What's New in Program Distribution?
Our next example of network distribution via IP is that of New Jersey Public Radio. This network originates at the studios of New York Public Radio (WNYC AM/FM and WQXR) at 160 Varick Street in New York City. (NJPR is comprised of four of the nine stations that made up the old New Jersey Network, which ceased operations at the end of June 2011.)
NJPR uses what most would consider more traditional means of program distribution for primary links, much of it remaining from the NJN facility; however, alternate links are done via IP, through various link types and equipment.
Stations making up the NJPR network are WNJO Toms River; WNJT Trenton; WNJY Netcong, NJ; and WNJP Sussex, NJ. The primary links to WNJT, WNJY and WNJP are via RF links that remain in place from the NJN days; they originate from Warren, NJ, which is about 16 miles WSW of Manhattan. From Warren, looking northeast, both Netcong and Sussex are served by a 950MHz radio shot. NJPR program makes its way from Warren to Trenton over a TV ICR belonging to New Jersey's Public Broadcasting Authority.
There are two links from Varick Street to Warren; the primary is a T1-based system, and the alternate link is a unicast stream, over the public Internet, that is encoded by an APT Horizon.
Alternate links for NJPR are via the Tieline Bridge-IT. This is a half-width, 1RU full-duplex codec that will encode in linear PCM or by Tieline's proprietary algorithms such as MusicPlus (which will provide up 22kHz of stereo audio with as little as 96kb/s) and Tieline Music (up to 15kHz of mono audio with 24kb/s). Optionally, the unit is available with Enhanced Apt-x, LC-AAC, HE-AAC version 1 or 2. Tieline's SmartStream IP software automatically manages jitter buffering and forward error correction. The unit can be configured from its front keypad and LCD display, or the Web-based GUI for all programming functionality. It has two GPIO inputs and outputs, as well as RS-232 capability for local and remote control of equipment at either end of your codec link.
One Bridge-IT at Varick Street encodes three separate unicast streams; one for Trenton, one for Netcong, and one for Sussex. A second Bridge-IT at Warren encodes an alternate stream for WNJO in Toms River as main link from New York. Each transmitter site uses a Bridge-IT for decoding of the unicast streams.
NJPR uses the Tieline Codec Management System as well. With this, it can remotely change the configurations of all the Bridge-Its so if for some reason the multi-unicast server at Varick Street fails, NJPR can reprogram the network so the unit in Warren will now become the multi-unicast server, and redirect all the receive Bridge-Its to look at Warren instead of New York.
The WNJP transmitter site in Sussex was a bit more of a challenge to the engineering staff of NJPR. There are no last mile wire or fiber lines to that transmitter site; so, DSL was installed at the facilities of WSUS in Franklin, NJ, (where there is line-of-site to the transmitter) and the group put its own 5.8GHz radio link in for the last mile. This radio is made by AvaLan and operates as an Ethernet bridge.
- continued on page 3
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