– 5-12 –
The GSM Standard requires that the receiver audio frequency response must fit within the mask shown below.
Figure 5.12. Handheld GSM Receive Audio Frequency Response
The phone is designed to meet requirements with a Type 1 artificial ear.
1
+1 dB
0 dB
+3 dB
2
–2 dB
0 dB
–0 dB
3
–5 dB
0 dB
–3 dB
4
–5 dB
–6 dB
–9 dB
A second speaker is mounted in the rear case for DTHF operation.
Ring tones and melodies are played via the loud speaker. The volume level of ring tones is defined by the 6-bit PWM register
setting in AD6537.
5.3.3. Receiver
5.3.4. Loud Speaker
Volume Level
PGA
Volume
Total Gain
5
0
-5
-10
-15
1,000
10,000
100
Frequency (Hz)
(dB)