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Service Manual
Analog Cellular Signal Summary (AMPS
and NAMPS)
The diagrams on the following pages out-
line the various uses of the signals employed
in cellular systems. These signals include:
SAT (Supervisory Audio Tone) 5970 Hz, 6000
Hz, or 6030 Hz. Used in AMPS for chan-
nel reuse, muting audio (squelch), and call
continuation [typically ± 2 kHz deviation].
Digital SAT (DSAT) - One of seven codes or
vectors used in NAMPS for the same pur-
pose as SAT
[± 700 Hz sub-audible NRZ
data].
Data - Transmitted at 10 kilobits/second in
AMPS and 200 bits/second in NAMPS. Data
is used for sending System Orders and Mo-
bile Identification. Do not confuse data with
the 10 kHz signaling tone. In AMPS, data is
transmitted as Manchester-encoded Fre-
quency Shift Keying (FSK), where the car-
rier is shifted high or low 8 kHz, and the trail-
ing edge transition is used to represent the
Figure 5. AMPS Deviation in kHz
±14
±12
±10
± 8
± 6
± 4
± 2
AMPS Deviation in kHz
AMPS Voice Channels
Data
SAT
© 2000 Motorola, Inc.
logic. In NAMPS, data is transmitted as NRZ
(Non-Return to Zero) FSK, where the carrier
is shifted high or low 700 Hz, and the fre-
quency shift itself is used to represent the
logic.
Signaling Tone (ST) - A 10 kHz tone used in
AMPS for mobile ringing, call terminations,
hand-offs, and switch-hook operation [typi-
cally ± 8 kHz deviation]. ST is always ac-
companied by SAT.
Digital ST (DST) - One of seven digital
equivalents of ST used on NAMPS channels.
The transmitted DST is always the comple-
ment of the assigned DSAT [± 700 Hz sub-
audible NRZ data].
Audio - Includes microphone audio and
DTMF [maximum ± 12 kHz deviation AMPS,
± 5 kHz deviation NAMPS]. DTMF devia-
tion should be measured on the radians scale;
use key five looking for 9 radians. Audio is
accompanied by SAT in AMPS signaling.
SAT
SAT
Audio
Audio
Signal
Tone
Cellular Overview
Analog Cellular
Control
Channels
Data
Data
7
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