Uniden BCD996T manual Conventional Scanning, Simplex Operation

even interfere with each other to the point where it is impossible to clearly receive any of the stations. A scanner, such as your BCD996T, equipped with CTCSS and DCS, can code each received frequency with a specific sub-audible CTCSS or DCS frequency or code. Then, when you receive multiple signals, you only hear the transmission with the CTCSS or DCS tone you programmed. If you do not receive the correct tone with a signal, the scanner’s squelch remains closed and you hear nothing.

The tables showing the available CTCSS frequencies and DCS codes are found in the Reference Section of this manual.

Conventional Scanning

Conventional scanning is a relatively simple concept. Each group of users in a conventional system is assigned a single frequency (for simplex systems) or two frequencies (for repeater systems). Any time one of them transmits, their transmission always goes out on the same frequency. Up until the late 1980s, this was the primary way that radio systems operated.

Even today, there are many 2-way radio users who operate using a conventional system:

•Aircraft

•Amateur radio

•FRS/GMRS users

•Broadcast AM/FM/TV stations

•Many business radio users

When you want to store a conventional system, all you need to know are the frequencies they operate on. When you are scanning a conventional system, the scanner stops very briefly on each channel to see if there is activity. If there isn’t, the scanner quickly moves to the next channel. If there is, then the scanner pauses on the transmission until it is over.

Simplex Operation

Simplex systems use a single frequency for both transmit and receive. Most radios using this type of operation are limited to line-of-sight operation. This type of radio is frequently used at construction job sites, and with inexpensive consumer radios such as GMRS/FRS radios. The range is typically 1-15 miles, depending upon the terrain and many other factors.

Understanding Scanning and the BCD996T

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