Mode-CS (Beta)

[peter@schou.be]

Sorry but i can't find the switch for activating the c/s beta, please see attached photos, unit should be a pi 2b

[Admin]

Sorry but i can't find the switch for activating the c/s beta, please see attached photos, unit should be a pi 2b

Can you please show a screenshot of the home Page ?
Thx
Lee

[peter@schou.be]

That was fast
Pls see attached

[Admin]

That was fast
Pls see attached

Hi Peter,
Looking at the home screen it appears that either you do not have a PilotAware bridge fitted, or the Bridge has a fault.
the line here :-
TRX .... Unavailable TX=0 RX=0 ...
Hence there is no valid barometric pressure reading available for altitude comparison.

Thx
Lee

[peter@schou.be]

Aha, that is correct, does the bridge need to be in place to monitor mode c/s , or does the presserende just need to be corrected ?

[Admin]

Aha, that is correct, does the bridge need to be in place to monitor mode c/s , or does the presserende just need to be corrected ?

Initially we allowed the user to dial-in a pressure setting, but users kept forgettin making the relative altitudes incorrect.
We took the decision to only allow the automatic calculation with an on-board pressure sensor

Thx
Lee

[AllanBirt]

Mode C - possibly, mode S are you sure ?

Sorry Lee, it was mode C, when I get time I'll send you my flight logs.
Allan

[peter@schou.be]

Hi Lee
Thanks, can the mode c/s be activated by installing a USB pressure sensor ?, and if yes can you suggest a model?
Thanks for your very prompt answers, impressing !
All the Best from D

[JCurtis]

If the baro sensor on the Bridge is addressed the same as before the Bridge came along, I might have a small board around you could plug onto the Pi instead of a bridge to get the Baro working.  Depends what Lee and his team have done with the development of the Bridge.

[peter@schou.be]

That is very kind !!!, lets see what lee comes up with :-)
brg
Peter

[Admin]

Mode C - possibly, mode S are you sure ?

Sorry Lee, it was mode C, when I get time I'll send you my flight logs.
Allan

Great data, have sent email, I think I can see an issue on the first interrogation of your Mode-C transponder
Thx
Lee

[Admin]

If the baro sensor on the Bridge is addressed the same as before the Bridge came along, I might have a small board around you could plug onto the Pi instead of a bridge to get the Baro working.  Depends what Lee and his team have done with the development of the Bridge.

Hi Jeremy, Peter,
Unfortunately not, at startup the software does a complete selfcheck of all of the systems including Baro and Transceiver - any detected failures (reported with a red icon on the home page) and it will not run I'm afraid

Thx
Lee

[peter@schou.be]

Hi Lee

Thanks for your answer,
this of cause is one way of selling the bridge, but unemployed at the moment i unfortunately have to be picky what i spend my money on, and the bridge = 1 hour of actual flying time.

for testing purposes is it possible to go back to a previous software version where mode c/s is visible ?
by the way, how may pilot aware units are sold to denmark ?

pleased to hear
best regards
Peter

[the_doc]

I think I managed to outwit the ModeC/S + filter last night. I was night flying in VMC on top of an overcast layer, and I am sure there was not a soul about, futher East Midlands Radar were giving me a traffic service and they were quiet, and nothing seen.

I started a descent from 3500 to 3000, at around 500fpm, and within a few seconds got a ModeC alert, red ring @ -100ft. I swiftly hit the altitude hold and as quickly as it appeared it then disappeared. I had a good look out and was so convinced it was my own ModeC transmission I continued descent. On doing so the same thing happened but within around 2 seconds the warning vanished again.

What I think is happening is that the cabin pressure is lagging a few hPa behind the actual barometric pressure as the autopilot starts the descent, then equalises again.  So the transponder is reporting a slightly higher pressure.

I found I can sometimes get the same short spurious -100 below by opening my DV window!!

Not sure if this helps in development. On the whole though, the filter is very helpful.

[Admin]

Hi Doc

I think I managed to outwit the ModeC/S + filter last night. I was night flying in VMC on top of an overcast layer, and I am sure there was not a soul about, futher East Midlands Radar were giving me a traffic service and they were quiet, and nothing seen.

I started a descent from 3500 to 3000, at around 500fpm, and within a few seconds got a ModeC alert, red ring @ -100ft. I swiftly hit the altitude hold and as quickly as it appeared it then disappeared. I had a good look out and was so convinced it was my own ModeC transmission I continued descent. On doing so the same thing happened but within around 2 seconds the warning vanished again.

What I think is happening is that the cabin pressure is lagging a few hPa behind the actual barometric pressure as the autopilot starts the descent, then equalises again.  So the transponder is reporting a slightly higher pressure.

I found I can sometimes get the same short spurious -100 below by opening my DV window!!

Not sure if this helps in development. On the whole though, the filter is very helpful.

I think you are right - you have outwitted my filter 
I have had a few reports about rapid ascent/descent, but opening the window is a new one, but I can see what is happening.

The Filter is using a number of heuristics to remove YOU (ie, Mode-C you) from its list of threats.
I have identified that there is a 10 second window, and if you ascend descend quickly enough it no longer thinks that your own Mode-C transponder is you - basically it moves outside the filter window.
So at 500fpm, that is 83ft over 10 seconds, add on the coarse granularity of 100ft altitude encoding for Mode-C and there you have it!
I had not thought about the window opening, but of course, this could have the same effect of altering the internal pressure, and fooling the pressure sensor temporarily, but that is something I cannot address.

Its at this point where I put on my jobs-worth hat and say - hey the Mode-C is BETA 

We think we have a fix for this particular situation of rapid ascent/descent, which we hope to test out in the air as soon as the weather improves, and if this provides better behavior under these circumstances, it will become part of the release.

Thanks for the feedback Doc- this is useful information

Thx
Lee