Locking pet door system

A pet door system for allowing pets to enter and exit a building, the building having an opening, the pet door system comprising:

• a first U-shaped flange for receiving a first side edge of the opening;
• a second U-shaped flange for receiving a second side edge of the opening;
• a top U-shaped flange for receiving a top edge of the opening;
• a pet door pivotally mounted within the opening between the flanges, the pet door having a plurality of edges;
• an aperture formed in a top edge of the pet door and extending into a top portion of the pet door;
• a groove extending from along each side of the aperture;
• a plunger alternatingly moveable through the top flange into and out of the aperture for alternatingly locking and unlocking the pet door, the plunger riding in the groove when out of the aperture;
• an electronics box mounted in the top U-shaped flange, the electronics box containing a receiver and microprocessor, the microprocessor activating and deactivating the plunger;
• a transmitter adapted to be mounted to a pet, the transmitter transmitting instructions to the receiver and microprocessor to activate the plunger;
• wherein upon the transmitter being positioned within a predetermined distance from the pet door, the plunger automatically moves out of the aperture to unlock the pet door allowing the pet door to pivot within the opening;
• and
• wherein upon the transmitter being positioned outside the predetermined distance from the pet door, the plunger automatically moves into the aperture to lock the pet door preventing the pet door from pivoting within the opening.