Pulse, a Technitrol Company and owner of the popular Excelsus DSL filter brand, and Comtrend Corporation, a leading supplier of DSL equipment, today announced the results of Internet protocol television (IPTV) over VDSL2 testing. The successful tests demonstrated error-free transmission of video, data, and voice over VDSL2 in difficult "ring trip" conditions. This technical breakthrough overcomes a major problem for telephone companies delivering IPTV over traditional phone lines.

When analog voice and digital video signals are transmitted simultaneously over VDSL2, there can be interference caused by ringing voltage or "ring trip." This may occur when a ringing telephone is answered and can corrupt the video, creating unacceptable video quality. The technical challenge has been to eliminate the video errors while maintaining DSL transmission rate and signal quality.

The interoperability tests were conducted last month at Broadcom's design lab in Mechelen, Belgium. Broadcom's test network included outside plant twisted-pair phone lines and coaxial cable. Comtrend featured their CT-5371 VDSL2 multimode DSL router based on Broadcom's VDSL2/ADSL2+ CPE and CO chipsets. Pulse provided a variety of components, including the Excelsus CP-V413 splitter circuitry and Pulse's multiport splitter design for central offices (COs). The test setup replicated conditions typically found in customer premises and CO environments. Under these conditions, the test results showed no bit rate errors.

"In a VDSL2 network transmitting video, the performance of modems, routers, and splitters is critical. Error-free performance from these devices in the presence of ring trip is key for the delivery of high quality IPTV services," said Greg Gough, Pulse's staff systems engineer. "Together Pulse and Comtrend have addressed the challenge of VDSL2 performance during ring trip," said Joe Maier, Comtrend's director of technology. Based on these positive test results, products from Pulse and Comtrend are now available for field tests in the public switched telephone network (PSTN).