LeSving wrote:
It’s the same as ADS-B in the US, there will be no use for ATC radars there either.
Just a note about ADS-B and radar in the US. There no plans to get rid of any of the primary radars. Secondary radar systems will still cover 100% of the airspace above 18000 MSL and in all of the terminal areas. At most, fewer than 50% of the secondary radars not in the terminal areas will be eliminated as a result of ADS-B.
Peter wrote:
If you connect a GPS output to a plain old GTX330, it will radiate the whole lot.
I think you might be confusing “enhanced surveillance” with “extended squitter”. They are different things entirely. (And “enhanced surveillance” is abbreviated EHS while “extended squitter” is abbreviated “ES”).
“Enhanced surveillance” does not transmit GPS position. It does transmit various pieces of flight data and settings.Here is the Eurocontrol explanation.
http://www.eurocontrol.int/articles/mode-s-operational-overview
NCYankee wrote:
Just a note about ADS-B and radar in the US. There no plans to get rid of any of the primary radars. Secondary radar systems will still cover 100% of the airspace above 18000 MSL and in all of the terminal areas. At most, fewer than 50% of the secondary radars not in the terminal areas will be eliminated as a result of ADS-B.
As much as I find Avinor’s plans strange, this is even stranger. The whole idea of ADS-B/WAM is to increase accuracy, increase coverage, increase capacity and reduce cost. By keeping the primary radars, the cost will be 3 times as much as with ADS-B/WAM. The primary radars do not add anything, other than making ATC spot non-transponding aircraft en route. Maybe those radars are part of the military, which they are not in Norway. The military here have separate radars. WAM also enables independence from GPS, which ADS-B obviously do not, and WAM/ADS-B work together seamlessly. Avinor do not say they will remove any of the secondary terminal radars (the primary radars at the main airports are already gone however, only “en-route” radars are left, some of them until 2035).
Anyway, do these secondary terminal radars work at all without transponder?
Peter wrote:
If you connect a GPS output to a plain old GTX330, it will radiate the whole lot.
Where did you read that, I can not find this in your reference?
Some transponders are ADS-B capable, suchs as all German manufactured units, and Trig’s for example. The standard GTX-328 doesn’t have ADS-B capability, neither does the GTX-330, though this one can be upgraded. Then it becomes a GTX-330ES (Extended Squitter) and transmits other data.
As Airborne Again suggested you are either confusing ES and EHS, or confusing the GPS input on the standard GTX-330. There is used for start / stop flight timer, groundspeed / track (as part of EHS) and as part of the dataconcentrator (The number of dataports on a GNS or GTN can be quite limited, on an aircraft with many options. In this case a GTX-33 can be used as dataconcentrator, using multiple input, and generate a single output)
Peter wrote:
If you connect a GPS output to a plain old GTX330, it will radiate the whole lot.
Peter,
I think this has already been covered, but a standard GTX330 does not broadcast or provide latitude and longitude position. The GTX330ES does this and it requires a hardware and software upgrade at the factory to convert a GTX330 to a GTX330ES. In the US, Garmin charges $1200 for the device upgrade.
LeSving wrote:
Anyway, do these secondary terminal radars work at all without transponder?
No, secondary radar is based on transponder and is not a true radar system as is primary radar. With secondary radar, the ground station broadcasts a query on 1030 MHz, and a transponder replies on 1090 MHz. Primary radar involves the radar ground station emitting RF pulses and receiving reflected energy that bounce off an aircraft and are detected by the radar receiver.
In the US, the secondary radars are owned by the FAA and operated by them. The military has their own primary radars. The primary radars backup the secondary radar and other forms of surveillance such as Multilateration and ADS-B. For example, a bogus ADS-B position report can be detected by there not being a primary target at the same location. In class E and D airspace below 10000 MSL, transponders are not required. For IFR without a transponder on board or one that has failed, primary radar is used after the controller and pilot go thru an identification sequence.
NCYankee wrote:
No, secondary radar is based on transponder and is not a true radar system as is primary radar.
Well, I would say that they are both “true” radar systems… A matter of words perhaps. Primary and secondary radars alike determine the distance to the target by the time it takes for the radar signal to be echoed back from the target and the bearing is determined by the direction of the radar antenna when the echo is received.
The difference is that in the case of primary radar the echo is an actual reflection of the radar signal while in the case of secondary radar the echo is provided by the transponder.
but a standard GTX330 does not broadcast or provide latitude and longitude position.
Maybe @wigglyamp can drop in with some details because he was close to this issue at the time.
