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The term "POD" designates the electronics and the housing for the electronics as a single unit. The POD package consists of the electronics and housing; cables for communication and solar collection; a solar collector; a mounting plate and mounting hardware; software installation and operating manuals. The POD can be operated in virtually any climate over the four seasons. The electronics is capable of monitoring thirty two sensor channels.
Cables and Sensor Wires
Between the POD and the sensors implanted in the plants is a "wiring harness". The individual sensor wires are encased into a woven plastic sleeve. Emerging from the sleeve every seven feet (2.1 meters) is a short length of wire about one inch (2.54 cm) long with a sensor wire connector at the end - seven sensor locations in one direction and eight sensor locations in the other direction from the POD. Sensor locations are on 7 foot (2.1 meter) centers.
An extension wire 75 inches (190 cm) long is connected to the short length wires emerging from the wiring harness. The PHYTOGRAM sensor is connected to the other end of this extension wire. (Just before harvest, the extension wire and sensor are removed but the wiring harness can remain on the drip line during machine harvesting.)
The wiring harness is installed along the drip line in drip irrigated plants. (This arrangement lends itself to permanent installation.) At the time of implant in production applications the sensors are connected to the extension wire - the extension wire connected to the wiring harness - and the wiring harness connected to the POD.
The POD can monitor sensors from two fifteen sensor wiring harnesses. In production agriculture applications, this permits simultaneous monitoring of petiole and fruit in fifteen plants or any combination of thirty sensors in various locations within the plant or plants.
Research Applications - Customized Installations
Sensor layout for research applications is highly customized to the particular objectives of the research. There are some broad guidelines to determine sensor compliment. In general, sensors wires move away from the POD as spokes in the wheel move away from the central hub. The POD has thirty-two sensor channels available. (Each automatic dendrometer requires two channels, all other sensors require one channel.) The standard distance from the POD to the sensor is forty meters. Greater distance is possible in individual circumstances. It is advisable to minimize the distance between POD and sensor consistent with research objectives.
Sensor wires can be run individually. Insulation on individual wires is tefzel which is moisture insensitive, but it is better to keep the sensor wires out of standing water. Sets of four sensors going to a particular location will be run in a sleeved cable. This is advantageous if animal interactions or heavy human traffic are anticipated. Shallow burial of the sensor wires is possible. The soil sensors are fabricated for extended duration deep burial.
Detailed specifications are shown below.
|Sensor Capacity||Thirty two channels. PHYTOGRAM and Environmental Sensors require one channel per sensor. Automatic Dendrometers require 2 channels per sensor.|
|Data Acquisition Rates||Data acquisition sampling rates can be set every 1, 2, 5, 10, 15, 20, 30, 60, 240, 720 and 1,440 minutes. Each sensor type can be sampled at its own rate. For production applications, data collection is usually every 30 minutes 24 hours per day.|
|Temperature Range||-50C to +50C|
|Standard Operational Range||Monitored plants must be within 40 meters of the POD in any direction. Further distances are possible at additional cost.|
|Memory Storage||The POD contains a two megabyte removable non volatile flash memory card. Acquisition of data from fifteen PHYTOGRAM hydration sensors at a rate of once per half hour for twenty-four hours requires 3,500 bytes of memory storage.|
|Environmental Operations||The POD will be mounted above ground and is equipped to pass air from inside to outside but not moisture|
|Physical Dimensions||The fiberglass POD is 10" x 8" x 6" (25.4cm x 20.3cm x 12.7cm). It is mounted on a polypropylene plastic plate 8" x 22.7" x 0.375" (20.3cm x 57.1cm x 0.94cm). All mounting hardware is size #10 stainless steel. The POD is built to be mounted above ground.|
|Solar Power||One solar cell, 4.5 by 6.25 inches (11.4cm by 15.9cm) usually mounted directly on the top of the POD. It can be mounted 25 meters from the POD if necessary. A shorter distance is desirable. In low sunlight locations, the size of the solar cell can be increased and connected to the POD via an extended cable.|
|Battery Life||With no solar charging the POD is capable of operating for one month; with solar charging battery life is unlimited|
|Data Transfer Hardware||On-site transfer is via RS232 link to a laptop computer. The cable is part of the package. Remote transfer is by cellular phone or radio. See separate description of alternatives. Data Transfer Methods|
|Data Transfer Software||PROCOMM (not provided in package) or HYPERTERMINAL (part of Windows 95,98, or NT) or equivalent programs.|
|Data Conversion Software||DOS based program to convert sensor data to text files. EXCEL macros to process data into graphical or tabular form.|
|Sensor Types||Potential, Current, Capacitance, Resistance, and Dendrometer.|
|Sensor Connectors||The POD has two DB25 male connectors for connection to sensors, ground wires, communication cable and solar cable.|
|PHYTOGRAM - Applications and specifications||Automatic Point and Band Dendrometers - For precise measurements of growth|
|POD - In the field data collection over extended periods of time||Manual Band Dendrometers - Schematic drawing and product characteristics|
|Equipment Cost and Support Services - Products, Services, and typical packages||Automatic Root Dendrometers - For measurement of diurnal cycles and growth rates of roots near the surface.|
|Environmental Sensors - For concurrent assays of air and ground temperature, light, and soil moisture||Sensor Cluster Layout - Field layouts of sensors for production and research applications|
|Data Transfer Methods - Various alternatives|
|Irrigation Scheduling- Optimize irrigation with the PHYTOGRAM technique||Communicating with Agricultural Electronics Corporation - By E-mail, Post Office, Telephone and Fax|
|Proton-Days - Quantify plant response to weather at different sites (similar to Degree-Days)||Dendrometer User Group Pages|
|Sucrose Transport - Method of determining magnitude and uniformity of sucrose transport between leaf and fruit||Water Content of Specific Crops|
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