Discover the Latest STL Solutions from Tieline
Introduction
IP data networks deliver a plethora of connection options to broadcasters these days, compared to when expensive synchronous data links and satellite transport options were the only options for many networks. In addition, the use of MPX codecs and progressively better IP connections in rural areas, is helping broadcasters shift to solutions with reduced transport costs, while still providing great flexibility. The other advantage of IP technologies is that they deliver affordable redundancy options and real-time monitoring and control, which was not always possible previously.
Codec Options
Tieline specializes in audio codec solutions for STLs with the Gateway and Gateway 4 products. The Gateway 4 supports transmission of 2 bidirectional stereo STL signals, whereas the Gateway offers up to 16 audio channels, so you can broadcast 8 discrete bidirectional stereo streams to multiple STL destinations. Both codecs also support multicasting and multiple unicasting to distribute IP streams around a network or to affiliates. Program configurations can be remotely changed or adjusted using an automated scheduler, providing flexibility in terms of content delivery and connections.
Tieline also has two MPX codecs, the MPX I and MPX II, which support sending the full uncompressed FM signal, or compressed μMPX to deliver high-quality multiplexed FM signals at lower bit-rates. These codecs support analog MPX (BNC) or MPX over AES192 to deliver a wide range of flexible composite encoder and decoder configurations for many different applications. Both products also offer return FM monitoring options and an optional satellite tuner card supports decoding DVB-S or DVB-S2 signals.
Most recently, Tieline’s Bridge-IT XTRA II codec was designed to offer an affordable STL solution. This codec supports full-duplex stereo or dual mono modes, to deliver inexpensive, reliable, and high quality professional broadcast solutions. This is delivered through native support for AES67, ST2110-30, ST2022-7, Livewire, RAVENNA and AMWA NMOS IS-04 and IS-05.
Improvements in Transmission Technologies
Advancements in modern communications technologies deliver more affordable and rock solid connectivity solutions for transporting primary signals, or reliable secondary/back-up connection options to STL sites. Many clients have used newer technologies such as Starlink services for primary or redundant internet connections to enable rock-solid connectivity using Tieline’s SmartStream PLUS technology.
Other clients are regularly using LTE/5G technology to not only broadcast live from stadiums for remotes, but also for backup connections for their tower sites, often on standby due to the metered nature of some wireless providers. At the end of the day, newer and more modern communications technologies are something all engineers should consider, especially if they are still paying for services like T1, DSL or cable internet services.
Managing Connectivity at Challenging Sites
Bandwidth and latency developments will be the next big advancement within the world of transmitter locations. As these locations are often on city borders, or in rural America, station engineers are no strangers to putting in whatever they can at those sites, whether it is a point-to-point wireless link, or a DSL link, as that is all they have access to. In the past few years, we’ve seen a number of clients starting to be able to put in fiber lines at these sites, with outrageous costs associated with them. Whether or not ISPs decide to upgrade networks willingly, or if they are forced through legislation, these network advancements will trickle down to the broadcast industry and allow networks and engineers to accomplish more.
Advantages of MPX Codecs
Sending transmission-ready FM-MPX composite signals from the studio allows broadcasters to maintain audio processing and RDS data insertion at the studio. This significantly reduces capital and operational costs by eliminating expensive processors and RDS equipment from transmitter sites, which in turn reduces a network’s carbon footprint by lowering on-site power consumption, wiring and rack space requirements. In addition, fewer site visits for service and support are required.
The ability to connect over WANs like the internet at low bitrates with µMPX is also a game-changer for broadcasters, as it dramatically expands the number of STL sites that can receive composite signals, reducing hardware requirements at many STL sites significantly.
The uMPX compression algorithm is specifically designed for FM and maintains perfect peak control, which eliminates the need for an expensive audio processor at each transmitter site. µMPX also allows for multipoint distribution via multicasting or multiple unicasting. This reduces costs further by affordably replicating streams at the studio using a single encoder, similar to how baseband IP audio streams can be replicated in audio codecs. This eliminates the need for multiple encoders, as well as processors and RDS equipment at transmitter sites. When this is multiplied across multiple STL sites the savings can be enormous.
Comparing Compressed and Uncompressed MPX Signals
Uncompressed MPX over AES (AES192) has a high bandwidth requirement of between 2.3Mbps (16-bit) and 4.6Mbps (24-bit). This requires high capacity IP links like fiber with reliable QoS. Compressed MicroMPX (µMPX) is supported at much lower bit-rates over both managed and unmanaged IP links. Theoretically any IP network with enough bandwidth available can transport low bandwidth µMPX signals, e.g. 320kbps for low bit-rate µMPX composite.
In addition, Tieline’s MPX codecs support encoding MPEG-TS over IP to transmit UDP streams over DVB satellite connections, which is another low bandwidth solution. MPEG-TS is the digital encoding format used in broadcasting over DVB satellite systems. When the satellite signal is received at the decoding MPX unit, a satellite tuner card can decode the DVB-S or DVB-S2 signal and the MPX unit outputs MPX composite directly into the exciter.
Codecs Versus Traditional STL Technologies
First let’s talk about hardware IP codecs and microwaves links. Depending on when, and who you got your microwave link from, you may have a viable easy-to-use solution for getting audio from A to B. However, not all microwave links support two-way audio, and nowadays some microwave link manufacturers don’t offer an audio channel, instead they are opting for a data only channel, which would still require the use of a hardware or software-based codec.
Regarding hardware versus software-based solutions, with a hardware-based solution, you don’t have to worry about matching audio cards with certain specs like RAM, CPU, and operating system, nor do you have to worry about rogue pieces of software like Microsoft’s notorious updater or anti-virus software. Your hardware codec integrates everything and is intuitively optimized for 24/7/365 mission critical broadcast operation.
What is not as well understood is that software only solutions require the end-user to adjust and optimize each component in the signal chain. This includes picking each component and ensuring it works smoothly with the others. This requires more work and configuration to ensure the other software functions on that operating system do not impact what you want the software-based codec to do.
Redundancy Options
STL sites are very often remote and far from data centers, but hardware codecs have proven they can deliver reliable solutions over a wide variety of IP transmission paths. Dedicated fiber paths are preferred for STL codec links with at least one reliable backup path also advisable. However, success can also be achieved with a combination of wireless point-to-point links, satellite connections like Starlink, and cellular.
Often a mix of IP transport options is used and layers of IP redundancy like SmartStream PLUS redundant streaming, Fuse-IP network bonding, and FEC, mitigate against packet loss to deliver rock-solid performance around the clock. Automated jitter buffer management is also advisable over imperfect IP networks with variable jitter. Backup options include alternative connections, HTTP streaming, input bypass to codec outputs, as well as audio file backup.
A bidirectional transmission path allows for remote audio monitoring and control. Software tools like the Cloud Codec Controller, as well as preconfigured automated alarms, and SNMP, provide additional automated monitoring of transmissions. Remote management software is worth its weight in gold as it helps fix problems fast to reduce dead-air and minimize remote transmitter site visits.
To learn more about the Tieline MPX I and MPX II, Bridge-IT XTRA II, Gateway and Gateway 4 codecs, visit www.tieline.com/product, or contact Tieline sales:
- For USA, Canada & Latin America contact: sales@tieline.com
- For Australia and International: info@tieline.com
