UMA1002 Datasheet, PDF (7/36 Pages) NXP Semiconductors – Data processor for cellular radio DPROC2

Philips Semiconductors
Data processor for cellular radio
(DPROC2)
Product specification
UMA1002
FUNCTIONAL DESCRIPTION
General
The UMA1002 (DPROC2) is a single-chip CMOS device
which handles the data and supervisory functions of an
AMPS or TACS subscriber set.
These functions are:
• Data reception and transmission
• Control and voice channel exchanges
• Error detection, correction, decoding and encoding
• Supervisory Audio Tone decoding and transponding
• Signalling Tone generation.
In an AMPS or TACS cellular telephone system, mobile
stations communicate with a base over full duplex RF
channels. A call is initially set up using one out of a number
of dedicated control channels. This establishes a duplex
voice connection using a pair of voice channels.
Any further transmission of control data occurs on these
voice channels by briefly blanking the audio and
simultaneously transmitting the data. The data burst is
brief and barely noticeable by the user. A data rate of
10 kbits/s is used in the AMPS system and 8 kbits/s in
TACS. The signalling formats for both Forward Channels
(base to mobile) and Reverse Channels (mobile to base)
are shown in Fig.14.
A function known as Supervisory Audio Tone (SAT), a set
of 3 audio tones (5970, 6000 and 6030 Hz), is used to
indicate the presence of the mobile on the designated
voice channel. This signal, which is analogous to the
On-Hook signal on land lines, is sent out to the mobile by
the base station on the Forward Voice Channel. The signal
must be accurately recovered and transponded back to
the base station to complete the ‘loop’. At the base station
this signal is used to ascertain the overall quality of the
communication link.
Another voice channel associated signal is Signalling
Tone (ST). This tone (8 kHz TACS, 10 kHz AMPS) is
generated by the mobile and is sent in conjunction with
SAT on the Reverse Voice Channel to serve as an
acknowledgement signal to a number of system orders.
The key requirements of a hand-held portable cellular set
are:
• Small physical size
• Minimum number of interconnections (serial bus)
• Low power consumption
• Low cost.
The DPROC2 is a member of our Cellular Radio chip set,
based on the I²C-bus, which meets these requirements.
A cellular radio system schematic using the chip set is
shown in Fig.11.
DPROC2 power-saving features
To support current saving in the application, DPROC2 has
three different modes of circuit operation implemented.
They are decoded by the I²C-bus register bit FVC and by
activity on the data transfer link (TXCLK and TXLINE).
In power-down mode the relevant digital circuits have the
clock disabled, the analog circuits have the bias currents
and the switched capacitor clock switched off.
• Normal mode: all circuit parts are operating (e.g. on
Voice channels)
• Power-down mode 1: the SAT path is in power-down
(e.g. during access of the RECC)
• Power-down mode 2: the SAT path and the total data
transmit path are in power-down (e.g. for Idle state,
DPROC2 operating only on FOCC).
System power-saving features
Besides the above mentioned power-down modes
DPROC2 also includes features to reduce system current
(e.g. switching off parts of the receiver, and put the system
controller into Idle mode for longer periods of time).
All these features are controlled by the I²C-bus. For further
explanation of the following features refer to the Section
“I2C-bus serial data link (SDA; SCL)” sub-section “I2C-bus
registers”.
MAJORITY VOTING (ONLY IN LQFP32)
Majority voting includes more intelligence. This feature is
enabled in FOCC with I²C-bus bit MAJ = logic 1.
If 3 consecutive identical words have been received it is
signalled via pin MVO. Therefore during the last 2 frame
words the receiver could be switched off to save system
current consumption.
CONTROL FILLER WORDS FILTER
System current can be further reduced by an on-chip
control filler words filter in FOCC, which enables the
detection of consecutive identical control filler words.
If consecutive control filler words are identical (i.e. DCC,
CMAC and WFOM) they will not be passed on to the
microcontroller. Consequently the system controller can
remain in power-saving mode.
1997 Jan 28
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