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5.11. Microphone
The microphone is a noise cancelling type to provide improved speech pick-up, noise immunity and reduced echo. The
GSM Standard requires that when in handheld mode, the transmitter audio frequency response must fit within the mask
shown below:
5.12. Receiver
5.12.1. Handheld Mode
Because IOTA is powered from a 2.85 V supply, a low impedance (dynamic) speaker must be used. The GSM
Standard requires that the receiver audio frequency response must fit within the mask shown below:
The phone is designed to meet requirements with a Type 1 artificial ear.
Figure 5.8. Handheld GSM Transmit Audio Frequency Response Mask
Figure 5.9. Handheld GSM Receive Audio Frequency Response
Volume Level
PGA
Volume
Total Gain
1
-6 dB
-12 dB
+2.21 dB
2
-3 dB
-18 dB
-1.12 dB
3
-6 dB
-18 dB
-4.32dB
4
-3 dB
-24 dB
-7.23 dB
5
-6 dB
-24 dB
-10.16 dB
Volume Levels
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