AUSTIN, TEXAS — The transition to digital solutions in the broadcast industry inevitably leaves long-reliable technologies in danger of obsolescence. In radio, ISDN appears to be one technology heading toward its sunset. There are clear indications that major carriers will no longer offer or support ISDN transport by 2019.
Univision Radio in Austin has long relied on ISDN to back up our main T1 STL circuits for FM stations KLQB(FM) and KLJA(FM). The rural locations of the two transmitter sites have long made T1 and ISDN transport the most reliable and effective connections for signal transport.
RELIABILITY
In addition to its fading status, one long-term concern of ours has been that the ISDN circuit shares a path with the T1 feed along the last mile to the tower sites. Recently, a construction team snapped a cable while breaking ground on a new project. This clearly exposed the danger of having a common point of failure for main and backup STL feeds.
We decided it was time to investigate IP transport for our backup STL feeds. We researched several options on the market and decided that GatesAir (formerly Harris) offered the most ideal solution through its range of Intraplex IP Link codecs. Our current architecture includes an IP Link 200 codec at the studio, which feeds independent audio streams to IP Link 100 units at each tower.
GatesAir won for several reasons that range from pricing to feature set, as well as the reliability of the company’s Intraplex solutions. We have used Intraplex T1 STL solutions as our main transport links for KLQB and KLJA for more than a decade. However, the IP Link offered several features and applications that set it apart from competitive solutions.
As we began to investigate IP transport, we knew we needed another way to get connectivity to the tower sites besides wired telco. We had a conversation with one of our wireless service tenants, which led to an agreement to provide bandwidth and TCP/IP connectivity to each tower site via wireless technology. The IP Link offers a bandwidth-efficient connection that allows us to transport high-quality HE-AAC format program audio at varying bitrates. We have experimented with bitrates between 48 kbps and 128 kbps, eventually settling on 64 kbps — a rate that produces excellent sound quality over the IP Link. This rate also stays within our uplink bandwidth on our studio DSL circuit, with room to spare.
Above all, the IP Link includes an advanced self-healing feature that enhances reliability for network-based signal transport. This was important considering what we went through to establish a temporary link when our T1 and ISDN feeds went down at the same time. Essentially, we wanted a robust and reliable IP transport link that would run without interruption. To date, there have been no hiccups.
Though the Intraplex T1 STL units have been rock-solid, their stability is irrelevant when there is a problem on the telco side. And as has been typical over the years, the T1 service has gone down due to telco-related reasons. Since deploying the IP Links in January, by the time I get the page alerting me to a T1 issue, the transport stream has seamlessly switched to the IP Link, which picks up the stream without missing a beat. The switch is barely detectable from the listener’s point of view, and the stability of the IP Link connection gives me plenty of time to troubleshoot issues with the main STL feed.
Setup was easy, with access to a Web browser to configure the IP connection, as well as standard audio and format settings. Upon creation of the audio profile, it was a matter of click, save and go. Since putting the codecs online, we’ve had little reason to monitor the units, though the IP Link 200 provides front-panel confidence monitoring that is useful. The device construction is solid, with a superb build quality.
The IP Link has proven to be an exceptional choice, providing an outstanding feature set and high reliability for IP transport at a price well within our budget.
For information, contact Keyur Parikh at GatesAir in Ohio at (513) 459-3519, or visit www.gatesair.com.
