Overall Gain

Unlike TGC, overall gain alters the amount of amplification applied to signals from any depth. This is used to increase or decrease the overall brightness of the image.

Overall gain amplifies the return signal and has no effect on the transmitted pulse. Therefore, gain cannot compensate for inadequate penetration. The only way to do this is to increase the output power of the equipment or change to a lower transmit frequency.

If overall gain is set too high, the overall gain amplifies noise within the image and reduces both spatial and contrast resolution (Fig 1).

If overall gain is set too low, the result is too dark and image detail is lost (Fig 2).