A large amount of passive sensors are deployed in the battlefield for target detecting, As they adopt passive detection,
and with low cost and small volume. However, no matter active and passive sensors, the resource deployment optimization problem
is quite common in practice. For the specific application of passive sensors, several reasonable approximating methods are taken to
derive the optimal deployment density of passive sensors, under the "OR" fusion law of detection for the best detection probability.
For the development cost, there is hardly any research on multi-hypotheses-tracking (MHT) for decentralized sensors
networking system, although the distributed spot-level fusion for sensors networking is a key function in multi-target
multi-sensor tracking system. MHT is a famous algorithm in target tracking, which is capable of track initiating,
updating, deleting, keeping. This paper puts forward an MHT algorithm for decentralized sensors networking at spot
fusion level which is validated by simulation results. Some important aspects in application are also put forward.