Specifications

AirPrime UMTS / LTE MC/SL-Series Extended AT Command Reference
146 Proprietary and Confidential 2130616
!AVRXPCMFLTR
Supporting chipsets (voice-
enabled devices only):
• MDM6200 (min f/w rev:
P1_0_0_4)
• MSM6290 (min f/w rev:
K1_0_2_0ap)
• QSC6270 (min f/w rev: S2.0)
Set/report the Rx PCM filter tap
The modem has a 7-tap PCM (Pulse Code Modulation) FIR (Finite Impulse
Response) filter. Use this command to set the Rx PCM filter tap for the specified
profile.
(This filter will be overridden if the PCM IIR (Infinite Impulse Response) filter is
enabled—see !AVRXPCMIIRFLTR on page 148.)
Note: This command is only useful when embedding the modem in a handset.
Mobile phones, PDAs or other handheld transmitters and receivers that incorporate
a GSM module are required to comply with the GSM 11.10 3GPP TS51.010 or 3GPP
TS26.132 standard, or with national standards or government regulations. To
conform to the relevant standard you may need to tune certain audio characteristics.
This command allows you to tune the receive PCM filter to alter audio
characteristics.
Settings are stored in non-volatile memory and persist across power cycles.
The process of tuning the receive audio characteristics generally involves these
steps:
1. Turn off the PCM filter (set <value> parameter to 0x0000 on Tap 6).
2. Use test equipment to obtain a frequency response curve with the passing
mask.
3. Identify the frequency bands that need correction to bring the overall response
within the bounds specified in the test case.
4. Use a filter design tool to determine the filter coefficients, convert to signed Q14
format, and enter the appropriate tap settings using the !AVRXPCMFLTR
command.
5. Repeat the process until the specifications are met.
Device-specific details:
• MSM6290 (Firmware revisions K2_0_7_8ap and lower):
• The change takes effect the next time the modem restarts.
• All other chipsets/firmware revisions:
• The change takes effect immediately for the specified profile.
Usage:
• Execution: AT!AVRXPCMFLTR=<profile>, <tap>, <value>
Response:
OK
Purpose: Set the Rx PCM filter tap for the specified <profile>.
• Query: AT!AVRXPCMFLTR?<profile>, <tap>
Response:
<value>
OK
Purpose: Return the filter setting (<value>) for the specified <profile>.
(Continued on next page)
Table 7-5: Voice command details (Continued)
Command Description