STUDIES IN RADIO BROADCAST TRANSMISSION 



189 



In order to receive and record the radio frequency wave it is, as 

 has already been shown, convenient to use a local oscillator to beat 

 it down to audible values. Since several oscillators for the separate 

 sets are likely to produce mutual interference a common one was 



Note 

 ®= Receivers 

 X=- Beating Oscillator. 



Fig. 33 — Diagram showing space relation of receiving sets for special test 



Fig. 34 — Sample single-frequency fading record from spaced receiving sets 



employed. This beating oscillator was situated at the testing station 

 and the receiving antenna at this point was used as a radiator. In 

 order to prevent overloading, the local receiver, the coupling to the 

 receiver input coil was balanced to give a minimum of the local signal. 

 Fig. 3-i is a sample of the record obtained. The continuous shadow 

 band at the top represents the local receiver output. One oscillator 



