System Requirements; General Notes - JPS QMT-1B Installation And Operation Manual

1.3 System Requirements

The IP network used with the SVM-3 modules must meet certain minimum requirements.
While the voter system may continue to work if some of these parameters are not met, the
overall system performance may be degraded.
For example, in order to time-synchronize audio signals, the quicker-to-arrive signals must be
delayed until the slowest one arrives. If the time variation is too long, normal communications
may be difficult to maintain.
For these reasons, the SVM-3 IP Backhaul is not intended to be run on public networks (i.e. the
Internet) because of widely varying performance. Note that public networks can be
overwhelmed during the types of incidents when proper performance is most vital.
The network that the SVM-3/QMT pair is used on must to meet the following specifications:
• 100 Kbits/per second throughput per QMT-1B audio channel in each direction. 200
Kbps for a duplex channel.
• Packet loss less than 0.1%.
• Differential latency between RX sites less than 10ms.
• Jitter less than 5ms.

1.4 General Notes

Compatibility with Simulcast Systems
Outgoing QMT-1B audio CANNOT transport outgoing simulcast audio precisely or be
consistently timed to support simulcast transmissions. It is suitable for single transmit site
operation, TX steering, and multisite (different frequencies at different sites).
Site Totals
• An SNV-12 system with IP backhaul can consist of a single chassis, with up to 12
SVM-2 or SVM-3 modules. A larger system uses a Master Chassis that is connected to
and controls one or two Expansion Chassis for a total of 36 plug-in modules.
• Each SVM-2 module can serve only one remote voting site, connected by traditional
analog methods.
• Each SVM-3 module can serve up to three remote voting receiver sites and always
counts as three sites towards the maximum system site total of 60 (even if an SVM-3 is
interfaced to fewer than three receivers).
The main point to remember is that any combination of SVM-2 and SVM-3 modules can be
used in an Expanded system however the total site count cannot exceed 60 sites.
QMT-1B Operations Manual
1-3