E7 non-linear pre-emphasis for MAC packet family signals

The use of additional linear pre- and de-emphasis can improve noise performance, but this is achieved at the expense of worsened FM threshold and increased interference levels into other services. E7 is a non-linear pre/de-emphasis which was developed at the IBA and which is designed to provide noise and interference improvement without incurring these penalties. It is a frequency dependent instantaneous compander system. At the transmitter, low level high frequency video components are boosted. High level high frequency components remain substantially unaffected. At the receiver, a complementary process is performed. Low level high frequency components including noise, are attenuated. In the UK, E7 has been used by the IBA on the uplink to the BSB satellite