RC servos are controlled by a signal that goes high for between 1ms to 2ms. This pulse is repeated every 10 to 20ms, but it's timing does not control the position of the servo.
http://www.dougrice.plus.com/hp/RCservo/rcservo.htm
Describes how servo motors work and how to convert a servo motor to a really nice compact gearhead motor with built in electronics.
http://www.seattlerobotics.org/guide/servohack.html
A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal.
http://www.seattlerobotics.org/guide/servos.html
After 1991 or so, most of the major brands of servos became compatible with each other. You can use any of these brands of servos with any brand of receiver.
http://www.fatlion.com/sailplanes/servos.html
This circuit slows the speed of a conventional proportional servo.
http://www.speedy-bl.com/goslow-e.htm
an interface to convert pulses such as provided by R/C receiver to a dual PWM signal required by an H-bridge to drive a DC motor.
http://www.bobblick.com/techref/projects/sv2pwm/sv2pwm.html
All the work controlling the servos is done in the preprogrammed PIC micro-controller.
http://www.ozitronics.com/docs/k102.pdf
http://www.imagesco.com/articles/picservo/01.html