[ARC5] A-10 Radios
Tom Lee
tomlee at ee.stanford.edu
Tue Jul 10 19:21:35 EDT 2018
Yes -- wideband FM has interesting characteristics, as mentioned in
connection with the term "capture". The demodulated SNR is not strictly
proportional to received SNR, unlike for AM. Above a certain threshold,
FM's output SNR pops up and stays high. Below it, it's crap. So a weak
signal hardly interferes with a sufficiently strong one; it's largely
suppressed. For AM, you can hear both. Which modulation you prefer
depends on what problem needs solving.
Narrowband FM behaves much like AM (little or no capture effect).
--Tom
--
Prof. Thomas H. Lee
Allen Bldg., CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3383 (public fax; no confidential information, please)
On 7/10/2018 4:09 PM, Jay Coward via ARC5 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 <http://www.bartlee.com/>
>
> {KV6LEE(at)gmail(dot)com} ##
>
>
>
>
> On Wed, Jul 4, 2018 at 5:31 PM K5MYJ <macklinbob at gmail.com
> <mailto: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 <mailto:kb2vtl at gmail.com>
> *To:* Scott Johnson <mailto:scottjohnson1 at cox.net>
> *Cc:* arc5 at mailman.qth.net <mailto:arc5 at mailman.qth.net> ;
> Robert Eleazer <mailto:releazer at earthlink.net>
> *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 <mailto: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
> <mailto:scottjohnson1 at cox.net>scottjohnson1 at cox.net
> <mailto:scottjohnson1 at cox.net>
> <mailto:scott.johnson at ieee.org>scott.johnson at ieee.org
> <mailto:scott.johnson at ieee.org>
> *From:* arc5-bounces at mailman.qth.net
> <mailto:arc5-bounces at mailman.qth.net>
> <arc5-bounces at mailman.qth.net
> <mailto: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 <mailto: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
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>
>
> Virus-free.
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>www.avg.com
> <http://www.avg.com>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
>
> ------------------------------------------------------------------------
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net <mailto:ARC5 at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net <mailto:ARC5 at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net <mailto:ARC5 at mailman.qth.net?>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
> This body part will be downloaded on demand.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20180710/14784022/attachment-0001.html>
More information about the ARC5
mailing list