In the beginning of the 21 th century very interesting project has been developed in Terayon communication systems, that became later Motorola.
The Terayon Voice over IP solutions were almost the first in the world complete hardware + software solution.
Large spectrum of applications was open for such the revolution technology. The telephone signal is supposed to be digitized and then transformed to IP packets. Instead telephone cables the information is transmitted over TCP/UDP/IP everywhere in world wide web.
A lot of standard telephony signals should be detected in this project: Caller ID, fax, modem, TDD, DTMF, etc. Different audio codecs have been implemented and optimized for TI DSP: G711, G723, G726, G.729.
The quality of communication was considered as sufficiently good with the acceptable delay < 120 mseconds.
Complete hardware +software solution has been developed in one company.
Technical realization of project.
Both hardware and software implementation took place in this project. MGCP server turned on the crate with multiple DSP cards.
Software was composed of protocol part (MGCP parsing and control functions), codecs implementation (optimization of pre-implemented C code to TI DSP assembly), DTMF, fax, modems coller ID signals implementation.
My participation in project:
The following task have been entrusted me:
- Development of low level hardware drivers
- Development of MGCP protocol parser
- Development of specifications on the signal processing detection: Caller ID, DTMF, Fax/Modems signals Audio Codecs.
- Development of architecture specification on the Voice over IP MTA project
- Development of TCP/IP network packets simulation
Environment and technics used in project:
Environment: C/C++, Lynx RTOS, Win32, Bounds Checker, MS Visio, MatLab, DSP, TCL/TK, Zarak Abacus, MTAs, Motorola 8000 Crate, PCI bus, Jeeni
Techniques: Goertzel algorithm, digital LP filtering, rejection filtering, Codecs 7.711,G723, G726, text protocol parsing, TCL test scenarios realization, real time Linux driver development.
Main results:
- Some signals processing algorithms implementation
- Documentation on the VoIP MTA architecture development
- VoIP SW/HW standard system tests realization
- Hardware Lynx driver implemented
- C/C++ MGCP parser part implemented
