Magnetron Transmitter for Carrier Takeoff and Landing (2009)
Under the sponsorship of the Naval Air Warfare Center, DTI successfully transitioned a DoD SBIR into a production modulator upgrade program for the Navy's SPN-41 transmitter which assists pilots in their final approach to a carrier landing. Previously, the set suffered from component failures and parts obsolescence, reducing its availability. DTI developed several prototypes in Phase I, did full development in Phase II and is now in ongoing production.
Key circuit techniques to drive the existing magnetron properly, using modern, highly reliable solid-state components, are required to improve the performance of the existing transmitter. These improvements also add the capability of reduced power output for minimum interference and observability in clear weather, and the ability to add new pulse codes for use with new receivers in future aircraft.
The transmitter generates short high voltage pulses using a pulse transformer. The circuit is operated via a two step turn on, unique to DTI. Variations in tube operation are accommodated by controlling both the power supply voltage and the time delay between the first and second voltage step. The tube waveform can be optimized to minimize the effects of thermal drifts, tuning, and aging. The optimization circuitry can accommodate variable pulse widths and repetition rates. The ability to optimize the waveform in real time is possible, but not implemented in this project.
The transmitter upgrade will be shipped as a retrofit kit of modules and wiring harness, which bolt into the existing housing.