. The Bell System technical journal . Fig. 5—Receiving test station near Riverhead, L. I. showing vertical antenna pro-jecting through roof of building form of the modulating signal could be seen and photographed at thatpoint, thus guarding against any possible distortion in the trans-mitter and enabling a direct before and after comparison to bemade. The telephone circuit was also used for communicationbetween engineers at the two terminal stations. At the receiving station double detection receivers and audio fre-quency amplifiers were employed. These did not have entirelyflat transmission c
. The Bell System technical journal . Fig. 5—Receiving test station near Riverhead, L. I. showing vertical antenna pro-jecting through roof of building form of the modulating signal could be seen and photographed at thatpoint, thus guarding against any possible distortion in the trans-mitter and enabling a direct before and after comparison to bemade. The telephone circuit was also used for communicationbetween engineers at the two terminal stations. At the receiving station double detection receivers and audio fre-quency amplifiers were employed. These did not have entirelyflat transmission characteristics over the audio frequency band,but in most of the tests this was of no importance. In cases whereit affected the results the making of necessary corrections was a simplematter. In tests involving beating the received signals down to audiofrequencies through the agency of a local heterodyning frequency, 152 BELL SYSTEM TECHNICAL JOURNAL this was supplied from a shielded vacuum tube oscillator which oncomparison with a
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
