Advice On How To Dispute 31 Over Speeding Ticket

Last August was travelling on the 401 by Chatham with two other vehicles going a similar speed. Cop was waiting under an overpass and I got the short straw. Ticket is for 131 in a 100 zone. Missed the first court date as I never received a trial date notice (this is actually true), had it reopened, and it's being held on Tuesday.

Received disclosure and it reads as follows:

How can I go about disputing this? Does the observer (I'm guessing she's a rookie) have to be there, or only the ticketing officer?

Appreciate any help

If there was 2 officers, then both need to appear in order to present all the evidence.

For those interested, the charge was withdrawn.

After looking closer at the ticket I realized that I was timed by a plane, but only received disclosure from the ticketing officer. Met with the prosecutor pre-trial and explained that I had an issue with only getting half of the disclosure. Told me to grab a seat. Came back and said that he was going to withdraw the charge due to lack of evidence.