RF FOR RTMS SYSTEMS INSTRUCTION MANUAL REVISION: 3/95 COPYRIGHT (c) 1995 CAMPBELL SCIENTIFIC, INC.
WARRANTY AND ASSISTANCE The RF FOR RTMS SYSTEMS are warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
RF FOR RTMS SYSTEMS TABLE OF CONTENTS PAGE SECTION 1. GENERAL RADIOTELEMETRY NETWORK 1.1 1.2 1.3 1.4 Introduction............................................................................................................................. 1-1 Field Station............................................................................................................................ 1-2 Base Station ................................................................................................................
SECTION 1. GENERAL RADIOTELEMETRY NETWORK 1.1 INTRODUCTION Data retrieval from a remote site can be difficult. To accomplish data collection from isolated sites Campbell Scientific, Inc. utilizes a radiotelemetry network. Dataloggers can be accessed by radiotelemetry which requires no physical connection from the computer to the datalogger. The radiotelemetry link reduces the number of visits to a remote site for data collection. The radiotelemetry network is designed for complete computer control.
SECTION 1. GENERAL RADIOTELEMETRY NETWORK 1.2 FIELD STATION Purpose: The field station is where the measurements are made. The Campbell Scientific datalogger resides at this station taking the desired measurements. Any field station can also operate as a repeater. The only requirement is that the station’s antenna must be able to communicate in all desired directions. This may require an omnidirectional antenna.
SECTION 1. GENERAL RADIOTELEMETRY NETWORK 1.3 BASE STATION Purpose: A base station utilizes a computer to collect data from the field station(s). Normally, all communication to the field stations originate at the base station. Data retrieval, remote programming, and system analysis can all be done from the base station. Equipment Required: • • • • • Radio RF Base Station OS/2 Computer with RTMS software Antenna and antenna cable AC power FIGURE 1-3.
SECTION 1. GENERAL RADIOTELEMETRY NETWORK 1.4 REPEATER Purpose: To act as relay between two communicating stations separated by too long of a distance or an obstacle which impedes direct communication. A repeater is not always required in a radiotelemetry network. A field station can also function as a repeater. Equipment Required: • • • • • Radio RF Modem Antenna and antenna cable 12V and 5V power supply (PS512M) Enclosure and other mounting needs FIGURE 1-4.
SECTION 2. ASSEMBLING THE RADIOTELEMETRY NETWORK This section provides a logical order for RF network assembly and deployment. Details of specific components in the system are described in Section 3 “Radiotelemetry Network Components.” This component section is cross-referenced throughout this assembly section. 2.1 FINAL LAYOUT The initial locations of the base, field, and repeater stations have likely been determined already. Locate RF stations on an area map, preferably a topographic map.
SECTION 2. ASSEMBLING THE RADIOTELEMETRY NETWORK when a valid network description containing remote sites is “made active” attempts to communication with the various remote sites will begin. It is often convenient to test the individual field/repeater first and add them to the network description after proper RF communication is confirmed. This is the process described in this section. 2.2.
SECTION 2. ASSEMBLING THE RADIOTELEMETRY NETWORK 1. Tripod or tower 2. Enclosure and datalogger - Turn on datalogger. 3. Antenna - Orient correctly; remember direction and polarization. 4. Solar Panel 5. Power Supply 6. Sensors 7. RF Modem - Set the Station ID according to the map. 8. Radio - Make sure to connect to RF Modem and to power supply. Connect to antenna before turning on. 2.
SECTION 2. ASSEMBLING THE RADIOTELEMETRY NETWORK 1. RF modem's ID matches ID in the RF Path. 2. Field station's radio and datalogger have sufficient power. 3. Radio is connected to RF modem. 4. RF modem is the only thing connected to datalogger's 9-pin connector. 2.6 ADDING STATIONS TO THE NET DESCRIPTION It is possible to deploy the entire RF datalogger network, testing the RF links as they are installed, without adding any of the remote site to the Net Description.
SECTION 2. ASSEMBLING THE RADIOTELEMETRY NETWORK second quality record would apply to how well the repeater received from the remote, and the third record would apply to how well the base received from the repeater. A "Quality Record" is made up of five values as follows: First Value Second Value Third Value Fourth Value Fifth Value test packet size; front of 2T envelop; back of 2T envelop; front of 1T envelop; back of 1T envelop.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS 3.1 THE RF95T MODEM As with the CR10 and CR10T datalogger, there are enough changes to the RF modems to warrant a new model name hence the RF95T and the RF232T. The RF95T and the RF232T differ from the RF95 and RF232 in the following respects: • The “T” versions use a new protocol requiring a different PROM. • The “T” versions are not supported by PC208. • The “T” versions use a larger capacity RAM chip.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS 3.1.2 RF95T STATES The ninth switch should be set in the RF95T-ME state (switch nine should be open, represented by a 1). Refer to Figure 3-2. The RF95T is shipped with the switch set for the RF95T-ME state. TABLE 3-1.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS Packet are routed from the computer to the dataloggers on demand. These maintenance type operations include the following: • Clock set or check. • Datalogger program download. • Get table definitions (query the datalogger to see what data it has). • Data advise notification (start, stop, or modify a data collection session with datalogger). If the RFBase is busy when in receives one of these packets it will hold it until it is free.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS not respond during this time, a “Bad Link” error messages is returned. The RFBase marks that remote as bad and will return a “Bad Link” message each time the computer attempts to send packets to that site. The RFBase will continue to include the failed remote as part of the polling process. If the remote ever responds to a poll, a “Communication restored” message will be sent, and the RFBase will again accept direct maintenance packets for that remote. 3.1.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS 3.2.2 RADIO SPECIFICATIONS The RF100 and RF200 radios are manufactured by E.F. Johnson. Campbell Scientific modifies the radios to work with the RF95T Modem. Table 3-5 contains a list of the main radio specifications. TABLE 3-5. Main Radio Specifications RF100 VHF RF200 UHF Channel Capability Dimensions (w/o mounting) Operating Temperature Range Emissions Designator Deviation 3420 4W 132-142, 142-150, 150-162, 162-174 1 3.6" x 2.9" x 2.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS 3.3.2 ANTENNA ORIENTATION Antennas must be oriented correctly to allow communication between RF sites. First determine if your antenna is omnidirectional or unidirectional. An omnidirectional antenna will transmit/ receive in a full 360 degree circle. Generally, an omnidirectional antenna will be a straight cylindrical rod which is to be mounted vertically at the top of a tripod.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS TABLE 3-7 Common Antennas and Characteristics VHF or Pipe UHF Cable Gain(dB) O.D. VHF Coax NM-L Unity 3/4" - 2 1/8" VHF Coax NM-L Unity 1" - 2 1/4" VHF Coax NM-L 3.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS 3.4.3.2 PS12LA Lead Acid Power Supply The PS12LA power supply includes a 12V, 7.0 amp-hour lead acid battery, AC transformer, and a temperature-compensated charging circuit with a charge indicating diode. An AC transformer or solar panel should always be connected to the PS12. The charging source trickle charges the lead acid batteries which power the datalogger.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS The RF232T Base Station includes an RF95T Modem with a carrier detect light. The RF95T Modem sits directly behind the RF232T front panel. For a description of the Carrier Detect Light and the communication protocol, refer to Section 3.1 "RF95T Modem." The Station ID Number of the RF95T comes shipped from the factory at 1. Under most circumstances there is no need to change this address. The RF232's 25-pin female port connects to the computer's 25-pin RS232 port.
SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS FIGURE 3-8.
SECTION 4. OPERATION OF THE RADIOTELEMETRY NETWORK All field stations can be accessed and monitored from the central base site. Regular visits to the field sites are required to ensure that all sensors are in place, enclosures are dry, solar panel is clean, and that the tripod and antenna are secure. Frequency of visits to the field sites are variable depending on environmental conditions and the sensors utilized. 4.
SECTION 4. OPERATION OF THE RADIOTELEMETRY NETWORK Do _____ RETRIES USING A _______ SEC PERIOD THEN USE _______ SEC: This allows specifying the rate of reties for a maintenance operation that fails. The intervals must be long enough to allow the operation being retried to complete. Generally, it is a good idea to make these fairly slow as they are not needed unless an operation fails. These are specified as part of the description for the RFBase and the field stations.
SECTION 4. OPERATION OF THE RADIOTELEMETRY NETWORK Enabling the HIPRIORITY flag will cause RTM, and in turn DlsMgr and the RFBase, to attempt to collect data as fast as possible from the station(s) used on the affected template. The RFBase will poll these sites as fast it can while maintaining polling on the other sites. The RFBase will continue polling at the hi priority rate for about one minute after RTM has stopped. This is also found under OPTIONS on the main menu.
SECTION 4. OPERATION OF THE RADIOTELEMETRY NETWORK Select CR10T as the DATALOGGER TYPE: parameters. Press the SPACE BAR to step through the options. Press ENTER to advance to the next parameter. Select the correct communication port by pressing the SPACE BAR at the USE ASYNCHRONOUS COMMUNICATION ADAPTER prompt. Select a baud rate of 9600 baud at the COMMUNICATIONS BAUD RATE prompt.
SECTION 4. OPERATION OF THE RADIOTELEMETRY NETWORK The CALL STATION stationname option is used to initiate a connection with the field site. After the call, GraphTerm remain in telecommunications (on-line) with the remote site. The call option can be used to test the communication path to a field site. Note that the LINK TEST FOR RF can also be used to test communications. The other GraphTerm options will automatically call the station when selected if it is not already “online.
SECTION 4. OPERATION OF THE RADIOTELEMETRY NETWORK The EXAMINE DATA TABLES option allows the datalogger tables to be displayed in tabular form. GraphTerm prompts will allow the selection of which tables and fields within the tables will be examined. As in the MONITOR MODE (see above) these displays are limited to the data in the datalogger and data is collected on demand. Old data maybe scrolled through or the displays can be allowed to “advance.
APPENDIX A. SETTING THE STATION ID Each RF modem has nine dip switches; the first eight must be set for a particular Station ID. Following is a list of all possible Station IDs with the corresponding setting of the dip switches. Here, 1 represents open, 0 is closed, and Switch 9 should be open.
APPENDIX A.
APPENDIX B. ALTERNATE BASE STATION CONFIGURATIONS The basic base station consists of a computer and the RF232T Base Station. There are other options for a base station including a portable base station, a phone-to-RF base station, and a phone-to-RF base station with measurement capability. B.1 THE PORTABLE BASE STATION The portable base station is an aid in setting up a large radiotelemetry network, or in troubleshooting RF network communication problems.
APPENDIX C. POWER CALCULATIONS There must be enough transmission power in any RF link to complete communication. The sources of power are the radio and the antennas. Conversely, power is lost both through the cables (coax loss) and over the distance of communication (path loss). The power of the signal received (Signal Power) can be calculated as stated below. The signal power must be greater than -95 dBm (-80 dBm @ 2.4K baud) to have a good radiotelemetry link.
APPENDIX D. FUNDAMENTALS OF RADIOTELEMETRY D.1 RADIO WAVES Radiotelemetry is the process of transferring information (data) in the form of radio waves. The data is transferred on a carrier wave which normally has a sinusoidal form. Therefore, the carrier wave can be described entirely by the frequency, amplitude, and phase with respect to a reference. The commonly used term for radiotelemetry, RF, refers to radio frequency, which in actuality is the frequency of the carrier wave.
APPENDIX D. FUNDAMENTALS OF RADIOTELEMETRY Every antenna has a known horizontal and vertical pattern of radiation. The horizontal radiation pattern consists of any segment of a 360 degree circle surrounding the antenna. The horizontal pattern is important to consider when a RF station is to communicate with more than one other RF station. The vertical pattern is the radiating pattern in the upward and downward directions. Any two communicating RF stations must have a minimum level of signal power.
