[ARC5] A-10 Radios

Wed Jul 11 15:18:52 EDT 2018

The big factor is bandwidth.  Aircraft frequencies are on a 5 KHZ spacing now.  Move 5 khz on narrow FM and you are talking over someone else. 

Wayne
WB5WSV  
  ----- Original Message ----- 
  From: Bart Lee 
  To: Jay Coward 
  Cc: Bob Macklin ; To: ARC-5 ; Robert Eleazer 
  Sent: Wednesday, July 11, 2018 2:10 PM
  Subject: Re: [ARC5] A-10 Radios

  Yes, the wiki says:

  Originally from amateur radio, the phrase was used to describe the way an FM transmitter will cut in and out as it nears the capture threshold of a moving receiver or transmitter as it passes through fresnel zones, thus chopping the speech of the transmitting operator. It is not clear if the phrase was intended to describe the loss of the speech, or if it actually referred to the chopping sound itself, which imitates the noise produced by dragging a stiff object across a picket fence.

  I first heard the term all too many decades ago in the Civil Air Patrol, as just a quick explanation for why AM instead of FM in aviation.  I have heard the effect on FM radio while driving.  I think Jeep is right that it's lock-in more than anything else that keeps aviation radio in AM, other than for long distance communications where power matters, hence SSB.

  73 de Bart, K6VK ##

  -- -- 
  Bart Lee

  Texts only to: 415 902 7168 

  www.bartlee.com 

  {KV6LEE(at)gmail(dot)com} ##

  On Tue, Jul 10, 2018 at 4:09 PM Jay Coward <jcoward5452 at aol.com> wrote:

    Hi Bart,
     Isn't this also known as "picket fencing" from multipath reception?
     Jay KE6PPF

    -----Original Message-----
    From: Bart Lee <kv6lee at gmail.com>
    To: macklinbob <macklinbob at gmail.com>
    Cc: To: ARC-5 <arc5 at mailman.qth.net>; Robert Eleazer <releazer at earthlink.net>
    Sent: Tue, Jul 10, 2018 2:00 pm
    Subject: Re: [ARC5] A-10 Radios

    FM received by a mobile (or air mobile) vehicle can "washboard" the received signal as the moving vehicle hits the incoming radio waves. Car radios on FM frequently have this issue. Aviation AM may or may not have been selected to avoid this problem, at 135 MHz and below. AM was the way aviation radio started, so there was some lock-in, especially after Curtis LeMay selected single sideband for SAC in the early 1950s. SSB's power advantages may also have come into play.  73 de Bart, K6VK ##
    -- -- 
    Bart Lee , K6VK, CHRS, AWA, ARRL

    Texts only to: 415 902 7168 

    www.bartlee.com 

    {KV6LEE(at)gmail(dot)com} ##

    On Wed, Jul 4, 2018 at 5:31 PM K5MYJ <macklinbob at gmail.com> wrote:

      The reason for the use of AM in aviation is you can hear when somone doubles. Not so with FM.

      The reason of low band FM is to communicate with the troops on the ground.

      I was in Korea in 1953. We used AT-6s for FAC operations. Our AT-6s had ARC-5 VHF radios.

      The people on the ground had ARC-3s in jeeps.

      Bob Macklin
      K5MYJ
      Seattle, Wa.
      "Real Radios Glow In The Dark"

        ----- Original Message ----- 
        From: Peter Gottlieb 
        To: Scott Johnson 
        Cc: arc5 at mailman.qth.net ; Robert Eleazer 
        Sent: Wednesday, July 04, 2018 2:45 PM
        Subject: Re: [ARC5] A-10 Radios

        In a practical sense for any of us the question might be whether in regular AM and FM use the radio performs any better than other radios. The answer is probably not. 

        Peter

        On Jul 4, 2018, at 12:45 PM, Scott Johnson <scottjohnson1 at cox.net> wrote:

          Most all USAF tactical assets now have the ARC-210, which covers all the military bands and modes from 30-512 MHz, and has built in ECCM and secure speech, as well as satcom capability (all with the proper antennas and switching, of course).  It is an awesome radio, but at $100K a copy, not on my wish list.  Like the ARC-164, it will probably soldier on for at least thirty years (it’s already about fifteen years old, but evolving, just like the -164)  
          Scott V. Johnson P.E. W7SVJ
          Sunburst Engineering Partners
          5111 E. Sharon Dr.
          Scottsdale, AZ 85254-3636
          H (602) 953-5779
          C (480) 550-2358
          scottjohnson1 at cox.net
          scott.johnson at ieee.org
          From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of Robert Eleazer
          Sent: Tuesday, July 3, 2018 9:55 AM
          To: arc5 at mailman.qth.net
          Subject: [ARC5] A-10 Radios
          When I was at the Pentagon the idea was to get rid of the A-10 and use F-16's.  The F-16 equipped with a weapons load comparable to an A-10 could do a very nice job of making sure no one got past the guard shack at the main gate of its home base. 
          The fear was that the A-10 was so slow that when the Warsaw Pact came through the Fulda Gap the A-10 would get hit on the first day of the war and although probably survive to make it home but we would not have time to repair it before the war was over.
          Some on Congress said that if USAF got rid of the A-10 the US Army should take over the airplane, it being a much better "mud mover."  The Army was terrified, saying that all their airplanes had to have at least two seats.
          Then came Saddam's invasion of Kuwait and the A-10 was the machine to have.  And when the war was over we had lost four A-10's and four F-16's  So much for survivability concerns.  A re-engining program was started for the A-10 a few years later. And the USSR went out of business on 25 Dec 1991; so much for the Fulda Gap concern
          To some in the USAF was faced with either keeping the A-10 or buying the F-35 - and the F-35 won.   I do not know if that insanity persists.
          The A-10 would have at a minimum VHF AM Air Band (108-132 MHZ), UHF AM (220-400 MHZ), and low band FM (30-76 MHZ) radios.  The ARC-114, ARC-115, and ARC-116 such as carried by US Army helicopters of the late 60's would do nicely but it no doubt has gear later than that.
          Anyway, look it up yourself.  The pilot's manual for the A-10 is available for free download here:
          http://www.476vfightergroup.com/downloads.php?do=file&id=42
          Wayne
          WB5WSV
               Virus-free. www.avg.com  

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