Original sentence: )  Most digital cable providers use QAM for video services and DOCSIS standards for data services.This has enabled digital cable providers to offer more channels, video on demand services (without use of a telephone line), telephone services, high speed internet services, and interactive television services via a secure digital distribution system (i.a secure encrypted signal to prevent eavesdropping and "stealing" service
Edited sentence: In 1989, General Instruments demonstrated that it was possible to convert an analog cable signal to digital and transmit it in a standard 6-MHz television channel.Most digital cable providers use QAM for video services and DOCSIS standards for data services.This has enabled digital cable providers to offer more channels, video on demand services (without use of a telephone line), telephone services, high speed internet services, and interactive television services  In addition, digital cable technology allows for error correction to ensure the quality of the received signal and uses a secure digital distribution system (i.a secure encrypted signal to prevent eavesdropping and "stealing" service)