Digital Signal Waveform. Source: Wikimedia Commons. See bottom of page for explanation.

Authorization to Use Digital Signals

Agency Actions

Request for Declaratory Ruling on the Use of Digital Modulation by Multipoint Distribution Service and Instructional Television Fixed Service Stations, Declaratory Ruling and Order, DA 95-1854, 11 FCC Rcd 18839 (1996).

FCC 96-304 Order

Executive Summary

In 1996, the Mass Media Bureau authorized the use of high-speed digital data applications, including Internet service, on Multipoint Distribution Service (MDS) channels and leased Instructional Television Fixed Service (ITFS) frequencies.

Digitization is the process by which analog signals are digitized (converted to streams of "1”s and "0"s) using an encoding process that extracts the information necessary for reconstruction of the input signal at its destination. By transporting only essential information, the amount of bandwidth the signal occupies is dramatically reduced. The ratio of compression determines the effective digital rate.

The Order approved the use of digital compression techniques for the provision of video, voice, and data services.

The Order authorized wireless cable operators to employ digital compression technology in order to increase the number of usable television channels available to them, and also encouraged the use of digital technology by the educational community.

A high compression ratio permits a wireless cable operator to offer six or more program streams over one 6 MHz channel that would accommodate only one analog program stream. At a six to one ratio, 198 digital channels could be delivered by a wireless cable operator using all of the ITFS and MDS channels.

The Bureau's streamlined rulemaking on this issue was designed to enhance the ability of “wireless cable” operators to compete with wireline cable and satellite television operators.

MDS operators were authorized to transmit digital signals for Internet service from the their facilities to multiple receiving (subscriber) locations

Any portion of an MDS or leased ITFS channel can be used for "downstream" Internet transmissions.

The Commission's Rules did not at that time authorize use of MDS or leased ITFS channels for "upstream" digital data transmissions required for Internet traffic. For example, MDS channel 2 or the ITFS A-group channels could not be used to transmit Internet messages from the locations of wireless cable subscribers, nor is such use contemplated in the digital Order.

However, recognizing the potential value of two-way over-the-air Internet service, the Bureau began issuing developmental authorizations for the purpose of evaluating technical approaches, systems, and related transmission parameters.

Licensees were required to ensure interference protection to co-channel and adjacent channel licensees.

The regulations requiring ITFS licensees transmit specified amounts of instructional programming to accredited educational institutions were retained.

Waveforms in Digital Systems

A digital signal waveform: (1) low level, (2) high level, (3) rising edge, and (4) falling edge.

In computer architecture and other digital systems, a waveform that switches between two voltage levels representing the two states of a Boolean value (0 and 1) is referred to as a digital signal, even though it is an analog voltage waveform, since it is interpreted in terms of only two levels. Source: WikipediaUser:Petr.adamek