The Story

A new fire station with a new fiber optic network was being built near a large state university. The new station provided a perfect site to support an additional radio receiver to help improve campus-wide radio coverage.

Learn how the campus added IP backhaul to its SNV-12 Voter for more radio coverage.

Like many LMR radio users with large campuses or areas to cover, the university was using a JPS SNV-12 Signal-and-Noise Voter – a device that chooses a single receiver that exhibits the best quality audio of all receivers in the channel – to ensure its radio users in the field are heard as clearly as possible. However, existing receiver audio signals were being backhauled by traditional analog lines like costly leased lines. To gain the full benefit of the new fiber network technology, the fire station’s receiver audio needed to be backhauled to the SNV-12 Voter over an IP network.

The Challenge

Add a single receiver to an existing SNV-12 Signal-and-Noise Voter to be supported over an IP network link, while retaining the full functionality of all analog links with existing receivers.

It was imperative that the existing LMR site connections, as well as the voter itself, continue to function just as well as before – if not better. None of that could change. Additionally, given the size of the university and the responsibilities of its staff, the overall voter system downtime needed to be kept to an absolute minimum.

The Solution

This is actually an elegant fix. The university was already using a modular JPS SNV-12 Voter for the analog connections to receiver sites. They were not using all the available module slots, which made it easy to upgrade the voter firmware and add an SVM-3 Digital Site Voter Module. Whereas the SVM-2 connected to one receiver site by traditional analog, the SVM-3 – and the new SVM-3B which supersedes and replaces it in most installations – connects to up to three receiver sites using IP backhaul. Plainly stated, it connects over a private network. A QMT-1B IP Backhaul Remote at the new fire station’s receiver site was also installed to help mitigate the effects of network jitter and loss of fidelity related to audio vocoders. Along with the audio, the QMT-1B sends audio quality and timing information to the voter so that all sites – regardless of backhaul method – are given equal consideration for voting of the highest quality receive audio.

The Result

The university retained all its pre-upgrade SNV-12 Voter equipment, allowing it to be upgraded economically and without any significant interruption to service. While the voter continued employing existing modules for the traditional backhauls, the new module seamlessly integrated the fiber optic network-linked receiver site into the SNV-12 system.

Integrations such as these have been made possible through the addition of an SVM-3 module in the Voter and a QMT-1B at the receiver site. Future upgrades could be even easier, since the SVM-3B has the capacity to support three sites. In the case of this university, they required only one, but the remaining two are available and ready to pair with additional QMT-1B IP Backhaul Remotes at new sites.

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