Emil Hopner

An experimental modulation-demodulation scheme for high-speed data transmission

An experimental low-cost system was designed to determine speed and reliability limitations on transmitting binary data over private telephone lines. A brief review of alternative approaches is given, with a description of the laboratory model. Performance of the equipment is reported with the reliabilities experienced at 600, 1000, 1600, and 2400 bits per second.

Phase reversal data transmission system for switched and private telephone line applications

A phase reversal data transmission system is described, capable of operating at 2000 bauds over private telephone lines and at 1200 bauds over switched networks. The advantages and limitations of the system are discussed from a theoretical and practical standpoint. The clocking problem in data transmission is considered and several approaches are indicated. A summary is given of extensive field tests over switched and private lines in Europe and on private (SAGE) lines in the U. S.

The digital data exchange--a space-division switching system

The user requirements for an automated switch for computer terminals in a large establishment or laboratory environment are discussed. This is followed by an explanation of the design requirements, and finally by a description of the significant features of the digital data exchange (DDEX), a microprocessor-controlled user-transparent space-division digital data switch of modular design which is capable of connecting 512 to 2048 lines from various types of IBM terminals to different control units, thereby substantially saving interconnection resources.

High-Density Binary Recording Using Nonsaturation Techniques

Commercially available magnetic tape units have longitudinal recording densities of up to 2000 bits per inch, whereas analog instrumentation recorders are capable of recording up to 10,000 cycles per inch. These figures contrast with a theoretical recording density limitation for iron oxide of 250,000 bits per inch, and the reasons for this discrepancy are analyzed. Two experimental systems having recording densities of 5000 and 10,000 bits per inch using analog recording techniques are described, Conclusions drawn from these experiments indicate that a density of 20,000 bits per inch should be possible using commercially available analog tape recording machines. Experimental machines indicate the practicability of densities on the order of 100,000 to 200,000 bits per inch, depending on the method of recording used.