by Alan Henney (firstname.lastname@example.org)
Charles County -- one of the fastest growing counties in the state -- has issued a request for proposals for a trunked radio system. Complaints about the county's existing radio systems include dead spots in the western and southern areas of the county, chronic interference from nearby school districts, and aging equipment.
Charles County seeks to lease or purchase an 800 MHz mixed analog/digital trunked system. The system will provide emergency call, private call, call alert, telephone interconnect, unit identification, and encryption. The system architecture will be compliant with the Association of Public-Safety Communications Officials (APCO) Project 16 standards for public safety trunked radio systems.
Although not a requirement, the county desires the trunked system to conform with the objectives of APCO Project 25 in terms of digital modulation; interoperability with equipment from other manufacturers; ability to support at least two simultaneous messages within a single 25 KHz channel assignment through either FDMA or TDMA technology; 9600 BPS working and control channel speed; ability to support Improved Multiband Excitation (IMBE) vocoder; advanced digital encryption such as DES; superior audio clarity through advanced error correction; data interface for MDTs; and ability to expand and grow.
The county seeks a system that can be cost-effectively modified to accommodate mobile data and vehicle locator systems (AVL) in the future.
The project will include: the installation of a digital-loop microwave system to connect the antenna sites; furnishing and installing remote site and monitoring and control systems; communications center equipment; system controller and audio switch; mobiles, portables and control stations; a fire station alerting sub-system; and integration of the new system with certain existing sub-systems.