Multiport Multiplex Program
Abstract
A video digital encoder/decoder has been developed and constructed that will encode, transmit, and reconstruct high-quality, real-time television pictures. The analog television signals are encoded into digital format using a differential pulse code modulation (DPCM) technique resulting in a transmitted data rate of 3 bits per picture element. This type of coder has potential application in areas where the signal-to-noise advantages of digital data transmission bandwidth of conventional pulse code modulation (PCM) coders that require between 6 and 8 bits of data per television picture element. DPCM coders compare the present sample picture element with the preceding sample picture element, and only the differnce is digitally encoded and transmitted. Digital accumulators are utilized to hold the previous picture element instead of analog integrators. This ensures perfect tracking between the encoder and decoder and eliminates the need for precision components and lengthy calibration procedures. The television signal is sampled at a rate of 10 MHz and digital data is transmitted at a rate of 30 Mbits per second. Error propagation is controlled. Data transmission errors are corrected and dc operating levels are restored at the beginning of every horizontal television line. Fabrication of the encoder and decoder utilized high-speed, commercially available, emitter-coupled-logic (ECL) integrated circuits installed on low-impedance, wire-wrap logic cards.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1975
- Accession Number
- ADB013811
Entities
People
- D. Gaston
- R. Morison
- T. Mcclung