Pioneering Armstrong FM-Broadcast Test Transmissions

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Preamble -- Carl Swanson
MP3  Preamble to the Test Recordings -- 3 min 12 sec,    6.03 Megabytes
Introductory remarks on the audio recordings of the tests by Carl Swanson.  The speech Maj. E. H. Armstrong gave to the Radio Club of America can be found after the test videos.

FM Test  1 -- Comparison of two, separate AM and FM radio stations in New York City as received in downstate New Jersey near Phildelphia PA.  Test was performed in 1935.
MP3 Audio File for FM Test 1 -- 2 min 43 sec, 3.74 Megabytes

FM Test 2 -- Comparison of AM and FM transmissions on the 2.5-meter band using the same transmitter from Yonkers, NY to Columbia University, performed in 1936 with Major E. H. Armstrong as disk jockey.
MP3 Audio File for FM Test 2 -- 1 min 57 sec,  2.80 Megabytes

FM Test 3 -- Two trans-Atlantic tests of FM on 23 MHz in 1950.  The first was under poor  propagation conditions, the second, a month later, under much better ones. 
MP3 Audio File for FM Test 3 -- 5 min 27 sec,  7.5 Megabytes

FM Test 4 -- Long distance transmission test on VHF between Cedar Rapids IA and South Dartmouth MA.  Noisy, but notable for detection of meteor scatter.  (1951)
MP3 Audio File for FM Test 4 -- 2 min 23 sec,   3.37 Megabytes

FM Test 5 -- First test transmission over a side channel (subcarrier) on April, 1952.  This technology, later, in modified form, became the means of transmitting stereophonic audio over present-day FM radio.
MP3 Audio File for FM Test 5 -- 3 min 46 sec,   5.31 Megabytes

FM Test 6 -- Comparison of main and side-channel audio transmission quality by live switching.  Test performed in August, 1952.

(Mouse-over red/green box in upper right for channel identification)
MP3 Audio File for FM Test 6 -- 1 min 53 sec,    2.67 Megabytes

FM Test 7 -- Direct comparison between side-channel (subcarrier) audio and conventional AM radio as received 75 miles from NYC in Peconic, LI, NY.  Test performed on Nov. 10, 1952.
MP3 Audio File for FM Test 7 -- 3 min 59 sec,    5.62 Megabytes

Armstrong FM Tests  20 Meg Original WMA Audio File for Complete FM Tests -- 22 min 12 sec,   20.4 Megabytes

Major Armstrong Speech
MP3 Armstrong Speech 18 min 10 sec.   34.1 Megabytes
Speech given by Major E. H. Armstrong in 1952 introducing the recipient of the Armstrong medal, Captain Henry J. Round, at the Radio Club of America.  In this speech, Armstrong recounts numerous advances in radio art and science from the 1900's to the 1920's in which Capt. Round was involved.

Captain Round perfected high-accuracy radio direction-finding in WWI which was instrumental in detecting the movement of the German High Seas Fleet prior to the Battle of Jutland.  He also discovered and reported on the phenomenon of electroluminesence in crystals of Carborundum (silicon carbide), leading eventually to the development of LED's.

Click here or on the image at left to download and play audio of the speech.    ( MP3     34.1 MB )     

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