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.