User guide
Table Of Contents
- Presentation
- Warning
- Copyright
- 1 References
- 2 Packaging
- 3 General presentation
- 4 Characteristics and Services
- 5 Use of the modem
- 5.1 Starting with the modem
- 5.2 Specific recommendations for the use of the modem in vehicles
- 5.3 GSM led of the modem
- 5.4 Echo function of AT commands deactivated
- 5.5 Checking the quality of the GSM reception signal
- 5.6 Verification of PIN code
- 5.7 Verification of modem registration on GSM network
- 5.8 Verification of modem registration on GPRS network
- 5.9 Verification of internal voltages of the modem
- 5.10 Main AT commands (HAYES)
- 5.11 Turning OFF the modem
- 5.12 Updating procedure of the modem
- 6 Trouble Shooting
- 7 Functional description
- 8 Technical characteristics
- 8.1 Mechanical characteristics
- 8.2 Electrical characteristics
- 8.3 Environmental characteristics
- 8.4 Standards/Conformities
- 9 Security recommendations
- 10 Recommended accessories
- 11 Client support
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Descriptions and non-contractual illustrations in this document are given as an indication only.
ERCO & GENER reserves the right to make any modification.
Dct_427_01
7.8.1 Microphone inputs
The microphone inputs are assembled in differential to reduce the noise in common mode and the TDMA
noise.
They already include the functionality for a microphone like Electret (0.5 mA and 2 Volts) and they are ESD
protected. This Electret microphone can be directly connected to these inputs allowing an easy connection to
a telephone handset.
The microphone impedance is around 1.5 k๎.
The gain of the microphone inputs is internally adjusted by a differential amplifier and can be adjusted with
the command AT+UMGC (see the document "u-blox_AT_Commands_Manual_xxx.pdf"). The amplifier has a
gain of 25.6 dB and a Bias generator that supplies an external voltage of 2 or 2.5V for the microphone Bias.
Table 25 : Description of microphone input
Signal
Connector Sub HD
Pins number
I/O I/O type Description
MICP 4 I Analog Positive input of Microphone
MICN 5 I Analog Negative input of Microphone
7.8.2 Loudspeaker outputs (Speaker)
The outputs are assembled in differential to reduce the noise in common mode and the TDMA noise.
These outputs can be directly connected to a loudspeaker.
Table 26 : Description of loudspeaker output
Signal
Connector Sub HD
Pins number
I/O I/O type Description
SPKP 10 O Analog Positive output of loudspeaker
SPKN * 15 O Analog Negative output of loudspeaker
* When the ANA2 option is present, the speaker audio output is available between the SPKP
(pin 10 of the 15-pin sub D HD) and the 0V.
In this case, the audio power available is divided by 2 compared with the ยง 8.2.4.2
Loudspeaker.