As ever there's probably many different ways to teach a stop whistle Tobias, some better than others. All I can do is tell you how I teach mine, which is a little different to yours :wink:
I start by making sure the dog knows 100% that one pip means sit, and unlike Katy, that includes by my side. I do lots of exercises relating to this, just to check, such as heeling the dog offlead and giving a pip for sit whilst I continue to walk on whilst the dog remains seated. I then return to the dog and continue to heel. I will also pip and leave the dog in a sit whilst I walk away and pretend to look at my watch, pick some flowers or whatever. I increase the distance and the time the dog is in the sit from me. I like to mix it all up. I'll check for absolute steadiness with thrown dummies whilst the dog is sitting.
Only when I am 100% sure that the dog knows that one pip means sit and stay, until I tell him otherwise, do I progress to the stop whistle variant. Everything about the stop whistle has to be positive. It really does. The dog has to come to learn that when you blow that whistle you are helping him/her. If the dog sees it as a hindrance then you will never get 100% on the stop whislte or anything like it.
So I take it slow. I get the dog bouncing close around me with my command 'get on', which means do whatever you like/you're off duty for the mo. I then blow the whistle and the dog sits. I make sure the dog is near to me at first when I do this as I want success for both of us. I will then do one of four or more things to reward the dog. It could be a retieve of a dummy; a titbit (the stop whistle is the only time I use food); walk to the dog and give lots of praise or a hunt command where I will quietly and covertly place a tennis ball on the ground whilst the dog is busy hunting. Sometimes other things. You get the picture I'm sure.
Gradually I let the dog roam further from me and continue to repeat the above - rewarding the dog on every occasion. By now the dog wants to stop as he knows he may get a retrieve/i will be very happy/he may get to hunt etc etc. Further still and if our training has advanced enough on other areas then I may do such things as redirect the dog from the stop whistle to a blind I have put out (in line with where I have stopped the dog) with a left or a right command etc. By this stage your dog should be super proficient and happy to stop. He should see the whistle as being a 'help' to him/her.
Two things I never do with the stop whistle now is:
1) stop the dog midway on a marked retrieve (very bad and creates a sticky dog)
2) once the dog has 'got it' keep adding in a stop whistle with every training session. It's too much and again can make a sticky dog.
I only ever use the stop whistle if the dog is about to run miles past a dummy and I need to tell him to hunt or if we have gone seriously off course and I need to redirect. On a day to day level though I often use it with dogging in at the shoot ie dog pushes birds home, they get up, I make the dog sit and be steady. His reward often is that afterwards he can carry on hunting for birds at my request.
Not sure how this will all relate to you and your tracking? Not sure if it is terribly useful and others may have better suggestions and tips :wink: Just my way for now.