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  • Originally posted by peterhr View Post
    There's a little calculator here http://www.ringbell.co.uk/info/hdist.htm that works out horizon distance depending on observer height........

    It suggests a plane at 38000 feet would be observable at about 250 miles (that's about 400 km). ..................

    trying to support something that's poked up into the turbulent air and might attract lightening.
    Well the equation is correct, its theoretical limit of 400Km is now a proven fact.

    As for lightning, the tower was designed with that in mind. It has multiple grounding electrodes at its base, and all cabling has lightning protection including the LMR-400 from the ADS-B antenna. I learned all about lightning protection and EMP hardening back in the 1980's, when I worked on a Military project for 3 years. If a Nuke goes off the EMP has the same effect as being stuck by lightning, so the same principles of protection are used.
    Last edited by 1090 MHz; 2013-10-21, 11:22.
    www.ADS-B.ca

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    • Originally posted by 1090 MHz View Post
      Well the equation is correct, its theoretical limit of 400Km is now a proven fact.
      Yes, that was the reason for making the post - it does help people understand why the limit is there.

      Even with the most excellent antenna we're not going to do better unless the planes go higher (pity skylab doesn't have ADSB)

      Comment


      • Originally posted by fungus View Post
        You're kidding Birdie-
        have a look at my post re the fires here in Australia- houses and gum trees dont go together. The fires have destroyed more trees (and houses) than we ever could. Do you live in a cave?
        Yes, I do live in a cave - a CONCRETE Cave - LOL

        I just learn from TV of the massive bush fire down under. Hope the weather changes and help fight the fire. Hope the fire is not caused by sabotages.
        F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.

        Comment


        • Originally posted by peterhr View Post
          Yes, that was the reason for making the post - it does help people understand why the limit is there.

          Even with the most excellent antenna we're not going to do better unless the planes go higher (pity skylab doesn't have ADSB)
          You are right. The MAIN factor for range is neither "best antenna" nor "antenna height". It is the aircrft height which plays major role. Please see sketch below.

          Antenna Height and Range-2.png

          .

          Comment


          • Originally posted by 1090 MHz View Post
            Well the equation is correct, its theoretical limit of 400Km is now a proven fact..........
            For strict Line-of-Sight propagation:
            Range (miles) = 1.23 √height of Aircraft (feet)
            As commercial aircrafts rarely fly above Level 400 (40,000 feet), the limit is = 1.23 √40000 = 246 miles = 396 km

            In fact, because of the refractive effects of atmospheric layers, the RF signals don’t propagate in strict straight lines. The propagation paths are somewhat curved, increasing the range slightly. Taking into consideration effect of atmosphere on the propagation path of the RF signals under normal atmospheric conditions, the formula for range becomes:
            Range (miles) = 1.41 √height of Aircraft (feet)
            As commercial aircrafts rarely fly above Level 400 (40,000 feet), the limit is = 1.41 √40000 = 282 miles = 454 km

            These calculations assume that :
            (1) Receiving Antenna is at Ground Level. If antenna is higher than ground level, it will increase the range slightly. Please see the sketch in my previous post.
            (2) There are no tall objects between Aircraft & receiving antenna to block the RF Signal.
            Last edited by abcd567; 2013-10-21, 19:48.

            Comment


            • Originally posted by peterhr View Post

              Even with the most excellent antenna we're not going to do better unless the planes go higher (pity skylab doesn't have ADSB)
              Well you're dead on about going into space .... Nav Canada and Aireon are working together to do just that.


              A new joint venture to install Automatic
              Dependent Surveillance – Broadcast
              (ADS-B) receivers on a constellation
              of Low Earth Orbit (LEO) satellites will expand
              air traffic surveillance coverage to the entire
              planet

              http://www.navcanada.ca/ContentDefin...ll_2012_EN.pdf
              Last edited by 1090 MHz; 2013-10-21, 21:31.
              www.ADS-B.ca

              Comment


              • Originally posted by 1090 MHz View Post
                ......Also my location lines up with runways 06R & 06L (Landings) and 24R & 24L (Take-offs) so I'm getting the flights directly overhead too......
                Have you noted that the Runway Numbers at the two ends of any runway have a difference of exactly 18?
                LB Pearson CYYZ has a runway numbered 06 at one end, and the same runway is numbered 24 at the other end 24-06=18.
                Other examples are:
                LB Pearson CYYZ Runway 33 &15 (33-15=18)
                LB Pearson CYYZ Runway 23 & 05 (23-05=18)
                Buttonville CYKZ Runway 21 & 03 (21-03=18)
                Buttonville CYKZ Runway 33 & 15 (33-15=18)
                Downsview CYZD Runway 33 & 15 (33-15=18)
                Billy Bishop Toronto City CYTZ 26 & 08 (26-08=18)
                Billy Bishop Toronto City CYTZ 33 & 15 (33-15=18).

                You can check other airports around the world, and you will find the same numbering system.
                I was wondering just how many of us know the reason? (I do . It is very simple.)
                Last edited by abcd567; 2013-10-22, 03:59.

                Comment


                • It's based on compass headings.

                  http://en.wikipedia.org/wiki/Runway

                  a runway numbered 09 points east (90), runway 18 is south (180), runway 27 points west (270) and runway 36 points to the north (360 rather than 0)

                  If you watch the track in degrees on a flight coming into YYZ, from my direction, you'll see about 48 degrees... so they rounded it up to 50 and then dropped the last digit, making it runway 5. Actually in this area was have a 10* magnetic deviation and in North America that lie within the Northern Domestic Airspace of Canada are numbered relative to true north because proximity to the magnetic North Pole makes the magnetic declination large. So this is why the first runway was numbered 06 ... not 05.
                  YYZ has an interesting runway numbering history too, I could write much longer about.


                  This is an interesting look into the control tower at CYYZ.
                  http://www.youtube.com/watch?v=uccaSHOfxJ0
                  Last edited by 1090 MHz; 2013-10-22, 02:59.
                  www.ADS-B.ca

                  Comment


                  • Originally posted by 1090 MHz View Post
                    It's based on compass headings.........http://en.wikipedia.org/wiki/Runway......
                    @1060MHz: Thank you very much for the detailed information and link to Wikipedia. This is the main advantage & purpose of a forum: exchange & spread of information/knowledge.

                    I have planned that if no one answers my question, I will give the explanation after waiting for few days. You made my work easy. Thanks a lot.

                    Comment


                    • Originally posted by abcd567 View Post
                      You are right. The MAIN factor for range is neither "best antenna" nor "antenna height". It is the aircrft height which plays major role.
                      But the antenna still needs to be high enough for good performance. Because my antenna is up high it sees down the the CYYZ airfield very well, giving my station location good ground coverage of the runway action too.

                      I tracked a Toronto to NYC flight one night... the flight stayed on my F-CYYZ2 radar for half of the trip switching next to F-KJFK1 which is in NYC. That was amazing to see and told me that this plane at 36000, in that location, had a radio line of sight with YYZ and JFK at the same time.

                      Check out the communications antennas at CYYZ. They have 2 antenna farms of towers adjacent to the airport. This is VHF/UHF and even looks like some ADS-B antennas up on those towers. How high up do you think these towers are ?
                      Attached Files
                      Last edited by 1090 MHz; 2013-10-27, 08:50.
                      www.ADS-B.ca

                      Comment


                      • Originally posted by abcd567 View Post
                        Have you noted that the Runway Numbers at the two ends of any runway have a difference of exactly 18?
                        LB Pearson CYYZ has a runway numbered 06 at one end, and the same runway is numbered 24 at the other end 24-06=18.
                        Other examples are:
                        LB Pearson CYYZ Runway 33 &15 (33-15=18)
                        LB Pearson CYYZ Runway 23 & 05 (23-05=18)
                        Buttonville CYKZ Runway 21 & 03 (21-03=18)
                        Buttonville CYKZ Runway 33 & 15 (33-15=18)
                        Downsview CYZD Runway 33 & 15 (33-15=18)
                        Billy Bishop Toronto City CYTZ 26 & 08 (26-08=18)
                        Billy Bishop Toronto City CYTZ 33 & 15 (33-15=18).

                        You can check other airports around the world, and you will find the same numbering system.
                        I was wondering just how many of us know the reason? (I do . It is very simple.)
                        London Heathrow has a pair of parallel runways 09L, 09R, 27L, 27R, then you look at Chicago O'Hare and they seem to have runways all over the place.

                        If Heathrow gets another pair of runways running east / west - what do you think the numbering would be (assuming they would be 09 / 27)?

                        Comment


                        • Originally posted by abcd567 View Post
                          Have you noted that the Runway Numbers at the two ends of any runway have a difference of exactly 18?
                          LB Pearson CYYZ has a runway numbered 06 at one end, and the same runway is numbered 24 at the other end 24-06=18.
                          Other examples are:
                          LB Pearson CYYZ Runway 33 &15 (33-15=18)
                          LB Pearson CYYZ Runway 23 & 05 (23-05=18)
                          Buttonville CYKZ Runway 21 & 03 (21-03=18)
                          Buttonville CYKZ Runway 33 & 15 (33-15=18)
                          Downsview CYZD Runway 33 & 15 (33-15=18)
                          Billy Bishop Toronto City CYTZ 26 & 08 (26-08=18)
                          Billy Bishop Toronto City CYTZ 33 & 15 (33-15=18).

                          You can check other airports around the world, and you will find the same numbering system.
                          I was wondering just how many of us know the reason? (I do . It is very simple.)
                          The reason it is 18, is that opposite ends of Runways are 180 degrees different from each other.
                          So Runway 33 would be 330 degrees and Runway 15 would be 150 degrees.

                          More info here: http://en.wikipedia.org/wiki/Runway
                          Last edited by speedbird1960; 2013-10-27, 11:12.
                          AMS Daily Fight Information: http://schiphol.dutchplanespotters.nl/

                          Comment


                          • Originally posted by peterhr View Post
                            London Heathrow has a pair of parallel runways 09L, 09R, 27L, 27R, then you look at Chicago O'Hare and they seem to have runways all over the place.
                            Dallas is a good one... they have 35L, 35R and a 35C for 'center' https://maps.google.com/?ll=32.87967...02411&t=h&z=19
                            www.ADS-B.ca

                            Comment


                            • Originally posted by 1090 MHz View Post
                              But the antenna still needs to be high enough for good performance. Because my antenna is up high it sees down the the CYYZ airfield very well, giving my station location good ground coverage of the runway action too.

                              I tracked a Toronto to NYC flight one night... the flight stayed on my F-CYYZ2 radar for half of the trip switching next to F-KJFK1 which is in NYC. That was amazing to see and told me that this plane at 36000, in that location, had a radio line of sight with YYZ and JFK at the same time.

                              Check out the communications antennas at CYYZ. They have 2 antenna farms of towers adjacent to the airport. This is VHF/UHF and even looks like some ADS-B antennas up on those towers. How high up do you think these towers are ?
                              Yes, the ADS-B antenna needs to be high enough to overcome the terrain obstructions.

                              Once the antenna is raised above the level of nearby tall objects, any further increase in height does not increase the range appreciably, but severely increases the cost of antenna tower.

                              Antenna which is slightly above the level of nearby tall objects, can look down to planes on the ground, as well as can receive signals from planes as far as curvature of earth permits, which is about 450 to 500 kms. NY is slightly over 500 kms from Toronto.

                              Me and my indoor antenna are located at 60 feet above ground level. I get a range of over 450 kms in all those directions where buildings surrounding my location are lower than 60 feet, but range reduces abruptly in the directions where buildings are taller than 60 feet.

                              Please see attached images:
                              (1) Screenshot of the ranges
                              (2) My indoor Antenna

                              (1) Range3.png ....... (2) MyAntenna.png
                              Last edited by abcd567; 2013-10-30, 21:08.

                              Comment


                              • Originally posted by abcd567 View Post
                                Yes, the ADS-B antenna needs to be high enough to overcome the terrain obstructions.

                                Once the antenna is raised above the level of nearby tall objects, any further increase in height does not increase the range appreciably, but severely increases the cost of antenna tower.

                                Antenna which is slightly above the level of nearby tall objects, can look down to planes on the ground, as well as can receive signals from planes as far as curvature of earth permits, which is about 450 to 500 kms. NY is slightly over 500 kms from Toronto.

                                Me and my indoor antenna are located at 60 feet above ground level. I get a range of over 450 kms in all those directions where buildings surrounding my location are lower than 60 feet, but range reduces abruptly in the directions where buildings are taller than 60 feet.

                                Please see attached images:
                                (1) Screenshot of the ranges
                                (2) My indoor Antenna

                                (1) [ATTACH=CONFIG]2827[/ATTACH] ....... (2) [ATTACH=CONFIG]2821[/ATTACH]

                                I made same antenna like you made it to see how far it works. With RadioShack in-line amplifier 950-2050Mhz...
                                But it didn't work well, the longest range was 70nm!
                                So what do you think, is it wrong with Amplifier or something else?
                                I live in an apartment 8th floor so that's high enough.

                                image.jpgimage.jpg

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