User's Manual

APPLICANT: MOTOROLA, INC. FCC ID: IHDT6AC1
Exhibit 8
44
The main problem causing the Buzz is drops in the Ground line
because the peak current during TX mode. In order to minimize
the Buzz the following acts should be done:
- Use short Flat cable.
- Connect the analog ground from the D15 to all the analog
circuits in the customer application without connecting them
to the power supply ground.
- all the capacitors to ground in the audio circuits should be
connected to the analog ground.
- Any reference voltage that may be used should have the
external capacitor connected to the analog ground.
5.2.3 Analog Audio with Handsfree
The audio In/Out from the D15 for analog Handsfree are the
same as for non Handsfree.All the consideration from Paragraph
5.2.2 are applicable for this mode too.
The additional consideration in this case is to switch the D15
DSP to Echo cancelling mode.
In oreder to switch to handsfree mode use the RS232 port by
sending a switch command.
ATS96=1 Echo canceller is activate. (Handsfree)
ATS96=0 Echo canceller is disabled. (headset - Default)