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Cellular Overview
Analog Cellular
the complement of the assigned DSAT.
SAT (Supervisory Audio Tone) and DSAT
(Digital SAT)
The Supervisory Audio Tone (SAT) is one of
three frequencies around 6 kHz used in
AMPS signaling. On NAMPS channels SAT
is replaced by one of seven sub-audible digi-
tal equivalents or vectors called DSAT. SAT
(or DSAT) is generated by the cell site,
checked for frequency or accuracy by the cel-
lular telephone, then transponded (that is,
not merely reflected but generated and re-
turned) to the cell site on the reverse voice
channel (REVC). The cellular telephone uses
(D)SAT to verify that it is tuned to the cor-
rect channel after a new voice channel as-
signment. When the central controller
(switch) signals the mobile regarding the new
Figure 4. Channel Assignments
SAT 0 (5970 Hz)
SAT 1 (6000 Hz)
SAT 2 (6030 Hz)
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Cellular System
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©2000 Motorola, Inc.
voice channel, it also informs the mobile of
the SAT frequency or DSAT vector to expect
on the new channel. The returned (D)SAT
is used at the cell site to verify the presence
of the telephone' s signal on the designated
channel.
In general there are three uses of (D)SAT:
(a) it provides a form of squelch; (b) it pro-
vides for call continuation (but if equipped
for it, the switch will allow for VOX on all
models); and (c) (D)SAT is used to prevent
co-channel interference.
DTMF (Dual Tone Multi-Frequency)
DTMF (Dual Tone Multi-Frequency) touch-
code dialing may also occur on voice chan-
nels. DTMF selects two tones from a total of
nine (cellular only uses seven of these tones /
four low and three high tones) to uniquely
represent individual keys.
Table 5. DTMF Values
Key
Low Tone
1
697
2
697
3
697
4
770
5
770
6
770
7
852
8
852
9
852
*
941
0
941
#
941
TDMA T2290/T2297
High Tone
1209
1336
1477
1209
1336
1477
1209
1336
1477
1209
1336
1477
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