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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