a way to communicate or stream the bits over the USB port via COM or Serial
If you are using the standard Uno Rev 3, just use Serial.print() to send formatted ASCII data via the USB connection, to a PC or Mac. The data will also appear on pin 1, as TTL level RS232 ASCII.
A terminal program can save the output to a log file.
The pulseIn() function can be used to measure the PWM period.