An ultrasonic heading measurement method, working under magnetic interference prohibitive for magnetometers, was prototyped, validated, and metrologically characterized. Two capacitive ultrasonic transducers convert the mechanical rotation in two correspondingly time-delayed electrical sine waves. Then, the time delay is estimated using the standard tree parameter sine-fitting algorithm. The prototyped goniometer achieves the same repeatability level (<36 mrad) of a magnetometer-based heading in the range [−437 mrad, 437 mrad]. Simultaneously, a throughput of 505 Sa/s is proven on an STM32F303xC Arm Cortex −M4 32-bit microcontroller. An interference analysis revealed the experimental deterministic error well explained by the combined effect of beacon and receiver directivity, as well as by the relative position of beacon, receiver, and reflective surfaces. Noise robustness was assessed in case of SNR decayed to 9.1 dB from the initial value of 36.6 dB; the maximum deterministic error in the range [−437 mrad, 437 mrad] increased less than 10% (from 21 to 23 mrad in absolute value).

中文翻译：

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一种对磁干扰具有内在鲁棒性的超声波航向测角仪

一种在磁力计不允许的磁干扰下工作的超声波航向测量方法被原型化、验证和计量表征。两个电容式超声波换能器将机械旋转转换为两个相应的延时电正弦波。然后，使用标准树参数正弦拟合算法估计时间延迟。原型测角仪在 [−437 mrad, 437 mrad] 范围内实现了与基于磁力计的航向相同的重复性水平 (<36 mrad)。同时，在 STM32F303xC Arm Cortex −M4 32 位微控制器上证明了 505 Sa/s 的吞吐量。干扰分析揭示了由信标和接收器方向性的组合效应以及信标、接收器、和反射面。在 SNR 从初始值 36.6 dB 衰减到 9.1 dB 的情况下评估了噪声稳健性；[−437 mrad, 437 mrad] 范围内的最大确定性误差增加不到 10%（绝对值从 21 到 23 mrad）。