You probably already read about it in the forums, but I thought I should write a nice blog article about it as well. Not everybody is digging the forums as troughly as we do... :)
We are now able to understand the proprietary DSL protocol of the RC receivers from ACT. This allows us to connect any receiver with a DSL interface to the NG. ACT produces great cheap and expensive PPM, PCM, SPCM and 2.4GHz receivers and most of them have a DSL interface. We can use all of them now! I've already ordered a SPCM receiver for myself... :)
To be able to test out the stuff, I've upgraded my NG to 1x sum signal + 1x DSL receiver, an ACT DSL8 to be exact.
My NG now looks like this:
Software support for DSL was added to the NG firmware and the NG is now able to use DSL receivers on any of it's UARTs. Being able to parse the DSL protocoll, we now have the possibility to connect serveral rc receivers at the same time to the NG. The current NG is able to use up to 3 rc receivers that way (2x DSL + 1x sum signal).
We implemented Diversity and Teacher/Student functionality! Teacher/Student was implemented in two different forms. We have the "ts-switch" mode which allows the user to switch between teacher and student mode using a behavior rule which is a able to check for arbitrary conditions eg. buttons, changes on sticks... essentially any behavior condition implemented. On the other hand we have the "ts-mix" mode, which will continiously mix the teacher and student signals.
We used the Teacher/Student mode for our first FPV tests and it performed perfectly.
Using the Diversity features seems a bit more troublesome. If you would like to do frequency diversity (as I do), then you have the problem to get two identical signals on two different frequencies into the air. It seems that there are not many possibilities to do that...
ACT offers a double sender module allowing Graupner MC24, MC22 and Futaba RCs to be extended. Sadly the module works with two quartz crystals and has no synthesizer. Since I extended my MC22 with a synthesizer, I don't really like the idea to go back to quartz crystals.
Another possibility would be to use two RC controls and link them using the teacher/student features of the RC. Since normaly only the teacher rc is sending a signal this will need some fiddeling in the remote controll to be able to have both rc send the same signal on two frequencies at the same time.
As you see, there's a lot room for further experiments!