Mark, a very good article from multichannelnews.
multichannel.com
TCI, with gear supplied by Harmonic Lightwaves Inc., is using DWDM to distribute dedicated signals to hubs, at which point signals are amplified and split for distribution to each node, in combination with nondedicated broadcast-video channels over the same fiber.
This combining of a single, dedicated service wavelength with the 80 or so broadcast-video channels at another wavelength into a single fiber going out to each node is not problematic with regard to the difficulties of combining QAM and analog wavelengths, because only a single QAM wavelength is involved, noted Mark Trail, director of product-line management for transmission systems at Harmonic.
The two signals operate at different power levels, with the digital arriving at 8 decibels per milliwatt to 10 dBm at the receiver, thereby avoiding interference between the two different wavelengths, Trail said.
This distribution topology avoids any need for regenerating signals at the hubs, relying instead on erbium-doped fiber amplifiers and WDMs to complete the hub-to-node links, he added.
"We have several other MSO customers that are making use of this technology," Trail said. Most are applying the technique in single systems before going to wider deployment, he added.
"It's not clear what the solution [for subdividing nodes] is," said Eric Schweitzer, director of product-line-receiver systems for Harmonic. "The leading options are frequency stacking versus wavelength-division multiplexing."
In the latter mode, each upstream feed from a coax node segment is fed into a wavelength-specific laser, and the wavelengths are combined into one fiber for the return. But this solution runs into the 1550-transmitter costs.
"We're also seeing some operators subdividing the node on the return path by using a separate [1310] transmitter and fiber for each path, but containing all of the electronics in a single housing," Schweitzer noted.
And here is what V-Bits brings to the table.
multichannel.com
There's a new entry on the shortlist of statistical-multiplexing players, and it is aiming to leverage its ties with Texas Instruments Inc. for programmable chips and with Harmonic Lightwaves Inc. for its existing cable relationships.
V-Bits Inc., a two-year-old Silicon Valley start-up headquartered in San Jose, Calif., came out of the laboratory recently with what it calls "RateMux," saying that the device will give Imedia Corp.'s similar "CherryPicker" a competitive rumble.
David Beddow, CEO of Tele-Communications Inc.'s National Digital Television Center -- where its Headend in the Sky feed originates -- said he's aware of V-Bits' strategy and he likes it.
"I think that the approach that the V-Bits folks have is a bit better, actually, than what Imedia is doing. However, [V-Bits is] not as far along as Imedia," Beddow said.
At the core of V-Bits' technique is a software-based statistical-multiplexing algorithm that differs from alternative techniques because it sits on TI's new 6000x-series chip. This translates into affordability, because the chips cost between $25 and $130 each, Zhang said. Plus, the chips were designed to be fully programmable, meaning that operators that want to tweak RateMux's performance after the product is installed can do so.
Harmonic has agreed to license RateMux, and it will build the technology into its "TRANsend" line of digital-headend gear. Ed Thomson, vice president of business development for Harmonic, said in a prepared statement that V-Bits' "compelling knowledge and expertise in the digital production environment was translated into a highly optimized solution."
We are gonna kick some ass.
Tim |
