A developmental model of an instrumentation video record/reproduce system for STADAN, ERTS, and Goddard Space Flight Center is discussed. Performance evaluations of three present-day systems and the model are presented

Tinsley, J. L.

English

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TECHNOLOGY ACCOMPLISHMENTS, 1970 183
FEASIBILITY MODEL OF A VIDEO INSTRUMENTATION
RECORD/REPRODUCE SYSTEM
J. L. Tinsley
Instrumentation video record/reproduce systems will be required for
STADAN, ERTS, and Goddard Space Flight Center data processing facilities
in the early 1970's. We began our program early in 1968 by conducting
parallel feasibility studies to determine the system configuration that
satisfied specific performance requirements. Two companies, RCA and
Ampex, both competent in video record/reproducers, were given study
contracts, and the better approach, by Ampex, was chosen for a prototype
video record/reproduce system. Performance evaluation with this unit will
serve as a basis for specifying production-type machines to satisfy both
STADAN requirements and the new requirements coming from the ERTS
project. These machines will require improvements in frequency response,
high data rate PCM, multispeed capability, time displacement error, tape
utilization, bit error rates, and reliability (Table 1). First, to obtain
perspective, let us look at the Ampex FR-600. This is not intended as a
one-to-one comparison, but the FR-600 is used because many people are
familiar with this machine. The Ampex FR-600 series recorders used in
STADAN have 0.6-MHz frequency response. The FR-2100 offers more than
a ten-to-one improvement over the FR-600. This also applies to most of the
other parameters listed in Table 1.
The design goals set in 1968 for frequency response were dc to 10 MHz
with a 6-MHz minimum. The frequency response obtained in the Ampex
FR-2100, on the other hand, was dc to 10 MHz and dc to 10 MHz/32 for a
second speed. The PCM digital performance design goals were 14 Mbit/s
with 11 Mbit/s minimum. Those obtained were 16 Mbit/s. Tests were
conducted to 20 Mbit/s. This was achieved by using the 10-MHz bandwidth
and Miller code PCM. For multispeed, two speeds were required. Those
obtained were a longitudinal speeds of 38.1 cm/s (15 ips) and 1.19cm/s
(0.47 ips) and scanning speeds (rotating head) of 50.3 m/s (1980 ips) and
1.57 m/s (61.9 ips).
https://ntrs.nasa.gov/search.jsp?R=19720018149 2020-03-17T03:52:54+00:00Z
184 GODDARD SPACEFLIGHT CENTER
The design goal for time displacement error (TDE)was 25 ns minimum;
less than 15ns was obtained. Tape utilization (packing)of ll6 kbit/cm 2
(750kbit/in. 2) was the design goal; 853 kbit/cm 2 (9550kbit/in. 2 was
obtained. A bit error rate of 1 error in l05 was the design goal. Presently it
is estimated to be 1 error in 106 or an improvement by a factor of l0 over
the design goal. Dual gap head assemblies were desired for improved
reliability. Redundant recording eliminates tape dropouts. Manufacturing
technology limits this development at this time, and dual gap heads were
not incorporated in the FR-2100.
Figure 1 shows a picture of the developmental model, the FR-2100,
scheduled for delivery in January 1971. In the lower left of the figure, a
swept frequency response of the system is shown. The top curve is for the
reproduce mode. The bottom curve shows a bipass of the tape, utilizing
electronics only, that illustrates the near transparency of the tape medium.
The picture on the fight demonstrates a PCM non-return-to-zero at
16 Mbit/s from both off tape and electronics-to-electronics. The future
plans for this system involve (l ) verification of all performance parameters
upon receipt of the equipment, (2) determination of the full capabilities of
the digital system such as multilevel coding, and (3) determination of the
reliability and head life characteristics.
In the development of such a system, one must continually look at
other devices and sources to determine the present-day state of the art. This
system has been five years in development, and other independent gains
have been made. Some present-day performances are illustrated in Table 2.
The two nearest competitors would be the Newell model AV-1500R
wideband longitudinal recorder and the RCA modified TR-70. The Newell
recorder is capable of a 15-MHz frequency response. This response is
obtained by high speed longitudinal recording. This approach has a
maximum recording time of 80 s/pass, unsuitable for continuous type
recordings. The RCA TR-70 has a full 10-MHz frequency response. This
should offer good competition on any new procurements. The system has
been demonstrated as a laboratory setup, and some additional work will be
required for a production system. The PCM digital capabilities for the
Newell system are 20 Mbit/s per channel operating at 2440 cm/s (960 ips).
The capability of the RCA unit should be equal to the Ampex FR-2100.
For multispeed, the Newell is supplied with the 7-speed transport at
38.1 cm/s (15 ips) to 2440 cm/s (960 ips). The multispeed capability was
TECHNOLOGY ACCOMPLISHMENTS, 1970 185 
demonstrated by RCA on another system. The time displacement error on 
the Newell recorder is of the order of 3000ns because this is a different 
type of recorder, not built specifically for low TDE. The performance of the 
RCA is not known. 
For tape utilization, the Newell provides a packing density of 
124 kbit/cm2 (800 b i t / k 2 ) .  The RCA system should be equal to the 
FR-2100. For bit error rate, one error in lo5 is estimated for the Newell 
system. The performance of the RCA machine has not been measured. 
FR 2100 
Video Instrumentation 
Record/Reproduce System 
to be delivered JAN,  1971 
frequency response 
I I 
0 10 MHz 
NRZ PCM 
16 Mbits/sec 
1 
Reproduce from 
TAPE 
ELECTRONICS to 
Electronics I 
(no tape) i 
Figure 1 
186 GODDARD SPACE FLIGHT CENTER
Table 1-Performance evaluation of AMPEX FR-2100.1
PERFORMANCE
PARAkETERS
eLFreq. _ Analog
b. PCM Digital System per-
formance
c. Mult Fkoead
d. Time Displacement
Error ( TDE )
e. Tope utilization
f. Bit Error Rote
g. Reliability
DESIGN GOALS
1968
DC tolOMHz( 6MHx-
mlnlmtmt)
14Mblts/s
IIMMts/s
I 2 speeds roqulrod
25ns mlrL
1t6kbits/cm 2
(750 _ts/sq._3
I Error in I0 °
Dual gap heads
AMPEX R_.2100, ViDeO INSTRUMENTA-
"lION REOORD/REPROOUCE SYSTEM PER-
FORMANCE. SEP'[ 1970
OC-K)MH: md OC-IOMHz (2ndsbeed)
32
16M bits/s - Test cood_'twd to 20Mbits/s.
This was achieved an the I0 MHz bo_lwldltt
using Miller Code- PCM.
Longitudinal Ipeeds-38,1cm,41 and 1.19cmAi{IStps
and 0.4711_) Scanning tpead_'otating tread) 50.3
m/s (19601p_ and 1.57m/s (61.91ps)
Less thon 15 ns
85.3 WDI_/c n_- (550 kbit s/r_T In.)
Estimated to be I error In 106.
Improvement of I0.
R_lundant recordlng to ellmlnate tope drop outs.
Mf9 technology limits this develops at this time.
noM.' PERSPECTIVE. Ampex FR-EK)O series recorders u=_:l in STAOAN hove 0.6 MH= fr_l:
' rupomm. The FR-2100 offers more than o I0 to I Improvement. This also
oppiles to most other parameters,
Table 2-Performance evaluation of three present-day systems.
PERFORMANCE AMPEX
PARAMETERS FR.2100 NIE'WI[LL MOOEL AVISOOR
eL Frequency
I_e I0 MHz 15 MHz
b. PCM Digital
System
c. Multi- speed
d. Time dis-
error
e. Tope utlllz-
otlae
f. Btt error
mfe
16Mbl_,_
2_
then
B53_dJts/
cmZ(S_o
kbltr./_l.ln)
lerror in
106
£_cellent rest)_se has
non continuous record-
tn_. 2,195m(T200') tape
has 80s/l_s recording
time.
20 M bits/s/ct_nnel
m 2440om/s(960tps)
7 speeds 38.10cm/s to
24.40¢m,_(151ps to 960ips)
3000 r_
124kblts/cm=
tlK)Okbits/sq.ln.)
Ierror in I08 Not confirmed
RCA MODIFIED
1R-70
I0 IVY-Is Gead froq.roqxme
d_ouldoffer cmnpotl-
tlQn an _ procure-
ments. System dern-
onstroted as lob sot-
up. Some oddltlonol
dev_op't roq'(L
Some os FR-2100
No. C4zpobllI11/was
demen, emother
system.
,p
Same osFR-2100
?


Feasibility model of a video instrumentation record/reproduce system

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