AirNav Systems Forum

AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: Jono_Kzn on June 11, 2010, 04:02:10 PM

Title: MODE-S
Post by: Jono_Kzn 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

Title: Re: MODE-S
Post by: DaveReid on June 11, 2010, 04:35:03 PM

Quote from: Jono_Kzn on June 11, 2010, 04:02:10 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.

Title: Re: MODE-S
Post by: Runway 31 on June 11, 2010, 04:36:15 PM

Jono, which aircraft is it?

Title: Re: MODE-S
Post by: Jono_Kzn on June 11, 2010, 04:53:29 PM

Its an ATR 72-212A

Title: Re: MODE-S
Post by: Runway 31 on June 11, 2010, 05:04:59 PM

What registration?

Title: Re: MODE-S
Post by: Jono_Kzn on June 11, 2010, 05:13:01 PM

5H-PWD

Title: Re: MODE-S
Post by: ACW367 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

Title: Re: MODE-S
Post by: ACW367 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

Title: Re: MODE-S
Post by: Runway 31 on June 11, 2010, 05:20:05 PM

Jono could you forward the hex code please.

Title: Re: MODE-S
Post by: Jono_Kzn on June 11, 2010, 05:26:25 PM

I sent it via PM

Title: Re: MODE-S
Post by: Jono_Kzn 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??

Title: Re: MODE-S
Post by: DaveG on June 11, 2010, 05:31:04 PM

Quote from: Jono_Kzn 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??

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

Title: Re: MODE-S
Post by: Jono_Kzn 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...

Title: Re: MODE-S
Post by: ACW367 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.