With this system, it is possible to sample and generate two or more simultaneous formats; one can be transmitted to ground station in real time, and other is stored for later transmission. Sensor output comparison data, plus information to control format, compression algorithm, and allowable degree of sensor activity, are stored in memory

Easton, R. A.

Hilbert, E. E.

English

NASA Technical Reports Server

July 1973	 B73-10290 
•	 NASA TECH BRIEF 
NASA Pasadena Office 
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. 
Flexible Format, Computer Accessed Telemetry System 
The problem: 
To automate simple decisions relating to sampling, 
multiplexing, coding, and storage of data in digital 
form. 
The solution: 
A concept for a flight telemetry system which is 
based on a nested DO-loop computer procedure to 
sample data sensors at any desired frequency and 
with random access. 
How it's done: 
Ordinarily, data management involves a more-or-
less fixed sampling sequence derived from a clock-
controlled commutator, but the system to be de-
scribed, called Computer Accessed Telemetry System 
(CATS), permits programmed sequencing of the 
commutator. With the new system, it is possible to 
sample and generate two or more simultaneous for-
mats at once so that one format can be transmitted to 
a ground station in real time, and the other is used 
on board or is stored for later transmission. A distinct 
advantage of the CATS is that the data from any 
randomly accessed sensor can be further processed 
on board in accordance with compression, activity-
monitoring, and computer-altering algorithms and 
basic sensor decisions before transmission. The CATS 
approach also enables a central computer and se-
quencer to diagnose spacecraft problems that require 
correlating the outputs of a number of sensors to 
reach a decision. 
In the implementation of CATS, sensor output 
comparison data, plus information to control the 
format, the compression algorithm, and allowable 
degree of sensor activity, are stored in a memory.
This information, for one sensor at a time, in any 
sequence, is loaded into input/output/control regis-
ters where it interacts with the control circuitry and 
with new data in the multialgorithm compressor; sig-
nificant changes are read back into the memory and 
then transferred to storage. The storage buffers also 
remove gaps due to compression and equalization; 
buffer groups are assigned different priorities for 
readout to telemetry in the proper sequence. The 
interface with the central computer and sequencer 
permits use of sophisticated programs to analyze and 
correct data anomalies by format changes or changes 
in algorithm. 
The hardware design for CATS is based upon 
highly-reliable redundant-element techniques which 
include: 1) a tree-switch commutator to provide 
minimum redundancy with highest reliability, 2) re-
dundant modular construction and roll-back program 
structure to avoid error propagation, as developed 
for a special computer, 3) memory organization that 
minimizes error propagation. 
The organization of CATS and its reliability fea-
tures make it attractive for use as a general-purpose 
data-handling system. 
Notes: 
1. The tree-switch commutator is described in Tech 
Brief B73-10289. 
2. Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP 73-10290
(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=19730000290 2020-03-17T06:54:53+00:00Z
Patent status: Source: Richard A. Easton 
This invention has been patented by NASA (U.S. and Edward E. Hilbert of 
Patent No. 3,665,417). Inquiries concerning nonex- Caltech/JPL 
elusive or exclusive license for its commercial devel- under contract to 
opment should be addressed to: NASA Pasadena Office 
NASA Patent Counsel (NPO41358) 
Mail Code l 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103
fl 
. 
B73-10290	 Category 02 


Flexible format, computer accessed telemetry system

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