Campbell TX325 User manual

Revision: 10/2020
Copyright © 2019 – 2020
Campbell Scientific, Inc.

Table of contents
1. Introduction 1
2. Precautions 1
3. Initial inspection 1
4. QuickStart 2
4.1 Data collection platform (DCP) installation 4
5. Overview 7
5.1 GOES, NESDIS, and transmit windows 8
6. Specifications 10
7. Installation 11
7.1 Field site requirements 11
7.2 LED function 12
7.3 Ports and connectors 13
7.4 Transmission antenna 14
7.5 GPS antenna 14
7.6 Data logger programming 14
7.6.1 Read and write settings 16
7.6.2 Read-only settings 17
8. Troubleshooting 19
8.1 Troubleshooting over-air transmissions 20
Appendix A. Eligibility and getting onto the GOES system 23
Appendix B. Data formats and transmission durations 24
B.1 ASCII data format 24
B.1.1 7-byte floating-point ASCII (GOESTable() format option 1) 24
B.1.2 ASCII table space (GOESTable() format option 2) 26
B.1.3 ASCII table space, comma separated (GOESTable() format option 3) 29
B.1.4 Line SHEF (Standard Hydrological Exchange Format) (GOESTable() format
option 6) 31
B.2 Pseudobinary data formats 32
Table of Contents - i

B.2.1 Campbell Scientific FP2 data 33
B.2.2 Pseudobinary 38
B.2.3 Additional pseudobinary representations 38
B.3 Transmission durations 38
Appendix C. Compliance documents and certificates 40
Table of Contents - ii

1. Introduction
The TX325 transmitter sends data via Geostationary Operational Environmental Satellites (GOES),
and is the successor to the TX321. In the Western Hemisphere, the TX325 is compatible for use
with NOAA GOES DCS with a coverage range including Canada, the United States of America,
and Mexico—as well as most countries in Central America and many South American countries.
The TX325 is the telemetry backbone for many data collection platforms (DCP) that use GOES.
The satellite transmitter can be integrated with a number of Campbell Scientific data loggers and
is an available communications option for many systems, serving a wide range of applications.
2. Precautions
lREAD AND UNDERSTAND the Safety section at the back of this manual.
lAlthough the TX325 is rugged, it should be handled as a precision scientific instrument.
lA proper antenna connection is required before transmission occurs. Failure to use a
properly matched antenna cable and antenna may cause permanent damage to the radio
frequency (RF) amplifiers.
lThe TX325 requires an active GPS antenna with a maximum gain of 25 dB. The TX325 will
supply 3.3 V to the active GPS antenna.
3. Initial inspection
lUpon receipt of the TX325, inspect the packaging and contents for damage. File damage
claims with the shipping company.
lCheck the ships with list to ensure all components are received.
TX325 Satellite Transmitter for GOES V2 1

4. QuickStart
Use our Device Configuration Utility to enter the required National Environmental Satellite Data
and Information Service (NESDIS) information that is unique to each data collection platform
(DCP). This QuickStart is for the CR6 (≥OS 10), CR300-series (≥OS 10), CR1000X (≥OS 4), and
GRANITE-series (≥OS1) data loggers.
1. Connect the data logger RS-232 to the TX325 RS-232 connector and connect the data
logger to a power supply. Also ensure the TX325 has power.
2. Connect to the data logger using Device Configuration Utility.
a. Do the following to directly connect your data logger to the Device Configuration
Utility:
i. Use the USB cable to connect the data logger to the computer.
ii. Click your data logger model for the Device Type in the Device Configuration
Utility.
iii. Click Direct for the Connection Type.
iv. Select the COM port on the computer to which the data logger is connected.
v. Click Connect.
b. For data loggers on an IP connection, do the following to remotely connect with the
Device Configuration Utility:
i. Click your data logger model for the Device Type in the Device Configuration
Utility.
ii. Click IP for the Connection Type.
iii. Type the Server Address.
iv. Type the PakBus/TCP Password.
v. Click Connect.
3. Click the Settings Editor tab.
TX325 Satellite Transmitter for GOES V2 2

4. Click the GOES Radio sub tab (FIGURE 4-1 (p. 3)).
FIGURE 4-1. Device Configuration Utility GOES Radio screen
5. Select Enabled from the Goes Radio Enabled field.
6. Select the Com Port to which the GOES radio is connected.
7. Type the Self-timed Message Windows (in seconds) as assigned by the GOES DCS Program.
8. Type the Platform ID (in HEX) as assigned by the GOES DCS Program.
9. Select the Random Transmission Baud Rate as assigned by the GOES DCS Program.
10. Type the Random Transmission Channel as assigned by the GOES DCS Program.
11. Select the Self-Time Baud Rate as assigned by the GOES DCS Program.
TX325 Satellite Transmitter for GOES V2 3

12. Type the Self-Time Channel as assigned by the GOES DCS Program.
13. Type the Random Transmission Interval as assigned by the GOES DCS Program. Format is
hh:mm:ss.
14. Type the Self-timed Transmission Interval as assigned by the GOES DCS Program. Format is
dd:mm:hh:ss.
15. Type the Self-timed Transmission Offset as assigned by the GOES DCS Program. Format is
hh:mm:ss.
16. Click the Deployment tab.
17. Click the Com Port Settings sub tab.
18. Select 9600 for the Baud Rate.
19. Click Apply to save the changes.
Now the settings are stored in the data logger. CRBasic programming is required to push data
over the network. The GOESTable() and GOESField() CRBasic instructions used in
conjunction with DataTable() facilitate the transmission of data across the GOES satellite
network.
4.1 Data collection platform (DCP)
installation
1. Yagi antenna installation procedure:
a. Mount the Yagi antenna to a pole or mast by using the U-bolts included with the
antenna mount.
TX325 Satellite Transmitter for GOES V2 4

b. Attach elements to boom.
NOTE:
When attaching elements to the boom, make sure to place them such that the
number of grooves on the element equals the number of dimples on the boom.
For example, the element with four grooves should be placed at the spot on the
boom with four dimples, and so forth.
c. Aim the Yagi antenna at the spacecraft; azimuth and elevation angle positions are
included on the bracket label.
2. GPS antenna installation procedure:
a. Connect the GPS cable to the GPS antenna.
b. Route the cable through the 0.75-inch IPS threaded pipe and insert the pipe into the
GPS antenna.
TX325 Satellite Transmitter for GOES V2 5

c. Mount the 0.75-inch IPS threaded pipe to a crossarm by using the Nu-Rail® fitting,
or CM220 mounting bracket.
CAUTION:
The GPS antenna will not receive a GPS signal through steel roofs or steel walls.
Concrete might also be a problem. Heavy foliage, snow, and ice will attenuate
the GPS signal.
3. Mount the TX325, the power supply, and the data logger to the backplate of an enclosure.
4. Mount the enclosure and solar panel to the pole or tripod.
TX325 Satellite Transmitter for GOES V2 6

5. Connect the COAXNTN cable to the Yagi antenna. Route the COAXNTN cable through the
enclosure conduit and connect it to the RF Out connector on the TX325 (FIGURE 4-2 (p.
7)).
FIGURE 4-2. TX325 connectors
6. Route the GPS antenna cable through the enclosure conduit and connect it to the GPS
connector on the TX325 (FIGURE 4-2 (p. 7)).
7. Plug the green connector from the power supply to the green receptacle on the TX325.
8. Connect the data logger to the TX325 RS-232 terminal.
9. Route the solar panel cable through the enclosure conduit and connect the red and black
wires to the CHG terminals on the CH150 or CH200.
5. Overview
The TX325 can transmit either self-timed or random GOES messages to the GOES West and GOES
East satellites. In a typical configuration, the TX325 is connected to a data logger via an RS-232
serial connection. The data logger makes measurements, then formats those values to create a
data packet, which is transferred to the transmitter at time of transmission. The data logger
buffers the message until its transmission window (or random transmission time), then transmits
the data at either 300 or 1200 bps.
TX325 Satellite Transmitter for GOES V2 7

GPS is required for the radio to work in the GOES network. The GOES network is a TDMA
network that requires all the radios in the network to have exact timing of their transmissions so
they don't step on each other during transmissions. Extremely accurate timing is obtained from
the integrated GPS receiver (±100 μs), and the internal clock is capable of maintaining accurate
time for a minimum of six days without a GPS fix. If the TX325 finds itself without an accurate
time, it suspends data transmissions until an accurate time is obtained. The GPS time is synched
every 11 hours. The data logger clock is synched with the GPS time of the TX325 when using a
GRANITE-series, CR6, CR1000X-series, and CR300-series data logger.
Features:
lESDIS HDR V2 certified
lBased on Signal Engineering OmniSat3 design
lCompatible with GOES DCS system
lEasy integration with Campbell Scientific data loggers
lField tested and proven track record of reliability
lEmbedded GPS receiver for stabilized internal time keeping and transmit frequency for
long service intervals
lLow standby current consumption for battery-powered systems at remote DCP installation
sites
lQuick assessment of radio health via monitoring of diagnostic data from the radio
lCompatible CRBasic data loggers: GRANITE series, CR6, CR1000X, and CR300 series are fully
compatible. The CR3000, CR800 series, and CR1000 have limited compatibility.
5.1 GOES, NESDIS, and transmit windows
GOES coverage area is latitude 68° North to 68° South and longitude 150° East to 2° West (see
FIGURE 5-1 (p. 9)). GOES satellites have orbits that coincide with the Earth rotation, allowing each
satellite to remain above a specific region (geosynchronous). GOES has two satellites: GOES East
located at 75° West longitude and GOES West located at 135° West longitude. Both satellites are
located over the equator. Within the United States, odd-numbered channels are assigned to
GOES East, and even-numbered channels are assigned to GOES West. Channels used outside of
the United States are assigned to either spacecraft.
TX325 Satellite Transmitter for GOES V2 8

FIGURE 5-1. Coverage of GOES East and GOES West satellites
The GOES system is administered by the National Environmental Satellite Data Information
Service (NESDIS), which assigns addresses, uplink channels, and self-timed/random transmit time
windows. Self-timed windows allow data transmission only during a predetermined time frame
(typically 10 seconds every hour). Random windows are for applications of a critical nature, such
as flood reporting, and allow transmission immediately after a threshold has been exceeded. The
transmission is randomly repeated to ensure it is received. A combination of self-timed and
random transmission can be executed by the TX325.
Refer to Eligibility and getting onto the GOES system (p. 23) for more information.
TX325 Satellite Transmitter for GOES V2 9

6. Specifications
Compliance: Refer to Compliance documents and certificates (p. 40) and
www.campbellsci.com/tx325
Transmissions supported: Timed (Scheduled), Random
Data formats: ASCII (SHEF), pseudo binary
Radio module: OmniSat-3
Temperature range
Operating: –40 to 55 °C
Storage: –55 to 75 °C
Case dimensions
Without connectors: 15.88 x 12.7 x 4.57 cm (6.25 x 5 x 1.8 in)
With connectors: 15.88 x 14.99 x 4.57 cm (6.25 x 5.9 x 1.8 in)
additional clearance required for cables, wires, and antennas
Weight: 0.77 kg (1.7 lb)
Supply voltage range: 10.5 to 16 VDC
Current drain at 12 VDC
While transmitting: < 2.5 A (1.8 typical)
Standby: < 5 mA (2.8 typical)
During GPS acquisition: < 50 mA (25 mA typical)
Baud rates: 300 and 1200 bps
Transmit power
Maximum: 31 dBm (300 bps), 37 dBm (1200 bps)
Maximum EIRP: 41 dBm (300 bps), 47 dBm (1200 bps); based on a
11 dbm gain antenna with 1 dbm line loss
Typical EIRP: 37 to 41 dBm (300 bps),
43 to 47 dBm (1200 bps)
Frequency range: 401.701 to 402.09925 MHz
TX325 Satellite Transmitter for GOES V2 10

Initialfrequencystability: ±20 Hz disciplined to GPS (GPS fix occurs after power up and once
per day thereafter)
Channel bandwidth: 1500 Hz (300 bps), 2250 Hz (1200 bps)
GPS receiver type: 3.3 V active
Maximum GPS antenna RF
gain: 25 dB
Timekeeping
Initial accuracy: ±100 μs (synchronized to GPS)
Drift: ±40 ms/day (without GPS)
GPS schedule: 1 fix at power up (updated at ~11-hour rate)
Transmissioncontinuation
without GPS fix: 6 days
Interface connectors
RS-232: DB9 F, DCE, 3-wire RS-232
Satellite RF transmit out: Type N jack
GPS: SMA jack
Power: 2-pin screw terminal, 0.2 in. pitch
7. Installation
7.1 Field site requirements 11
7.2 LED function 12
7.3 Ports and connectors 13
7.4 Transmission antenna 14
7.5 GPS antenna 14
7.6 Data logger programming 14
7.1 Field site requirements
The GPS antenna must have a clear view of most of the sky and the transmission antenna must
have a clear view of the spacecraft. The TX325 must be installed in a well desiccated,
TX325 Satellite Transmitter for GOES V2 11

environmentally sealed enclosure. Its mounting plate has keyholes for securing the TX325 to the
backplate of a Campbell Scientific enclosure. Most GOES systems are powered by a battery
charged by a solar panel. The solar panel must have a clear view of the southern sky. Pay special
attention to winter sun angles.
7.2 LED function
A green Status LED and a red Failsafe LED indicate the state of the TX325 transmitter by using
various blink patterns. Table 7-1 (p. 12) and Table 7-2 (p. 12) provide the blink patterns for the
green Status and red Failsafe LEDs, respectively.
Table 7-1: Green LED Status indicator blink patterns
Blink pattern Indicates
At power up, blinks on and off
two times.
Normal software is running.
RS-232 control interfaces enabled.
Power-up initialization complete and ready to receive
commands.
At power up, blinks on and off
three times.
Bootloader software is running.
Ready to load new operating system.
On continuously. Transmitter failed to start up normally after power up. Turn
the transmitter off and on to reboot.
Table 7-2: Red LED Failsafe indicator blink patterns
Blink pattern Indicates
Blinks on and off four times per
second. A transmission is in progress.
Blinks on and off two times per
second for 30 s.
The post-transmit interval is in progress. The transmitter
enters this state after its RF output is turned off either by a
Reset command or by the normal completion of a data
message transmission. The radio needs to wait 30 seconds
before making another transmission to keep it from going
into Failsafe mode.
On continuously.
TX325 is in the Failsafe mode. To clear a Failsafe mode, push
the Reset button (FIGURE 8-1 (p. 20)). A power cycle will NOT
clear the Failsafe mode.
TX325 Satellite Transmitter for GOES V2 12

7.3 Ports and connectors
The RS-232 port is a DB9 male connector configured as DTE. Only three pins are used, transmit
on pin two, receive on pin three, and ground on pin five. Transmit is an output and receive is an
input to the TX325. The RS-232 port allows the transmitter to be connected to a data logger.
Refer to the following table for the cable options and data logger connection.
Table 7-3: Cable options, data logger compatibility, and data logger connections
Cable description Compatible data loggers Data logger connection
RJ45 to DB9 female cable (-R
option when ordered with the
TX325)
Granite-series, CR6, CR1000X RS-232/CPI RJ45 port
SC110 TX/RX cable (-C option
when ordered with the TX325) Granite-series, CR6, CR1000X
White: Odd Cor Uterminal
Brown: Even Cor Uterminal
Yellow: G
Clear: Gor ⏚
RS-232 DB9 female to DB9
male serial cable (-S option
when ordered with the TX325)
CR300-series, CR3000,
CR800-series, CR1000 RS-232 9-pin port
The RF Out connector is for attaching the transmission antenna. A properly matched antenna
cable and antenna must be connected to the TX325 before transmission occurs.
WARNING:
Failure to use a properly matched antenna cable and antenna may cause permanent damage
to the radio frequency (RF) amplifiers.
The nominal impedance is 50 ohms; the frequency range is approximately 400 to 403 MHz. At
300 bps transmission rates, the maximum transmit power is 31 dBm. At 1200 bps, the transmit
power is 37 dBm.
The GPS port on the TX325 is an SMA female connector for attaching an active 3.3 V GPS
antenna. Operation without a GPS antenna connected will not cause damage, but the
transmitter will not transmit without a valid GPS fix. The transmitter uses the GPS receiver for two
functions. The precise GPS time is used to ensure scheduled transmissions occur at the proper
time. The one-second GPS synchronization pulse is used to ensure a precise, drift-free carrier
frequency.
The TX325 power connector has two pins: ground and 12 V for connection of the power supply.
The input power requirement is 10.5 to 16 VDC can use up to 2.5 A. A power supply consisting of
TX325 Satellite Transmitter for GOES V2 13

a CH150 or CH200 regulator, BP12 or BP24 battery, and a solar panel typically can support these
requirements. For this power supply, the regulator connects to the TX325 power connector.
7.4 Transmission antenna
The TX325 transmission antenna is a right-hand circular polarized Yagi with 11 dBi gain. A bracket
is included with the antenna for mounting to a mast or pole. The antenna is directional and
should be aimed at the spacecraft. Both elevation and azimuth are unique to the location on the
planet and must be set. A poorly aimed antenna will cause a drop in signal strength or possibly
prevent successful transmission. As a guide, if the antenna is aimed 20 degrees off the spacecraft,
the received power will be half of a properly aimed antenna. Beyond 20 degrees, the received
power drops off quickly.
NOTE:
When attaching elements to the boom, make sure to place them such that the number of
grooves on the element equals the number of dimples on the boom. For example, the
element with four grooves should be placed at the spot on the boom with four dimples, and
so forth.
7.5 GPS antenna
The GPS antenna mounts to the end of a crossarm by using a 0.75-inch IPS threaded pipe and a
0.75-inch-by-1-inch Nu-Rail® fitting or CM220 mounting bracket. Mount the GPS antenna
above obstructions, but with the shortest cable possible. The GPS antenna will not receive GPS
signals through steel roofs, steel walls, or possibly concrete. Heavy foliage, snow, and ice will
attenuate the GPS signal. An unobstructed view provides better GPS performance resulting in
fewer ( or no) missed transmissions. Poor GPS antenna placement increases the number of
missed transmissions, and possibly stops all GPS transmissions.
7.6 Data logger programming
NOTE:
This section provides programming information for the GRANITE-series (≥OS 1), CR6 (≥OS
10), CR1000X (≥OS 4), and CR300-series (≥OS 10), data loggers. For information on
programming the CR3000, CR800-series, and CR1000 data loggers, refer to the example
program at www.campbellsci.com/downloads/tx325-example-program-cr3000-cr1000-cr800
or contact Campbell Scientific.
TX325 Satellite Transmitter for GOES V2 14

The CRBasic program can read and enter TX325 settings. Settings can also be entered using the
Device Configuration Utility (see QuickStart (p. 2)). Table 7-4 (p. 16) provides the TX325 settings
that can be read and entered. Table 7-5 (p. 17) provides the read-only settings.
The CRBasic program should include the GOESTable() and GOESField() instructions used
in conjunction with the DataTable() instruction to facilitate the transmission of data across
the GOES satellite network. The GOESTable() instruction has the following syntax:
GOESTable (Result, ComPort, Model, BufferControl, Fields_Scan_Order,Newest_
First,Format)
The Result is a string variable that holds either the data to be output in its specified format or
a message indicating there are no data to output to the transmitter. For the Model, enter 3 to
use the TX325. For the BufferControl, a value of 0 writes to the self-timed buffer and a value
of 1 writes to the random buffer. Data formats and transmission durations (p. 24) discusses the
Format options.
The GOESField() instruction has the following syntax:
GOESField(NumVals, Decimation, Precision, Width, SHEF)
The NumVals is the number of historical values of the field to output. For Decimation, enter
1 to output every value, enter 2 to output every other value, etc. Width specifies the number of
characters in the field. Use empty quotes ("") for SHEFif no SHEF code is specified.
An example of using the the GOESTable() and GOESField() instructions follows:
DataTable (ST_DATA, TRUE, -1)
DataInterval(0, 15, Min, 4)
GOESTable (st_table_results, COMRS232, 3, 0, TRUE, TRUE, 3)
GOESField (4, 1, 3, 6, "")
Sample (1, battery_voltage, IEEE4)
GOESField (4, 1, 3, 6, "")
Sample (1, panel_temperature, IEEE4)
EndTable
In the main portion of the program, settings are written using SetSetting() instruction with
the following the syntax:
SetSetting ( "FieldName", Value )
The FieldName must be enclosed in quotes as shown. The following example instruction sets
the port used to communicate with the TX325 to the RS-232 port:
SetSetting(“GOESComPort”, COMRS232)
The CRBasic program reads the TX325 settings using the following format:
Variable = Settings.FieldName
For example, goes_comport = Settings.GOESComPort reads the Com port setting and
stores it in the GOESComPort variable. The TX325 settings are typically read in a
TX325 Satellite Transmitter for GOES V2 15

SlowSequence section of the program. Table 7-4 (p. 16) provides the TX325 settings that can
be set and read. Table 7-5 (p. 17) provides the read-only settings.
A downloadable example program is available at: www.campbellsci.com/downloads/tx325-
example-program-granite-cr6-cr1000x-cr300.
7.6.1 Read and write settings
Table 7-4: Read and write TX325 settings
Field Name Description
GOESComPort Port used to communicate with the GOES transmitter.
GOESEnabled
Controls whether the data loggers polls the GOESComPort to see if a
TX325 radio is attached to it. With the default setting of 0 (not enabled),
the data logger ignores all other GOES settings. A value of 1 enables the
setting.
GOESMsgWindow Length, in seconds, of the assigned self-timed transmission window
assigned by NESDIS. Valid entries are 1 to 110 s.
GOESPlatformID 8-digit hexadecimal identification number assigned by NESDIS. Value is
a string.
GOESRTBaudRate Baud rate for the random transmissions. Valid settings are 100, 300, or
1200. The baud rate must match the user's NESDIS-channel assignment.
GOESRTChannel
Channel used for the random transmission assigned by NESDIS. Valid
channel numbers are 0 through 566. The default value of 0 disables
random transmissions.
GOESRTInterval
Average time between random transmissions. The value is a string
entered in the format of “Hours:Minutes:Seconds”. Typically, the
assigned interval is in hours, so the minutes and seconds parameters are
left at 0. For example, “01:00:00” setups up an hourly interval. Maximum
interval is 24 hours; minimum interval is 1 minute.
GOESSTBaudRate Baud rate for self-timed transmissions. Valid settings are 300 or 1200. The
baud rate must match the user's NESDIS-channel assignment.
GOESSTChannel
Channel used for the self-timed transmission assigned by NESDIS. Valid
channel numbers are 0 through 566. The default value of 0 disables the
self-timed transmissions.
TX325 Satellite Transmitter for GOES V2 16

Table 7-4: Read and write TX325 settings
Field Name Description
GOESSTInterval
Time between self-timed transmissions. The value is a string entered in
the format of "Days:Hours:Minutes:Seconds". Typically, the assigned
interval is in hours, so the days, minutes and seconds parameters are left
at 0. For example, "00:01:00:00" sets up an hourly interval. Maximum
interval is 14 days; minimum interval is 1 minute.
GOESSTOffset
Time after midnight for the first self-timed transmission as assigned by
NESDIS. The value is a string entered in the format of
"Hours:Minutes:Seconds". Typically, only hours and minutes are used,
and seconds are 0, unless the transmission window is less than 60
seconds. Maximum offset is 23:59:59. A value 0 results in no offset.
GOESRepeatCount Number of times within the random transmit interval that the TX325 will
transmit the message data. Valid entries are 1 to 3.
7.6.2 Read-only settings
Table 7-5: Read-only TX325 settings
FieldName Description
GOESid
Current ID programmed into the radio. The ID isn’t
programmed into the radio until right before a radio
transmission starts.
GOESdateTime Current date and time (UTC) of the TX325 radio. Value is a
string.
GOESversion Current radio firmware version. Value is a string.
GOESCurrentbattery Battery voltage in VDC.
GOESCurrenttemperature Current radio temperature in degrees Celsius.
GOESbatteryBeforeTx Battery voltage of the radio just prior to its last
transmission.
GOEStemperatureBeforeTx Radio temperature before the last transmission.
GOESbatteryDuringTx Radio-battery voltage during the last transmission.
GOESLatitude Latitude in decimal format of the GOES radio.
GOESLongitude Longitude in decimal format of the GOES radio.
TX325 Satellite Transmitter for GOES V2 17