[Milsurplus] Naval Aviation Navigation Cone of Silience

[B. Smith]

No "cone of silence" but when the aircraft was  cruising  for example: at 
18,228 feet and directly over the station the "DME" distance will read 3 
miles, but  that was not really the distance to the station but your 
"altitude" in nautical miles.  You knew when you had passed the station as 
the DME would stop decreasing and start increasing.
 Anyone confused yet?    :-)

Due to the "rotation" and the method of bearing generation etc. of the 
transmitter antenna the early TACAN systems had a nasty quirk of "locking 
on" forty (40) degrees off of the real bearing or a multiple of 40 degrees 
such as 80, 120 etc.  Made it interesting on those middle of the night 
penetrations when that was all that was on the aircraft --- When this 
happened you were always in  bad weather, short of fuel and ideas.


breck k4che
Dover, Delaware. Ann't nutten in Dover except a NASCAR track, chickens, and 
hams that can't solder.




> What?!  No cone of silence?  The interrogation is accomplished by 
> transmitting a pair of pulses 3.5 microseconds wide and separated by 12 
> microseconds from the interrogator on the aircraft at an assigned TACAN 
> frequency.  These pulse pairs are received by the transponder beacon 
> examined for proper characteristics (width, spacing) and if acceptable 
> generate a reply pulse pair.  The time of the two way travel plus 
> processing time is converted to distance in nautical miles.
>
> Jim de wd4air
>
>
>>From: Peter Gottlieb <pgottlieb at hudsonshores.com>
>>Reply-To: pgottlieb at hudsonshores.com
>>To: D C *Mac* Macdonald <k2gkk at hotmail.com>
>>CC: whitaker at ieee.org, k2gkk at juno.com, milsurplus at mailman.qth.net
>>Subject: Re: [Milsurplus] Naval Aviation Navigation
>>Date: Tue, 14 Mar 2006 09:54:45 -0500
>>
>>DME uses pulse pairs with a fixed, calibrated response delay.  The range 
>>given is what's called slant range and not map distance, so if you are at 
>>30,000 feet and right over the VORTAC (VOR-TACAN) it will show 5 naut 
>>miles.  In civilian VORTACs there is a combination of civilian VOR for 
>>azimuth info and a DME/TACAN subset for distance info.
>>
>>Peter
>>
>>
>>D C *Mac* Macdonald wrote:
>>>I had thought that the DME portion was actually a
>>>transponder that sent out the pulse in response to
>>>an interrogation signal from the aircraft.  Admittedly,
>>>it's been a long time since I had contact with this
>>>sort of thing.  Last time I worked in avionics was
>>>in 1984 and tech school was long before that!
>>>
>>>73  ---  Mac, K2GKK/5
>>>
>>>
>>>
>>>----Original Message Follows----
>>>From: C Whitaker <whitaker at pa.net>
>>>Reply-To: whitaker at ieee.org
>>>To: "D C (Mac) Macdonald" <k2gkk at juno.com>
>>>CC: whitaker at ieee.org, milsurplus at mailman.qth.net
>>>Subject: Re: [Milsurplus] Naval Aviation Navigation
>>>Date: Tue, 14 Mar 2006 09:30:04 -0500
>>>
>>>de WB2CPN
>>>
>>>Mac, the antenna wouldn't have to rotate and produce
>>>the azmuth information if all you wanted is DME.   On
>>>a VORTAC the VOR antenna rotates a heart-shaped
>>>pattern which makes the azmuth info.  The 12 uS pulsed
>>>DME signal antenna usually sits on top of the VOR antenna,
>>>is omni-directional, and doesn't rotate.
>>>
>>>73  Clete
>>>
>>>
>>>______________________________________________________________
>>>Milsurplus mailing list
>>>Home: http://mailman.qth.net/mailman/listinfo/milsurplus
>>>Help: http://mailman.qth.net/mmfaq.htm
>>>Post: mailto:Milsurplus at mailman.qth.net
>>>
>>>
>>______________________________________________________________
>>Milsurplus mailing list
>>Home: http://mailman.qth.net/mailman/listinfo/milsurplus
>>Help: http://mailman.qth.net/mmfaq.htm
>>Post: mailto:Milsurplus at mailman.qth.net
>
>
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>