PowerFLARM 3.0 and TIS

I had previously run some quick tests feeding PowerFLARM "TIS" data to my Garmin 396. I didn't continue the evaluation because, without any indication of mode C/S targets, it wasn't going to replace my Zaon MRX.

Today I ran a ground evaluation of the new non-direction target indication provided in FLARM 3.0

I found that, when the non-directional symbol was displayed, it was very clear. However there appear to be a number of issues:

1. The altitude data is often hidden by one of the symbols that define the circle.

2. The displayed altitude is usually 100ft lower that that displayed on the FLARM screen.

3. Perhaps most concerning - the non-direction traffic symbol is never displayed if there is any other traffic (ADS-B or FLARM) being displayed, even if the non-directional target is the closest in distance and altitude.

I don't know if item 3 is a restriction in the data interface, a bug in the 396 TIS display software, or an issue with the data being transmitted by FLARM. It does make the feature essentially worthless though so I hope it can be resolved.

Display of ADS-B targets was very clear and far superior to the depiction on the PF Portable or the Butterfly display. Of course there is a lot more display area to work with. However, several times I saw an ADS-B target on the FLARM display but not on the 396 even though it was in the displayed range.

This interface has great potential for those with Garmin displays but it doesn't seem to be quite ready yet.

Andy

Andy,

thanks for your report. With Garmin's TIS protocol, we're running
into several limitations that are due to the very coarse nature of
the protocol. For example, direction is only in multiples of 45 degrees.

As a consequence, we explicitly recommend *against* using
a TIS-speaking device as the sole FLARM display in an installation.

We've been in touch with Garmin at the Aero in Friedrichshafen
and invited them to implement the open FLARM specific protocol on their devices. Feel free to ask Garmin about an ETA!

1. The altitude data is often hidden by one of the symbols that define the circle.

Layout of the screen is entirely determined by the display, and there are
probably dozens which implement TIS. FLARM has no influence on that.

2. The displayed altitude is usually 100ft lower that that displayed on the FLARM screen.
May be a rounding issue, I'll check the FLARM part.

3. Perhaps most concerning - the non-direction traffic symbol is never displayed if there is any other traffic (ADS-B or FLARM) being displayed, even if the non-directional target is the closest in distance and altitude.

You probably only had 'informational' (non-threat) targets. FLARM *will* send the non-directional target on TIS *if* it is more dangerous than FLARM or ADS-B traffic
around. In case of non-threat traffic (the most frequent case and what you're
probably seeing) is that there's no threat traffic. In this case
we do indeed prioritize directional targets. The reason is, again, a limitation
of the TIS protocol.


Display of ADS-B targets was very clear and far superior to the depiction on the PF Portable or the Butterfly display. Of course there is a lot more display area to work with. However, several times I saw an ADS-B target on the FLARM display but not on the 396 even though it was in the displayed range.

The TIS protocol is limited to 8 targets maximum and the range (defined
by the protocol) may be lower than the FLARM range. TIS devices may
have their own horizontal and vertical range settings, did you check?

Best
--Gerhard, FLARM dev mgr

Gerhard,

Thank you for the reply. It's good to know you are still monitoring
RAS.

I have included my comments below:

As a consequence, we explicitly recommend *against* using
a TIS-speaking device as the sole FLARM display in an installation.

Accepted. The 396 is used in my PA28-180 and the FLARM Portable will
also be in view.

We've been in touch with Garmin at the Aero in Friedrichshafen
and invited them to implement the open FLARM specific protocol on their devices. *Feel free to ask Garmin about an ETA!

Thanks for trying.

Layout of the screen is entirely determined by the display, and there are
probably dozens which implement TIS. * FLARM has no influence on that.

Understand - thanks

2. The displayed altitude is usually 100ft lower that that displayed on the FLARM screen.

May be a rounding issue, I'll check the FLARM part.

Thanks for checking


3. Perhaps most concerning - the non-direction traffic symbol is never displayed if there is any other traffic (ADS-B or FLARM) being displayed, even if the non-directional target is the closest in distance and altitude.

You probably only had 'informational' (non-threat) targets. *FLARM *will* send the non-directional target on TIS *if* it is more dangerous than FLARM or ADS-B traffic
around. *In case of non-threat traffic (the most frequent case and what you're
probably seeing) is that there's no threat traffic. *In this case
we do indeed prioritize directional targets. *The reason is, again, a limitation
of the TIS protocol.

Yes, all the target were "informational". However I think the reason
the non directional targets are not displayed is related to this
statement "The TIS protocol is limited to 8 targets maximum".

The manual for the Garmin 396 describes the supported TIS symbols.
There is no non-directional symbol specified. Not surprising since
TIS would have no reason to send that information. It appears that
the FLARM transmitted non-direction target is made up of 8 separate
target symbols. If that is the case then all the available targets
are used up if a non-directional target is transmitted.

Would it be possible to modify the protocol to allow simultaneous non-
directional and directional targets. Possible solutions could
include:

1. Alternate between display of non-directional and directional
targets on each data transmission.
2. Progressively reduce the number of symbols used in the non-
directional target symbol and allocate each of the freed symbols to a
directional target.

*TIS devices may have their own horizontal and vertical range settings, did you check?

There is no user defined vertical or range TIS setting in the Garmin
396. Several times. when a non-directional target was displayed, an
ADS-B target replaced it when the non-directional target did not
increase in altitude or distance. Also, I have a second FLARM
system. As soon as the second FLARM system provides the system under
test with a FLARM target the non-direction target is removed.

Best regards,

Andy

Hi Andy,

TIS would have no reason to send that information. It appears that
the FLARM transmitted non-direction target is made up of 8 separate
target symbols. If that is the case then all the available targets

Yes, that's indeed the case.

Thanks for your suggestions. We'll consider them, but
I'm afraid we have higher priority issues. Also, I'm afraid that the
alternating solution might confuse (some) displays. Whatever we do,
the TIS is simply not designed for non-directional targets and the only real
solution is for Garmin to support the FLARM protocol.

Please be assured, though, that PCAS targets *do* have priority over
directional targets once they become more dangerous. So, our implementation
does not compromise safety in any way.

Best
--Gerhard (FLARM dev mgr)

An update for anyone interested in using the PF TIS output -

I reduced my ADS-B range and altitude to more reasonable flight numbers (5 miles, 2,000ft. This stopped distant ADS-B targets taking priority over local non-directional targets on the 396 TIS display. Of course I also lost the display of the these distant target of the PF display.

Given the restrictions of the TIS protocol it would be useful if the TIS data range and altitude settings could be set independent of the local display settings.

Andy

Andy,

Given the restrictions of the TIS protocol it would be useful if the TIS data range and altitude settings could be set independent of the local display settings.

I see your point. But it also adds more complexity to an already pretty complex system...

Best
--Gerhard

Hello Gerhard,

I just found this discussion whilst looking for details how the Garmin TIS protocol can handle Mode-S targets.

Do you plan to ever implement a loop antenna (integrated antenna like modern ADF antennas) in order to give also a directional information about Mode-S targets? This feature combined with the already existing Mode-S amplitude ranging would solve the problems with the TIS interface and the biggest concern "against" Powerflarm.

I studied aviation engineering and I am doing my commercial pilot licence right now. I tried to convince my local flying club of installing PF and ADS-B out in our fleet (five planes), but there were too many concerns about the non-directional Mode-S targets. The solution with PF wasn't evaluated as good enough for spending about 10.000€ in a CAS for the fleet.

We are just looking for a system which provides displaying ADS-B targets as well as directional Mode-S targets (like the Zaon XRX), preferably displayed on the GNS430. As long as these claims can't be satisfied, I won't be able to convince our managing committee of buying any CAS for our fleet.

Unfortunately ADS-B isn't planned to be mandatory for all aircraft in Europe, so I think the focus should be how we can get the non-ADS-B targets displayed in an appropriate form since a Mode-S transponder is the only system nearly all SEP and TMG are equipped with.

The general aviation needs just an affordable single device which is combining the advantages of the Zaon XRX and PF. That would be a real innovation.

I hope you understand my point and that my feedback is incentive enough to take that feature into account and into your intern discussions.


Kind regards
Simon