SP: Development of an Interference Temperature Monitor

智力优势：无线电频率干扰（RFI）监测是频带分配和减少用户之间有害干扰的重要工具。过去，人为干扰的主要来源是汽车点火。现在，人为干扰的主要来源是电子设备、数字应答机、计算机等。和无线计算机网络是相对较新的进入者，并且正在使用码分多址（CDMA）来有效地利用频谱具有功率控制，以最小的发射机功率最大化容量。这些设备产生的扩频不能轻易地与高斯噪声区分开来而不知道解扩信号的代码。另一个类似噪音信号的来源来自新的数字电视发射机。为了避免有害的干扰和尽量减少环境中的噪声水平的升高，重要的是要监测这种噪声的水平。频率在500 MHz和20 GHz之间的自然环境噪声主要由来自地面的约300 K、来自宇宙背景的约3 K和来自大气的约5 - 30 K组成。在射电天文波段和其他它只接收波段，防止噪声温度的任何增加是很重要的，而测量其他波段的噪声温度可以提供有用的信息，以优化频谱的有效利用，用于各种应用，包括射电天文学和无线通信。麻省理工学院Haystack天文台建议开发一种监测器，以测量频率范围为30至1500 MHz，经过校准以提供以开尔文为单位的输出度量，并具有足够的灵敏度，能够将受保护的仅接收波段（如射电天文学、遥感和深空波段）中的不需要的噪声量化到几开尔文的水平。这支持了NSF和FCC之间的联合倡议。在第一阶段，提议者计划研究接收机和校准设计，这些设计需要提供灵敏度和准确度，而没有显著的内部互调、寄生响应和杂散信号。在这一阶段，他们还将在马萨诸塞州韦斯特福德的麻省理工学院干草堆天文台使用目前可用的设备，根据RFI环境的连续测量结果，制定设计规范。在第二阶段，我们建议原型的干扰temperaturemonitor和测试设计在干草堆。在第3阶段，我们建议在马萨诸塞州和南部新罕布什尔州地区的几个地点进行系统测试。未来，根据结果，这样的监测系统可以在其他地方复制，以收集数据集来描述其他地方的RFI环境。更广泛的影响：通过这个项目，提案人旨在提高对无线电波技术的属性及其各种应用的认识，如射电天文学和无线通信，以及射频干扰环境。因此，一个简单的射频干扰监测系统将被开发用于大学预科教育设置，以帮助学生和教师与无线电波信号的测量技术和周围的学校和城镇的环境。这些数据可以通过互联网进行相互比较，Haystack天文台将开发基于网络的教育材料，介绍无线电波的研究及其各种应用。建议者会特别安排在天文台附近地区的学校安装简单的无线电接收器和天线，让学生参与测量无线电频率指数。作为澳大利亚SEARFE项目的一部分，将促进与澳大利亚学生和教师的合作，以加强关于这一主题的国际网络。2003年夏天，在干草堆天文台开始了一个与当地教师合作的项目，作为国家科学基金会“教师研究经验”方案的一部分，以启动这一活动。

Intellectual Merit: Radio Frequency Interference (RFI) monitoring is an important tool in theassignment of frequency bands and in the reduction of harmful interference between users. In thepast, a major source of man-made interference was from automobile ignition. Now a majorsource of man-made interference is from electronic devices, digital answering machines,computers etc. Communication devices like cellular phones, and wireless computer networks arerelative new comers and are making efficient use of the spectrum using Code Division MultipleAccess (CDMA) with power control to maximize capacity with the minimum transmitter power.These devices generate a spread spectrum which cannot be easily distinguished from Gaussiannoise without knowledge of the code to de-spread the signal. Another source of noise-like signalscomes from the new digital television transmitters. In order to avoid harmful interference andminimize the elevation of the noise level in the environment, it is important to monitor the levelof this noise. The natural environmental noise for frequencies between 500 MHz and 20 GHzconsists mainly of about 300 K from the ground, 3K from the cosmic background, and about 5 to30 K from the atmosphere. In the radio astronomy bands and other itreceive onlyle bands, it isimportant to prevent any increase in the noise temperature while measurement of the noisetemperature in other bands can be useful information needed to optimize the efficient use of thespectrum for various applications including radio astronomy and wireless communications.MIT Haystack Observatory proposes to develop a monitor to measure the interference levels inthe frequency range 30 to 1500 MHz, calibrated to provide the output metric in units of degreesKelvin, and with sufficient sensitivity to be able to quantify, to a level of a few degrees Kelvin,the unwanted noise in the protected receive-only bands like those for radio astronomy, remotesensing, and deep space bands. This supports the joint initiative between the NSF and the FCC.In phase 1, the proposers plan to study receiver and calibration designs needed to provide the sensitivityand accuracy without significant internal inter-modulation, spurious responses and spurioussignals. In this phase they will also set specifications for the design based upon preliminarymeasurements, using currently available equipment, of the RFI environment at the MIT HaystackObservatory, in Westford, MA. In phase 2 we propose to prototype the interference temperaturemonitor and test the design at Haystack. In phase 3 we propose to conduct tests of the system at afew locations in the Massachusetts and Southern New Hampshire area. In the future, dependingon the results, such a monitoring system could be replicated elsewhere to gather a data set tocharacterize the RFI environment at other locations.Broader Impact: Through this project, the proposers aim to enhance the awareness of the properties ofradio wave technology and its various applications such as radio astronomy and wirelesscommunications, as well as the radio frequency interference environment. Thus, a simple RFImonitoring system will be developed for use in pre-college educational settings to acquaintstudents and teachers with the measurement techniques of radio wave signals and theenvironment around their schools and towns. Such data could be inter-compared using theInternet, and Haystack Observatory will develop web-based educational materials to introduce thestudy of radio waves and their various applications. In particular, the proposers will arrange for thedeployment of simple radio receivers and antennas, available commercially, to local area schoolsaround the Observatory to engage students in RFI measurements. A collaboration with studentsand teachers in Australia, as part of the Australian SEARFE project will be promoted to enhanceinternational networking on this topic. A project with local area teachers as part of NSF'sprogram 'Research Experiences for Teachers (RET)' at Haystack Observatory is starting insummer 2003 to initiate this activity.