A radio scanner is a type of receiver that allows the user to listen to radio transmissions. It changes frequencies frequently depending on the availability of a signal.
The handheld radio scanners are portable. They are powered by batteries, therefore, can be carried around. The ease of movement limits the frequency range over which the scanner can detect signals. However, this problem can be solved by changing the antenna. A different antenna system would enable the user to detect more signals.
The base radio scanner is large, and usually has a built-in power supply. It uses a robust antenna system based on location. Therefore, it can detect more signals than the handheld type. Signals can be picked from up to forty miles away. This scanner can also be made mobile by fixing it in a vehicle. When attached to a car, it can be used to relay information about emergencies with ease.
This type of scanner has a limited frequency range. It picks stored signals in a specific area or radio transmission going on at a time.
This scanner picks trunked signals. Trunked signals are many different signals that use one frequency for transmission. Frequencies are shared among many users. All signals are transmitted to a central station. The central station selects the frequency with which the signal will be transmitted. The frequency is not fixed for every user.
A trunk tracking scanner is set to detect signals only from a specific user. Therefore, tracking a particular transmission is made easy. For instance, if the signals from the fire department and police department share a similar frequency, a scanner can be set to pick only signals from the fire department. Hence, it will be easy to follow communication from the fire department.
Sensitivity refers to the ability of the scanner to detect all signals even those that are very weak. Selectivity, on the other hand, refers to its ability to separate one signal from other signals. In metropolitan areas such as cities, the signal is likely to be strong. Therefore, a scanner would pick the signals easily despite its sensitivity levels. In a rural area, radio transmission is weaker hence a more sensitive scanner is required to pick the signals.
In an area with a high number of radio transmissions, a scanner with high selectivity would be necessary to separate signals. Scanners with low selectivity pick signals over a wider range. The user will hear many conversations at the same time, and this may cause confusion. Some scanners have a selectivity that can be set. If radio transmissions are many, a high selectivity is set. High selectivity and sensitivity are generally desirable for a scanner to work effectively.
The rate at which a scanner detects many frequencies is critical especially in emergency use. Older models detect around twenty-five per minute, a rate which is too low for emergencies. Modern types use microprocessors hence have higher rates. Also, the scanner should be able to retrieve a given frequency from the memory pool at record speed.
Radio scanners support a certain number of channels. If the scanner accommodates a larger number, it will be suitable for monitoring many frequencies. It does not need to be reset if the user wants to monitor a new channel. On the other hand, a scanner that accommodates few channels makes it difficult to follow many signals and to follow a new signal. A scanner with a large memory pool would be ideal. It would allow the user to store many frequencies, therefore, eliminating the need to keep searching for frequencies. It would be even better if it can store the frequencies on its own. The scanner should allow the user to switch any frequencies on and off as they wish.
The type of antenna will determine the scanner's ability to detect long or short-range frequencies. There are two types of antennas; the built-in type and the external antennae. The external antenna is stronger than the built-in type. They can detect signals from miles away. Scanners with built-in antenna, however, are convenient to carry around. The type of antenna suitable for a user will depend on their preferences. Users who prefer portability will benefit from scanners with a built-in antenna. Those who want to detect long-range signals would appreciate the external antenna. Long antennas increase the accuracy of frequency detection. Models with antennas that can be extended therefore offer better performance.
The handheld scanner offers the convenience of portability. However, it needs batteries, which may die out during scanning of important emergency information. Also, they work over a short range. Base scanners have inbuilt power supplies. They cover a greater frequency range and have better audio systems. Both choices are appropriate depending on the intended use. If one intends to move about with a scanner, the handheld one would be the best choice. For more specialized use, such as in police stations or fire stations, a base scanner is the better choice.
Good signal transmission depends, to a large extent, on the terrain of the area. Flat open areas allow for the best signal transmission. Therefore, a scanner used on flat terrain would easily pick all types of radio transmission. Mountainous regions and areas with many trees have the worst transmission. Mountains and trees block signals. Trees may also act as antennae and direct the signals to the ground preventing their detection by the scanner. A plain radio scanner has a better chance of detecting radio transmission in a mountainous or forested area than a trunk scanner. The user should aim to detect short-range signals as these would be easier to detect in such a region.
It can support upto 9000 channels and is suitable for busy departments.
It is the easiest to reset and use therefore can be used by anyone.
It has the ability to scan and identify upto 39000 objects hence is good for professional use.
It can capture the most complicated trunk radio systems, therefore, is best for professional use.