9CAP PCM data transmission. *Binary codes & signal etc.*
12-09-2003 | 08:43 PM
#1
Thread Starter
9CAP PCM data transmission. *Binary codes & signal etc.*
Here's what I need to do.
I'm designing a circuit/system to act like a failsafe unit. It will fly my plane to a preset position (THE FIELD) should the signal from the Tx be lost. The two main components are a GPS receiver for position sensing and a "Basic Stamp 2p40" microcontroller for decoding the GPS data, converting it and then sending an output to the Rx telling it where to position the servos.
*** Here's my problem.
I can't comunicate with the Rx unless I know how to 'talk' to it.
I know that the Rx operates on a 70MHz carrier signal which has a 455KHz signal imposed on it. The 455KHz signal is to my understanding what contains the 20ms frames with the binary servo position data and checksum error detection code.
*** Here's what I don't know.
What order is the binary servo position and checksum data sent. I need to know this in order to program the Basic Stamp so that it will send data to the Rx in the same manner the Tx does.
*** Here's what I need to know.
Everything about that 455KHz signal. I need to know in which order the binary #'s/pulses are sent, there time duration, magnitude, spacing, etc. etc. I need to be able to have my Basic Stamp send data to the Rx in the same manner as the Tx.
*** The 149DP Rx has the DSC plug which I might be able to use also. Going this route would COMPLETELY eliminate interfirence between the Basic Stamp and the Rx. This is what I prefer to do, but in this instance also I first must know how the DSC works and how and in what order it sends data. The amplitude, period, period variations of the signal are also required info to implament this type of control.
Anyhow, Thanks in advance and any aditional info you deem aplicable would be appriciated as well.
Regards,
Bryan
www.rc-hanger.com
I'm designing a circuit/system to act like a failsafe unit. It will fly my plane to a preset position (THE FIELD) should the signal from the Tx be lost. The two main components are a GPS receiver for position sensing and a "Basic Stamp 2p40" microcontroller for decoding the GPS data, converting it and then sending an output to the Rx telling it where to position the servos.
*** Here's my problem.
I can't comunicate with the Rx unless I know how to 'talk' to it.
I know that the Rx operates on a 70MHz carrier signal which has a 455KHz signal imposed on it. The 455KHz signal is to my understanding what contains the 20ms frames with the binary servo position data and checksum error detection code.
*** Here's what I don't know.
What order is the binary servo position and checksum data sent. I need to know this in order to program the Basic Stamp so that it will send data to the Rx in the same manner the Tx does.
*** Here's what I need to know.
Everything about that 455KHz signal. I need to know in which order the binary #'s/pulses are sent, there time duration, magnitude, spacing, etc. etc. I need to be able to have my Basic Stamp send data to the Rx in the same manner as the Tx.
*** The 149DP Rx has the DSC plug which I might be able to use also. Going this route would COMPLETELY eliminate interfirence between the Basic Stamp and the Rx. This is what I prefer to do, but in this instance also I first must know how the DSC works and how and in what order it sends data. The amplitude, period, period variations of the signal are also required info to implament this type of control.
Anyhow, Thanks in advance and any aditional info you deem aplicable would be appriciated as well.
Regards,
Bryan
www.rc-hanger.com
12-10-2003 | 10:44 AM
#2
My Feedback: (11)
RE: 9CAP PCM data transmission. *Binary codes & signal etc.*
With PCM coding, you can't rely on 20 mS frames. That's for analog PPM systems. PCM coding has its own timing system. Unfortunately, the exact coding scheme for Futaba PCM systems is considered proprietary, and Futaba, Japan has not released it.
Your best bet would be to use the analog servo output signals from each channel and route them through your processor.
Such discussion on how to do this is well beyond the scope of this forum. How to implement such a device would best be discussed in the general radio forum.
Your best bet would be to use the analog servo output signals from each channel and route them through your processor.
Such discussion on how to do this is well beyond the scope of this forum. How to implement such a device would best be discussed in the general radio forum.
