20-520.fm Page 19 Wednesday, August 4, 1999 3:06 PM
UNDERSTANDING BANKS
Channel Storage Banks
To make it easier to identify and select the channels you want to listen to, channels are divided into 10 banks of 30 channels each. Use each channel-storage bank to group frequencies, such as the police department, fire department, ambulance services, or aircraft (see “Guide to the Action Bands” on Page 52). For example, the po- lice department might use four frequencies, one for each side of town. You could program the police frequencies starting with Channel 1 (the first channel in bank 1) and program the fire department frequencies starting with Channel 31 (the first channel in bank 2).
Service Banks
The scanner is preprogrammed with the frequencies al- located by police, fire/emergency, aircraft, marine, and weather services. This is handy for quickly finding active frequencies instead of searching through an entire band (see “Scanning Service Banks” on Page 23).
UNDERSTANDING TRUNKING
In the past, groups that broadcast frequently, such as po- lice departments, were restricted to transmitting on just a few frequencies. This resulted in heavy traffic and often required 2-way radio users to wait for a specific frequen- cy to clear before transmitting.
Trunked systems allow more groups of 2-way radio users to use fewer frequencies. Instead of selecting a specific frequency to transmit on, a trunked system chooses one of several frequencies when the 2-way radio user presses PTT (push to talk). The system automatically transmits the call on that frequency, and also sends a code that identifies that 2-way radio user’s transmission on a data channel.
This scanner lets you select the data channel frequency that you want it to monitor, so you can hear both the call and response transmissions for that 2-way radio user and therefore follow the conversation. (You cannot listen to the data channel itself).
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