A simulator is described which generates and transmits a beam of audible sound energy mathematically similar to the SPS power beam. The simulator provides a laboratory means for analysis of ground based closed loop SPS phase control and of ionospheric effects on the SPS microwave power beam

Ott, J. H.

Rice, J. S.

English

NASA Technical Reports Server

A SONIC SATELLITE POWER SYSTEM MICROWAVE POWER TRANSMISSION SIMULATOR 
James H. Ott 
James S. Rice 
Novar Electronics Corporation, Barberton, Ohio 
ABSTRACT 
A simulator is described which generates and transmits a beam of audible sound energy mathematically similar 
to the SPS power beam. The simulator provides a laboratory means for analysis of ground based closed loop SPS 
phase control and of ionospheric effects on the SPS microwave power beam. 
INTRODUCTION SI IUTOR CAPABILITIES 
Novar E lec t ron ics  Corporation is i n  the  f i n a l  
s t ages  of cons t ruc t ing  and t e s t i n g  a  S a t e l l i t e  Power 
System Microwave Transmission Simulator. In a  
ground based l abora to ry  environment, the  s imulator  
generates  and t ransmi t s  a  beam of aud ib le  sound 
energy which is mathematically s i m i l a r  t o  t h e  micro- 
wave beam which would t ransmit  energy to  e a r t h  from 
a  Solar  Power S a t e l l i t e .  
SIMULATOR DESCRIPTION 
Figure 1 shows the major func t iona l  p a r t s  of 
t h e  s imulator .  The Sonic Spacetenna (Figure 2) i s  
1 . 3  meters i n  diameter and contains  3200 independent 
t r ansmi t t ing  elements. These elements a r e  connected 
i n  a  64 row by 6 4  column matr ix.  Each column i s  
driven by a  d r i v e r  which mult iplexes each of t h e  64 
rows 32,000 times per second. This enables  the  
s imulator 's  computer to  con t ro l  the amplitude, 
phase, and frequency of each of  t h e  3200 transducers .  
The simulator i s  designed to  t ransmit  a  coherent 
sonic power beam a t  12 kHz. Any i l lumina t ion  t a p e r ,  
e .g . ,  Gaussian, can be programmed and t h e  r e s u l t a n t  
ground p a t t e r n  s tud ied .  A computer, RAM Memory, 300 
>n3 d i s c  dr ive,  and l i n e  p r i n t e r  a r e  incorporated to  
provide a  very high degree of experimental f l e x i b i l -  
i t y .  
A unique f e a t u r e  of Novar's Sonic Simulator i s  
i t s  a b i l i t y  t o  provide a c t u a l  photographs of t h e  
t ransmit ted power beam. Figure 3  shows a  scanning 
system which provides an i n t e n s i t y  modulated r a s t e r  
of  the  son ic  beam. By adding a  phase s i g n a l  t o  the  
i n t e n s i t y  modulator, t h e  phase coherence can a l s o  
be photographed. This technique, developed a t  Bell 
Labs i n  t h e  e a r t y  1950 ' s l  w i l l  provide photographic 
records s i m i l a r  to Figure 4 .  
As soon a s  the Sonic Simulator i s  opera t iona l  
(mid-February, 1980), i t s  i n i t i a l  use w i l l  be t o  
generate  a  col l imated coherent sonic beam to  v e r i f y  
t h a t  t h e  beam divergence and s ide lobe  c h a r a c t e r i s t i c s  
a r e  i n  s a t i s f a c t o r y  agreement with the  aper tu re  il- 
lumination equat ions which have been used t o  de f ine  
t h e  SPS microwave beam. 
The concept of "ground based" phase con t ro l  
implies  a  closed loop phase con t ro l  system which 
makes cor rec t ions  i n  dev ia t ions  i n  SPS beam po in t ing  
and focusing from ground based measurements of t h e  
received power beam. In  o ther  words, ground based 
phase con t ro l  i s  a  servo con t ro l  system which l i k e  
any servo system has a measureable t r a n s f e r  funct ion,  
frequency response, s t e p  response, no i se  f a c t o r ,  
r e so lu t ion ,  loop s t a b i l i t y ,  e t c .  Novar i s  using i t s  
+ Fllter J, 
- Dlgltal 
- Phase E I I - btector  + Fllter t - 1 1 
- 
bteCtOr  
Computer 
25BK 
RAM 
ROM 
Program 
3WMB Line 
Memory Memory 
Diskand Printer 
Controller 6W LPM 
ppp 
FIGURE I 
SONICSPS PHASECONTROL SIMULATOR 
MAJOR FUNCTIONAL BLOCKS 
1 4 1  
https://ntrs.nasa.gov/search.jsp?R=19810008029 2020-03-21T15:12:05+00:00Z
interferometer  phase con t ro l  technique to  focus and 
point  the sound beam. The open and closed loop 
c h a r a c t e r i s t i c s  of the Sonic Simulator w i l l  be 
measured. A descr ip t ive  servo loop diagram and 
t rans fe r  func t ion  w i l l  be developed and a l l  measured 
c h a r a c t e r i s t i c s  w i l l  be t e s t e d  f o r  agreement with 
control  system theory. The next  s t e p  w i l l  then be 
to  analyze and mi t iga te  t h e  e f f e c t s  of unwanted in- 
t e r f e r i n g  inpu ts  such a s  a i r  cur ren t s  i n  t h e  labor- 
a to ry  and t h e  r e f l e c t i o n  of the  sonic beam of f  
walls .  
PHOTOGRAPHIC SCANNING SYSTEM 
.A preclslon mechan.ca, scannlng system prov,des an 
actual photograph of the sonic beam. Thecamera lens 
The Sonic Simulator can be read i ly  forced to  
deal  with t h e  same no i se  c h a r a c t e r i s t i c s  a s  t h e  
ionosphere would introduce i n t o  t h e  r e a l  world SPS 
phase c o n t r o l  system. This would be accomplished 
by a l t e r i n g  the propagation of the  s imula to r ' s  sonic 
beam through the  use of sculptured r e f l e c t i n g  sur- 
faces and con t ro l l ed  a i r  turbulance.  
remains open in a darkened room while the sound-to- 
iight modulator (device being pointed at) provides a 
iight output proportional to the intensity of the sonic 
beam. The modulator is scanned up and down and 
forward and backward to provide a photograph of a 
cross section of the beam. 
Ionospheric e f f e c t s  w i l l  impact an SPS Phase 
Control System s imi la r  t o  the way t h a t  no i se  and 
o f f s e t  e r r o r  impact any closed loop servo system. 
Therefore, conventional con t ro l  system syn thes i s  
techniques should be a b l e  to  reduce SPS phase con- 
t r o l  e r r o r s  due to ionospheric e f f e c t s .  
Ana ly t i ca l  techniques w i l l  be developed t o  
permit the  v a l i d a t i o n  of these  sonic propagation 
models a g a i n s t  measured ionospheric parameters. 
This would, f o r  example, lead t o  the  q u a n t i t a t i v e  
cor re la t ion  of ionospheric e lec t ron  densi ty p a t t e r n s  
with the  sound r e f l e c t i n g  s u r f a c e ' s  roughness and 
placement. 
FIGURE4 
REPRESENTATIVE PHOTOGRAPH OF A MECHANICALLY 
SCANNED SONIC BEAM (Bell System Technical Journal, 
1851) 
CONCLUSIONS 
It i s  expected t h a t  a number of conclusions can 
be provided regarding t h e  a p p l i c a b i l i t y  of t h e  son ic  
simulation technique to  t h e  f u t u r e  development of 
the SPS power t ransmission system. I f  conclusions 
a r e  favorable,  we would expect t h a t  t h e  son ic  simu- 
l a t o r  w i l l  provide a low cos t  a l t e r n a t i v e  t o  many of 
the time consuming o r b i t i n g  s a t e l l i t e  experiments 
t h a t  would otherwise be necessary. 
REFERENCE 
1. W. E. Kock and F. K. Harvey, "A Photographic 
Method f o r  Displaying Sound Waves and Micro- 
wave Space Pat terns,"  Be l l  System Technical 
Journa1,Volc 30, Ju ly  1951, pp. 564-587. 


A sonic satellite power system microwave power transmission simulation

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