CREATIVE ELECTRONICS ELT 1091 Manual de usuario
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CREATIVE ELECTRONICS ELT 1091
OWNERS MANUAL
Creative Electronics, P.O. Box 2466, Orofino, ID. 83544,
Phone (208) 435-4002 Email
nas@cpcinternet.com
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CONTENTS PAGE
QUICK START OPERATING INSTRUCTIONS 4
TESTING PROCEDURE EXPLAINED 5
INTRODUCTION TO 406 MHz BEACONS 6
UNIT DESCRIPTION
FEATURES 8
CONTROL FUNCTIONS 10
DISPLAY PAGES & ELEMENTS 11
HEX CODE DISPLAY 14
OPERATION 16
INTERPRETING ERROR MESSAGES AND TROUBLE SHOOTING 18
USING CONTINUOUS MODE TO FIND AN OPERATING 121.5 Mhz BEACON 18
TESTING
AVIATION ELTs AND BEACONS UTILIZING A TRIGGERING OR AUTOMATIC SWITCH 19
MARINE ELTs AND OTHER ELTs UTILIZING A MANUAL SWITCH OR OTHER METHODS 20
PERSONAL LOCATING BEACONS (PLB) 20
SPECIFICATIONS 22
APPENDIX
A. OPERATIONAL MESSAGES 24
B. ERROR MESSAGES 25
C. REGISTERING ELTS 28
D. COSPAS SARSAT SYSTEM 29
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E. 406 TO 406.1 ELT OPERATION AND CHARACTERISTICS 30
F. 121.5 ELT OPERATION AND CHARACTERISTICS 32
G. BATTERY CONSIDERATIONS 33
H. RF SHIELDED CONTAINERS 34
I. FIELD STRENGTH MEASUREMENTS 41
J. TESTING LIMITATIONS 43
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QUICK START OPERATING INSTRUCTIONS
1. Turn power on by selecting either POWER METER if using internal antenna
load, or FIELD STRENGTH if receiving from beacon’s own antenna
2. Toggle NEXT to make new tests, toggle PREVIOUS to review previously
saved tests
3. If POWER METER was selected, connect beacon to ANTENNA LOAD then
skip to step 4, if FIELD STRENGTH mode was selected, toggle NEXT to continue,
PREVIOUS to start continuous 121.5 mode.
4. Toggle NEXT to continue saving current series of tests, toggle PREVIOUS to
reset memory and then start a new series of tests.
5. Using the toggle, select the operating frequency of the beacon if known
following the display prompts, if unknown, select the default UNKNOWN.
. If frequency selection is correct, toggle NEXT to continue, PREVIOUS to
return to selection display and redo
8. The READY message should be displayed along with the battery condition
and the tester is armed to receive and test a signal
9. Activate beacon
10. Observe the results. GREEN LED = OK, RED LED = ERROR. Use the toggle to
select the various displays showing either error messages if any, or the measured
results eventually toggling back to the READY message page
NOTE: IT IS IMPORTANT TO COMPARE THE DISPLAYED HEX CODE WITH THE ONE
ASSIGNED TO THE BEACON AND THE COUNTRY DISPLAYED WITH THE COUNTRY
THE BEACON IS REGISTERED TO. SEE PAGES 12 AND 14. IF DIFFERENT, THE
BEACON IS DEFECTIVE.
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TESTING PROCEDURE EXPLAINED
The 406 Mhz. emergency beacon system, unlike the previous simple system, has
many features designed to enhance reliability and reduce search times. As such,
it sends a more complicated signal and is therefore important that all aspects of
its signal are tested and verified. There are 2 basic types of tests, RF power
output from the beacon (power meter), and the amount of power being radiated
from the antenna (field strength) and permitting both should be accomplished.
The POWER METER mode of testing is an off the air test and requires at least 3
transmissions from the beacon
to complete. This is an actual operational test of
the beacon that checks all aspects of the signal it is sending. This method is only
possible on beacons that use an external antenna giving direct access to the
transmitter typically aviation ELTs, and some marine beacons
The other is an on the air test, FIELD STRENGTH, of the beacon and uses the test
mode function required for all beacons. The test function is identified as such to
the COSPAS SARSAT system so that it will not trigger a search, but as such not all
aspects of the beacon are tested. Instead of measuring the power output of the
beacon, this test measures the strength of the RF field the beacon and its antenna
are producing. This is a product of not only the amount of power generated by
the beacon but also the efficiency of the antenna system.
Unless you want to initiate a search, DO NOT OPERATIONALLY ACTIVATE A
BEACON WHILE CONNECTED TO AN ANTENNA. After the second transmission, it
will set off an alarm and start a search. The Creative Electronics tester includes an
ANTENNA LOAD to replace the beacon antenna when testing the beacon and is
also used in the POWER METER mode to measure the actual power the beacon is
producing. When running this test, the beacon should be placed in a RF shielded
container to prevent accidental radiation of a signal that the system could
receive, since a plastic enclosure will not shield the signal and the cables used to
connect the tester to the beacon need to be double shielded cables.
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INTRODUCTION TO 406 MHz BEACONS
Currently there are several types of Emergency locating transmitters or beacons. One of which
is the earlier 121.5 MHz type and another, the newer 406 MHz to 406.1 MHz type. The earlier
type transmits a continuous amplitude modulated signal without any information and relied on
persons who heard it to use direction finders to locate the source. While better than nothing,
the system was prone to many false alarms, and significant delays until the signal was first
discovered. The newer system resolved these problems by incorporating an identifying
message in the transmission along with optional location information and a system of orbiting
satellites that continuously monitor the 406 to 406.1 MHz band and relay the signals back to
Earth command centers.
There are two basic messages each having many variations tailored to suit the application using
the beacon. One is the short message (440 mS) which has no location information. The other is
the long message (520 mS) which can include location information. A portion of both messages
contain the following basic information; the protocol being used, the identity of the beacon, its
country of registration, and if it is a normal actual alarm or a test signal. If it is the long
message, also included is the last location, within a limited time frame, when the beacon was
activated.
Some additional requirements are to be met. When the beacon is activated for an actual alarm,
there is a brief delay prior to the first actual transmission. This is to allow the beacon to be
deactivated if the activation was inadvertent. Then once the transmission starts, the first 160
mS are to be un-modulated, in other words no data is sent. This is followed by a short
synchronizing signal which is then followed by the message sent in a specialized digital format
that contains the information needed to help identify and locate the beacon. This transmission
is supposed to be made at approximately 50 second intervals which are to be random in nature
so as to minimize any two beacons from continuously interfering with each other. There are
other features of the system which have been well thought out and implemented; the details of
which can be found in the specifications for the system from the Cospas Sarsat web site.
UNIT DESCRIPTION
The Creative Electronics model ELT 1091A ELT tester was designed for use by aviation
maintenance technicians and others who have the need to routinely test ELTs and PLBs to
determine that they will work properly when called on to do so. As such it was not designed to
be used as a laboratory test instrument to obtain the original certification of such devices. The
tester will however determine if the ELT/PLB is working properly, and decode and display the
message it is sending. The tester has been designed to be simple and intuitive to use and
provide a thorough test of the ELT/PLB and supply a simple go / no go indication along with the
message information generated by the ELT/PLB. It is up to the user of the tester to make sure
that the sent HEX code and country of registration are correct. (SEE PAGES 12 & 14)
The tester consists of two receivers, one for 121.5 Mhz. and the other for 406.0 to 406.1 Mhz.,
a dedicated MCU, a clock timing reference source, an 80 character display, 4 bicolor LED’s, an
audio amplifier with speaker and a substitute 50 ohm antenna load.
The ELT 1091A tester incorporates a power switch which is used to determine which of the two
operating modes is desired, POWER METER or FIELD STRENGTH. The other switch, a spring
loaded center off toggle switch is primarily used to cycle thru the various display pages as well
as control several other functions to be described later. The results of the various tests are
provided by 3 red/green LEDs and the 80 character LCD display arranged with 4 lines of 20
characters each.
Power is supplied by 8 AA batteries. A special monitoring circuit turns the tester off if there is
no activity for 15 minutes to conserve the batteries. If the battery voltage gets below a level
that will affect the accuracy of the tester, the BATTERY LED will turn red, and the display will
display a message to replace the batteries, and the tester will become disabled. An additional
circuit monitors the internal temperature of the tester and will disable the tester if the
temperature is out of the normal operating range that would affect the accuracy of the tester.
The display will display either a temperature too high or too low message. The tester will
remain disabled until the internal temperature is returned to the normal operating range.
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FEATURES
Simple to use
Tests all 121.5 Mhz. and all 406 to 406.1 Mhz. ELTs and PLBs
Decodes and displays the message
15 minute inactivity shutdown to conserve the batteries
Internal 50 ohm antenna load for power measurements
Measures RF power output
Measures relative RF radiated field strength
Pass / fail red or green LED indication of test results
80 character display (4 lines of 20 characters).
Displays protocol, format, message, and test measurement values
Measures for 121.5 Mhz.
Frequency
Modulation
Power or field strength
Measures for 406 Mhz.
Frequency
Modulation
Power or field strength
Transmitter output stability
Transmission time
Transmission recycling time
Data clocking rate
Un-modulated time
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Decodes and displays
Short message
Long message
15 digit hex code
ELT / PLB type
Marine protocols
Aviation protocols
User protocols
Standard protocols
National standard protocols
PLB protocols
Country codes (displays country)
Location protocols
Operating mode (normal or test)
Aux ELT data
Unit 15 hex identification
Stores the previous test results for later viewing
Utilizes a dedicated imbedded MCU not dependent on WINDOWS ™or any other operating
system
Includes an amplifier with a speaker to aurally monitor the received signal
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CONTROL FUNCTIONS
POWER SWITCH
Power meter mode
Measures the RF power of both the 121.5 Mhz. or the 406 Mhz. to 406.1 Mhz.
transmitters
Field strength mode
Measures the relative RF field strength being radiated from the antenna for both
the 121.5 Mhz. and 406 Mhz. to 406.1 Mhz. transmitters
FUNCTION SWITCH
On startup
Selects new tests or review previous tests
Selects either continuous 121.5 Mhz. field strength mode or 121.5 and 406 – 406.1
normal mode
Selects to continue test group, or clean memory of previous test results
Used to select the operating frequency of the 406 Mhz. to 406.1 Mhz. ELT
On receiving a signal on 121.5 Mhz.
In continuous field strength mode, selects numeric or bar graph display mode
In normal mode toggles display between the status page, measurements page, and
Field strength ready page.
In field strength mode while receiving a signal on 121.5 with the ready page displayed,
will mute or unmute the 121.5 audio
On receiving a signal on 406 Mhz. to 406.1 Mhz.
Toggles display between the following in order
Identification / location page
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