Air traffic detection question

I couldn't speak for the 200 model to be honest with you. The model I
got is the ATD-300. I watched it closely for a while and it was very
hard to understand what it was tracking. The NM half would show
anywhere between 5 to 0 and the altitude would jump around a lot. At
times it would appear to be functioning correctly, but then it would
go back into a very random cycle of range and altitude. If I turn off
my transponder it appears to settle down a bit. It may be having a
hard time trying to hear my transponder, but I can't tell for sure.
At one point I watched a twin Cessna fly within a half mile of me and
about 200-400 feet above me, but the only thing I got on the display
was that it was somewhere between 4 miles and 0 miles and above me 100
feet, then it would report below me 300, then show *my* altitude with
no range. Most of the time the range would change from 4 or 5 miles
to 0-1 miles within 5 to maybe 10 seconds. I think the ATD-300 is the
lest expensive out there, doesn't appear to be very accurate in WHAT
it displays.


"James M. Knox" wrote in message ...
(FISHnFLY) wrote in
om:

Has anyone flown with any of these new "portable tcas" devices? I
recently got a Monroy ATD-300, which is the lowest price, that gives
range and altitude, but have been very disappointed in the
performance. My experience is that the altitude and range of aircraft
it is reporting are constantly changing drastically.

I haven't had a chance yet to put an ATD-300 through it's paces, nor to
compare it to the latest new crop that have come out in the last few
months. I do have an ATD-200 in my plane and find it somewhere between
useful and toy. Toy, because it probably only identifies about 30% of
the traffic in a useful fashion (has a habit of not lighting up until
the traffic has passed G). Useful, because it sometimes does alert me
to look for traffic out in the boonies, when there hasn't been another
aircraft within 100 nm for the last 2 hours (hard to keep a good scan
going under those conditions). A large percentage of the time it gives
false alarms.

None of these are going to give you anything more than a very loose idea
of range. Any appearance of good range information is a lie -- a big
smoothing algorithm that makes it look like good data, but still may be
grossly inaccurate.

The older units did NOT do a real decode on altitude and hence might
trigger on a jet 30,000 feet above you, and fail to detect a '172 flying
200 feet below. The newer ones are supposed to pick up the transponder
altitude, but probably have trouble keeping it matched to the
appropriate target. [I develop algorithms for the military to track
airborne threat targets and it can get complicated.] Does it vary the
altitude substantially when you are pretty sure there is only one threat
nearby?



-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

(FISHnFLY) wrote in
om:

I couldn't speak for the 200 model to be honest with you. The model I
got is the ATD-300. I watched it closely for a while and it was very
hard to understand what it was tracking. The NM half would show
anywhere between 5 to 0 and the altitude would jump around a lot.

Can you define "a lot"? The range problem is something I would expect.
But the altitude (if there is only one target anywhere near) should be
accurate. Having said that, both your altitude and that of the threat
aircraft can be jumping around by at least 100 feet (for a minimum
"jitter" of a couple of hundred feet).

So... Are you only seeing it "jump around a lot" +/- maybe 300 feet? Or is
the altitude readout REALLY varying massively?

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

"A lot" being + 300 for about 1 seconds then - 600 for another half
second to +700 then it will stick for a while, only to go back to very
odd changes. If I read this right I would have had 60 aircraft around
me between 5 to 0 miles and one at just about every altitude.
Occasionally it will resort to showing what appears to be actual
altitude, but I can't tell for sure when it switches. My overall
opinion is that it doesn't seem to be able to "lock" onto any one
particular aircraft, but instead will swing between many, or be
misreading them all together. I flew with it again this evening and
it did basically the same thing, only this time I had a low wing piper
pass directly above me, not more than 100 to 200 feet, and it kept
telling me someone was way below me at "0 NM to 3 NM"

I am starting to think that the ATD-300 is still in a "beta-test"
mode, and perhaps not ready for prime time. I got one of these right
out of the release along with three other guys, and we have all had
about the same results. I am considering trying their competitor
trafficscope while I still have the ATD to see side by side for myself
how they compare in accuracy. I was going to get another competitor
called proxalrt into the ring as well, but the only place that carried
it said they don't keep it in stock.

We'll see.




"James M. Knox" wrote in message ...
(FISHnFLY) wrote in
om:

I couldn't speak for the 200 model to be honest with you. The model I
got is the ATD-300. I watched it closely for a while and it was very
hard to understand what it was tracking. The NM half would show
anywhere between 5 to 0 and the altitude would jump around a lot.

Can you define "a lot"? The range problem is something I would expect.
But the altitude (if there is only one target anywhere near) should be
accurate. Having said that, both your altitude and that of the threat
aircraft can be jumping around by at least 100 feet (for a minimum
"jitter" of a couple of hundred feet).

So... Are you only seeing it "jump around a lot" +/- maybe 300 feet? Or is
the altitude readout REALLY varying massively?

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

(FISHnFLY) wrote in
om:

"A lot" being + 300 for about 1 seconds then - 600 for another half
second to +700 then it will stick for a while, only to go back to very
odd changes. If I read this right I would have had 60 aircraft around
me between 5 to 0 miles and one at just about every altitude.

Yeah, I'd call that "a lot". G It's certainly more than could be
accounted for by normal encoder "quantization" error.

Your guess about what may be happening sounds like a good possibility.
Having developed a lot of this software for the military, it *is* difficult
to keep multiple threat tracks identified uniquely. Of course, that is
with all the aircraft involved possibly undergoing high-G high speed
maneuvering. The ATD-300 has less sensor data available than I have in the
typical fighter aircraft, but the targets are also doing a LOT less
maneuvering.

I am starting to think that the ATD-300 is still in a "beta-test"
mode, and perhaps not ready for prime time.

The ATD-200 had similar problems, and a bunch of them had to be sent back
for "adjustment." They kept picking up the host aircraft as a threat.

This could explain the behavior in regards to the altitude with the
Monroy unit, which does not use any altimeters.

http://www.surecheck.net/avionics/altimeter.html

I think it was the Ryan series of tcas that when first launched only
used altitude from the "host" transponder, rather than directly from
the encoder, and found it was not a 100% reliable way to get altitude.
The squawk code apparently is the major problem, and with no "second
opinion" from an additional altimeter, I can see how the Monroy unit
might get confused.





(FISHnFLY) wrote in message . com...
"A lot" being + 300 for about 1 seconds then - 600 for another half
second to +700 then it will stick for a while, only to go back to very
odd changes. If I read this right I would have had 60 aircraft around
me between 5 to 0 miles and one at just about every altitude.
Occasionally it will resort to showing what appears to be actual
altitude, but I can't tell for sure when it switches. My overall
opinion is that it doesn't seem to be able to "lock" onto any one
particular aircraft, but instead will swing between many, or be
misreading them all together. I flew with it again this evening and
it did basically the same thing, only this time I had a low wing piper
pass directly above me, not more than 100 to 200 feet, and it kept
telling me someone was way below me at "0 NM to 3 NM"

I am starting to think that the ATD-300 is still in a "beta-test"
mode, and perhaps not ready for prime time. I got one of these right
out of the release along with three other guys, and we have all had
about the same results. I am considering trying their competitor
trafficscope while I still have the ATD to see side by side for myself
how they compare in accuracy. I was going to get another competitor
called proxalrt into the ring as well, but the only place that carried
it said they don't keep it in stock.

We'll see.

Hello,
Sorry to jump into your exchange ... You may consider trying a Prox
alert R5 which monitors up to three threats simultaneously.

Don't ask me to elaborate online on other devices since i work for
Prox alert.

As we are an honest company we have no problem to offer a 30 days
money back
guarantee. www.prox alert.com (HQ in Phoenix AZ)

We will be happy to answer your technical questions about affordable
collision avoidance devices.

Thierry

(FISHnFLY) wrote in message . com...
I couldn't speak for the 200 model to be honest with you. The model I
got is the ATD-300. I watched it closely for a while and it was very
hard to understand what it was tracking. The NM half would show
anywhere between 5 to 0 and the altitude would jump around a lot. At
times it would appear to be functioning correctly, but then it would
go back into a very random cycle of range and altitude. If I turn off
my transponder it appears to settle down a bit. It may be having a
hard time trying to hear my transponder, but I can't tell for sure.
At one point I watched a twin Cessna fly within a half mile of me and
about 200-400 feet above me, but the only thing I got on the display
was that it was somewhere between 4 miles and 0 miles and above me 100
feet, then it would report below me 300, then show *my* altitude with
no range. Most of the time the range would change from 4 or 5 miles
to 0-1 miles within 5 to maybe 10 seconds. I think the ATD-300 is the
lest expensive out there, doesn't appear to be very accurate in WHAT
it displays.


"James M. Knox" wrote in message ...
(FISHnFLY) wrote in
om:

Has anyone flown with any of these new "portable tcas" devices? I
recently got a Monroy ATD-300, which is the lowest price, that gives
range and altitude, but have been very disappointed in the
performance. My experience is that the altitude and range of aircraft
it is reporting are constantly changing drastically.

I haven't had a chance yet to put an ATD-300 through it's paces, nor to
compare it to the latest new crop that have come out in the last few
months. I do have an ATD-200 in my plane and find it somewhere between
useful and toy. Toy, because it probably only identifies about 30% of
the traffic in a useful fashion (has a habit of not lighting up until
the traffic has passed G). Useful, because it sometimes does alert me
to look for traffic out in the boonies, when there hasn't been another
aircraft within 100 nm for the last 2 hours (hard to keep a good scan
going under those conditions). A large percentage of the time it gives
false alarms.

None of these are going to give you anything more than a very loose idea
of range. Any appearance of good range information is a lie -- a big
smoothing algorithm that makes it look like good data, but still may be
grossly inaccurate.

The older units did NOT do a real decode on altitude and hence might
trigger on a jet 30,000 feet above you, and fail to detect a '172 flying
200 feet below. The newer ones are supposed to pick up the transponder
altitude, but probably have trouble keeping it matched to the
appropriate target. [I develop algorithms for the military to track
airborne threat targets and it can get complicated.] Does it vary the
altitude substantially when you are pretty sure there is only one threat
nearby?



-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

Thierry wrote:

Hello,
Sorry to jump into your exchange ... You may consider trying a Prox
alert R5 which monitors up to three threats simultaneously.

Don't ask me to elaborate online on other devices since i work for
Prox alert.

As we are an honest company we have no problem to offer a 30 days
money back guarantee. www.proxalert.com (HQ in Phoenix AZ)

We will be happy to answer your technical questions about affordable
collision avoidance devices.

Thierry, I like the target squawk code readout as well, but it comes
at more than double the price... Still alot cheaper than the $19k
units that are out there too... G

Darrel,
The Prox alert R5 new low price is 1045 USD. We sell direct.
The R5 outperforms everything available at similar price range.
It a real bargain.
Thanks,
Thierry

Darrel Toepfer wrote in message ...
Thierry wrote:

Hello,
Sorry to jump into your exchange ... You may consider trying a Prox
alert R5 which monitors up to three threats simultaneously.

Don't ask me to elaborate online on other devices since i work for
Prox alert.

As we are an honest company we have no problem to offer a 30 days
money back guarantee. www.proxalert.com (HQ in Phoenix AZ)

We will be happy to answer your technical questions about affordable
collision avoidance devices.

Thierry, I like the target squawk code readout as well, but it comes
at more than double the price... Still alot cheaper than the $19k
units that are out there too... G