Tethered Balloon for Checkout of Computer-Controlled Antennas

Abstract

During operational tests of the U.S. Navy's Poseidon missile, an instrumented ship tracks every test missile launched by the nuclear subs. The key sensor aboard this launch-area support ship, the USNS RANGE SENTINEL, is its antenna system. Onboard computers switch the ship's four independent, main S-band antennas (Fig. 1) to capture up to four missiles fired in succession and to expedite command action (e.g., continued flight or destruct). This multi-antenna control by computer leads to a complex testing problem for the computer software, constrained by the need for cost effectively proving the software's operational capability without penalizing hardware development. Rigid control of hardware-caused variables, and a near-operational test environment, are vital Software test prerequisites. To this end, using a stable RF pointing source at altitude above the antennas (i.e., to reduce parallax distortion and multipath effects) is a preferred approach in testing antenna-management software. This paper describes two experiments* to (1) initially establish the feasibility of using an airborne S-band telemetry transmitter as an RF signal source for checking out the USNS RANGE SENTINEL's antenna control, and then (2) demonstrate the effectiveness of this RF source in verifying the ship's antenna alignment and validating the operational antenna software.