Technical Manual
MX800 Transceiver T19 Option
1.7.3 Tone Remote Control
Tone Remote Control (TRC) is a Motorola control sequence used in keying transmitters.
The TRC sequence comprises three basic elements: High Level Guard Tone (HLGT), Function
Tone (FT), and Low Level Guard Tone (LLGT). The TRC sequence follows an audio level
convention whereby the FT is 10 dB below the HLGT and the LLGT is 30 dB below the HLGT.
The relative audio levels of the HLGT, FT and LLGT are usually referenced to a system Test
Tone level. This Test Tone is defined as a 1000 Hz signal sent from the controller at the system
operating level by which the transmitters are aligned to produce nominal analog transmit
deviation (3 kHz deviation for a wideband radio). Relative to the Test Tone, the HLGT is 5 dB
above the Test Tone, the FT is 5 dB below the Test Tone and the LLGT is 25 dB below the Test
Tone. The tone durations are 120 ms for the HLGT, 40 ms for the FT and the LLGT is a
continuous tone. The LLGT occurs only in the "Transmit On" function. The transmitter stays
keyed so long as this tone is present and only if this tone was preceded by the proper tone
sequence.
The HLGT (commonly 2175 Hz) is a tone that indicates the start of a TRC control sequence. The
FT is used to tell the transmitter on what frequency channel to key or is used to define other
functions to be performed. FT values range from 750 Hz to 2350 Hz in 100 Hz steps (excluding
2150 Hz and 2050 Hz). The 1950 Hz function tone is the standard key on Channel 1 frequency.
As previously mentioned, the LLGT is to tell the transmitter to key up.
Both the HLGT and the LLGT can be collectively called the Guard Tone (GT) and must have the
same frequency. There are several choices for the GT, depending on the enforced tone standards,
2175 Hz (commonly used in US systems), 2100 Hz (5-tone ZVEI), and 2325 Hz (5-tone CCIR /
EEA).
Table 5.1. Tone Remote Control Frequencies
Frequenc
y (Hz)
Single Channel Base
(T1R1)
Two Channel Base
(T2R2)
Four Channel Base
(T4R4)
Eight Channel Base
(T8R8)
2050
Monitor
Monitor
Monitor
Monitor
1950
Transmit on Channel 1
with subtone
Transmit on Channel
1 with subtone
Transmit on Channel
1 with subtone
Transmit on Channel
1 with subtone
1850
Transmit on Channel 1
without subtone
Transmit on Channel
2 with subtone
Transmit on Channel
2 with subtone
Transmit on Channel
2 with subtone
1750
Reserved for second
receiver
Reserved for second
receiver
Reserved for second
receiver
Transmit on Channel
7 with subtone
1650
Reserved for second
receiver
Reserved for second
receiver
Reserved for second
receiver
Transmit on Channel
8 with subtone
1550
Repeater disable
Repeater disable
Repeater disable
Repeater disable
1450
Repeater enable
Repeater enable
Repeater enable
Repeater enable
1350
Wildcard 1 on
Wildcard 1 on
Transmit on Channel
3 with subtone
Transmit on Channel
3 with subtone
29
© SPECTRA ENGINEERING 2010 Revision 1.0.4