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TRUNK TRACKING

Your scanner is designed to track transmissions on Mo- torola Type I, Type II, and hybrid analog trunking sys- tems, which are extensively used in 800 MHz communications. Remember these important points when tracking transmissions:

•Your scanner monitors Type II systems by default. However, you can change this if the system in your area is different (see “Types of Trunking Systems” below and “Scanning Type I and Hybrid Trunked Systems” on Page 50 for more information).

•Your scanner cannot track transmissions on non- Motorola trunking systems.

•Your scanner cannot track an 800 MHz trunked system and scan conventional frequencies at the same time.

•The frequencies for many of the 800 MHz public safety systems are listed in the separate “National Public Safety Trunked System Frequency Guide” included with your PRO-91.

TYPES OF TRUNKING SYSTEMS

Your trunk tracking scanner can monitor two basic types of systems — Type I and Type II. Instead of selecting a specific frequency to transmit on, a trunked system chooses one of several frequencies in a 2-way radio us- er’s talk group when that user presses PTT (push to talk). Thus, trunking systems allocate a few frequencies among many different users, but the way Type I and Type II systems do this is slightly different. One impor- tant distinction between these systems is the amount of data transmitted by each radio when its push-to-talk (PTT) button is pressed. In a Type I system, the radio’s ID and its current affiliation (the trunk system it belongs to) are both transmitted. In a Type II system, only the ra- dio’s ID is transmitted.

Why the difference? In Type I systems, each radio in the trunk group individually transmits its own affiliation, while the trunk system maintains a database that deter- mines each radio's affiliation(s) in Type II systems.

Another difference between the systems is that Type I systems are arranged in a fleet-subfleet hierarchy. For example, it is possible for a city using a Type I system to designate 4 fleets, each with 8 subfleets.

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Radio Shack PRO-91 owner manual Trunk Tracking, Types of Trunking Systems
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PRO-91 specifications

The Radio Shack PRO-91 is a handheld scanner that appeals to both amateur radio enthusiasts and professionals seeking a reliable and versatile communication device. Known for its user-friendly design and wide range of features, the PRO-91 is an excellent choice for monitoring various frequencies, including VHF and UHF bands.

One of the standout features of the PRO-91 is its capability to scan frequencies in the 25-1300 MHz range, which allows users to listen in on a variety of communications. This includes police, fire, and emergency services, as well as amateur radio transmissions and aircraft communications. The scanner supports both analog and some digital formats, making it adaptable to different communication standards and ensuring users stay updated with relevant broadcasts.

The PRO-91 comes with 200 programmable channels, allowing users to store their favorite frequencies for quick access. It also features a million frequency search capability, enabling it to detect active signals within the scanning range. Additionally, the scanner includes a priority channel function, permitting users to designate a specific frequency to continuously monitor while scanning through other channels.

Another notable characteristic of the PRO-91 is its triple conversion design, which enhances sensitivity and selectivity, resulting in improved audio clarity and reduced interference. The unit is equipped with a robust speaker that delivers clear sound quality, making it easy to understand transmissions even in noisy environments.

Users will appreciate the ergonomic design of the PRO-91, which features intuitive controls and a backlit LCD display for easy visibility, even in low-light conditions. The keypad layout is designed for straightforward operation, allowing even novice users to navigate through menus and settings with ease.

The PRO-91 is powered by a rechargeable battery, offering extended usage without the need for constant battery replacements. Its compact and lightweight construction makes it portable, making it suitable for on-the-go monitoring.

In conclusion, the Radio Shack PRO-91 offers an impressive array of features, technologies, and characteristics that cater to diverse scanning needs. With its wide frequency range, programmable channels, and superior audio quality, it stands out as a reliable choice for anyone looking to explore the world of radio communication. Whether for recreational use or professional monitoring, the PRO-91 ensures users remain connected to the signals that matter most.
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