Questions tagged [mode-s]

Mode S is a type of aircraft transponder used in conjunction with Secondary Surveillance Radar. Mode S equipped aircraft transmit an aircraft specific unique code, which can be used for selective interrogation by surveillance equipment.

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Can you use a mode 3AC interrogator in EU airspace?

I'm investigating the possible application of mode 3AC interrogators in EU airspace. My experience is unfortunately limited to North America, and I'm unfamiliar with Mode S systems / function. All ...
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80 views

How are Mode 2 pulses encoded?

I'm working on a research project looking at Mode 3A/C replies and have noticed some pulse patterns that look very similar which I suspect are Mode 2 replies. They appear to differ by just one pulse. ...
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How do I use the Mode S MB Data subfield of the ASTERIX data item I062/380?

In the ASTERIX message cat062, there's a data item I062/380 -Aircraft Derived Data- which has a Subfield #25 called "Mode S MB Data". What is this subfield for? The field is 56 bits long, which ...
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How to know which data came from Mode S and which came from ADS-B (FIS-B)?

I'm dealing with recorded ADS-B data as a part of my thesis (programming-oriented). I have a table of ADS-B communication of an aircraft (image below) - I know, that some of these recorded data in ...
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1answer
154 views

What benefits does Automatic Dependent Surveillance bring to continental ATC over Mode S?

In particular, to the extent that there are mandates for it in USA and Europe? I checked various posts here and official descriptions (e.g., faa.gov), but I can't figure out the following: For ...
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What needs to be done when experiencing severe turbulence at an altitude of FL270 with No ATC and Mode C failure? [closed]

Flying at FL270, you experience sever turbulence and Mode C failure, and the ATC channel is heavily Occupied, what should a pilot ideally do?
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1answer
426 views

What are the radius of containment (Rc) and horizontal protection limit (HPL) and how are they related to Type Code?

In ICAO Document 9871 (Technical Provisions for Mode S Services and Extended Squitter) page 30 they have mentioned it in the form of a table. But they haven't explained HPL and Rc in detail.
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695 views

How to extract the interrogator ID from a DF11 message?

I've written a class which decodes raw Mode S messages. Whilst browsing the ICAO specs the other day I noticed that the Interrogator ID is sent back in the DF11 message. I thought that it would be a ...
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1answer
1k views

What's required for the ADS-B to function? A GPS or Mode S Transponder?

Jeppesen defines the ADS-B as a surveillance system broadcasting GPS-derived positions and other information such as velocity over the data link. Yet, the Wiki article on ADS-B relates it to the Mode ...
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Can ADS-B DF-17 messages with a non-zero remainder after CRC check be used?

For fun I've been using an AirSPy SDR (Software Defined Radio) to receive and decode ADS-B packets, primarily DF-11 and DF-17 messages. The code is written in C++ and works reasonably well. It ...
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1answer
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What is the minimum set of registers to fill for ADS-B?

I am researching about Automatic Dependent Surveillance-Broadcast mode of Mode S currently. On a third party document, I encountered a list of transponder registers to be filled; 05, 06, 07, 08, 09, ...
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What aircraft would have these tail numbers?

Last night I was looking at a flight radar on my phone, and I saw two blips flying close to each other over Camden, NJ. They were heading northeast at around 250 knots, and the only information ...