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‘FHE DEVELQPMENT GE A TELEMETRY’
SHOCK MEAfiURfNG SYSTEM

“tests {:or the Dogma oi; M. 5.
MICHIGAN STATE UNIVERSE”

Stephen Russefi Pierce
1968

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ABSTP fi’J’I‘

THE DEVELOPHENF OF A,TELEHETP RY
SHOCK I'EASLRING SYSTEI .

by Stephen Russell Pierce

A.self-contained telemetry shock measuring system
has been developed for use in the measurement of package
environment. A description of the operation and com;
ponents of the system is presented.‘ The system is capable
of measuring shocks of 10 to 250 g's with durations of

0.24 millisecond to 250 milliseconds.

 

 

THE DEVELOPIVBZNT OF A TELET-IISTRY
SHOCK MEASURING SYSTEl-i

By

Stephen Russell Pierce

A.THESIS

Submitted to
‘Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE
School of Packaging

1968

ACKNOWLEDGl-ENT

The author expresses his sincere thanks to
Dr. J. W. Goff for his helpful suggestions, without
which this study would not have been possible. The
author would also like to thank Mr. Hallard N. Brooks

for his advice and encouragement.

Ho
Ho

ACIOJOWLEDGMENT. ._ . .
TABLE OF CONTENTS . .
LIST OF TABLES. . . .
LIST OF ILLUSTRATIONS
INTRODUCTION. . . . .

DEVELOPPENT OF THE TELEI-iETRY

TABLE

SHOCK I~IEASURING SYSTEM

CONCLUSIONS . . '. . .~

APPEI‘IDIX 1’ I o o o o -
APPENDIX II . . . . .4

BIBLIOGRAPHY. . . . .

OF CONTENTS

Ho
Ho
Ho

22
24
38
39

LIST OF TABLES

Page

Table 1 Recorded shocks and durations
for the vibra-check pad. . . . . . . . f . 28_

Table 2 Recorded shocks and durations for
the no. 1265 pure gum rubber pad . . . . . 29

Table 3 Recorded shocks and durations
for the lead pellets . . . . . . . . . . . 30

Table 4 Recorded voltage outputs of subcarrier
discriminators for different frequency
input 8 O O O O C O O C C C O C C . . O O O 33
Table 5 Channel 1 total system calibration . . . . 35
Table 6 Channel 2 total system calibration . . . . 36

Table 7 Channel 3 total system calibration . . . . 37

iv

Figure
Figure
Figure

Figure
Figure

Figure

LIST OF ILLUSTRATION

System outputS. . . . . . .
Telemetry paekage. . . . . .

Block diagram of an I’M/PM
telemetry system . . . . . .

Assembled shock measuring
telemetry package. . .'. . .

Subcarrier discriminator (top
and receiver (bottom) ._. . .

Telemetry package calibration

)

mom-ting. O I O O O 0 O O O O O O O O O O O

Page

12
13
20
21

25

INTRODUCTION

With the increased demand for SOphisticated packaging,
the need has arisen to measure the environment through
‘which a package travels on its way to the ultimate consumer.
This environment includes both the handling and the in-
transit environments. This paper is concerned with the
development of instrumentation capable of measuring the
mechanical shock components of these environments. The
intransit environment is defined as those shocks occurring
while the package is being moved by any tranSport vehicle
other than a handling vehicle such as a lift truck. Those
shocks occurring during loading, unloading, and physical
movement into and out of storage are defined as the handling
environment. Once the packaging designer knows the shocks
encountered in these environments, he will be better pre~
pared to develop a package that will provide protection
for the product.

The develOpment of instrumentation for‘measuring the
shock components of the environment was undertaken with
the understanding that such instrumentation should be
self-contained, of minimum size, and capable of measuring
the shocks encountered in the package environment. After
studying the instruments available for measuring shock,
it was decided that accelerometers having a frequency
reaponse from 2 to 5,000 cycles per second were adequate

for measuring shocks in the package environment. Other

types of instrumentation were discounted due to their
inadequate frequency response. Although an accelerometer
had adequate frequency response for measuring the shock
environment, it lacked the requirement of being self-
contained. The accelerometer is not capable of record—
ing within itself. This brought about the problem of
finding a way to record the output from the acceler-
ometer, which is the measurement of the shock, and an

adequate way to get the signal from the accelerometer to

equipment capable of recording the shocks.

 

The §hock And Vibration Handbook defines telemetry

"as the indication, measurement, or integration of a

quantity at a distance by electrical translating means." 1

It goes on to say that "this definition implies a complete
system:_ transducers to convert the measurand to an
electrical equivalent, encoding and transmitting equipment,
and receiving and decoding equipment capable of providing
an indication or record of_events as they occur at the
remote location." 2 I
There are two types of telemetering systems available.
They are designated as the FM/FM system and the FEM/FM

system. The FM/FM system.is a frequency division system.

A.PDM/FM system.is a time division system.

leril M. Harris and Charles B. Grade, Shock And
Vibration Handbook (New York: McGraw-Hill, Inc., 1961),
p. 19-76.

’0

‘Ibid, p. 19—75.

 

A.PDM/FM system is a pulse duration modulation on a
frequency modulated carrier. 3 Data channels are sequentially
sampled by commutation. This type of srstem.was not used
because of its low frequency response. The maximum
frequency reSponse of a PDM/FM system is from 1 to 3 cycles
per second, which is much lower than the required frequency
.reSponse.

An Ft-I/FM system is a frequency division of frequency
modulated subcarriers transmitted by a frequency modulated
radio-frequency carrier. 4 All this means is that one
modulated frequency is used to modulate another frequency.
This system of telemetry was chosen because of its frequency
response capabilities. FM/FM telemetry offers frequency
reSponse capabilities from 0 to 2,100 cycles per second.

m/FM telemetry can be used in either a single channel
system or a multiplex system. A multiplexing FIE/FM telemetry
system utilizes two or more different subcarrier frequencies
to modulate one transmitter. Each channel in the system
has a different subcarrier frequency that is linearly
mixed with the other subcarriers cf the system.by a mixing
amplifier. “The mixing amplifier, which is sometimes called
an adder network, performs an arithmetic addition of the
voltages of the subcarrier frequencies. The output from

the adder network goes into a single transmitter whose

 

31bid, p. 19-77.

4Elliot L. Gruenberg, Handbook Of Telemetry And Remote
Contrgl (New York: ‘McGraw-Hill, Inc., 19673, p. 6-3.

carrier frequency transmits all the subcarrier frequencies.
With.multiplexing, only one receiver is needed because there
is only one radio-frequency carrier involved. The output
of the receiver is fed in parallel to subcarrier dis—
criminators which select the subcarrier for which they

are set and translate it back into analog input. Using all
the IRIG (see.Appendix 2) FM/Fm.telemetry subcarrier
oscillator bands available, 18 different subcarrier oscill-
ators could be used to simultaneously frequency modulate
one radio-frequency transmitter. With each channel of
telemetry in a multiplexing system having a different
subcarrier center frequency, the frequency response of
ieach channel will be different. The IRIG FM/FM telemetry
subcarrier oscillator bands are arranged so that there is
no overlap from one band to another.

When using multiplexing telemetry, one cannot utilize
the maximum frequency response available with single
channel telemetry. The frequency response of a given band
of telemetry is based on the maximum deviation of the
subcarrier frequency from its center frequency and a modu-
lation index of five.5 Therefore, with a lower subcarrier
center frequency, one has a lower frequency reSponse.

’ Single channel telemetry was decided upon because of
its high frequency response capabilities. Single channel

telemetry has one radio-frequency carrier for each sub-

 

5Harris and Grade, p. 19-79.

carrier frequency and one receiver for each radio-frequency
carrier. This system enables one to use the subcarrier
oscillator with the highest center frequency and frequency

I."

response for each channel in the system.

I

DEVELOPIENT OF THE TELEMETRY SHOCK PERSURIUG SYSTEM

Qascription of system operation

 

The Operation of one complete channel of the telemetry
shock system.will be described by the output from each
component in the system. All channels operate in the
same manner, therefore, the description of one channel of
the telemetry shock system.will be adequate for the whole
system. Shown in figure 1 is a diagram of the outputs
from each component in the system.

The first component in the system is an accelerometer.

The accelerometer measures shock and has an output voltage

proportionate to the magnitude of the shock. Assume that
some external force applies a sinusodial shock of 250 g's
for 10 milliseconds to the base of the accelerometer.
Any shock applied to the base of the accelerometer is
defined as a positive shock and a shock applied to the
top of the accelerometer is defined as a negative shock.
An 18 volt battery is used to supply power to the acceler-
ometer. The 18 volts from the battery flow through a coupler
before entering the accelerometer. The coupler consists
of a 10,000 ohm source resistor and a capacitor. The re—
sistor provides a current limiting device for the acceler-
ometer and the capacitor prevents d~c feedback into the
accelerometer from other components in the system. The
sensitivity of the accelerometer in this system is 10

millivolts per g. 'Therefore, with a positive shock of

 

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250 g's, the output of the accelerometer will be a plus
2.5 volts. The output of the accelerometer increases
from 0 volts to 2.5 volts in 5 milliseconds and then
decreases to 0 volts again in another 5 milliseconds when
the 250 g—lO millisecond shock is applied. This is shown
in figure 1. i

The voltage output from the accelerometer is too
large to be compatible with the input sensitivity of the
voltage controlled subcarrier oscillator. Therefore, the
voltage is reduced by a ratio of 50 to l by running it
through an attenuator. The attenuator consists of two
resistances inseries to ground that simply reduce the
voltage input by some factor depending on the resistances.
'The output voltage from the attenuator is a plus 50 milli-
volts for the 250 g shock under consideration.

This plus 50 millivolts then goes into a voltage
controlled subcarrier oscillator (V00). The function of
the VCO is to convert the input voltage to a subcarrier
frequency. ,An\8.4 volt battery supplies power to the
VCO and a transmitter. With a 0 volt input the subcarrier
oscillator has an output of 70,000 cycles per second.

This is called its center frequency. The input sensi-

tivity of the VCO is a i 50 millivolts. The 3 50 milli-

volt input will vary the center frequency by i 15 per

cent. Hence, the plus 50 millivolts input into the

VCO will give an output signal from the VCO of 80,500

cycles per second. (15% of 70,000 cps = 10,500; 70,000 cps +

10,500 CpS = 80,500 ops). The change in frequency output
from the VCO is presented in figure 1~by showing one cycle
of each frequency and the period of the frequencies. The
first cycle of output represents 0 volts input into the
VCO and the second cycle shows 50 millivolts input. The
intermediate frequencies between the 70,000 cycles per
second center frequency and the 80,500 cycles per second
modulated frequency are not shown in the diagram. However,
the frequency is increased proportionately from the center
frequency as the voltage increases until the maximum
80,500 cycles per second frequency is reached. Then the
frequency is decreased to the center frequency as the
voltage drops back to 0 volts. It takes 5 milliseconds
for the frequency to reach its maximum and 5 milliseconds
for the frequency to decrease to the original subcarrier
oscillator center frequency. This maintains the duration
factor of the shock recorded for later reduction. All of
the above mentioned frequencies are called subcarrier
frequencies because they will be used to modulate another
carrier frequency. The carrier frequency modulated will
be that of 'he transmitter.

The transmitter in this system has a carrier frequency
or center frequency of 245 megacycles per second. This
carrier is a radio-frequency carrier Which means it is
capable of sending signals without a connecting wire.

The radio-frequency carrier is modulated i 75 kilocycles

per second with a i 15 per cent modulation of the sub-

10

carrier frequency. Therefore, with the subcarrier fre-
quency output of 80,500 cycles per second, the radio—
frequency carrier will be modulated to 245,080,500 cycles
per second. This change in frequency output is shown in
figure 1 in the same manner it was shown for the output

of the VCO. The radio-frequency carrier is increased to
its maximum frequency by an increase input from the sub—
carrier frequency and then is decreased to its center
frequency as the subcarrier frequency decreases to its
center frequency. A shield was built into the transmitter
to reduce proximity effects on the carrier frequency. This
same shield is arranged to act as the radiating element
eliminating the need for an external antenna. The signal
radiated from the shield is sent through the air to a
receiver located remotely from the transmitter.

From this point in the system, it is the function of
the components to reduce the transmitted frequency to the
original voltage output of the accelerometer. The receiver's
function is to select the carrier frequency of the trans-
mitter, to reject all other frequencies received by the
-antenna and to reduce the carrier frequency to the original
subcarrier frequency. The output of the receiver is shown
in figure 1. This output is the same as the output from
the voltage controlled subcarrier oscillator. The receiver
simply reverses the process of the transmitter. Output

from the receiver is then fed into a subcarrier discriminator.

The function of the subcarrier discriminator is to

ll

reduce the subcarrier frequency to a voltage. This
component functions in reverse of the VCO. Therefore,
the output of the subcarrier discriminator will be the
k 2.5 volt signal output fro: the accelerometer.'

In summary, the Voltage output signal of the acceler-
ometer, which is a measure of the shock, is converted to
frequencies and then changed back from the frequencies to
-the original voltage output of the accelerometer. This
system performs the function of accurately measuring shock

from a remote location without the aid of wires.

Component description

 

The deve10pment of a telemetering shock measuring
system was undertaken to provide a system.capable of
measuring shocks occurring inside the package as well as
shocks transmitted to the package as a whole. A package
was needed that could house and protect the internal.
components of the system. A.mahogany wood block.was
selected for the package because of its shock properties
(see Appendix 1).‘ The wood block was cut to the desired
size and shaped to accomodate the components of the system.
The block is shown in figure 2.

A.block diagram of the overall system is shown in
figure 3. The first components in the system are three
Kistler Model 818 Piezotron accelerometers which are used
to measure the shock. The accelerometers are mounted .

triaxially in the mahogany block which permits the system

 

 

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14

to measure a shock in any direction.

A Kistler Model 818 Piezotron accelerometer is a
low impedance piezoelectric accelerometer which utilizes
the advantages of exceptionally high Open-circuit voltage
sensitivity and the stability of quartz crystal elements.
When power is supplied to the accelerometer, the quartz
crystal inside is saturated with electrons. When an
externally applied force deforms the quartz crystal,
electrons flow to a capacitor. Depending on the quantity
of electrons released and the size of the capacitor, a
voltage of some magnitude is produced. All Piezotrons
have a standardized voltage sensitivity of 10 millivolts
per g which simplifies the multichannel operation of the
system.

The second components in the system are couplers.
A coupler consisting of a 10,000 ohm.source resistor and
a coupling capacitor is required for each accelerometer.
The 10,000 ohm resistor is used for reference sensitivity
and the coupling capacitor is used in series with the out-
put lead to block the bias voltage from the direct coupled
(d-c) equipment used in the rest of the system.' An 18
volt power supply is connected to the couplers which supply
the Piezotrons with 1.8 milliamps. The output from this
accelerometer coupler system.is 1 2.5 volts. The input

sensitivity of the voltage controlled subcarrier oscillator

15

(V00) into which the signals are to be fed is i 50 milli-
volts. Therefore, the output voltage of the accelerometer
signal had to be attenuated to be acceptable for the VCO.

Attenuators comprise the third series of components.

An attenuator consists of two resistances in series with

one of the resistances grounded. These attenuators reduce
the voltage output of the accelerometers by a ratio of

50 to 1. In this system, the voltage flows from the acceler-
ometer system into a 27,400 ohm resistor. This resistor

is in series with a 547 ohm resistor which is in parallel
with the output voltage lead to the VCO. The lead to the
VCO takes the voltage output from the 27,400 ohm resistor
which is 1/50 of the input voltage to that resistor.

The fourth components shown in the block diagram are
voltage controlled subcarrier oscillators (VCO). The VCO
units used in this system are Model ll25-E‘s, manufactured
‘by Signatron, Inc. of Gardena, California. Voltage controlled
oscillators are used to convert analog voltages to FM
subcarrier frequencies. 'Any IRIG band is available for use
with a VCO. The frequency reSponse required dictates
which IRIG band is needed. IRIG band B was selected for
this system.because of its high frequency reSponse, 0 to
2,100 cycles per second. IRIG band E has a center frequency
of 70,000 cycles per second and a 3 15 per cent deviation
of the center frequency for 3 50 millivolts input. The
subcarrier frequency is dependent on the voltage input to

the V00. With a 0 volt input, the subcarrier frequency

16

will be.70,000 cycles per second and with a + 50 millivolts
input the subcarrier frequency will be 80,500 cycles per
second (15% of 70,000 cps = 10,500 cps; 70,000 Cps +

10,500 ops = 80,500 Cps). The output of the voltage
controlled oscillator, the subcarrier frequency, is fed
into mixing amplifiers or what is sometimes called adder
networks. I

When FM multiplexing telemetry is used, the adder
network linearly mixes the frequency modulated output-
voltage from all the subcarrier oscillators in the system.
This linear mixing is just an addition of the voltages.

In this system, only single channels are used for each
transmitter. Therefore, the adder network does not
function as a linear mixer. The only function it serves
in single channel systems is the prevention of feedback
into the VCO.

Model 201 low powered transmitters manufactured by
Signatron, Inc. comprise the fifth series of components.
IThe purpose of the transmitter is to provide a modulated
radio-frequency signal of sufficient power to reach a
remote receiver. For typical environments, the usable
distance is 50 feet. For more ideal environments, distances
Up to 300 feet can be obtained. These transmitters are
available in the frequency range of 215 to 260 megacycles
per second and are frequency modulated by the subcarrier
frequency from.the VCO. Plus or minus 100 per cent modulation

of the subcarrier frequency will modulate the transmitter.

frequency i 75 kilocycles per second. This modulated
frequency is sent through the air waves to be picked up
by a receiver.

The last three series of components in the system,
the receiver, the discriminators, and the recording equip-
ment, are external to the mahogany block and require
external power.

The receivers in this system are Model 4200 manu-
factured by Signatron, Inc. They provide reception of
signals in the 215 to 260 megacycle FM band which makes
.them.compatible with the transmitters used. The receivers
perform three functions. One, they select the desired
radio-frequency from the other signals that are received
by the antenna. Second, they amplify the selected radio-
frequency carrier to a usable level. Third, they de-
modulate the radio-frequency to retrieve the subcarrier
frequency that was the output of the voltage controlled
subcarrier oscillators. 6

The first function of a telemetry receiver is performed
with two components. The first component is a tuning
condenser similar to the tuningcondenser in a home radio.
This component allows one to tune in the carrier frequency.
The second component is a radio—frequency amplifier filter
which amplifies the signal and filters out frequencies

other than the carrier frequency. The signal then goes

6Gruenbere‘ p. 6~28.

u!

18

through two intermediate frequency amplifiers that further
amplify the signal and narrow the frequency band. The
three amplifier-filter components serve the second function.
Finally, the signal enters a demodulator which reduces

the signal to the transmitted base band waveform.

The subcarrier frequency output from the receivers
goes into the next series of components in the block
diagram, the subcarrier discriminators. The subcarrier
disoriminators in this system are model SlOO-E manufactured
by Signatron, Inc. They have an output of i 2.5 volts
'which is the same as the output of the accelerometers.

A subcarrier discriminator consists of four main components:
a band pass input filter, limiter, demodulator, and a
low-pass output filter.7 The band pass input filter acts
somewhat like the tuning condenser of the receiver in that
it selects the desired frequency band and rejects all

other frequencies. The signal then goes into the limiter/
discriminator which demodulates the FM subcarrier frequency.
After demodulation, the output goes through the low-pass
output filter which removes undesirable noise from the,
signal.' The signal is then amplified to a suitable

output level. I .

The last block in the diagram is a magnetic tape
recorder which is used for recording and storing the

signals. The signals on the tape can be monitored at

7Gruenberg, p. 6-00.

19

some later time with an oscillisc0pe. Pictures of the
desired signals can be taken or the signals can be re-
corded on an oscillograph for permanent records.

The assembled shock measuring telemetry block is
shown in figure 4. This block contains all the components
in the block diagram up to the receivers. A.subcarrier

discriminator and receiver are illustrated in figure 5.

20

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Figure 4 —

Assembled shock measuring telemetry package.

21

 

.Figure 5

Subcarrier discriminator (top) and receiver (bottom).

The telemetry shock measuring system developed has

been calibrated (see Appendix 1) and successfully used in
[both drOp testing and inclined impact testing. The system
has a frequency reSponse from 2 to 2,100 cycles per second
which makes it capable of measuring half sine shock pulses
with durations from 0.24 millisecond to 250 milliseconds.
The system is capable of measuring shocks with magnitudes
from 10 g's to 250 g's. Shown in Table 4 are the results of
a frequency calibration for the telemetry components of the
system. .As the frequency of a constant input signal was
increased, the output voltage of the subcarrier discrimin-
ators decreased. All channels had a flat frequency response
from 2 to 250 cycles per second. Therefore, half sine shock
pulses with durations from.2 milliseconds to 250 milliseconds
could be measured without any extra calibrations. Half
sine shock pulses with durations from 0.24 millisecond to
2 milliseconds can also be measured, but the magnitude of
the shock will have to be corrected using a calibration
factor for the frequency of the shock. Complex shock pulses
containing no components representing frequencies above 250
cycles per second will be accurately presented.

1 In additional studies, an attempt should be made to re~
duce the noise level of the system. If the noise level could
be reduced to less than 5 millivolts, shocks and vibrations

‘with magnitudes greater than 0.5 g could be measured.

22

APPEI‘IDICES

APPENDIX I
TELEMETRY SHOCK MEASURING SYSTEM CPJIBRHTION

In the development of the telemetryshock measuring
system, each component was individually calibrated whenever
possible and the system as a whole was calibrated. This
appendix will present the procedure and results of these

calibrations.

 

Instrumentation_package

The instrumentation package was made from Honduras
mahogany wood. The wood block was cut to the desired
size and shaped to accomodate the measuring and trans-
mitting components of the system. Honduras mahogany
wood had been tested for shock transmissibility and the
results revealed that this material had little effect on

shock transmission. 8

Test procedure

The instrumented package was fastened to the drop
head of a L.A.B.‘Model 16—42-100 free fall shock machine
as shown in figure 6. Sides and ends of the block.were
subjected to a series of shock pulses of known magnitude,

duration and waveshape. A Kistler‘MCdel 808 S/N 128

 

_ -——v _ __w

8 O O o O 0

Stephen Pierce and Robert Fiedler, "A.Determination
of The Shock Transmission Characteristics of Mahogany"
(unpublished technical research paper, School of Packaging,

4""

‘Michigan State University, 190,).

24

‘1 "11"

 

25

 

.— — - “W"—'—'-

Figure 6

Telemetry package calibration mounting.

26

quartz accelerometer was mounted directly to the drOp
head as a control accelerometer. The three Kistler
Mbdel 818 piezotron accelerometers mounted triaxially

in the block were the test accelerometers. The signals
‘were monitored from the accelerometers without telemetry.

Half sine shock pulses of short duration were achieved
with a rubber Vibra-Check deceleration pad (Lowell Ind.).
Half sine pulses of long duration were achieved with a
No. 1265 Pure Gum rubber pad (Queen City Rubber 00.).

Saw tooth wave shapes were produced using lead pellets
(molded in the School of Packaging laboratories, Michigan
State University).

Signals from the control accelerometer were fed
through a Kistler Model 565 S/N 193 charge amplifier into
one channel of a Tektronix Mbdel 584 storage oscilloscope.
Signals from the test accelerometers were fed through
Kistler Model 5488 couplers into the, other three channels
of the same scope. .A Tektronix oscilloscope camera C-12

was used to record the shock pulses.

Test results

Readings from the control accelerometer and the
test accelerometers are listed in tables 1, 2, and 3.
The data is presented with reference to the side or end
of the block which was in contact with the drop head.
Referring to figure 6, the and shown in contact with the

drOp head is defined as.end l and the end not in contact

27

with the drop head is defined as end 2. Side 1 is defined
as the face having the accelerometer opening. Side 2 is.
the right side of the block. Side 3 is the side opposite
side 1 and side 4 is Opposite side 2. Side 1 could not

be tested because of the wires from.the accelerometers.
The data presented indicate practically no effect on shock

transmission by the instrumented_block.

 

TABLEJZ

RECORDED SHOCKS AND DURATIONS
FOR THE NO. 1265 PURE GUM {UBBER PAD

Control Accelerometer Test Accelerometer
(Kistler 808) (Kistler 818)
Deceleration Duration Deceleration Duration
(in g's) (in ms) (in g's) (in ms)

END 1 40 11 4O 11
75 9 75 9

110 8.5 110 8.5

END 2 48 12.5 48 12.5
85 9 85 9
110 8 112 8
SIDE 2 44 12 44 . 12

90 9.5 90 9.5
110 ' 9 110 9
SIDE 3 40 11 40 11
69 10 7O 10
120 9 118 9
3113s, 4 39 10 . 40 ‘ 10
' 65 9 65 9
98 8 97 8

29

 

TABLE 3

RECORDED SHOCKS AND D'RATIONS
FOR THE LEAD PELLETS

Control Accelerometer Test Accelerometer
(Kistler 808) (Kistler 818)
Deceleration Duration Deceleration Duration
(in g's) (in ms) ' (in g's) (in ms)
END 1 38 6.4 40 6.4
50 6 50 6
55 6 55 6
END 2 as 6.4 40 6.4
55 6 52 6
60 ' 6 6o 6
SIDE 2 42 5.6 44 5.6
55 5.6 52 5.6
65 ‘ 7 63 7
SIDE 3 42 , 6 ' 42 6
i 50 6 . 50 6
'65 5.6 65 5.6
SIDE 4 42 ' ‘ 6.6 44 ‘ 6.6
55 6 ' 55 6
6O 6 60 6

30

 

31

Attenuators

The attenuators are used to reduce the voltage from
the accelerometers by a factor of 50. The exact value
of the resistors used for the attenuator was found by
using a type 1650-A impedance bridge manufactured by
General Radio Company. The results of the calibration
demonstrated that the attenuators reduced the input

voltage by a factor of 50.

Test procedure

A Hewlett Packard 3300 A function generator was
used to supply a sinusodial input to the attenuators. A
voltage from 0 to 2.5 volts was applied to the attenuator.
The output from the attenuator was fed into one channel
of a Tektronix‘Model 564 storage oscillosc0pe. _The
input to the attenuators was also monitored on another
channel of the same sc0pe. A.Tektronixoscilloscope
camera C-12 was used to record the data. The frequency
of the input was varied from 0 to 5,000 cycles per second.

The frequenCy had no effect on the output voltage.

VCO, transmitter, receiver. and discriminatgg

The VCO, transmitter, receiver, and discriminator
were tested together for calibration. They were tested
to determine the effect of frequency on voltage output
from the discriminator. It was found that the frequency
of the input signal had no effect of the output voltage

of the discriminator. As the frequency was increased

 

 

TABLE 4

RECORDED VOLTAGE OUTPUTS

0F SUBCARRIER DISCRIMINATORS
FOR DIFFERENT FREQUENCY INPUTS

 

 

 

 

 

 

 

 

mmmmll QmmmIZ Qmmm13
Frequency Vbltage Frequency Voltage Frequency Voltage
Input Output Input Output Input Output
(in cps) (in volts) (in cps) (in volts) (in ops) (in volts)
'0 2.5 0 2.5 0 2.
50 2.5 50 2.5 50 2.5
100 2.5 100 2.5 100 2.5
150 2.5 150 2.5 150 2.5
200 2.5 200 2.5 200 2.5
250 2.5 250 2.5 250 2.5
300 2.5 300 - 2.5 300 2.45
350 2.45 350 2.5 350 2.40
400 2.40 400 2.45 400 2.35
450 2.37 450 2.20 450 2.33
500 2.35 530 2.40 500 -2.30
600 2.25 600 2.35 600 2.25
700 2.15 700 2.25 700 2.1
800 2.05 800 2.15 800 2.0
900 1.95 900 2.10 900 1.95
1000 1.85 1000 2.00 1000 1.80
1100 1.75 1100 1.90 1100 1.70
' 1200 1.65 1200 1.85 1200 1.65
1300 1.55 1300 1.80 1300 1.55
1400 1.45 1400 1.75 1400 1.45
1500 1.40 1500 1.65 1500 1.35
1600 1.30 1600 1.60 1600 1.30
1700 1.25 1700 1.55 1700 1.2
1800 1.20. 1800 1.45 1800 1.15
1900 1.10 1900 1.40 1900 1.1
2000 1.05 2000 1.35 2000 1.05
2100 1.00 2100‘ 1.3 2100 1.00

 

33

 

 

34

Total system

 

In this calibration the accelerometer output was
the input to the VCO. The system was assembled as it would

be used in field testing.

Test procedure

The instrumented package was fastened to the drOp
head of a L.A.B. Medel 16-42-100 free fall shock.machine.
Each side and end of the block was subjected to a series
of shock pulses of known magnitude, duration and waveshape.
Sinusoidal shock pulses from 3‘to 12 milliseconds duration
were used in the calibration. A Kistler Model 818 piezo—
tron accelerometer, mounted directly on the drOp head,'
was used as a control accelerometer. '

Signals from the subcarrier discriminators were
recorded on a Tektronix Model 564 storage oscilloscope

as was the Signal from the control accelerometer.

Test results

Readings from the control accelerometer and the test
accelerometer are are listed in tables 5, 6, and 7.
Channel 1, positive, has been referred to as side 3 in
the instrumentation package calibration. Channel 2,
positive, would be and 1. Channel 2, negative, would be
end 2. Channel 3, positive, would be side 2. Channel 3,

negative, would be side 4.

 

TABLE 5

CHANNEL 1
TOTAL SYSTEM CALIBRATIOF

Control Accelerometer Test Accelerometer
Deceleration Deceleration
(in g's) (in g's)

Positive Direction (side 3)

30 30
40 ‘ 40
60 65
65 65
90 90
100 100
115 115
140 140
165 170
180 p 180
195 195
200 200
220 220
230 225

Negative Direction (side 1)

25 25
50 50
7O 7O
75 75
90 85
95 95
110 110
135 130
150 140
240 220

35

 

TOTAL SY

Control Accelerometer
Deceleration
(in g's)

TABLE 6

CHANNEL 2
STEM CALIBRATION

Test Accelerometer
Deceleration
(in g's)

Positive Direction (end 1)

 

TABLE 7

TOTAL SYSTEM CALIBRATION

Control Accelerometer Test Accelerometer
Deceleration Deceleration
(in g's) (in g's)
Positive Direction (side 2)
10 8
45 43
70 70
80 80
140 136
180 180
210 210
240 240

Negative Direction (side 4)

18 16
45 43
70 66
90 90
110 110
140 140
160 158
190 190
210 210

230 235

37

 

APPENDIX II
INTER-RANGE INSTRUEENTATIOI GROUP

IRIG (Inter-Range Instrumentation Group) is an
organization composed of representatives from several
guided missile ranges. There are 10 working groups
within IRIG that work in different areas, one of which
is the Telemetry Working Group (TWG). IRIG has done
extensive work in the standardization of radio telemetry.
They have published IRIG Document 106-60 entitled
"Telemetry Standards." .IRIG Document 106-60 contains
information on instrumentation, magnetic recording,
frequency utilization parameters, as well as definitions
of terms and descriptions and uses of the different

types of telemetry system.

38

 

BI BLI OGRAPHY

Gruenberg, Elliot L. fiandhogk_of Telemetry and Remote
Control. New York: McCraw-Hill Book Company, Inc.,
1967. -

 

Harris, Cyril M. and Charles E. Crede. Shpck And Vibratigg
Handbook. NeW'York: mcGraw—Hill Book Company, Inc.,
1961.

Pierce, Stephen R. and Robert Fiedler. "A.Determination
of The Shock Transmission Characteristics of Mahogany,"
unpublished technical research paper, School of
Packaging, Michigan State University, 1967.

39

 

 

 

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