911 Dispatch Console Computer
Overview
A leading supplier of communication systems for first responders contacted Sealevel to redesign the 911 dispatch computer used for secure voice to IP communications. An important goal of the new system was to handle the processing and I/O required by their application without the obsolescence issues inherent with their previous “white box” servers and off-the-shelf PCI bus audio cards. The customer also wanted to combine the functionality of an external audio extender product with the main console computer in a single, compact design that could be mounted easily in an equipment rack or under the surface of a desk.
Application Requirements
- Dual-Core i7 Processor
- Up to 8GB DDR3 RAM
- Dual Gigabit Ethernet
- Display Port Video
- 7 USB Ports
- DSP for Audio Processing
- 2 Audio Codecs Providing 12 Input and 12 Output Channels
- 6 Optically Isolated Inputs
- 6 Dry Contact Outputs
- 12VDC Power Operation
- 1U Rackmount Packaging
The Sealevel Solution
The COM Express architecture provides an ideal solution for combining the custom audio circuitry that interfaces to operator microphones, speakers, and headsets with an off-the-shelf processor module that can be readily upgraded without system redesign. Two audio codecs are used to provide the analog coding and encoding necessary to transmit the voice data between 911 dispatchers located in the call centers and remote emergency personnel.
Key Design Challenge
Carrier Board Layout and Routing
To accommodate the required 19″ 1U rackmount mechanical size, careful layout and routing of the carrier board PCB was important not only in placing the more than 1800 required components in the allotted 14″ x 10″ space but also in maintaining the signal integrity of the analog audio signals. An important consideration during layout was to separate the analog and digital sections of the board to avoid the fast-switching digital clock signals from inducing noise in the audio. Also critical was routing the signals to the desired 38 I/O connector placements on the PCB to simplify cable routing to the rear of the system’s enclosure.