Specifications

Modem Option for data communication

ACC-513 and ACC-514 are new kinds of internal option-modems, which are applied to SD-160

series to increase capability for data application. The goal of internal modem is to improve the

efficiency for data transmission and provide maximum flexibility for user application. In former

case, the most obvious method of increasing the efficiency is to maximize the data signaling

speed in the limited channel bandwidth. But, FSK, called direct FM modulation, has very wide

transmission bandwidth requirement. To solve this problem, Maxon supplies GMSK(Gaussian

Filtered Minimum Shift Keying) internal option-board. In latter case, to improve quality of service,

some of service provider (or user) want to apply new radio to their existing system without

additional investment to establish new system even if it’s audio system. But, data application

can’t be directly applied in audio system because of its spectra characteristic. Generally, spectra

of data have wider bandwidth than audio. So, direct application of data is not matched with

audio system and its application. For instance, if sub-audio(Tone) SQ system is applied to data

application, its frequency spectra conflict with that of sub-audio. Moreover, if inputted data is

filtered by audio filter circuit to avoid this problem, some of that will be broken. Therefore, to get

over these problems and provide maximum flexibility, Maxon prepares FFSK(Fast Frequency

Shift Keying) internal option-board.

Our internal modem option boards consist of Slave MCU, Modem IC, and extra circuitry. These

option-boards directly communicate with DTE (Data Terminal Equipment) to send and receive

the meaningful data through the DB-15 connector on digital board of SD-160. These are

designed to accept RS232 serial data format and also capable of high speed wireless data-

transmission between two or more devices. More detail information for modem option boards is

given in technical manual for ACC-513/514. Moreover, 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

1200 1200

Narrow (12.5KHz)

2400 2400

1200 1200

2400 2400

Standard (25KHz)

4800 4800

Table 3.6. Available Baud rate for FFSK modem