[ARC5] ARR-1

[Mike Everette via ARC5]

Mike,

That's correct; the transmitter was modulated by a frequency in the AM BCB range; but still, the two carriers mixed in the receiver, rather than using a local oscillator, to produce the "IF" frequency.

In that sense, it was a direct application of the Fessenden principle.

I don't believe the concept of sidebands was understood -- or at least not very well -- circa 1902-1903.  Fessenden's research notes seem to indicate a more empirical understanding of modulation, at that point.  He was working to develop voice transmission as far back as the early to mid 1890s, and in fact made the sucessful transmission in the laboratory in 1899 followed by the first on-the-air voice communication in December 1900 (between 2 sites one mile apart).  Modulation was accomplished by inserting a carbon microphone into the antenna circuit.  The transmitter was a spark-gap type with a very high "break" frequency, something like 10 kc, to try and keep the noise of the gap outside the range of speech; but in actuality it didn't completely eliminate the noise.

73

Mike
WA4DLF


--------------------------------------------
On Wed, 9/17/14, Michael A. Bittner <mmab at cox.net> wrote:

 Subject: Re: [ARC5] ARR-1
 To: "Mike Everette" <radiocompass at yahoo.com>, ARC5 at mailman.qth.net, kgordon2006 at frontier.com
 Date: Wednesday, September 17, 2014, 10:30 AM
 
 
 
  
  
 
 
 
 Mike, Thanks for the interesting history on
 Fessenden's invention.
  
 His principle was used in some LF marine and
 aeronautical beacons with the 
 carrier and Morse ID sent on two frequencies separated by
 1020 Hz.  What it 
 amounts to is a SSB unsupressed carrier system.
  
 I disagree that the YG/ZB system used this exact
 system.  It was just 
 plain old AM - double sideband, unsuppressed carrier. 
 UHF 
 carrier AMed by a BCB frequency.
  
 Mike, W6MAB 
  
  I
 
   ----- Original Message -----
 
   From: 
   Mike Everette 
   via ARC5 
   To: ARC5 at mailman.qth.net
 ; kgordon2006 at frontier.com
 
   Sent: Wednesday,
 September 17, 2014 6:58 
   AM
   Subject: Re: [ARC5]
 ARR-1
   
 
   Getting back to the YE/ZB. This system represents the
 ONLY direct 
   application, as far as I am aware, of Fessenden's
 original Heterodyne 
   principle. 
   
 The thinking was, "UHF" signals would be
 line-of-sight only, 
   undetectable by an enemy over the horizon (yeah, right)
 but perfectly readable 
   by aircraft at altitude. Two signals were transmitted
 simultaneously in the 
   234-258 mc band, separated by a value from 540-830 kc
 which would be tunable 
   on a low frequency receiver such as the RU, ARA or ARC-5.
 All of these could 
   serve as the IF for the ARR-1 (which actually was not a
 "converter" in the 
   classic sense, but rather more of a "heterodyne
 detector"). The ARR-2, of 
   course, was a self-contained receiver which had several
 fixed IF frequencies 
   between 540 and 830 
 kc.
 
 73
 
 Mike
 WA4DLF