User Report: Sharpening Time Alignment With Belar

Reliability, consistency and stability keep long-time customer happy

User Reports are unpaid testimonials by users who have already purchased gear. A Radio World Product Evaluation, by contrast, is a freelance article by a paid reviewer who typically receives a demo loaner.

VALLEY FORGE, PA. — Broadcast Sciences is a full-service engineering firm that provides an array of services to the broadcast and wireless communications industries. This includes everything from licensing to facility design and construction, as well as ongoing maintenance of studio and transmitter facilities for AM, FM and TV operations of any size.

In radio, one of the more interesting recent technical challenges to arise is the growing need for precise time-alignment between FM and HD Radio signals. The goal is to ensure a seamless transition between the digital and analog signal as listeners travel beyond the range of the HD Radio signal. If that HD/FM alignment is not maintained, the listener experience is jarring — and the complaints come pouring in.

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RELIABILITY
To address this important need, we gradually have standardized on the Belar FMHD-1 modulation monitor in new builds and existing facility upgrades. Additionally, we have begun exclusively to specify the Belar FMCS-1 all-in-one monitor for FM-only projects. Many of the existing facilities we service had, or still have, fully-functioning Belar analog modulation monitors installed 20 to 30 years ago. It’s a testament to the reliability and longevity of Belar modulation monitors, and we are retiring these only to benefit from the latest features associated with the current generation of products, including HD Radio monitoring capabilities.

Belar has always been the industry standard for accuracy in modulation monitoring, and that still holds true with their digital equipment. Belar is our preferred vendor for HD Radio monitoring due to their consistency and accuracy when it comes to HD/FM time alignment and relative loudness monitoring. The FMHD-1 and FMCS-1 both have feature sets that surpass competitive monitors. These are important reasons we specify Belar products whenever possible.

The recently-introduced Automatic Delay Correction software in the FMHD-1 works well for FM/HD time-alignment. Due to the encoding delays associated with the HD audio, the FM audio has to be delayed by an equal amount (approximately 8 seconds) to ensure seamless blending. Due to timing imperfections and transport issues, it is not unusual for the required delay to vary or “drift” over time.

Belar’s architectural flexibility provides options on how corrections are applied to maintain precise time alignment. As opposed to making the adjustments “inside the box.” the FMHD-1 communicates the required adjustments to an exporter or an audio processor with an internal delay line. The preference as to whether the delay is provided by the exporter or audio processor is often a function of the topology of the system, including where the exporter and audio processing are located.

Belar’s WizWin software provides another valuable benefit: remote monitoring. Many of our transmitter sites are located on distant mountaintops, or comprise large regional networks with widely dispersed locations without a local studio. The WizWin software lets us log in to remotely monitor important parameters related to audio and RF performance, including time alignment and audio level consistency for HD Radio, as well as analog parameters such as total modulation, RDS, and subcarrier injection levels.

Using WizWin, we can pinpoint quickly whether an issue is tied to a program delivery, transmitter or audio processing problem; and if a trip to the transmitter site is required. Additionally, we have alarm relays configured on each monitor, which are interfaced to the remote control systems for alarm notifications such as if the time alignment drifts outside a specified window, or if there is a total loss of HD carriers or audio.

One key differentiator is the fact that Belar uses the same interface for both local and remote monitoring. Many pieces of broadcast equipment provide a different interface in each instance, with a specific set of features available from the front panel, and a subset (or superset) of those features for remote monitoring that often have a completely different look and feel. Having an identical interface for both monitoring approaches is a nice change.

Belar regularly releases software and firmware upgrades that can be installed in the field without requiring hardware upgrades or modifications. We continue to receive improvements and useful new features added to the FMHD-1 especially. Based on these attributes, it’s clear that Belar’s customer service and technical innovation continues to excel, and will save us and our clients money in the long run.

For information, contact Mark Grant at Belar Electronics in Pennsylvania at (610) 687-5550 or visit www.belar.com.

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