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AGC Automatic Gain Control Cell Phone Signal Boosters & Amplifiers

Automation Gain Control or AGC cell phone signal boosters have a mechanism whereby constantly fluctuating cellular signals are maintained within set parameters by adjusting itself down to prevent lowering of power or shutdown of a mobile reception amplifier. Spikes in signal power are common due to wireless service provider testing of towers or weather related changes. AGC or Automatic Gain Control feature of our signal amplifiers keeps them at a steady maximum range to provide good indoor reception all the time. Watch the video below for illustrations and more details. All SureCall and Wilson Pro repeaters or amplifiers have this very crucial feature built into them.


ALL SureCall products have automatic gain control. This also applies to the products that have knobs or switches (Fusion4Home, Fusion5s, Force5). If the knobs and switches are set a full gain and left alone, the booster will automatically adjust if oscillation is detected. This was mandated by the FCC.

Transcript: You have probably heard the term AGC or automatic gain control before, but what exactly is it and why should you care? If your signal amplifier has automatic gain control, AGC is crucial in maintaining top performance of your cell phone signal amplifier. All Wilson Pro signal amplifiers feature automatic gain control. In fact, we have over 50 patents in the industry but this isn't true for all boosters on the market.

Cell signal is not a constant, it is continually fluctuating due to all sorts of factors. The number of uses on a tower, carrier testing, and environmental factors such as weather all effects cell signal. For example, if an amplifier system is set up in the summer when the trees are in full leaf, when fall comes and the leaves fall, more signal will pass through to the amplifier. Without AGC, this may overload the amplifier and shut it down.

With AGC, however, the amplifier simply adjusts itself down and continues to provide strong boosted signal. So, maybe you're thinking, when will overpowering even be an issue if you set up a signal booster properly? This is actually fairly common for a number of reasons.

First, and most obvious would be the construction of a new cell tower nearby but there are a number of less obvious reasons that you may not have thought up like carriers doing tests on the network for example. Carriers often perform tests on their towers which can result in spikes in signal level. If this happens, it will overpower the signal booster and shut it down.

Another example is the fluctuation of users. Populated sections of a city like downtown areas can change drastically during the work day when everyone's there using their phones, versus night time or weekend's when they are home. During busy times of the day, the signal is weakened with so many users taking up all the bandwidth. When they all leave, the power goes back up so if you set up a signal booster during a busy time of day when everyone's there and the signal is weaker, when everyone leaves, the signal goes back up and there goes the booster - shutdown.

The same thing goes for large events like concerts or football games. What about trees? If you set up a booster in the summer and have it tuned properly, it could overload when fall comes and all the leaves fall off the trees, letting more signal pass through Even weather can have a major impact on the cell signal. Nobody wants to deal with signal booster issues every time it rains or the leaves fall or there's a college football game in town.

In short, AGC monitors the incoming signal level from the cell tower and adjusts the various cell spectrums on the amplifier to ensure you're getting the maximum amount of coverage area. AGC also prevents oscillation issues in strong signal environments. The amplifier will reduce its gain for each frequency spectrum individually as to not overload and shut down, thus giving you greater coverage area inside.

Each carrier uses different bands and frequencies so having an amplifier that will adjust each frequency separately is important. Without AGC, if one frequency has an overpowering signal, it will overload the amplifier and provide no coverage inside for any carrier, even though the other carriers have an acceptable incoming signal level. With AGC, the amplifier will simply adjust the gain down for the overpowering frequency and still provide strong coverage for all the other frequencies inside. You probably don't notice it but cell signal at any location wavers up and down many times throughout the day.

With AGC, your signal coverage remains constant as the booster continually adjusts itself. Without AGC, your booster is stuck where you set it. No improvement if the signal gets stronger, it may even shut down due to overpowering, and worse coverage if the incoming signal drops. Most boosters do have some sort of functionality to adjust them for incoming signal level like this. A bunch of dip switches which are cumbersome and confusing to use. These manual adjustments will also affect all bands and they don't change with the condition which is no good for anyone.

Plus, AGC adjusts the gain algorithmically which is much more precise and exact than a person can do on their own. AGC is also important in preventing oscillations with signal amplifiers. If the inside antenna and outside antenna are too close together, they will interfere with each other and cause oscillation. You can compare this to the feedback between a microphone and speaker. Think of this as two spheres of signal around antennas. If this signal is too strong, the spheres of signal around the antennas will overlap one another communicating with each other and causing a feedback loop or oscillation.

To prevent this, AGC will reduce the gain, therefore shrinking the signal spheres so that they are no longer overlapping and eliminating the oscillation. However when the gain was reduced, so is the coverage area of the indoor antenna. So, if the amplifier is using AGC to prevent an oscillation issue and you're not getting adequate coverage area from the indoor antenna, you should consider adding more separation between the antennas or shielding them from one another to maximize the gain and coverage area of the indoor antenna.


All SureCall boosters have automatic gain control. This also applies to the products that have knobs or switches (Fusion4Home, Fusion5s, Force5). If the knobs and switches are set a full gain and left alone, the booster will automatically adjust if oscillation is detected. This was mandated by the FCC.