" according to information provided by Paul R Signorelli, WØRW.

RWOP is a system based on the BA1304 Electronic Message Unit (EMU) of the UK/PRC 319 HF/VHF man-pack tactical radio. It uses standard frequency shift keying (FSK) with 850 Hz shift and forward error correction (FEC) to protect against reception errors. The bandwidth is dependent on keying speed:

The EMU has a 20-button numeric key pad. RWOP uses two digits to represent letters and other characters, as follows:

00 = Space
01 = A
02 = B
.
.
.
26 = Z
30 = . (period)
31 = !
32 = @
33 = #
34 = -
35 = "
36 = , (comma)
37 = ?
38 = /
39 = "="

Message numbers begin with "8" because 8 looks like a # number sign :

80 = 0
81 =1
....
89 = 9

The first data group of all messages should be the date-time group and should be sent in the clear as direct numbers for simplicity.

This simple numeric message conversion protocol will allow numeric messages to be sent using the BA1304 EMU. The numeric message is not encoded for the purpose of obscuring meaning of the message. It is simply an alternative character set and the message can be easily transcribed.

Here is a sample message:

182000 (sample date-time group)
031700
040500
238018
230003
151215
180104
150011
EOM (End of message)