Oracom PROFI MX160 - Manual (Page 7)

2. Description of Radiomodem MX160
2.1. Radio part
The architecture of MX160 radio modems resolves most of the requirements placed on a top quality
user friendly radio modem with a very short switching time between receiving and transmitting. Frequency
synthesis enables operation on any random channel from a given frequency band. The operation of
the radio data transceiver module is controlled and diagnosed by the micro-controller. The receiving
part of the radio modem works with double mixing. Concentrated selectivity is divided between both
intermediate frequency levels. The first filter carries out basic channel pre-selection up until attenuation
which ensures the linear function of the following second mixer and intermediate frequency amplifier.
The second filter of concentrated selectivity has an attenuation characteristic necessary for channel
selection in the used channel spacing of 200 kHz. Logic circuits, switching stations between modes of
receiving and transmitting, have high noise immunity and switch respective blocks sequentially. This
minimises most transient parasite states and optimises bandwidth during switching. Station block modes
are logically tied and switching of the station to transmitting mode is tied to the frequency synthesiser
lock, the internal temperature of the radio transceiver module and the value of the supply voltage.
2.2. Modem part
The control microcomputer has 4 MB of FLASH memory and 16 MB of RAM memory available. The
battery, real time backup supply, detector of supply voltage failure and watch dog circuits belong
amongst the other circuits of this block. If there is a supply voltage failure the fact is recorded into
memory with the respective time data thanks to the charge stored in electrolytic capacitors. The user
therefore has information available about the time and duration of possible faults caused by power
failures. It is possible to connect equipment with signalling rates up to 115.2 kbit/s to the modem via
the RS232 data interface. RS232 interface converters are protected against overvoltage with TRANSIL
elements. A lithium battery is used for backing up in the modem part.
Note
Owing to the use of lithium batteries in the modem part it is not recommended to store them
for a period of longer than 2 years.
2.3. Supplying
The radiomodem is supplied by the DC current 13.8 V. The consumption in the quiet state is from 350
to 500 mA according to module used, the consumption at transmitting is up to 2 A. The modem can
be set in the SLEEP mode when the consumtion drops down to 2.5 mA. The return in the active mode
can be done by the signal inputting on the serial port or after a preset time.
2.4. Radio Modem Assembly
Radio modems MX160 are special devices which require skilled assembly. All supplied equipment is
assembled by RACOM at the user’s site. For subsequent maintenance RACOM specially trains the
user’s skilled staff and as an additional aid provides them with Operating regulations for radio data
networks and MORSE Firmware – Documentation.
7 © RACOM s.r.o. – Wideband modems – PROFI MX160
Description of Radiomodem MX160