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DEVELOEMENT OF A RADIO TEARS ITTIR EUR nan

IN ANIMAL Iovnunxm STUDIES

by

JOHN R. PAUL

AN ABSTRACT

Submitted to the College of Agriculture of Michigan
State University of Agriculture and Applied
Science in partial fulfillment of the
requirements for the degree of

kASTnR OF SCIENCE
Department of Fisheries and uildlife
1960

M?

ABSTRACT

A miniature radio transmitter was designed for use
in animal movement studies, operating on 27 megacycles.
Two patterns of mounting the transmitter on animals
were used, the block and the collar forms. including
battery, each weighed 38-40 grams.

A nine-volt battery provided sufficient power to
Operate the transmitter about three days. Optimum
transmitting antennae were found to be 8 to 16 inch
lengths of insulated wire. The range of transmission
varied from 50 yards to four miles, depending primarily
on the receiving apparatus. The presence of vegetation
around the transmitter seemed to enhance signal reception.
The transmitter proved to be durable under rough

treatment.

DdVELOPMfiRT OF A RADIO TRALSRITTER FOR USE IN

ANILAL MUVALENT STUDIES

by

JOHN R. PAUL

A THESIS

Submitted to the College of Agriculture of Michigan
State University of Agriculture and Applied
Science in partial fulfillment of the
requirements for the degree of

“3TH OF sources

Department of Fisheries and Jildlife

1960

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ACKNOWLEDGSLJKTS

I wish to eXpress my sincere gratitude to Dr.
George A. Petrides, Professor, Department of Eisheries
and Wildlife at hichigan State University, for his
suggestion of this project and his aid and cooperation
in carrying it out. kany thanks must go to Robert
Altenhof for his considerable technical assistance in
the development of the radio. I would also like to
thank Dr. Peter I. Tack, head of the Department, for his
close interest and COOperation and to the several other

staff and graduate students who g<ve help and advice.

ii

TABLE OF COLTNKTS

LIST OF FIGURES . . . . . . . . . .
INTRODUCTION . . . . . . . . . . .
TRANSMITTER . . . . . . . . . . .
General Description . . . . .
Block Pattern . . . . . . . .
Collar Pattern . . . . . . .
Battery . . . . . . . . . . .
Antenna . . . . . . . . . . .
RECEIVING EQUIPMENT . . . . . . . .
TESTS or EQUIPMENT . . . . . . . .
Range . . . . . . . . . . . .
Harness . . . . . . . . . . .
Dog-style . . . . . . . .

Vest . . . . . . . . . .

Collar . . . . . . . . .

SUMMARY . . . . . . . . . . . . . .
LITERATURE CITRD . . . . . . . . .
APPENDIX A . . . . . . . . . . . .
APPENDIX B . . . . . . . . . . . .

111

Page

iv

10
10
15

13

14
15
17
18
19

LIST OF FIGURES

FIGURE

1. Schematic representation of oscillator and
amplifier stages of miniature transmitter .

2. Transmitter, collar and block forms . . . .

5. Amplifier-oscillator combination and basic
oscillator section . . . . . . . . . . . .

4. Transmitter, oscillator section . . . . . .

5. Rabbit with collar transmitter mounted . .

iv

lNTRODUJTION

Most studies of animal movements have been based
on direct observations of marred animals or on observ—
ations of their signs. The recent development of
miniature radio components, however, has provided the
means by which accurate indirect observations of animals
may be possible over continuous periods of time.

In one of the first studies of this nature, Ryan
(1957) developed a transmitter to be used on deer.

It was quite cumbersome, however, largely due to the
use of vacuum type tubes. LeMunyan at al. (1959),
using transistors, designed a circuit for use in a
study of woodchuck populations. In that study, the
transmitter was miniaturized and inserted within the
animal's body. Its range of transmission was limited

to 25 yards and, as that device was used, it would be

2

of limited value in studies of wide-ran,

ing animals.

U L

The present effort was to develop a small and
ineXpensive transmitter that could be attached
externally and be used in tracing the movements of

wide—ranging animals such as deer and cottontail rabbits.

TRAN SM I TTE R

A miniature transmitter was deveIOped using a
circuit (Figure 1) modified from Von Wald {1958).

It was essentially a continuous-tone, crystal-con-
trolled oscillator.

A Class C communications license was secured from
the Federal Communications Commission to use 26.995,
27.045, 27.095, 27.145, 27.195, and 27.255 megacycle
frequencies, within the Citizens' Band.

The transmitter was constructed in two different
patterns, the block and the collar \Figure 2). Each
unit, including battery, weighed 58-40 grams (l.4 ounces).
when constructed in the block pattern (Figures 3 and 4),
the components were mounted on light plastic sheets or
on fiberboards. The plastic sheeting or boards served
to hold the components in a fixed position, adding
to the transmitters stability and preventing short
circuits across bare wires. The dimensions of le block
transmitter were approximately 47 x 30 x 20 millimeters.

In the collar pattern {Figures 2 and 5), the
components were connected in linear fashion, enabling
the transmitter to be mounted on a leather strap. In

this pattern, more care had to be taken in insulating

Figure 1. Schematic representation of oscillator and
amplifier stages of miniature transmitter.

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Figure 2. Transmitter, collar and block forms.

Figure 5. Amplifier-oscillator combination and basic
oscillator section.

     
 

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Figure 4. Transmitter, oscillator section.

Figure 5. Rabbit with collar transmitter mounted.

 
  
    

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and protecting the components.

In constructing either unit, the fixed capacitor
was mounted inside the coil to conserve space.

The power supply was furnished by a nine-volt
battery. The smallest available of this voltage was
the Mallory TR-177 mercury battery, which is especially
designed for transistor application. It is cylindrical,
41 mm. x 13 mm. and weighs 18 grams.

Several transmitters Operated intermittently
during periods of 5-5 days showed little drop in the
output of the batteries (as measured on a vacuum tube
voltmeter), and in a continuous test, the oscillator
transmitted for about three and a half days. Presumably,
longer periods of operation could be attained by using
additional batteries or by using a device to yield
intermittent Operation. Over a four month period, one
transmitter was Operated almost daily for periods of
a few minutes to 24 hours each day. At the end of this
period the battery had lost very little voltage.

One peculiar requirement in the placement of the
parts was noted. If the resistor was placed closer than
one-fourth inch from the crystal, the transmitter failed

to work properly.

The transmitting antenna selected was merely a
piece of light insulated wire, the base Of which was
wrapped around the coil. In testing the transmitter,

a length of wire was fastened to one of the bare wire

ends shown in Figure 4. When the antenna exceeded

eight to sixteen inches in length, no appreciable increase
in signal reception was noted until a length of five to
six feet was reached. By adding some coils to the
antenna, it was found that an increased length of wire
could be used with little increase in the projecting
length of antenna.

It was found that differences in the diameter
of the transmitting antenna had no effect on the trans-
mitted signal, but under field conditions it became
evident that if the antenna was not made of spring
steel or other durable material, it easily became
broken in vegetation.

A supplementary amplifier circuit also was designed
(shown also in Figure l) but only the oscillator was
tested in this study. The amplifier section, it was
felt, could be added when more range and power was
desired but these characteristics did not seem necessary

in the earlier stages of deveIOpment. Furthermore,

with the added bulk of the amplifier section, the
transmitter would be useful primarily for larger animals
(Figure 3). Parts lists for both oscillator and

amplifier sections are given as appendices.

RECEIVING EQUIPILINT

Several different receivers were used to test the
transmitter. It was found that any receiver would
work so long as it had good sensitivity (approximately
two microvolts) and was capable of receiving frequencies
in the 27 megacycle range.

The receiver used for a majority of field tests
was a battery-Operated heathkit "Mohican", model
number GC-lA. This is a portable, all band receiver of
moderate sensitivity and light enough (18 pounds) to
be carried in the field. A detailed description of this
receiver can be obtained from the manufacturer

(Heath Company, l960).

lO

TESTS OF EQUIPLmILT

The range of the transmitter varied, depending
on the environment, the sensitivity of the receiver and
the receiver's antenna characteristics. The biggest
factor affecting reception appeared to be the receiving
antenna. Large antennae always picked up the signal
at greater distances than small antennae.

Ranges of one-half to three-fourths of a mile were
usually obtained when a man carried the transmitter and
the receiver was mounted with a lOO-foot wire antenna
or a two-element beam antenna. Using a 54-inch whip
antenna, the range of reception was fifty yards. Many
of these tests were made in residential areas where
traffic was profuse, yet little radio interference was
noted in receiving the signal.

When the portable receiver was raised from the
ground to a higher position, the signal strength in-
creased. When the receiver antenna touched the ground,
the signal drOpped. The higher the antenna was raised,
the better the reception. If a coil shaped antenna
was used, turning the antenna downward diminished the
signal.

Further experimentation with the receiving antenna

11

apparatus will be necessary before extensive field
use of the transmitter will be possible.

The transmitter was constantly submitted to shock
and stability tests during the range determinations.
Vigorous shaking and throwing of the transmitter to the
ground failed to stop its operation. In one instance,
the transmitter was dropped 15 feet from the top of a
ladder, yet no interruption in signal reception occurred.

Touching the transmitting antenna to the ground
had no effect on the signal, but if that antenna came
in Contact with bodies of water several feet or more
in surface area, signal intensity was increased.

Early in the testing it was noted that when a
person touched the transmitter or was very close to it,
signal strength was increased. Tests showed that the
range was increased thirty to fifty percent when the
transmitter was held in the hand as Opposed to being
placed on the ground. Ranges of one-fourth to one-third
mile were obtained, however, when the transmitter was
placed on the ground and away from people. As a person
approached the transmitter to within two to four inches
of it, the volume of tne signal increased. This in-

dicated a probable decided advantage in using the

12

transmitter on larger animals.

The presence of vegetation around the transmitter
markedly increased the range of reception. In a plowed
field, the signal could not be received beyond 100
yards, yet with the same receiving apparatus and the
transmitter placed in a field containing vegetation or
brush, the range increased to in excess of one-fourth
mile. .

On two occasions the transmitters were fastened
on dogs. The first was in the city and the dog was
allowed to run free within a half-mile of the receiver.
The transmitter was fastened to the dog's harness and
the antenna was located on its back. Signal reception
was easily maintained during this test. The receiving
antenna then was a 150 foot wire.

The second time a hunting dog was used on a local
farm with the transmitter fastened to the dog's collar.
Upon release the dog hunted vigOrously, thoroughly
testing the transmitter's stability. Visual contact
with the dog showed the range of the transmitter to be
approximately one-fourth mile. Contact was lost
sporadically as the dog ran outside of the transmitting

radius of the radio, yet the transmitted tone was

13

easily picked up as the dog moved back within range.
After about an hour contact was lost and later observ-
ation of the transmitter showed that the antenna was
broken off at the base.

Other tests were made with cottontail rabbits.
Several harnesses were tested, each with a simulated
transmitter mounted on it:

Dggfstyle Harness - Three rabbits were trapped and
a canvas harness similar in style to that worn by dogs
was applied. One rabbit, kept in captivity, success-
fully removed the harness within four hours. Of the two
released, one was subsequently recaptured two days later.
The rabbit had chewed through the front strap, allowing
the harness to twist around its body. This harness
was judged to be unsuitable.

Vest-style Harness - Elasticized cloth was cut in
vast fashion and drawn over a rabbit's head. This
allowed full freedom of its front legs and positioned
the transmitter over the shoulders. Of the three
animals fitted with the vest, two were retrapped, one
twice. All recaptures, occurring one, two and five
days after release, revealed harnesses in good condition.

One rabbit was observed in the field with this harness

14

and no apparent difficulties in movement were noted. This
harness was judged satisfactory for mounting of the
block transmitter.

Collar - The collar is the only method by which an
actual transmitter was applied to a rabbit. The radio
components were secured to a leather collar with
several turns of insulated wire. Sponge rubber strips
were placed between and around all components to serve
as an insulator and shock absorber. Plastic elec-
trician's tape was wrapped around the outside of the
sponge rubber to hold it securely.

The rabbit with the transmitter mounted (Figure 5)-
was first placed in a wire cage and observed. The
position of the transmitter seemed satisfactory since
the rabbit was unable to beat it against the cage with-
out doing itself physical damage. The animal's body
thus tended to protect the transmitter. Slight varia-
tions in the signal were noted when the rabbit jumped
about in the cage, but in general, there was no appre-
ciable change in signal reception during a 48 hour period.
A temperature range of 40 degrees during the experiment
caused no apparent effects. This harness was judged

to be satisfactory.

15

SUMMARY

A miniature radio transmitter was designed for use
in animal movement studies, Operating as a Class C
station on 27 megacycles (Citizens' Band). It was
crystal-controlled and emitted a continuous tone.

Two patterns for mounting the oscillator-trans-
mitter on animals were used, the block and the collar.
Their weights, including battery, were 58—40 grams each.

The power supply was furnished by a nine-volt
mercury battery which maintained a radio signal for
about three days. Tests indicated that the best
transmitting antenna was a piece of wire eight to six-
teen inches long, preferably of Spring steel or some
other durable material.

An amplifier section for the transmitter was
designed to increase the range of transmission. This
section was not tested at this time.

Signal reception ranges varied with the quality
of the receiving apparatus and with the nature of the
environment. The range varied from 50 yards to four
miles. The larger the receiving antenna, the better the

reception.

16

Shock tests failed to halt the transmitter's op-
eration.

Ranges varied from one-half to three—fourths of a
mile when the transmitter was carried in the hand and
large receiving antennae were used. Jhen a man carried
the transmitter the range was increased thirty to fifty
per cent over times when the transmitter was placed on
the ground. Unheld transmitters had a range of one-
fourth to one-third mile.

The presence of vegetation around the transmitter
increased the range of transmission. when transmitters
were placed in plowed fields, the ranges were sharply
reduced.

Tests using dogs to carry the transmitter were made
on two occasions. Ranges of about one-fourth mile were
obtained in the dog tests, and the stability of the
transmitter proved quite high. The necessity of making
the transmitting antennae of strong material, such as
spring steel, became evident.

Three styles of harness for fastening transmitters
to rabbits were tested. Dog-style and vest harnesses
were tested only with simulated transmitters. An actual
transmitter was applied in collar form to a rabbit.
Results indicated the vest and collar harnesses to be

satisfactory.

17

LITmRATURE CITbD

Heath Company, 1960. hohican communications receiver,
model GO-lA. Benton harbor, Lichigan, 77 pp.

LeMunyan, 0., W. White, a. Nyberg and J. Christian.
1959. Design of a miniature radio transmitter for
use in animal movement studies. J. Wildl. Ngt.
23:107-110.

Ryan, P. 1957. A method for determination of deer
movement patterns. M.S. Thesis, Syracuse Univer-
sity, New York.

Von Wald, E. 1958. A transistor handytalky for 10
meters. QST 8(3) :11-14.

F‘ rd F’ re F' +4

18

APPENDIX A

Parts list - Oscillator section

 

Crystal - one of the following frequencies: 26.995,
270045, 270095, 270145, 270195, E'fld
27.255

Variable Capacitor - 5-80 micro-micro-farads

Fixed Capacitor - 500 micro-micro-farads

Transistor - RCA 2N584

Resistor - 470 K ohms, i watt

Coil - % inch in diameter, 22 turns of f20 wire

Battery - 9 volt, Mallory model TR-l77

P4 +4 F' P4

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19

APPENDIX B

Parts list - Amplifier section

 

Transistor - RCA 2N584

Resistor - 55 K ohms

Resistor - 100 ohms

Variable Capacitor - 5-30 micro-micro—farads
Fixed Capacitors — 500 micro-micro-farads

Coil - % inch in diameter, 22 turns of # 20 wire

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