Campbell ST21 User manual

ST-21 Argos
Satellite
Transmitter
User Manual
Issued 10.12.12
Copyright ©2006-2012 Campbell Scientific, Inc.
Copied under licence by Campbell Scientific Ltd.
CSL 884

Guarantee
This equipment is guaranteed against defects in materials and workmanship.
This guarantee applies for twelve months from date of delivery. We will
repair or replace products which prove to be defective during the guarantee
period provided they are returned to us prepaid. The guarantee will not apply
to:
•Equipment which has been modified or altered in any way without the
written permission of Campbell Scientific
•Batteries
•Any product which has been subjected to misuse, neglect, acts of God or
damage in transit.
Campbell Scientific will return guaranteed equipment by surface carrier
prepaid. Campbell Scientific will not reimburse the claimant for costs incurred
in removing and/or reinstalling equipment. This guarantee and the Company’s
obligation thereunder is in lieu of all other guarantees, expressed or implied,
including those of suitability and fitness for a particular purpose. Campbell
Scientific is not liable for consequential damage.
Please inform us before returning equipment and obtain a Repair Reference
Number whether the repair is under guarantee or not. Please state the faults as
clearly as possible, and if the product is out of the guarantee period it should
be accompanied by a purchase order. Quotations for repairs can be given on
request. It is the policy of Campbell Scientific to protect the health of its
employees and provide a safe working environment, in support of this policy a
“Declaration of Hazardous Material and Decontamination” form will be
issued for completion.
When returning equipment, the Repair Reference Number must be clearly
marked on the outside of the package. Complete the “Declaration of
Hazardous Material and Decontamination” form and ensure a completed copy
is returned with your goods. Please note your Repair may not be processed if
you do not include a copy of this form and Campbell Scientific Ltd reserves
the right to return goods at the customers’ expense.
Note that goods sent air freight are subject to Customs clearance fees which
Campbell Scientific will charge to customers. In many cases, these charges are
greater than the cost of the repair.
Campbell Scientific Ltd,
Campbell Park, 80 Hathern Road,
Shepshed, Loughborough, LE12 9GX, UK
Tel: [phone]
Fax: [phone]
Email: [email protected]
www.campbellsci.co.uk

PLEASE READ FIRST
About this manual
Please note that this manual was originally produced by Campbell Scientific Inc. primarily for the
North American market. Some spellings, weights and measures may reflect this origin.
Some useful conversion factors:
Area: 1 in2(square inch) = 645 mm2
Length: 1 in. (inch) = 25.4 mm
1 ft (foot) = 304.8 mm
1 yard = 0.914 m
1 mile = 1.609 km
Mass: 1 oz. (ounce) = 28.35 g
1 lb (pound weight) = 0.454 kg
Pressure: 1 psi (lb/in2) = 68.95 mb
Volume: 1 UK pint = 568.3 ml
1 UK gallon = 4.546 litres
1 US gallon = 3.785 litres
In addition, while most of the information in the manual is correct for all countries, certain information
is specific to the North American market and so may not be applicable to European users.
Differences include the U.S standard external power supply details where some information (for
example the AC transformer input voltage) will not be applicable for British/European use. Please
note, however, that when a power supply adapter is ordered it will be suitable for use in your country.
Reference to some radio transmitters, digital cell phones and aerials may also not be applicable
according to your locality.
Some brackets, shields and enclosure options, including wiring, are not sold as standard items in the
European market; in some cases alternatives are offered. Details of the alternatives will be covered in
separate manuals.
Part numbers prefixed with a “#” symbol are special order parts for use with non-EU variants or for
special installations. Please quote the full part number with the # when ordering.
Recycling information
At the end of this product’s life it should not be put in commercial or domestic refuse
but sent for recycling. Any batteries contained within the product or used during the
products life should be removed from the product and also be sent to an appropriate
recycling facility.
Campbell Scientific Ltd can advise on the recycling of the equipment and in some cases
arrange collection and the correct disposal of it, although charges may apply for some
items or territories.
For further advice or support, please contact Campbell Scientific Ltd, or your local agent.
Campbell Scientific Ltd, Campbell Park, 80 Hathern Road, Shepshed, Loughborough, LE12 9GX, UK
Tel: [phone] Fax: [phone]
Email: [email protected]
www.campbellsci.co.uk

i
Contents
PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.
1. Overview......................................................................1
1.1 Specifications.........................................................................................1
1.2 Serial Port...............................................................................................1
1.3 Data Buffers ...........................................................................................2
1.4 Multiple Argos ID Numbers..................................................................2
1.5 One Argos ID Number...........................................................................3
2. Datalogger Programming...........................................3
2.1 Argos Setup............................................................................................3
2.1.1 Result Code.....................................................................................3
2.1.2 Buffer Number................................................................................3
2.1.3 Decimal ID Number .......................................................................3
2.1.4 Frequency........................................................................................3
2.2 ArgosData...............................................................................................3
2.2.1 General Description........................................................................4
2.2.2 ResultCode......................................................................................4
2.2.3 ST21Buffer .....................................................................................4
2.2.4 DataTable........................................................................................4
2.2.5 NumRecords ...................................................................................4
2.2.6 DataFormat .....................................................................................4
2.3 ArgosDataRepeat ...................................................................................4
2.3.1 Result Code.....................................................................................5
2.3.2 Repetition Rate ...............................................................................5
2.3.3 Number Repeats..............................................................................5
2.3.4 Buffer Number................................................................................5
2.4 ArgosTransmit........................................................................................5
2.4.1 Result Code.....................................................................................5
2.4.2 Buffer Number................................................................................5
2.5 ArgosError (Error as string)...................................................................6
2.5.1 ErrorCodes......................................................................................6
3. ST-21 Installation........................................................6
3.1 BNC Antenna Connector and Antenna ...................................................6
3.2 Environmental Enclosure.........................................................................7
4. Satellite Orbit Patterns...............................................7
5. Antenna Placement ....................................................8

ii
Figures
1-1. ST-21 Argos Satellite Transmitter.........................................................1
1-2. The ST-21’s 9-pin connector attaches to the datalogger via the
SC12 cable..........................................................................................2
3-1. The ST-21’s BNC connector attaches to the antenna via the
antenna cable ......................................................................................6
3-2. The #12022 antenna...............................................................................7
Tables
1-1. ST-21 Serial Port Configuration............................................................2

1
ST-21 Argos Satellite Transmitter
1. Overview
The ST-21 is a certified Argos PTT satellite transmitter for use with Campbell
Scientific CRBasic dataloggers. Service Argos data transceivers fly aboard two
NOAA polar orbiting satellites. With an orbit altitude close to 800 kilometres, the
satellites are at a relatively low orbit. The low orbit allows for low transmit
power, low battery power requirements and the use of an omni-directional
antenna. The orbit period is approximately 1 hour and 45 minutes, which allows
hourly data at extreme northern and southern latitudes. Near the equator there are
about six satellite passes per day that are not evenly spaced. During the average
satellite pass, the satellite is in view for about 10 minutes.
Figure 1-1. ST-21 Argos Satellite Transmitter
1.1 Specifications
Power supply: Nominal 12 volts DC, 10 volts DC minimum,
16 volts DC maximum
Current drain
at 12 volts:
1.12 mA quiescent, 375 mA during transmit
Data buffers: 7 buffers, 32 byte each. Note: 28 bit ID numbers reduce
buffers to 31 bytes.
Operating
temperature:
-30° to 70°C
Dimensions: 19 L x 6 H x 3 W cm (7.5 L x 2.25 H x 1.25 W inches)
Weight: 224 gm, 7.9 oz
1.2 Serial Port
The ST-21 is specifically designed to work with Campbell Scientific CRBasic
dataloggers. The ST-21 serial port connects to the CS I/O port of the datalogger
via an SC12 cable (see Figure 1-2). The datalogger provides 12 volt DC power
and ground through pins 8 and 2 respectively. Communications utilize the
Campbell Scientific Synchronous Device for Communications (SDC) protocol,
which allows several devices to be connected to the CS I/O port at the same time.
Each device is addressed or pin enabled; the ST-21 is address 4.

ST-21 Argos Satellite Transmitter
2
Table 1-1. ST-21 Serial Port Configuration
Pin number Function
1 +5 volts
2 Ground
3 NC
4 TXD (data out)
5 NC
6 SDE (input)
7 CLK/HS (input)
8 +12 volts
9 RXD (data in)
Figure 1-2. The ST-21’s 9-pin connector attaches to the datalogger via the
SC12 cable
1.3 Data Buffers
The ST-21 has 8 internal data buffers. Before a data buffer can be used, a valid
Argos ID number, repetition rate and frequency must be assigned to the buffer.
The Argos ID numbers must be entered as a decimal and a Hexadecimal number.
The ST-21 uses the Hexadecimal format to determine if the ID is a 28 bit ID
number. When using 28 bit ID numbers, 31 bytes of data can be stored in the
buffer. When using 20 bit ID numbers, 32 bytes of data can be stored in the
buffer. The data buffers are numbered 0 through 7, with 7 being reserved for
other uses.
Data buffer setup can be done by the factory or under datalogger control. The
factory settings are stored in non-volatile memory. Settings that have been
changed by the datalogger are erased when the ST-21 resets.
1.4 Multiple Argos ID Numbers
The use of multiple ID numbers can significantly change how the datalogger is
programmed. When multiple ID numbers are used, the ArgosTransmit() function
works best. When ArgosTransmit() is executed, the contents of the specified data
buffer are transmitted once. ArgosTransmit() gives full control of timing of
transmissions to the datalogger programmer. Special care must be taken to avoid
transmitting too often. The programmed repetition period must match the System
Use Agreement between the user and Service Argos.