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这促使uct is no longer available.
CWS655A 922 MHz无线土壤水探测澳大利亚
Services Available
Repair Yes
校准 Yes
Free Support Yes

Overview

The CWS655A is a wireless version of our CS655 soil water reflectometer. It has 12 cm rods and monitors soil volumetric water content, bulk electrical conductivity, and temperature. This reflectometer has an internal 922 MHz radio that transmits data to a CWB100A Wireless Base Station or to another wireless sensor. The 922 MHz frequency is used in Australia, Israel, and other countries worldwide.

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Benefits and Features

  • 多功能传感器 - 介电介电常数，散装电导率（EC）和土壤温度
  • 校正了土壤纹理和电导率的影响的测量
  • Internal frequency-hopping, spread-spectrum radio provides longer range and less interference
  • Battery powered
  • 一种可靠，低维护，低功率的方法，用于在有线传感器不切实际或不可能的应用中进行测量
  • Transmissions can be routed through up to three other wireless sensors
  • Compatible with CR800, CR850, CR1000, and CR3000 dataloggers

这促使uct will be discontinued as of 10 April 2017. Please review theCWS-Series and CWB-Series Discontinuation Noticefor further details.

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Detailed Description

The CWS655A has 12-cm rods that insert into the soil. It measures propagation time, signal attenuation, and temperature. Dielectric permittivity, volumetric water content, and bulk electrical conductivity are then derived from these raw values.

Measured signal attenuation is used to correct for the loss effect on reflection detection and thus propagation time measurement. This allows accurate water content measurements in soils with bulk ≤3.7 dS m-1without performing a soil-specific calibration.

Soil bulk electrical conductivity is also derived from the attenuation measurement. A thermistor in thermal contact with a probe rod near the epoxy surface measures temperature. Horizontal installation of the sensor provides accurate soil temperature measurement at the same depth as the water content measurement. For other orientations, the temperature measurement will be that of the region near the rod entrance into the epoxy body.

Why Wireless?

There are situations when it is desirable to make measurements in locations where the use of cabled sensors is problematic. Protecting cables by running them through conduit or burying them in trenches is time consuming, labor intensive, and sometimes not possible. Local fire codes may preclude the use of certain types of sensor cabling inside of buildings. In some applications measurements need to be made at distances where long cables decrease the quality of the measurement or are too expensive. There are also times when it is important to increase the number of measurements being made but the data logger does not have enough available channels left for attaching additional sensor cables.

Specifications

Weather Resistance 传感器和电池组的IP67等级（必须正确安装电池组。每个传感器都经过泄漏测试。）
Operating Temperature Range -25°至+ 50°C
操作相对湿度 0 to 100%
Power Source 2 AA batteries with a battery life of 1 year assuming sensor samples taken every 10 minutes (Optional solar charging available.)
Average Current Drain 300 μA (with 15-minute polling)
Rod Length 12 cm (4.7 in.)
Dimensions 14.5 x 6 x 4.5 cm (5.7 x 2.4 x 1.77 in.)
Weight 216 g (7.6 oz)

Measurement Accuracies
Volumetric Water Content 在具有溶液电导率≤10ds/m的矿物土壤中，±3％VWC典型。使用TOPPS方程（M3/m3).
Relative Dielectric Permittivity
  • 溶液EC≤8ds/m（1至40介电介电功能范围）的±（3％读取 + 0.8）的±（3％）
  • ±2 for solution EC ≤ 2.8 dS/m (40 to 81 dielectric permittivity range)
Bulk Electrical Conductivity 阅读的±5% + 0.05 dS /米)
Soil Temperature ±0.5°C

Internal 25 mW FHSS Radio
Frequency 920 to 928 MHz
Where Used 澳大利亚和新西兰
FHSS Channel 50
Transmitter Power Output 25 mW (+14 dBm)
Receiver Sensitivity -110 dBm (0.1% frame error rate)
Standby Typical Current Drain 3 μA
Receive Typical Current Drain 18 mA (full run)
传输典型电流流量 45 mA
Average Operating Current 15 μA (with 1-second access time)
Quality of Service Management RSSI
附加的功能 GFSK调制，数据交织，正向误差校正，数据争夺，RSSI报告

Compatibility

Note:The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product Compatible Note
CR1000(retired)
CR200X(retired)
CR206X(retired)
CR211X(retired)
CR216X(retired)
CR295X(retired)
CR3000(retired)
CR5000(retired)
CR6 CR6 Datalogger必须具有数据记录器OS 4.0版或更高版本。
CR800
CR850
CR9000X(retired)

Downloads

CWS655 Firmware v.5 (433 KB)03-30-2016

Latest firmware for the CWS655.

查看更新历史记录

Wireless Sensor Planner v.1.7 (30.5 MB)08-08-2013

The Wireless Sensor Planner is a tool for use with Campbell Scientific wireless sensors. It assists in designing and configuring wireless sensor networks.

常见问题

Number of FAQs related toCWS655A:33

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  1. 使用CWS655，在哪里进行电导率测量？

    大量的电导率（EC）测量是沿传感器杆进行的，它是在土壤前12厘米上的EC平均读数。

  2. Can the CWS655 be repaired?

    Damage to the CWS655 electronics or rods cannot be repaired because these components are potted in epoxy. A faulty or damaged sensor needs to be replaced. For more information,refer to the修复和Calibrationpage.

  3. With the CWS655, where is the water content measurement made?

    The volumetric water content reading is the average water content over the length of the sensor’s rods.

  4. With regard to the CWS655, is there a generic calibration equation for artificial soil?

    The equation used to determine volumetric water content in the firmware for the CWS655 is the Topp et al. (1980) equation, which works for a wide range of mineral soils but not necessarily for artificial soils that typically have high organic matter content and high clay content. In this type of soil, the standard equations in the firmware will overestimate water content.

    When using a CWS655 in artificial soil, it is best to perform a soil-specific calibration. For details on performing a soil-specific calibration,refer to “The Water Content Reflectometer Method for Measuring Volumetric Water Content” section in theCS650/CS655手册. A linear or quadratic equation that relates period average to volumetric water content will work well.

  5. 如何校正CWS655读数的温度？

    There is not an easy way to correct CWS655 readings for temperature. The CWS655 temperature sensor is located inside the sensor’s epoxy head next to one of the sensor rods. The stainless-steel rods are not thermally conductive, causing the reported soil temperature reading to be the temperature of the sensor head near the soil surface. Because the sensor is installed vertically with the sensor head above ground, the soil temperature reading is not representative of the temperature over the length of the 12 cm rods, but the reading is closer to the temperature of the soil surface. Performing a temperature correction requires a separate temperature sensor to be buried at approximately 6 cm deep and combines that data with the values reported by the CWS655.

  6. 关于CWS655，有机土壤有通用的校准方程吗？

    No. The equation used to determine volumetric water content in the firmware for the CWS655 is the Topp et al. (1980) equation, which works for a wide range of mineral soils but not for organic soils. In organic soils, the standard equations in the firmware will overestimate water content.

    When using a CWS655 in organic soil, it is best to perform a soil-specific calibration.有关执行土壤特异性校准的详细信息，refer to “The Water Content Reflectometer Method for Measuring Volumetric Water Content” section in theCS650/CS655手册. A linear or quadratic equation that relates period average to volumetric water content will work well.

  7. Does the CWS655 correct readings for temperature changes?

    No. The temperature sensor is located inside the sensor’s epoxy head next to one of the sensor rods. The stainless-steel rods are not thermally conductive, so the reported soil temperature reading is actually the temperature of the sensor head near the soil surface.

    Because the sensor is installed vertically with the sensor head above ground, the soil temperature reading is not representative of the temperature over the length of the 12 cm rods, but the reading is closer to the temperature of the soil surface. Because the temperature reading is not representative of the entire thickness of soil measured for water content, no attempt was made to correct the water content readings for temperature changes.

  8. How was the general calibration performed for the CWS655?

    Period average and electrical conductivity readings were taken with several CWS655 probes in solutions of varying permittivity and varying electrical conductivity at constant temperature. Coefficients were determined for a best fit of the data. The equation is of the form

    Ka(σ,τ) = C0*σ3*τ2+ C1*σ2*τ2+ C2*σ*τ2+ C3*τ2+ C4*σ3*τ + C5*σ2*τ + C6*σ*τ + C7*τ + C8*σ3+ C9*σ2+ C10*σ + C11

    where Kais apparent dielectric permittivity, σ is bulk electrical conductivity (dS/m), τ is period average (μS), and C1到c11are constants.

  9. Can the CWS655 be calibrated by incremental insertion into saturated soil?

    No. The abrupt permittivity change at the interface of air and saturated soil causes a different period average response than would occur with the more gradual permittivity change found when the sensor rods are completely inserted in the soil.

    For example, if a CWS655 was inserted halfway into a saturated soil with a volumetric water content of 0.4, the probe would provide a different period average and permittivity reading than if the probe was fully inserted into the same soil when it had a volumetric water content of 0.2.

  10. Can the CWS655 be partially inserted into the soil?

    由于报道的体积水含量读数是沿整个杆的平均读数，因此应将传感器完全插入土壤中。否则，读数将是空气和土壤的平均值，这将导致水含量低估。如果传感器杆太长，无法一直进入土壤，坎贝尔Scientific建议以一定角度插入杆，直到被土壤完全覆盖为止。

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