>Hi Philippe,
>
>Clyde wrote:
>>>
>>> I don't believe there is a standard - all the manufacturers have
>>> their own encoding schemes. The servos are still driven with PWM
>>> signals, but the PCM receivers are not interchangable,
>
>then you replied:
>>
>>         - SURE there is a PCM standard, what it's in the hard is a
>> special code which identify the receiver. In many transmitter it's
>> not possible to exchange this code, that's the reason why you cannot
>> exchange a ROBBE PCM receiver and a FUTABA PCM receiver.
>>
>>         - It's quite easy for me to design a numerical way to send
>> servo position to a receiver. But my purpose is not to create a new
>> encoding scheme, but to be as far as compatible with other materiel.
>
>>From a practical stand-point, I'd have to agree with Clyde that the
>PCM receivers are not interchangeable.  And you may be right that they
>all use the same encoding -- but I've never seen any information on
>the PCM encoding or signature that causes the receiver to belive it
>is receiving a valid signal.
>
>The PCM transmitters & receivers are the top of the line and command
>premium prices.  I believe each manufacturer considers their encoding
>proprietary.  You can probably reverse engineer it.  But I doubt that
>any manufacturer would guarantee not to change their PCM protocol, or
>even notify you of the change, unless you were buying huge volumes.
>
>On the other hand, you might get lucky and find such a standard.  If
>you do, I'd be very interested in having a copy.
>
>                                                Lee Jones
>
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>