Channel Mode Setup

Last updated: December 2, 2008

This section is only applicable to GSM.

The channel mode function allows you to command a mobile to switch between the available channel modes either before a call is originated, or while a call is connected with any or all of the supported measurements running. In half rate speech mode you can also set the half rate sub channel. Table 1: Logical Speech Channels contains all the Logical Speech Channel modes available.

If you change the channel mode when no call is connected, the mobile is requested to go into the selected channel mode the next time a mobile originated or mobile terminated call is initiated.

If you change the channel mode when a call is connected, the mobile is requested to go into the selected channel mode immediately.

You should only change the channel mode when the test set is in active cell operating mode.

Table 1: Logical Speech Channels

The following measurements are supported in enhanced full rate, full rate and half rate speech modes:

• Analog Audio (AAUDio)
• GSM Bit Error
• GSM Fast Bit Error (FBERror)
• Dynamic Power (DPOWer)
• I/Q Tuning (IQTuning)
• Output RF Spectrum (ORFSpectrum)
• Phase and Frequency Error (PFERror)
• Power versus Time (PVTime)
• Transmitter Power (TXPower)

You can initiate a Decoded Audio (DAUDio) measurement in enhanced full rate and half rate speech modes. However, this measurement is not supported in this channel mode and the integrity indicator will report that the results are questionable (see Decoded Audio Troubleshooting ).

The following measurement is also supported in AFS (Adaptive Full) and AHS (Adaptive Half) speech modes:

• AMR In-Band Frame Error (IFER)

If the mobile station is not capable of performing a loopback type I, meaningful results will not be generated for the IFER measurement. Also, if the Speech Frame Delay is set to Auto, the IFER measurement will not begin at all if the mobile station does not support loopback type I. See In-Band Frame Error (IFER) Measurement Description .

If you switch the channel mode between the different speech modes when the downlink speech source is set to Echo (see CALL:TCHannel:DOWNlink:SPEech ), you may hear momentary audio bursts from the mobile.

The Channel Mode can be manually selected by navigating to the TCH Parms menu, and pressing Channel Mode Setup ( F11 ). The TCH Parms menu is accessed by pressing F8 on the Call Parms menu, see How Do I Change Call Parameters? .