STUDIES IN RADIO BROADCAST TRANSMISSION 153 



fashion to the more involved ones. The simplest records are fading 

 records of the unmodulated carrier frequency of 610 kc. At the 

 receiver the carrier was heterodyned with a local oscillator to pro- 

 duce a beat tone of about 250 cycles which was fed through amplifiers 

 to the oscillograph elements. 



A representative sample of the form of signal records made in the 

 manner described above which show the variation in the amplitude of 



Pig 7_Interior view of Riverhead testing station showing recording apparatus 



the received carrier signal with time, is given in Fig. 8. It shows a 

 typical fading record made at Stamford, Conn., May 16, 1925. The 

 timing interval on strip 6 is 2.6 seconds. 



The feed of the photographic paper tape through the oscillograph 

 was varied somewhat during the course of the experiments but was 

 generally in the range of 6 to 12 inches a minute. At this rate the 

 record of an audible frequency signal is a shadow band of varying 



