AIS Baseband IC with/without RF Synthesiser
CMX7032/CMX7042
Analog I/O Functions
Auxiliary ADC system
o
o
Two 10-bit successive approximation ADCs with integrated sample and hold
One AuxADC is dedicated to RSSI measurement in a user defined window, the other is
available for general use
Ramping auxiliary DAC
o
DAC sequences through a user-configured sequence of DAC output values to develop a
specific rising/falling DAC output signal. This is useful for ramping an RF PA, and can be
configured to happen automatically at the start and end of a burst.
Can operate as a general purpose DAC, if desired
o
Three general purpose auxiliary DACs
System Functions
All internal subsystems are controlled via a single serial host interface to reduce host µC pin count
and simplify external host driver complexity.
Transaction oriented command/response logical host interface executes tasks supporting normal
operation, device configuration, and functions to assist manufacturing calibration trimming of
external circuits.
Internal system clock derived from RF synthesiser reference oscillator and eliminates the need for
additional XTAL or baseband clock oscillator.
User clock synthesisers generate two clocks for external use and eliminates an external clock
synthesiser when needed to support peripheral devices.
User selected method for loading a Function Image™ - either from the host µC via C-BUS or from
an external serial memory.
Integrated 2.5V regulator can develop 2.5V from required 3.3V supply.
Powersave facilities minimize total system power.
6.2 AIS system formats
The AIS system uses two basic channel access mechanisms: Self Organising Time Division Multiple
Access (SOTDMA) and Carrier-Sensing Time Division Multiple Access (CSTDMA). The CMX7032 and
CMX7042 are compatible with both systems and offer additional features which simplify the
implementation of CSTDMA. The SOTDMA system is detailed in ITU-R M.1371-1 and IEC 61993-2 while
the CSTDMA is detailed in IEC 62287.
The CSTDMA system is used in the implementation of the Class B-CS AIS. This requires the receiver to
monitor the first part of a slot for an existing AIS transmission from another station before deciding to use
the slot for its own transmission or aborting and selecting a different slot.
The SOTDMA system is used in the Class A and Base Station AIS as well as the Class B-SOTDMA AIS
standard.
The CMX7032 and CMX7042 are particularly well suited to the Aids to Navigation applications where
power consumption must be minimised.
The relevant International standards are:
[0]
[1]
[2]
[3]
[4]
[5]
[6]
ITU-R M.1371-4
IEC 61993-2 Class A
IEC 62287-1 Class B CSTDMA
IEC 62287-2 Class B SOTDMA
IEC 62320-1 Base Station
IEC 62320-2 Aids to Navigation
IEC 61097-14AIS-SART
2012 CML Microsystems Plc
18
D/7032/42_FI1.2/13
CMLMICRO [ CML MICROCIRCUITS ]
