Multi-Tech Systems 92U09D24824 ユーザーズマニュアル
Chapter 2 – SocketModem
Cell & iCell GPRS (MTSMC-G2)
Multi-Tech Systems, Inc. GPRS SocketModem Developer’s Guide (S000521A)
45
Microphone Inputs
Note:
For Voice Build Only.
The MIC inputs are differential ones. They already include the convenient biasing for an electret
microphone (0.5 mA and 2 Volts). This electret microphone can be directly connected on these inputs.
The impedance of the microphone has to be around 2K. These inputs are the standard ones for a
handset design.
microphone (0.5 mA and 2 Volts). This electret microphone can be directly connected on these inputs.
The impedance of the microphone has to be around 2K. These inputs are the standard ones for a
handset design.
The gain of the MIC inputs is internally adjusted. The gain can be tuned from 30dB to 51dB. The
connection to the microphone is direct.
connection to the microphone is direct.
Changing the Quad Band
If for any reason, such as moving the modem from one geographical area to another, you want to
change the band, you can accomplish this by using the +WMBS AT Command.
change the band, you can accomplish this by using the +WMBS AT Command.
Steps for Changing the GSM Band
Use a terminal application such as HyperTerminal for entering the AT Command.
1.
To open HyperTerminal, click Start. Then select Programs > Accessories > Communications. Then
click HyperTerminal.
2.
When the command window opens, type AT+WMBS=<Band><Param>. Press Enter.
3.
For <Band>, enter the option you desire:
4 = Dual-band mode 850/1900MHz
5 =
Dual-band mode 900/1800MHz
For <Param>, enter the option you desire:
0 = Modem must be reset in order to use the specified band(s). This is the default.
1 = Modem restarts immediately using the specified band(s).
Example:
AT+WMBS=4,0. Press Enter.
MIC2N
MIC2P
C1
C1 = 22pF to 100 pF
33 pF recommended
33 pF recommended