System fixes location of charge buildup in clouds. It provides range, azimuth, and elevation in real-time so that warning of charge buildup can be implemented

Lennon, C. L.

English

NASA Technical Reports Server

- Time - 
December 1975 
•	
NASA TECH BRIEF 
John F Kennedy Space Center
B75-10297 
H 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Time-of-Arrival Lightning Activity Location System 
S
The problem: 
Charge buildup in clouds that occurs prior to a 
thunderstorm could result in lightning being triggered 
by the launch of a missile. 
The solution: 
A time-of-arrival lightning activity location system 
fixes the location of a charge buildup not only in range 
Minicomputer 
RF	 Transient 
A-i	 Amplifiers
	 Recorders (30 to 50 MHz) 
A-2 
A-3 
A-4
and azimuth but also in elevation. The information is 
available in near-real-time so that a warning of charge 
buildup can be implemented.
Display 
L 
Cassette 
Recorder 
Oscilloscopes 
(5 	 1 A1 
©	
A-2 
A-4
Time Resolution = 
0.01 ps for Azimuth and Elevation 
•
	
Lightning Activity Location System Implementation
	
0.05 ps for Range 
(continued overleaf) 
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https://ntrs.nasa.gov/search.jsp?R=19750000297 2020-03-19T20:16:39+00:00Z
How it's done: 
The system is based on the precise detection (at four 
carefully-placed detection stations) of the time-of-
arrival of-radio-frequency signals emitted by electrical 
discharges in the sky that take place during 
thunderstorms and thunderstorm buildup. From the 
time of arrival, the system computes the azimuth, the 
elevation, and the range of an electrical discharge. 
The system consists of four high-speed analog-to-
digital (A/D) converting transient recorders that 
continually sample and digitize the incoming wave-
forms. A minicomputer controls the system, processes 
the data, formats the data for recording on a cassette 
recorder, and produces a plot of the range, azimuth, 
and elevation of the detected electrical discharge on a 
computer display terminal, seconds after the event. 
Signals arriving at the four broadly-tuned, verti-
cally-polarized, onmidirectional antennas (shown as 
A-i, A-2, A-3, and A-4) are filtered (30 to 50 MHz), 
then are amplified and envelope detected by log-IF 
amplifiers, and then are fed to four transient 
recorders. The transient recorders use digital tech-
niques to record defined segments of an analog signal. 
A signal that exceeds a prescribed level at station 
A-2 triggers all four transient recorders. Once 
triggered, the wave-shape data of 1,024 samples, 
taken at intervals of0.01microsecond prior to and 
after the trigger, are available to the computer. Data 
prior to the trigger are available since the input 
signals are continuously sampled and stored and 
being replaced by new data.
After applying threshold and wave-shape criteria, 
the computer determines the maximum amplitude of 
each wave shape and then uses a correlation routine to 
calculate the time differences in arrival relative to 
station A-2. The time intervals are used by the 
computer to solve for azimuth, elevation, and range 
which are then displayed on the terminal. In addition 
to the display, the data are also continuously recorded 
on a cassette recorder which can record more than 4 
days of data unattended. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Kennedy Space.Center 
Code AA-STA-1 
Kennedy Spce Center, Florida 32899 
Reference: TSP75-10297 
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
Patent Counsel 
Kennedy Space Center 
Code AA-PAT 
Kennedy Space Center, Florida 32899 
Source: Carl L. Lennon 
(KSC-1 1006)
is 
B75-10297	 Category: 02 (Electronics Systems)


Time-of-arrival lightning activity location system

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