The T221 Mode provide a method to accomplish test case 22.1 in 3GPP TS51.010. What the test set need to implement is as the following description quoted from TS51.010:"The SS measures the MS transmitter output power on TDMA frames 6, 19, 32 and every subsequent 13th TDMA frame to TDMA frame 214. The SS also monitors the MS_TXPWR_CONF field in the uplink SACCH L1 header for the four SACCH multiframes after the SS signals the power change."Given that this feature needs to measure multiple frames continuously at the precise position, a protocol trigger will be used since protocol knows the exact position of the burst need to be measured. The test provides the TC221 setting to control whether or not the protocol trigger is generated. Set the T221 Mode to On will generate protocol triggers on TDMA frames -6, 6, 19, 32 and every subsequent 13th TDMA frame to TDMA frame 214 in a SACCH block and report the four MS_TXPWR_CONF value. The protocol trigger will start from the next SACCH block after the TC221 is set to ON.
The GPIB command to set the T221 Mode is CALL:TCHannel:T221:MODE
See How Do I Change Cell Operation Parameters? to access this setting.