The Voice Transcoding Subsystem (VTS) is a software product, typically used in circuit-switched trunking applications, which implements T1 and E1 transcoding as specified in the ANSI T1.302a- 1992 and ITU-T G.761 specifications. VTS compresses two T1 or E1 lines into a single line or decompresses a single span into two. Compression is accomplished using G.726. Although it can be adapted to other processors, VTS is specifically optimized for the Texas Instruments TMS320C6000 DSP. In full-duplex mode it operates on a pair of TI TMS320C6211-150 processors, or on a single more-powerful member of the ‘C6000 product family.
VTS replaces the transcoder chipset from Brooktree (now Mindspeed, a subsidiary of Conexant) that includes the Bt8110 ADPCM Processor and the Bt8200 ADPCM Formatter. VTS emulates the control structure of those chips to maintain compatibility with legacy control software.
VTS consists of four modules: E1 Compressor, E1 Decompressor, T1 Compressor, and T1 Decompressor. The VTS product deliverable includes example DMA code for controlling software transfers on a ‘C6211 processor, but generally the OEM must implement code for interfacing with the hardware.
Example hardware-configuration software is also supplied for the Multi-Channel Buffered Serial Ports and the DMA channels that are standard on the ‘C6000 line. The OEM can replace or modify this code as required.