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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Is a Mode S address changed when an aircraft is sold to another country?

The 24 bit Mode S address is issued by the national CAA where the aircraft is registered. If it is sold to another country, with another CAA, is the Mode S address maintained or is a new one assigned?
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7 votes
1 answer
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Does ADS-B use its own antenna?

In the aircraft we have: ADS-B out/in using 1090ES A/C or Mode S transponder for SSR grounding interrogation. Does the ADS-B out use the same antenna as Mode S or does it use its own antenna?
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4 votes
1 answer
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Does the ATC not receiving Mode C and intermittently other transponder information imply that the Mode S transponder itself has an issue?

I had ATC report to me inflight today that they were not receiving my Mode C (altitude data). Intermittently, they also reported they were not seeing any other transponder information. My transponder ...
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4 votes
2 answers
322 views

Why is a Mode S transponder required to be installed and working for TCAS II to be operational?

I am wondering why a Mode S transponder is required to be installed and working for TCAS II to be operational? I read such phrase in Eurocontrol ACAS II guide and I don't understand why mode A/C is ...
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5 votes
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What's the relation between ADS-B and MODE S

I know that ADS-B uses 1090ES or UAT to transmit their signal, and 1090 ES is related to MODE S. Here's my questions. What's the 1090 ES? If a aircraft uses 1090 ES as their ADS-B out, Does aircraft ...
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-3 votes
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What information does Mode S provide?

What information about own aircraft does TCAS Mode s( all call) send in the interrogation? What information does Mode S transponder(intruder)replay to TCAS interrogation?
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1 vote
0 answers
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Is a Mode S transponder required as part of TCAS I?

Is a Mode S transponder required as part of TCAS I?
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2 votes
1 answer
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Relation between Squawk code and ICAO adress

I can see in ADS-B downlink format 5 or 21, it is possible to answer squawk code. I am wondering how ATC will know which squawk code is coming from which aircraft? There is no possibility to encode ...
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2 votes
1 answer
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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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2 votes
1 answer
124 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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1 vote
2 answers
298 views

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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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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-2 votes
1 answer
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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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1 vote
1 answer
710 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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1 vote
1 answer
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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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6 votes
1 answer
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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5 votes
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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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5 votes
1 answer
247 views

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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4 votes
3 answers
817 views

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 ...
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