Modem option for data communication
DESCRIPTION
The ACC-513E and ACC-514E are internal option-modems, which are applied to the SD-170EX series to increase capability
for data applications. The goal of an internal modem is to improve the efficiency for data transmission and provide
maximum flexibility for user applications. The most obvious method of increasing the data efficiency is to maximize the data
signaling speed in the limited channel bandwidth. But, FSK, called direct FM modulation, has a very wide transmission
bandwidth requirement. To solve this problem a GMSK (Gaussian Filtered Minimum Shift Keying) internal option-board can
be used. Generally data has a wider bandwidth than audio. So, direct application of data is not matc hed with an audio
system and its application. For instance, if sub-audio (Tone) SQ system applied to a data application, its frequency conflicts
with that of sub-audio. Moreover, the inputted data is filtered by the audio filter circuit resulting in broken data transmission.
To overcome these problems and provide maximum flexibility, an FFSK (Fast Frequency Shift Keying) internal option-board
can be used.
COMMUNICATION BETWEEN DTE AND OPTION-BOARD
Our internal modem options consist of Slave MCU, Modem IC, and extra circuitry. These option-boards directly
communicate with DTE (Data Terminal Equipment) to send and receive meaningful data through the DB -15 connector on
the digital board of the SD-170EX. These modems are designed to accept RS232 serial data format and are also capable of
high speed wireless data-transmission between two or more devices. More detailed information for the modem option
boards is given in the technical manual for the ACC-513E/514E. Your dealer will help you define a TX On/Off delay time,
RX On delay time, Baud Rate, Modem Enabled, Modem Baud Rate, Data flow control, and Test Mode.
Table for modem speed
Channel Space
DTE Baud Rate
Modem Baud Rate
N
arrow (12.5KHz)
1200
1200
2400
2400
S
tandard (25KHz)
1200
1200
2400
2400
4800
4800
Table 1. Available Baud rate for FFSK modem
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