540 BELL SYSTEM TECHNICAL JOURNAL 



Remotely Controlled Receiver for Radio Telephone Systems} H. B. 

 Fischer. New radio receiving equipment for shore station used in 

 ship-to-shore telephone circuits has been developed. This equipment 

 is designed to operate on a remotely attended basis and may be located 

 a considerable distance from the telephone terminal equipment. The 

 radio receiver forming a part of the equipment has a codan circuit 

 which operates reliably under high noise conditions and does not 

 require adjustments to compensate for variations in the noise level. 

 An emergency battery power-supply system is provided which is auto- 

 matically connected to the receiver when the primary alternating- 

 current power supply fails. Power failures are indicated at the tele- 

 phone central office. A test oscillator which is controlled from the 

 telephone central office is provided which may be used to check the 

 operation of the receiver or to measure the frequency deviations of the 

 incoming signals. The various apparatus units are mounted in two 

 weather-proof cabinets which may be fastened to the same telephone 

 pole which supports the receiving antenna. 



Analysis and Measurement of Distortion in Variable-Density Re- 

 cording} J. G. Frayne and R. R. Scoville. Several types of non- 

 linear distortion in variable-density recording are discussed and 

 methods of measurement outlined. The two-frequency inter-modula- 

 tion method is described. Mathematical and experimental relation- 

 ships between per cent inter-modulation and per cent harmonic dis- 

 tortion are established. The inter-modulation method is applied to 

 film processing for the determination of optimal negative and positive 

 densities and overall gamma. Variance of these parameters from those 

 indicated by classical sensitometry are traced to halation in the emul- 

 sion and to processing irregularities. The use of special anti-halation 

 emulsions appear to reduce residual distortion effects and tend to 

 bridge the gap between inter-modulation and sensitometric control 

 values. 



Rubbed Films of Barium Stearate and Stearic Acid J L. H. Germer 

 and K. H. Storks. Films of barium stearate and of stearic acid have 

 been prepared on polished chromium and on smooth natural faces of 

 silicon carbide crystals. After these films have been rubbed with clean 

 lens paper, electron dififraction patterns are obtained from them by the 

 reflection method. Well rubbed films give patterns characteristic of a 

 single layer of molecules standing with their axes approximately normal 



5 Proc. I. R. E., April 1939. 



6 Jour. S. M. P. £., June 1939. 

 "^ Phys. Rev., April 1, 1939. 



