Editing Explorer 7 (section)

=== Ground Based Ionospheric ===
An all-transistor beacon telemetry transmitter was operated at a fundamental frequency of 19.9915 [[Hertz|MHz]]. This transmitter, which was powered by solar cells and rechargeable nickel-cadmium batteries, provided 660-mW of power at the fundamental frequency. It also radiated the second and third harmonics (15-mW each) at 39.9830 and 59.9745-MHz. Beacon receivers were known to have been located in [[Washington, D.C.]], and [[Chicago]], [[Illinois]]. Interpretation of the changes of beacon signal characteristics between the satellite and the ground station showed irregularities to be present at all times of the day with horizontal dimensions of {{cvt|5|km}} to {{cvt|500|km}}. Data were received over a period of 16 months.<ref name="Instrument6">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1959-009A-06|title=Experiment: Ground Based Ionospheric|publisher=NASA|date=28 October 2021|access-date=2 November 2021}} {{PD-notice}}</ref>