Specifications

Motorola Tone Signalling.
Within the Motorola tone signalling format, the controller sends three tones to the remote site
every time PTT is operated or a function switch is operated. The tones are basically a high
level guard tone (used to alert or wake up the base station) a function tone, and a lower level
key tone which is the same frequency as the high level guard tone. The low level tone
continues to be sent for the period that the PTT key is operated.
The base station installer will need to determine the function required, the button it is
allocated to on the control unit, and the frequency used for that function within the radio
system. The chart below shows the common Motorola settings. Note that the signal tone will
only perform one function, this is determined by the programming of the base station.
A line proving tone may be generated by the base station, and will consist of one of the guard
tone options, again determined at system set up. The line proving tone is present all the time
until the receiver mute on the base station opens and then the tone is removed.
The Motorola Tone set and Functions
Guard Tone Options- both high and low level.
2100Hz
2175Hz
2325Hz
Ack tone from base station 850Hz
Additional tones and function options
Frequency OptionA Option B Option C
2050Hz CTCSS toggle
1950Hz #1 function Channel 1
1850Hz #2 function Channel 2
1750Hz RX 2 Mute Channel 3
1650Hz RX 2 Mute Channel 4
1550Hz Max Squelch TT off CTCSS On
1450Hz Min Squelch TT On CTCSS Off
1350Hz #3 Function CTCSS 1 select Wild Card 1 On
1250Hz #4 Function CTCSS 2 select Wild Card 1 Off
1150Hz CTCSS 3 select Wild card 2 On
1050Hz CTCSS 4 select Wild card 2 Off
All of the above functions are set within the Motorola base station when it is programmed.
The DRC-1 function and Shift-function keys can be programmed to send these tone
frequencies to the remote base station.
In any signal sent to the base station, the tone must have three components. A high and low
level guard tone plus a function tone sandwiched between them. When the PTT is operated,
the system must re-write the channel in use. If 2100Hz is used a guard tone, then for example,
2100 high-1950-2100low are sent. The 1950 sets or resets the station to channel 1 and the
guard tones wake the base station and keep it keyed whilst the PTT is held on.