Platform design includes timers which limit data transmission to times when satellites are within radio communication range. As result of reduced power requirement, data-collection platforms now can be equipped with significantly lighter battery packages

Kurvin, C. W.

English

NASA Technical Reports Server

August 1974	 B74-10088 
NASA TECH BRIEF 
•	 Goddard Space Flight Center
	
A 
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-Control System for Communication Between Data-Collection 
and Orbiting Satellites 
The problem: 
Data-collection platforms frequently are used in 
remote, uninhabited areas of the Earth. They are 
mounted on meteorological balloons and sea buoys, are 
attached to migrating animals, or are positioned on some 
fixed geographical location. Because they are out of the 
radio transmission range of most data-collection centers, 
these platforms communicate directly with Earth-orbiting
satellites which, in turn, relay information to data 
centers on Earth. Presently used platforms are not very 
versatile: they contain relatively-heavy solar-cell packages 
for the continuous transmission of data. As a result, 
data are often transmitted when satellites are out of 
radio range. Moreover, in biological studies, the heavy 
solar-cell packages limit platform application to only a 
few animal species.
S. 
S
	 Platform Schematic
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19740000088 2020-03-17T14:05:55+00:00Z
The solution: 
A new platform design includes timers which limit 
data transmission to times when satellites are within 
radio communication range. As the result of a reduced 
power requirement, data-collection platforms now can 
be equipped with significantly lighter battery packages. 
How it's done: 
The platform includes two timers, one for generating 
time windows synchronized in time with the orbit of the 
satellite and the second for generating time windows 
synchronized with the spin of the Earth. A first signal 
is generated at a time when the satellite is expected to 
be in radio range and is used to turn on the platform 
receiver. At this point, communication from the satel-
lite to the platform is enabled. The satellite then 
transmits an interrogation command, to which the 
platform responds by briefly turning on its transmitter 
to transmit the data. After a period of time sufficient 
for communication, the platform receiver is turned off, 
thus conserving battery power. 
The platform, as shown in the block diagram, 
contains an orbit timer and a spin timer. The times 
T 1 through T8 are determined by the relative position 
of the platform with respect to the moving satellite 
from the well-known equations of motion. Once T 
through T 8 are determined, they are programmed into 
the hardware. 
In this configuration, time T 1 is the start or leading 
edge of the orbit-day intersection window, while T2 
is the end or trailing edge of that window. Similarly, 
1 3 and T4 , respectively, define the obit-night inter-
section. Times T 1 and T2 set and reset, respectively, 
the first flip-flop, causing a pulse of 10 minutes duration 
at the flip-flop output. This pulse defines the day 
intersection window. Similarly, T 3 and T4 initiate the 
second flip-flop, defining the night intersection. In a 
similar manner, the outputs of the spin timer, T 5 and T6 
and T 7 and T 8 , initiate their respective flip-flops, also 
defining day and night intersections, respectively.
The pulses appearing at the AND gate outputs are 
fed to an OR gate, which turns on transistor Q 1 . The 
turned-on transistor energizes a relay, which connects 
the battery power to the receiver. When an interrogation 
command is received from the satellite, a pulse is 
generated by a pulse-forming network, turning on 
transistor Q2 . Q2 energizes the second relay, turning on 
the transmitter for a designated time duration. The 
transmitted data includes the information collected by 
the platform as well as the received signal from the 
satellite to pinpoint the exact location of the platform. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Goddard Space Flight Center 
Code 207.1 
Greenbelt, Maryland 20771 
Reference: TSP74-10088 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Inquiries concerning nonex-
clusive or exclusive license for its commercial develop-
ment should be addressed to: 
Patent Counsel 
Goddard Space Flight Center 
Code 204 
Greenbelt, Maryland 20771 
Source: Charles W. Kurvin of 
Radiation, Inc.
under contract to
Goddard Space Flight Center 
(GSC-1 1182) 
B74-10088
	 Category O2,03,05


Time-control system for communication between data-collection and orbiting

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