PPM signal timing on Turnigy 9x training port

[fanfanlatulipe26]

I am using a Turnigy 9x, with standard Turnigy module,with ER9X r820 software(but it seems that it is in fact the r821 release)
The module has been modify in order to not overload the PPM signal (well known "1k ohm" mod)
I want to use the transmiter with a flight simulator with a USB interface but got some problems: jitter, chanel numbering etc...
I had a look at the PPM signal on the trainer port and play with the Model Setup/Protocol options.
I got a pulse spacing arround 0.2us far away from the default 300us. This value does not change a lot even when playing with the "pulse spacing" value.
Others timings seem good.
Am I missing something or do not understand the "standard ppm" timing ?

I don't see also any change in the wave form with the "Shift Sel" option NEG/POS

pulse between 2 channels

wave form with 4 channels

[jhsa]

I have tried on my radio and POS and NEG are working as they should.
Most simulator dongles do not accept more than 4 channels. Some accept 6, so try sending only 4 as a test.
I know you did the resistor mod, but try also to remove the RF module.
There is a protocol called "PPMSIM". Try it. This protocol was implemented to avoid people having to do the resistor mod

João

[fanfanlatulipe26]

Thank you for your help.
I am no longer using the simulator dongle: just a USB logic analyzer, sampling at 24mhz
I made the test with / without the module, with / without PPMSIM , with 6 channels, playing also with the pulse spacing parameter.
I always get a waveform with the spacing pulses being around 0.3us / 0.5us , about 1/1000th the nominal value.
POS / NEG option makes no change (the level between the pulses burst should be high or low following the option ? is'nt it ? . Just inverted signal)
My ER9X version:
Vers: V1.747-Mike
Date: 30.11.2016
Time: 13:41:02
SVN: er9x-r820

I reloaded it from http://www.er9x.com/ with the "last" binary.It should be r821.
I forced the transfer in eePe and status was OK .eePe does not show that a newer version exists ....

[jhsa]

I don't understand, with my Er9x radio all works as expected.. I have scoped it last night, and all seens to be ok. I also see it changing between positive ad negative. The firmware should be exactly the same
I will have a look again.
Something that might be worth mentioning, the channel positions are set by the time between 2 consecutive pulses and not the lenght of the pulses themselves. So if a pulse is generated 1500uS after the first one, it means that the channel is centered..

[fanfanlatulipe26]

OK, but the length of the stop pulse should be arround 300us / 500us (according to vairous "specification found on the web), varying with the pulse spacing parameter.
Other parts of the frame seem OK, the time between the stop pulses varying with the sticks position within "standard" values

[fanfanlatulipe26]

oops ! my fault.
Do'nt know what happened but now all is good.

I suspect a bad contact with the jack, but not sure ....
At first I used a 3mm male stereo jack and I am sure that I plugged / unplugged the jack many times, still having strange results.
What is strange is that only the stop pulse looked bad. The other pulses and the general wave form looked good.
I then used a mono male jack and the test turned to be OK.
I reverted back to the stereo jack and the results are still good . ...

Well, maybe I'll open the transmiter and see what happen with a male stereo jack.

Thank you for your help
Francis