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Author Topic: Imposible Range  (Read 2565 times)

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Judwin45

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Imposible Range
« on: June 23, 2014, 09:55:51 PM »
Hi
 
Can anyone suggest how I have picked up TF-BBH at a range of 290miles when my normal max range is about 114 miles.

I think I have attached a screen shot!

Regards
Keith
5 miles south of EGDY

CYYZGUY

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Re: Imposible Range
« Reply #1 on: June 23, 2014, 10:03:31 PM »
Hi Judwin, every once and awhile, I get returns like that....However I had my antenna up over 35 Meters..that may have helped...  You seem to have very limited range, so I cannot explain it.  Maybe the signal was reflecting off of an object...

Jason
2 Nm North from Canada's Busiest Airport CYYZ

DPD 1090 Mhz Antenna with LMR-400 Cable
Antenna 35 Feet (11 Meters) standing tall
Dedicated Airnav Station with 16 Gigs ram
Dedicated Radarbox24 Station with 16 Gigs ram
40" LED Monitor
40" LED Monitor
BCD996XT, BCT15X, BCT15X, BCT15 and BCD436 receiver

RodBearden

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Re: Imposible Range
« Reply #2 on: June 23, 2014, 10:34:33 PM »
Another possibility is that the aircraft was within your normal range but reporting a wrong position. A B734 is quite likely not to have GPS.

Maybe you've done it already, but a little research on the flight might tell you if the reported position was close to its actual route.
Rod

FACTflights

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Re: Imposible Range
« Reply #3 on: June 25, 2014, 09:12:26 AM »
Rod has probably hit the nail on the head.

There is another possibility - Thermal Inversion.

When  layers  of  warm  air  form  above  layers  of cold air, the condition known as temperature inversion develops.  This  phenomenon  causes  ducts  or  channels to  be  formed,  by  sandwiching  cool  air  either  between the  surface  of  the  earth  and  a  layer  of  warm  air,  or between  two  layers  of  warm  air.  If  a  transmitting antenna extends into such a duct, or if the radio wave enters  the  duct  at  a  very  low  angle  of  incidence,  vhf and uhf transmissions may be propagated far beyond normal  line-of-sight  distances.  These  long  distances are  possible  because  of  the  different  densities  and refractive qualities of warm and cool air. The sudden change in densities when a radio wave enters the warm air above the duct causes the wave to be refracted back toward  earth.  When  the  wave  strikes  the  earth  or  a warm  layer  below  the  duct,  it  is  again  reflected  or refracted  upward  and  proceeds  on  through  the  duct with  a  multiple-hop  type  of  action.
John
ZS1AGH
We live under a rock:  Table Mountain

Icom IC 706 Mk II G; Icom IC 726; Icom IC T22E; Yaesu 290R; Alinco DJ-V5 
No HF antennae at the moment.

Judwin45

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Re: Imposible Range
« Reply #4 on: July 13, 2014, 10:14:51 PM »
Hi

I have picked up the same aircraft (TF-BBH, flight TAY29V) tonight at 2050 local time again at a range of over 200 miles over France.

The only info from the internet suggests a flight between Liege and Dublin. Has anyone else picked up this flight tonight.

No big deal, I am just intrigued.

Regards
Keith
5 miles south of EGDY

cosmefulanito

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Re: Imposible Range
« Reply #5 on: July 21, 2014, 12:51:24 AM »
Real position 401 nm or 742 Km. Amazing !!!!