Rumour posted around the web suggests the company has gone bust.
That would mean there is now no “portable” product on the market that delivers azimuth information on Mode A/C/S transponding targets. There are several which give you an altitude based warning but with no azimuth (bearing) it is of little use other than to keep you extra awake.
It just leaves the full active TCAS systems like this one – pricey at €10k+.
It ain’t rumour but fact – they went out of business last month
Oh, my little Zaon MRX has recently gone a but ‘funny’ (not for the first time, or even the second time), and I was contemplating sending it back again.
I wonder what happened. At one point they were THE portable PCAS, but I have to be honest it’s performance for me was less than impressive (maybe the bigger XRX was better), though I wont deny that it alerted me to some traffic I might not have otherwise seen. That said I also saw a lot of traffic, it hadnt, so that devalues the device significantly, with our without azimuth. I guess PowerFlarm and all that hype is all the rage now. The PowerFlarm still has too many limitations to be used as a totally reliable PCAS – which would always be the case anyhow unless you had a ‘proper’ £10k type system.
My personal impression is that all the passve traffic device which exist here in Europe do not work properly. Our plane has got I think a TAS, I think the TAS610. It works very well if the other plane has got the transponder switched on. But it is very expensive. Recently I flew in a bigger plane and the range of the system installed there was simply amazing. We could see traffic over a very big area.
That being said I believe a much better passive system could be build. One could take several requests from known stations like airliners with TCAS and ADS-B, ground stations etc. and calculate the position of the target precisely. But it would be a complex development. I spoke with people from Flarm and GNS GmbH and they said the development cost would be high, so they rather continue to sell the devices they have. I’m occupied with datalink weather, else I would try to build it myself.
That leaves the “cheap” passive market to Monroy.ATD300 in this price range…it has now ARINC429 output for a GNS ..people using it with the external antenna claim good results…
One could take several requests from known stations like airliners with TCAS and ADS-B, ground stations etc. and calculate the position of the target precisely. But it would be a complex development. I spoke with people from Flarm and GNS GmbH and they said the development cost would be high, so they rather continue to sell the devices they have. I’m occupied with datalink weather, else I would try to build it myself.
That’s a good idea really! That would mean a MMPCAS 
(Multi Mode Passive Collision Avoidance System)….only now design it…..ugh…. 
I don’t understand how Monroy can get the bearing correct with one antenna wire. TCAS systems have four antenna wires and use phase array antenna’s (to identify the) target’s bearing. Also TCAS systems have top and bottom antennas and apart from that theTCAS processor works in combination with another host of LRU’s like, Mode S, Air Data, Radio Altimeter to adapt sensitivity etc…Indeed one could simplify the system significantly, but the challenge is still correct BEARING data
A couple of years ago, at EDNY, I spoke to PowerFlarm – the company which the whole world is supposedly watching – and asked them if they are interested in doing a product which does azimuth, like the Zaon. The chap I spoke to said he was their chief designer. I suggested to him that he could start off by looking at the way radar guided missiles resolve the reflected signal from the target, using a very simple array of waveguides. That technology is public domain in that you can see the missile heads open in museums etc. I think Zaon used a simplified version of it.
He was completely uninterested, saying nobody would want azimuth data.
My personal impression is that all the passve traffic device which exist here in Europe do not work properly
I think that about sums it up. I have flown with at least two people (that I can recall) who had the bigger Zaon and it was generating false alarms.
Before I had the Avidyne TAS605 box installed, I looked around the US market, where there were some products which claimed to offer azimuth, using a single blade antenna and they were much cheaper than the Avidyne (or Garmin or Honeywell) boxes. But the customer reviews on them were basically crap, and I could not understand how such products could possibly work. It can’t be done with a single blade antenna, even one which contains two antennae within the single blade.
TCAS systems have four antenna wires and use phase array antenna’s (to identify the) target’s bearing.
You may well be right but I don’t think they do anything that clever.
The Avidyne (formerly Ryan) TAS boxes need the two coax cables from each antenna pair to be within 5cm of each other. They seem to use the relative signal amplitude only.
Garmin, I vaguely recall, don’t need equal cable lengths so maybe they are doing something else, or maybe they have a calibration function which takes out the errors during install.
I don’t think you can get direction with a phased array detector at the low frequencies used (~1GHz). It would be like trying to DF a long wave (LW) signal – it isn’t really possible AFAIK. And using the fact that the signal hits one before the other is tricky; speed of light is 1ns per ft so you would need to resolve something like 10ps, which is possible with electronics, but what is the risetime of a typical transponder transmission? This is the most obvious way to do it but I am sure nobody has achieved it.
For a passive system I think it is the wrong strategy to detect the bearing directly.
I think it is better to detect the absolute position of the target and compare that to the GPS position of the aircraft. Image you know where a TCAS source is by analysing its ADS-B output. Then you detect when the interrogation hits you. Then you detect when the answer to that interrogation comes in from the aircraft you want to detect. So now you know how far the cimulated distance from the source, to the target to your own aircraft is.
As we know the position of the source and our own we can establish an elipztical surface where the target can be. Then we get the altitude information of the target also so we have an eliptical line where it can possibly be. Now either take a second source or the same source which moves fast as most TCAS equiped ADS-B airlines will. With 3 sources you can tell where the target is.
The challenge is to build a device which listens on the transponder interrogation and the answer frequency simulataneously. It must also be able to timestamp the requests properly. But I think it will be superior to all the other passive systems out there.
The question is how many can you sell at which price and how expensive is the development. Especially since there is so much non working stuff in the market it will take quite some money to convince people your device is different.
Peter, if you read the details in my link BEARING then indeed there are other solutions but all of them have there draw backs…The ideal would be install a small AWACS antenna on each aircraft and make it spin fast
But indeed a combination of other technologies may improve the Bearing detection…(ADS-B) ….Why Funkwerk didn’t go further I think is just this complexity as Sebastian describes…
Sebastian, what about non ADS-B aircraft…? There is no other way then try to find the target bearing then by finding the bearing directly somehow…
see abstract
Within a TCAS system, interrogations often occur at the rate of 1 per second. In prior inventions, relative bearing determination is often made after two or more interrogations. Thus, bearing update is often after a delay on the order of a few seconds. Each message transmission from a transponder unit is typically 64 uSec or 120 uSec in length, and is made up of several pulses that are typically 0.5 uSec each in duration.Consequently, there exists a need for improved receiver systems for measuring the bearing of an intruder aircraft.
Sebastian, what about non ADS-B aircraft…?
The idea is not to detect ADS-B aircraft. But the idea is to use the TCAS interrogation of airliners (or known ground stations), use their ADS-B output to know where the TCAS interrogation signal physically originated in space and detect the absolution position of other transponder only aircraft. The idea is similar to passive radar systems which use the radar energy send out by secondary sources. I’m pretty sure it can be done but I’m also sure it will require a lot of effort.
