Transponder install.

[Ultralights]

Gday all, i am no good at aviaonics at all, and no noting of how to install a transponder, i have an aircraft that might require a transponder in the near future, and basically, i am asking, what is needed for a complete working transponder setup? do you just buy the transponder and antennae, install it, wire it up and off you go? how does it get height information to transmit?

 

thanks in advance

 

Rob.

 

 

[Tomo]

how does it get height information to transmit?

Depending on the type of interrogation, the transponder sends back a transponder code (or "squawk code") (Mode A) or altitude information (Mode C). Another mode called Mode S (Mode Select) is designed to help avoiding overinterogation of the transponder (having many radars in busy areas) and to allow automatic collision avoidance. Mode S transponders are 'backwards compatible' with Modes A & C.

 

The transponder receives and transmits signals which in turn the radar thingo's can decipher where you are. So all you need is the required Antennae/Ariel and you should be away.

 

You do have to program it somehow so that they know what aircraft it actually is, I'm not real sure about that bit, also some require certification in that aircraft before use in certain area's I believe... anyway that's outa my awareness zone.

 

Please note, I'm not real experienced with this, just saying what I understand so far.

 

 

[Guest Crezzi]

Depending on the type of interrogation, the transponder sends back a transponder code (or "squawk code") (Mode A) or altitude information (Mode C). Another mode called Mode S (Mode Select) is designed to help avoiding overinterogation of the transponder (having many radars in busy areas) and to allow automatic collision avoidance. Mode S transponders are 'backwards compatible' with Modes A & C.

Wouldn't it have been better to just provide a link to the Wikipedia article ?

 

 

[Tomo]

Wouldn't it have been better to just provide a link to the Wikipedia article ?

Well yeah If you like, though I didn't get it directly from there, I have a program on my computer so I didn't have the link.

 

 

[Ultralights]

im not really concerned to much on how they work, more, what is required in the aircraft. transponder plus antennae plus encoder? does the encoder attache to the back of a standard altimeter? do you need an encoder? is just the transponder and antennae all you need?

 

 

[Guest basscheffers]

To get Mode C (which is altitude reporting) you need:

 

- Transponder

 

- Altitude encoder

 

- Antenna

 

- Cabling

 

The encoder simply connects to static and is calibrated to 1013; ATC applies the QNH in their read out, you don't have to set it.

 

There's two types of encoder/transponder combination, analog ("gray code") and digital. ("RS-232") Obviously, your units must be compatible!

 

Most EFIS solutions, like Dynon, have encoder output. In Dynon's case it's digital, but for gray-code transponders, they sell a converter. So if the aircraft already has that, you can probably use it.

 

Now before you can use it in CTA, it must be calibrated by a LAME, and this has to be re-done every two years I believe.

 

At this moment, you might want to think about spending more and getting a Mode-S transponder, which can provide ADS-B. Unfortunately, it is likely to become mandatory in future. ADS-B uses GPS to report your position and other data. The main reason for doing so (ATC has radar!) is that anyone in the area can pick up the signal and display traffic, like TCAS-II, but many times more accurate and affordable. (if still pricey at the moment)

 

Hope I didn't tell any lies and that it's been helpful!

 

 

[ahlocks]

Maaaate.....

 

Has this bloke got a deal for you!

 

http://www.recreationalflying.com/forum/suppliers-services/96341-austec-avionics.html

 

And he lives right here on the forum!!

 

 

[Mazda]

That is not quite true about ADS-B. Not everyone can pick up the signal and display traffic at all, they require ADS-B "in" which is very expensive and not like TCAS at all as it does not provide an audio signal with traffic advisory or resolution advisory due to patent issues.

 

If the other aircraft had ADS-B "in" and happened to look at the screen at that particular moment they might see you.

 

Yes, ATC would see you if you were in coverage and could pass you on as traffic, but it is a misconception that if you "have ADS-B" you can see all other traffic.

 

 

[ZULU1]

Take a look at our club website, Ballito Microlight Club http://www.balaero.co.za as a club we have the new King Shaka International right next door to us opening on May 1st. It is a public site but you will be able to see the installations on a trike, the memorandum of agreements, the final airspace (box) allocated to us and also our own squawk code. We called it project parrot after the original IFF used in WW2. Most have installed the Trig TT21s (Mode S device). It has ADS B capabilities as well. This I believe is a test project between us and the SACAA and I may add all concerned have been very user friendly. The club has some good negotiators I may add !! It seems pointless installing a Mode C here as we are led to believe that its going to be replaced RSA wide in 2012 and Namibia has installed 42 station WMA network already.

 

Cheers Paul

 

 

[Guest Crezzi]

Microair's website has installation manuals for both their transponder & encoder - a read through those should give you a fair idea about whats involved with fitting them

 

Cheers

 

John

 

 

[sain]

mode S doesn't provide ADSB. Its a standard that predates ADSB. ADSB provides a GPS based location reference and a unique identifier. I think Mode S provides a unique identifier and a wider squawk code range.

 

I don't think mode s is a legitimate mode for Australia, so it'd be wasted money.

 

Its probably best to check that information with somebody who pays attention more than I do.

 

 

[Guest basscheffers]

The way I understand it is:

 

- Mode S transponders send GPS position and aircraft ID in the Extended Squitter. (ES)

 

- ATC receives this and uses it for their own displays

 

- ATC transmits the information back out

 

- Transponders with Traffic Information System (TIS) receive this

 

- A compatible moving map GPS/PFD/MFD connects to transponder and reads the info to display traffic.

 

A Garmin GTX330 Transponder and Aera 500 GPS is all you need to get both ADS-B in and out. Expensive? Depends. The GTX330 costs twice as much as a comparable Mode C; US$3600 vs. $1800.

 

Not something I'd like imposed on me, but also not something completely unnafordable.

 

Now the beauty of ADS-B in remote areas is that instead of an expensive radar system that provides positioning, all you need on the ground is an omni directional antenna that excites the transponder to get them to transmit their position. That would give "radar" coverage where before it was not feasible.

 

 

[Guest Crezzi]

- Transponders with Traffic Information System (TIS) receive this

- A compatible moving map GPS/PFD/MFD connects to transponder and reads the info to display traffic.

You need a Mode-S/ADS-B receiver to connect to the GPS for ADS-B "in" - its not part of the transponders that are currently available AFAIK. You can then "hear' the position reports from other aircraft independently of any ATC involvement.

 

Cheers

 

John

 

 

[Guest basscheffers]

You need a Mode-S/ADS-B receiver to connect to the GPS for ADS-B "in" - its not part of the transponders that are currently available AFAIK.

John, read the specs on that GTX330; it has the receiver built in and according to Garmin, all you need is the low-cost Aera 500 to display it. (More expensive units like 430/530/etc. work also)

They also say it gives audible (voice) alerts about traffic. But unlike TCAS-II, I don't think the aircraft in question are negotiating about it. (the patent thing?)

 

 

[Guest Crezzi]

John, read the specs on that GTX330; it has the receiver built in and according to Garmin, all you need is the low-cost Aera 500 to display it. (More expensive units like 430/530/etc. work also)They also say it gives audible (voice) alerts about traffic. But unlike TCAS-II, I don't think the aircraft in question are negotiating about it. (the patent thing?)

You are quite right about the GTX330 but doesn't the Traffic Information Service (which, as you originally wrote, depends on radar coverage) specific to the USA ?

 

As I understand it, thats not compatible with the ADS-B proposal here (which does currently require a separate receiver to get cockpit traffic info) ?

 

Cheers

 

John

 

 

[Guest basscheffers]

Good question, I'm not sure. I would hope it's using the same TIS link here as in the US, but Automatic Dependent Surveillance Broadcast (ADS-B) - Airservices Australia doesn't seem to mention anything about TIS.

 

 

[Mazda]

That's why ADS-B hasn't been mandated. There is no world standard yet. The US actually proposes two separate systems, one for high level, one for low level. The planned model for the US low level one does NOT use Mode S extended squitter, which means US pilots will need both a transponder and ADS-B. However the US hasn't mandated ADS-B for quite some years and things may change.

 

In parts of Europe there is yet another system.

 

The problem is the US manufacturs most equipment, and if we end up with a different system, there won't be any mass produced units at a reasonable price because we don't have the market.

 

Also beware of ways to display traffic because there are standards for approved ADS-B and so far the approved "in" units are tens of thousands of dollars - if you can find one.

 

 

[Guest Andys@coffs]

With reference to the Mode S / ADSB /no mode S in Australia thing, Ithink the truth is a bit more complicated than a one liner. It is true that Mode S predates ADSB. Original Mode S equipment that is unmodified is generally known as short squitter Mode S. Most Mode S equipment has or can be modified to provide Long Squitter (more Data) ADSB requires an underlying Long Squitter Mode S capable transponder. So saying Mode S is not ADSB is technically correct, yet most (non engineer non avionics techs) people will believe mode S is part of ADSB.

 

Microair have a couple of docs that are relevant and tangentially relevant:-

 

http://www.microair.com.au/admin/uploads/MicroairModeSinAust01R1.pdf

 

Also on the about us page they have the following section:-

 

Microair is currently developing a T1000-TX ADS-B Transponder as part of its ADS-B series.

 

After the ADS-B the transponder we will be re-configuring our transponder to Mode S to suit the new requirements in the European marketplace. ( Im thinking perhaps someone to whom engrish was a second language wrote that)

 

....and a whole bunch of other waffle....

 

An old ASA document that has some useful technical descriptions of what it is and how it works can be found here:-

 

http://www.airservicesaustralia.com/projectsservices/projects/adsb/docs/news/ADS-B_Avionics_Issue_4_1.pdf

 

Lastly, it was my undestanding (20yrs ago in my trade training) that IFR/SSR was triggered via a sweeping narrow beamwidth interegation beam. In this way only a subset of the in range transponder fitted aircraft would be interegated at any one time.

 

If we were to use an omni powered interegation antenna, then potentially all devices in range at the time would be asked to repsond at (roughly... plus minus propogation delays) the same time. Originally the time between interegation request and the time the reponse was recieved enabled the gnd station to determin range to target. Obviously if the response contains nav data then that isnt important, however, if I understand correctly an omni request would be like a person asking a hall full of people to tell him their first name all at the same time...good luck with making anything sensible of the responses.

 

Andy

 

 

[Guest basscheffers]

if I understand correctly an omni request would be like a person asking a hall full of people to tell him their first name all at the same time...good luck with making anything sensible of the responses.

As a computer/network guy, this doesn't worry me as this is roughly how ethernet works; if two cards detect a "collision", the both have a random timeout and try again.

I would imagine that digital ADS-B transponders will have a random delay between interrogation and transmit, making it unlikely they transmit at the same time. If there is a collision, well, then there is another interrogation half a second later. So even in busy airspace, every aircraft will be picked up every few seconds in the worst possible scenario.

 

I'm sure the boffins have thought about this!

 

 

[Bill Hamilton]

At this moment, you might want to think about spending more and getting a Mode-S transponder, which can provide ADS-B. Unfortunately, it is likely to become mandatory in future. ADS-B uses GPS to report your position and other data.

Folks,There is little likelihood of ADS-B/C OUT becoming mandatory any time in the foreseeable future, except where it is already in use ----- above FL 310 ----fact!!

Have a look at what Airservices says about coverage with the present number of ground stations. Even to produce coverage down to 10,000 ft, close to 200 ground stations would be needed (I don't remember the exact number but you could dig it up from ASA). To produce coverage down to 5000', something over 300 ground stations would be required, plus one or two additional satellites to handle the traffic.

 

And all for what ???---- In present G airspace, and potential E, or current C, there is simply no collision risk safety problem that would justify such a huge expenditure for a non-problem.

 

The real cost/benefit outcome made it a non-starter.

 

The so called cost/benefit figures in the DP were nonsense, they complied within NO KNOWN guidelines, certainly not Office of Best Practice Regulation (OBPR), Productivity Commission, or A-Gs Department. Once the DP got beyond the protagonists and their cheer squads, and was considered at a higher level of Government, most of the proposal was dropped like a hot brick.

 

Claims of subsidies for GA etc. were pie-in-the-sky, none of the airlines ever agreed to the cross subsidy to GA. Recreational wasn't even seriously mentioned.

 

 

We are so short of avionics LAMEs that, based on the "proposed" time scale for ADS-B, even if ALL OTHER AVIONICS WORK was dropped in 2009, and that continued for about 5 years, there was no way the proposed fitting timetable could have been achieved---- even if the equipment was available at the claimed prices, which it still isn't

 

All the replies to the discussion paper on the subject are public documents, have a look at them. One has my name on it, I have put a lot of figures on the record, and included the coverage charts.

 

Even arguments about "safety" for "Regionals" doesn't stack up, they will only see the same thing as they already see with TCAS 11, if you have a Mode C transponder ---- despite a lot of ill informed claims to the contrary ----- even if they had ADS-B IN, which is not part of the modifications I have seen in airline aircraft.

 

A Mode C transponder is a fraction of the price of even the cheapest currently available ADS-B Mode S (which is a Garmin 330, from memory--- lots of claims by others are vapor) is about about 10 times a cheap Mode C transponder. Beware claims about several European/Australian "manufacturers", so far they do not meet Australian specifications, usually in the GPS area, but also sometimes in the Mode S transmission format.

 

Most of the "mandatory" proposals were put by organizations with a financial interest in ADS-B/C installation.

 

If you still want to fit a Mode S transponder --- just in case ---- make absolutely certain it meets the FULL requirements for ADS-B, as required by Australia/ICAO.

 

Regards,

 

PS:

 

(1)There are three ICAO standards for ADS-B, all mutually incompatible. They are UAT, VDL-4 and 1090ES.

 

Australia has chosen to impose the "airline" 1090ES on the rest of Australia, locking us out of the cheap UAT equipment available in US.

 

With 1090ES equipment, the ADS-B/C data is carried on the vacant DF 17 and 18 message slots on the Mode S signal.

 

The 1090ES format is a very old technology "narrow" band (around since the 1970s) with literally no room for further expansion as a datalink --- an extremely shortsighted decision forced by cash strapped airlines ---- it was touted as cheap and quick, and is neither, turning out to be a far more expensive update than either VDL-4 of UAT ---- but that is what happens when technical decisions are made by accountants.

 

And, for their troubles, airlines flying in US or Europe have a deadline for installing a datalink for routine ATC communications ---- if they had thought ahead of their next quarterly report, UAT or VDL-4 would have served multiple roles, which is what ICAO intended, originally.

 

A VDL-4 (from memory, I don't think it is UAT) datalink network (privately owned) is well on the way in Australia ---- for airline use, to replace ACARS --- which has run out of bandwidth.

 

UAT is CDMA (as per current/future mobiles) , VDL-4 is TDMA ( first generation digital phones)

 

(2) Re. the Garmin prices, it is only the "top of the line" 330 with "antenna diversity" that fits the bill, and you need a C 145 or C 146 GPS input., so add that in.

 

 

[ianboag]

If you're reasonably brave .....

 

Got to Barnstormers.com. Buy a basic second-hand King txpdr (KT-76 or 79) for about $US600. Make sure you get the mounting tray as well. You might get an encoder in that price, but encoders new in Oz are only about $100. If you're lucky you might get the encoder/txpdr wiring loom as well. Ditto for antenna.

 

Send it to a local avionics shop and ask them to do a wiring harness (if it didn't already come with one) for the txpdr/encoder connection and to calibrate is (maybe $600 or so all up).

 

Then just bolt it in to your plane wherever you can find a place that fits. Mine went under the bottom edge of the dash above my knees. The only things it connects to are power and static pressure (for the encoder).

 

IB

 

 

[Bill Hamilton]

Folks,

 

Have a look at US eBay for transponders, usually a huge number available. PayPal buyer protection rules can be quite a help, if things turn sour.

 

<http://motors.shop.ebay.com/Aviation-Parts-/26435/i.html?_dmd=1&_dmpt=Motors_Aviation_Parts_Gear&_pcats=6028%2C6000&_sop=1&_rdc=1>

 

Regards,