PPM and PCM RF sections in modular radios
02-22-2005, 02:29 PM
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PPM and PCM RF sections in modular radios
General question:
1)Is the RF module in a PCM radio identical to one in a PPM radio??. Is it a basic FM transmitter???
2)I assuming all info (ppm) or (pcm) data is processed prior to reaching the RF module...IS that true??
3) If you removed the "data" line from a FM RF Plug IN module and kept it powered up would you get the same RF carrier signal regardless of radio type (PCM or PPM)??
Here is where I am going with this... I have a spare HiTec RF module that came from a PCM radio and want to install it into a (outdated ) futaba FG series radio. Other than the obvious plug compatibility problem, would it work???
1)Is the RF module in a PCM radio identical to one in a PPM radio??. Is it a basic FM transmitter???
2)I assuming all info (ppm) or (pcm) data is processed prior to reaching the RF module...IS that true??
3) If you removed the "data" line from a FM RF Plug IN module and kept it powered up would you get the same RF carrier signal regardless of radio type (PCM or PPM)??
Here is where I am going with this... I have a spare HiTec RF module that came from a PCM radio and want to install it into a (outdated ) futaba FG series radio. Other than the obvious plug compatibility problem, would it work???
02-22-2005, 02:35 PM
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RE: PPM and PCM RF sections in modular radios
From the JR aspect, the RF PCB / Modules are identical. The PPM/PCM signal is generated in the processor section.
If you remove the data line, then depending on how the signal line is biased, then the RF Frequency could either be on freq, low freq or high freq.
For test purposes and alignment of the Tx Deviation, I have an interface cable that will either toggle the data line INTO the Module/PCB either High or Low. The data line FROM the processor I terminate so it isnt passed to the RF side.
Re the last, I do not know either the Hitec or Futaba kit so cannot comment on it ( apart from probably being illegal from the FCC point of view. )
[8D]
If you remove the data line, then depending on how the signal line is biased, then the RF Frequency could either be on freq, low freq or high freq.
For test purposes and alignment of the Tx Deviation, I have an interface cable that will either toggle the data line INTO the Module/PCB either High or Low. The data line FROM the processor I terminate so it isnt passed to the RF side.
Re the last, I do not know either the Hitec or Futaba kit so cannot comment on it ( apart from probably being illegal from the FCC point of view. )
[8D]
02-22-2005, 02:38 PM
#3
My Feedback: (27)
RE: PPM and PCM RF sections in modular radios
There is no difference but:
If you install that HiTec module( I am assuming you are talking the old large module) in a Futaba FG radio the FM shift will be backwards. You should check to see how wide the deviantion or FM shift is.
The Futaba was never FCC certified with a HiTec module....not legal and if something happens you will have NO AMA insurance.
Pete
HiTec service center
If you install that HiTec module( I am assuming you are talking the old large module) in a Futaba FG radio the FM shift will be backwards. You should check to see how wide the deviantion or FM shift is.
The Futaba was never FCC certified with a HiTec module....not legal and if something happens you will have NO AMA insurance.
Pete
HiTec service center
