DC Circumference Dendrometer
The DC series dendrometers are used for high-precision and continuous measurement of changes in stem circumference. These devices are suitable for long-term use in outdoor conditions. Due to their extremely low power consumption, Ecomatik dendrometers are ideal for battery-powered solutions, e.g., in IoT applications.
Changes in stem circumference are recorded by a metal cable that wraps around the stem. This cable is comprised of a special alloy with the lowest possible coefficient of thermal expansion. In comparison to a steel band, the temperature-dependent error is approx. 10 times lower and thus makes a complicated and error-prone correction calculation unnecessary. Friction and pressure between the cable and the stem surface are minimized by special slide rings.
The simplest model in the DC series, the DC1, is attached to the measuring object by the tension of the spring-loaded cable. The tension force is imparted tangentially, and the circumferential signal is recorded directly via the metal cable.
DC3 and DC4 are improved versions of the DC series. The tension force exerted by the sensor spring is transmitted to the measuring wire in radial, and not tangential (cf. DC1), direction. This patented, special design of the DC3 and DC4 dendrometers significantly improves the comparability of the measurement data from objects of different diameters. Additionally, this design ensures a consistently stable installation on objects with both small and very large diameters (more information: difference between the various circumferential dendrometers).
Advantages
- Maximum stability against wind, snow, falling branches and fruits
- Easy and injury-free installation
Specific to the DC3 & DC4 models
- Suitable for all stem diameters (> 5 cm)
- Improved data comparability between measurements on tree diameters
- Exact measurements (even with very large trees)
Limits
- Not suitable for measurements underwater nor under snow cover
Specific to the DC1 model
- Measurement data between trees with very different diameters are usually not comparable.
- Measurement values on trees with increasing diameter may be problematic due to the decreasing contact pressure between cable and trunk surface.
Specific to the DC3 & DC4 models
- Raw measurement data must be converted to circumference in mm (Excel program available)
- The cross-section of the measurement object should be approximately circular
Models
| Model name | Suitable for diameters | Measurement range |
|---|---|---|
| DC1 | 5 – 32 cm | 11 mm |
| DC3 | > 5 cm | 25.4 mm |
| DC4 | > 5 cm | 50.8 mm |
Technical data
Sensor model name | Circumference Dendrometer 1 Type DC1 | Circumference Dendrometer 3 Type DC3 | Circumference Dendrometer 4 Type DC4 |
Scope of application | Slow/average growth rates | Slow/average growth rates | Fast-growing |
Suitable for diameter | 5 – 32 cm | > 5 cm | > 5 cm |
Special features/limitations | Confined comparability with different trunk diameters | Comparability for different trunk diameters improved. | Comparability for different trunk diameters improved. |
Measurement range | 11 mm linear ≙ 11 mm circumference | 25.4 mm linear ≙ circumference (diameter-dependent): 50 mm (at Ø 10 cm) 35 mm (at Ø 50 cm) 28 mm (at Ø 100 cm) | 50.8 mm linear ≙ circumference (diameter-dependent): 107 mm (at Ø 10 cm) 80 mm (at Ø 50 cm) 65 mm (at Ø 100 cm) |
Resolution | Data logger dependent e.g.: CR300 series: 0.01 µm Dendrometer logger DL18: 0.2 µm | Data logger dependent e.g.: CR300 series: 0.03 µm Dendrometer logger DL18: 0.5 µm | Data logger dependent e.g.: CR300 series: 0.05 µm Dendrometer logger DL18: 1 µm |
Accuracy | Dendrometer dependent: max. ± 4.5% of the measured value (stable offset) Data logger dependent e.g.: CR300 series: ± (0.04% of the measured value + 0.3 µm) Dendrometer logger DL18: ± (0.1% of the measured value + 0.45 µm) | Dendrometer dependent: max. ± 1.97% of the measured value (stable offset) Data logger dependent e.g.: CR300 series: ± (0.04% of the measured value + 0.6 µm) Dendrometer logger DL18: ± (0.1% of the measured value + 1 µm) | Dendrometer dependent: max. ± 0.98% of the measured value (stable offset) Data logger dependent e.g.: CR300 series: ± (0.04% of the measured value + 1.2 µm) Dendrometer logger DL18: ± (0.1% of the measured value + 2 µm) |
Output signal | Analogue, 0V to Vex (excitation supply voltage) | Analogue, 0V to Vex (excitation supply voltage) | Analogue, 0V to Vex (excitation supply voltage) |
Temperature drift of the sensor | < 0.2 µm/°C in the whole measurement range | < 0.2 µm/°C in the whole measurement range | < 0.2 µm/°C in the whole measurement range |
Temperature coefficient of the stem embracing cable wire | < 1.4 ×10-6/K | < 1.4 ×10-6/K | < 1.4 ×10-6/K |
Linearity | < 1% | < 0.7% | < 0.5% |
Operational conditions | Normal outdoor conditions, -25 to 70 ° C, 0 to 100% relative air humidity; unsuitable underwater and below snow cover | Normal outdoor conditions, -25 to 70 ° C, 0 to 100% relative air humidity; unsuitable underwater and below snow cover | Normal outdoor conditions, -25 to 70 ° C, 0 to 100% relative air humidity; unsuitable underwater and below the snow cover |
Weight (sensor without cable) | 13 g | 37 g | 47 g |
Power supply | Vex (! stabilized !) 0.5 to 10 VDC, Power consumption max. 0.28 µWh per measurement | Vex (! stabilized !) 0.5 to 10 VDC, Power consumption max. 0.28 µWh per measurement | Vex (! stabilized !) 0.5 to 10 VDC, Power consumption max. 0.28 µWh per measurement |
Material | Stainless steel and aluminium | Stainless steel and aluminium | Stainless steel and aluminium |
Sensor cable length | 5 m, extendable on request to max. 100 m | 5 m, extendable on request to max. 100 m | 5 m, extendable on request to max. 100 m |