GR4x to GR64 Migration Guide
3.3
General Signal Differences
3.3.1
Audio Interfaces
The behavior of the audio interfaces from an electrical signal perspective is similar in
the GR64 to that of the GR4x series devices.
It is anticipated that there will be minimal or no change to existing application
circuitry for the analogue audio sections. Certainly, it should be possible to achieve
reasonable audio quality by maintaining the same interface components. Some
inevitable fine tuning of audio profiles may be necessary.
The GR64 analogue audio input levels are different to the predecessor products, as
are the internal link gains, plus the GR64 has dynamic AGC on the downlink which
further improves performance. To optimize analogue audio interface performance
users may, at their discretion, adjust input gain scaling and output component values.
It is recommended that users test their existing implementation to assess whether
this is necessary.
The PCM (digital) audio interface in the GR64 is pin compatible with the predecessor
products for a standard 4-wire synchronous serial interface:
•
PCM data from Wireless CPU® to host
•
PCM data from host to Wireless CPU®
•
PCM Frame Sync
•
PCM Clock
The GR64 PCM interface will function in the same sampling manner as the GR4x
products, which uses a 16-bit frame size, 13-bit word, sampled at 8ksps. The GR64
PCM interface functions in a master only mode.
The GR64 PCM word format for regular GSM voice communications is LSB justified,
unlike the predecessor products which were offset. Some minor adjustment in
existing user application may be necessary to perform bit re-alignment to cater for
this difference.
Details of the audio electrical interfaces and PCM frame structure can be found in the
GR64 Integrators Manual available upon request from the Wavecom M2M Customer
Support.
Migration Guide
This document is the sole and exclusive property of WAVECOM. Not to be distributed or divulged without prior written agreement.
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GR4x to GR64
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