Very Low Frequency radio signal amplitude data from the VTX, NWC, and JJI transmitters observed from a sub-tropical low latitude station in Cooch Behar, India during three solar eclipses in 2019 and 2020

The Zip file contains Very Low-Frequency radio signal amplitude data from the VTX, NWC, and JJI transmitters observed from a sub-tropical low latitude station in Cooch Behar, India during three solar eclipses in 2019 and 2020. A 3.66 meter E-field whip antenna placed at 25 m height from the ground and an amplifier circuit have been used as a receiver. The whip antenna receives the E-field of VLF radio signals (3-30 kHz) from all directions. Signals trapped by the antenna induce a voltage which is then carried by a co-axial cable (75 ohms) into a low noise two-stage pre-amplifier of DC gain factor 21. This pre-amplifier has two-stage amplification of the signals done by a low noise dual-mode operational amplifier (OP27G). An audio transformer is connected between the pre-amplifier and computer microphone input to cancel out the chance of formation of the ground loop. The signals are recorded by the 32-bit sound card of a dedicated computer and a data logger software (Spectrum lab V2.7b20) at a sample rate of 4 Hz. A narrow bandwidth of ±50 Hz is maintained around each monitored frequency. The time-stamp of the recording unit is synchronized with a time server, which has an automatic update facility. The data file here is given with a 1-minute time resolution. These data files are useful to study the effects of solar eclipses on the D-region ionosphere. Further, the difference in solar eclipse effects on the ionosphere during summer and winter can be studied with this data set.

该压缩文件包含来自 VTX、NWC 和 JJI 发射器的极低频无线电信号幅度数据，这些数据由印度库奇贝哈尔一个亚热带低纬度站点在 2019 年和 2020 年三次日食期间观测所得。接收器为放置于地面 25 米高度、长度为 3.66 米的 E 场鞭状天线和放大电路。鞭状天线接收来自各方向的 VLF 无线电信号电场（3-30 kHz）。天线捕获的信号在导线中感应出电压，随后通过同轴电缆（75 欧姆）传输至直流增益系数为 21 的低噪声双级前置放大器。该前置放大器通过低噪声双模运算放大器（OP27G）实现双级信号放大。音频变压器连接至前置放大器和计算机麦克风输入之间，以消除形成地环的可能性。信号由专用计算机的 32 位声卡和数据记录软件（Spectrum lab V2.7b20）以 4 Hz 的采样率记录。每个监测频率周围保持 ±50 Hz 的窄带宽。记录单元的时间戳与时间服务器同步，该服务器具有自动更新功能。此处提供的数据文件具有 1 分钟的时间分辨率。这些数据文件对于研究日食对 D 区电离层的影响非常有用。此外，利用此数据集还可以研究夏冬两季日食对电离层影响的差异。