Wideband Preselectors

The Wide World Of Wideband Preselectors

How on earth would receivers, whether they’re for the C-band, Ku-band, or any other band in the RF spectrum, receive frequencies without “preselectors”? According to communications industry experts, a “preselector” improves or enhances the overall performance of any type of receiver, but it is deemed more helpful to receivers which have broadband front-ends that often falls prey to signal overloads (like scanners and plug-and-play consumer-market receivers). Here’s a not-so-layman’s look at the functions and specifications of wideband preselectors.

What Exactly Is “Wideband”?

Before heading straight to checking out the specifications of a wideband preselector, let’s first define what “wideband” truly means. Wideband refers to a transmission channel, or medium, which has a bigger or wider bandwidth than a single voice channel, or carrier wave of a certain modulated frequency.

And in the field of communications, a system will be referred to as “wideband” if the message bandwidth exceeds, or goes beyond, the coherent bandwidth of the channel.

And because many communication links today have very high data rates, they are often compelled to utilize a wider bandwidth. And while some communication links or systems have low levels or rates of data flowing, they still use a wider bandwidth in order to gain certain perks or advantages.

Wideband versus Narrowband

As the term states, wideband communication utilizes a wider portion or segment of the RF spectrum. And how does it compare to the “narrowband”? Well, wideband communication permits spreading the signal to encrypt it, and it allows for “notching” out narrow noise sources in the RF spectrum.

Communicating in the wideband is also done exclusively in the top-tier frequencies, like 433 MHz and above, and examples of wideband communication systems today are the wireless networks like Wi-Fi, LTE and HSP.

On the other hand, “narrowband” communication uses a smaller, or “narrow” bandwidth, and are utilized in a slower form of communication, wherein voice or slow streams of data need to be transmitted.

However, narrowband signals have a longer, far greater reception range, because narrower signals can be utilized, and they can edge out unwanted wideband noise. Narrowband communication is utilized in AM and FM radio, Morse code, satellite downlinks, GPS signals and weather transmissions of agencies like the NOAA.

How Preselectors For The Wideband Work

A preselector’s other main job is to protect extra-sensitive receivers from being damaged by sudden spikes in voltage, signal overload from nearby transmitters, and static input damage.

In most preselectors today, some loss at the tuned frequency is seen, or felt. Much of the loss is seen, or takes place, in the device’s turning coil, or “inductor”.

Wideband preselectors often work by isolating the desired channel from unwanted or noisy interference.

For example, certain wideband preselectors are utilized to isolate the FM band from the reception of VHF signals, and from other potentially interfering off-air sources or frequencies. Some devices are also used to ensure high channel selectivity, including adequate sensitivity, at all combination frequencies.