uln2803apg toshiba shows noise
The ULN2803 is an inverting open collector driver and the noise you are seeing is likely due to high frequency pick-up when the device is open circuiting between pulses. Try lowering (or connecting) a pull-up load to your local Vcc and see how the noise reduces in amplitude.

Here's what a single channel looks like: -



If you need to drive a digital signal from one PCB to another there are push-pull drivers that might be better suited.