Servos - Digital vs Analog - which are compatible

[iambujo]

Hello - So I was doing some quick research to find legal servos under 4Watts when I noticed 2 types, digital and analog. As I see in the link below, the HS-322 in the KOP appears to be analog.
http://www.servocity.com/html/hs-322...rd_deluxe.html

The PWM code and wiring to the DSC creates a pulse width modulated signal to control servos as I understand it (I would have considered that a digital input, though averaged over time that creates an analog voltage). I haven't put a logic analyzer on it to see the signals yet, but I am curious the difference between analog and digital servos, and where in the FRC KOP info it defines which type of servo is compatible (if it does).

So are digital input servos compatible with FRC SW and the DSC? Or just analog servos?
http://www.servocity.com/html/hitec_servos.html

Thanks

[AdamHeard]

Both digital and analog servos use the same signal, and as long as they meet the power specs FIRST mandates, I don't see why either would be illegal.

The difference is entirely internal to the servo. The difference pretty much comes down to the pulserate on the motor itself; analog servos are in the range of 50Hz, digital are often 300 Hz+. The result is smoother operation with more precision.

In the rc racing world, this is a big deal. For FRC applications where you move front point A to B, digital is not worth the cost premium.

[iambujo]

Ok that's good news, thanks. I may have read some info on the web too quickly, hence the question. I thought the signal was different as well, but I guess it is just how the microprocessor within the servo analyzes the signal and translates it to power cycles on the motor.

http://www.futaba-rc.com/servos/digitalservos.pdf