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Author Topic: MODE-S  (Read 4181 times)

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Jono_Kzn

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MODE-S
« on: June 11, 2010, 04:02:10 PM »
Hi,

Howcome I can hear an aircraft clearly but radarbox does not show the traffic?  The aircraft in question definately has mode-s only.

Does a mode-s transponder only broadcast when a radar station interrorgates it?

Thanks

Jono

DaveReid

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Re: MODE-S
« Reply #1 on: June 11, 2010, 04:35:03 PM »
Does a mode-s transponder only broadcast when a radar station interrogates it?

If the aircraft has TCAS, it should send acquisition squitters once every second.  RadarBox should pick those up.
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Runway 31

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Re: MODE-S
« Reply #2 on: June 11, 2010, 04:36:15 PM »
Jono, which aircraft is it?

Jono_Kzn

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Re: MODE-S
« Reply #3 on: June 11, 2010, 04:53:29 PM »
Its an ATR 72-212A

Runway 31

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Re: MODE-S
« Reply #4 on: June 11, 2010, 05:04:59 PM »
What registration?

Jono_Kzn

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Re: MODE-S
« Reply #5 on: June 11, 2010, 05:13:01 PM »
5H-PWD

ACW367

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Re: MODE-S
« Reply #6 on: June 11, 2010, 05:13:19 PM »
There are two forms of transponder, Mode S or Mode S ADS-B. Only the ADS-B version includes positional data as derived from onboard navigation systems. As the non-ADS-B do not transmit their coordinates, radarbox cannot plot them on a map. Most aircraft below jet airliner size have not yet been fitted with ADS-B transponders

ACW367

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Re: MODE-S
« Reply #7 on: June 11, 2010, 05:18:58 PM »
Radarbox receives encoded radio messages rather than radar images. Only if that broadcast radio message contains a position report can it be plotted on radarboxes virtual map

Runway 31

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Re: MODE-S
« Reply #8 on: June 11, 2010, 05:20:05 PM »
Jono could you forward the hex code please.

Jono_Kzn

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Re: MODE-S
« Reply #9 on: June 11, 2010, 05:26:25 PM »
I sent it via PM

Jono_Kzn

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Re: MODE-S
« Reply #10 on: June 11, 2010, 05:26:49 PM »
Yes I understand that but the aircraft in question has mode-s which doesnt display all the time.  I pick it up when it is close but it dissapears off the screen however i can hear the ATC traffic clearly....

Just wondered howcome i can hear the atc clearly but the radarbox does not show its recieving the mode-s traffic??

DaveG

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Re: MODE-S
« Reply #11 on: June 11, 2010, 05:31:04 PM »
Yes I understand that but the aircraft in question has mode-s which doesnt display all the time.  I pick it up when it is close but it dissapears off the screen however i can hear the ATC traffic clearly....

Just wondered howcome i can hear the atc clearly but the radarbox does not show its recieving the mode-s traffic??

Simple answer to this could be your RB aerial has a blind spot at where the aircraft is either on distance, direction or alt
Cornwall, UK

Jono_Kzn

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Re: MODE-S
« Reply #12 on: June 11, 2010, 06:00:00 PM »
I have a DPD antenna is there any specific tips for placement?  I have it about 16 feet in the air.  However there are quite a few trees around me...

ACW367

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Re: MODE-S
« Reply #13 on: June 11, 2010, 06:33:38 PM »
Jono

Mode S radio signals are line of sight so high ground trees block the transmissions if the aircraft goes behind them.

PS I have sent you a PM on a different topic.