Technical Manual
MX800 Transceiver T19 Option
There is support for a number of common SELCALL tone sets as well as an option to create a custom
tone set. Although 12 tones are commonly used in SELCALL systems, a tone set of 15 tone frequencies is
defined to allow future expansion of the protocol and system. There are currently no plans to support the
hexadecimal sequential code (HSC) system. The number of symbols (tones) per SELCALL packet is
selectable from 1 to 12. Tone durations have been specified nominally and tones within the allowable
tolerance will be decoded. Tones not complying with the tone duration requirements will be discarded as
will the SELCALL packets containing them.
The SELCALL system as implemented currently only supports fixed size packets, although the packet
size is user programmable. This means that if the number of digits is set to 5, then only the SELCALL
packets with 5 tones will be decoded. This is to reduce the likelihood of false decodes due to in-band
audio.
The Base Station ID is the SELCALL packet that will be transmitted if the push-button on the front panel
is depressed. This will cause the transmitter to key-up and send the SELCALL sequence after the protocol
silence preamble.
Hardware configuration consists of setting jumper JMP20 to positions 2-3 (DCFM) and adjusting the tone
level (RV1) to obtain a deviation of 2500 Hz (wideband).
1.6.3 Enabling and disabling SELCALL
The SELCALL system can be toggled using Configuration Menu - Selective Calling (SELCALL) Menu,
Toggle SELCALL mode (
C L 1
). Once the SELCALL system is disabled, the terminal screen should
look similar to this, Figure 1-3 Menu with SELCALL
Figure 1-3 Menu with SELCALL disabled
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© SPECTRA ENGINEERING 2010 Revision 1.0.4