SRC-Ⅰ/30 Type Quasi-Continuous Variable-Range Altimeter

Source - Type I/30

Quasi-continuous variable-range altimeter

Instruction Manual

Important Note:

1. Please be sure to keep this manual in a safe place for future reference.

2. In addition to the basic functions of the Brulé altimeter, this altimeter also supports variable-distance altitude measurement. When placing an order, please pay attention to its functional advantages and the specific model designation of the instrument body.

3. This instrument has been professionally calibrated for accuracy at the factory; do not disassemble it yourself during use.

4. This altimeter complies with the technical requirements of the national forestry industry standard LY/T 2076-2012, “Handheld Forest Altimeter.”

5. The SRC-Ⅰ/30 altimeter is an upgraded and replacement model of our CGQ-1 altimeter, with patent number ZL201120044992x. Harbin Optical Instruments Factory holds the exclusive manufacturing rights, and we will pursue legal liability for any infringement involving the production or sale of counterfeit products.

One , Overview

The SRC-Ⅰ/30 quasi-continuous variable-distance altimeter (hereinafter referred to as the SRC-Ⅰ/30 altimeter) is a new patented product jointly developed by our factory and Shandong Agricultural University (Patent No.: ZL201120044992x). Thanks to its innovative quasi-continuous variable-distance dial design, its field performance has been significantly enhanced. Compared with the conventional Brunelleschi altimeter (CGQ-1 model), this product not only provides basic functions for angle and height measurement but also allows flexible selection of measurement points in the field. This technological advancement effectively addresses the challenge of selecting appropriate measurement points in forested areas due to obstructed lines of sight, making it particularly suitable for use in China’s densely populated mountainous forests. Consequently, it is an urgently needed, practical altimetry tool for current production.

II. Structure and Principle

(1) Basic Structure

The basic structure of the instrument (see Figure 1) consists primarily of three parts:

(1) Aiming system (collimator, collimation aperture, front sight),

(2) Vertical needle control system (start button, stop plate mechanism, etc.),

(3) Numerical reading system (dial, plumb line, etc.).

(2) Principle of Height Measurement

When using a level instrument to measure the elevation of a point, the collimation aperture in the telescope and the sighting notch form a measurement line, which makes a specific angle of inclination with the horizontal plane. Given the horizontal distance, the elevation can be determined directly from the tangent function. As shown in Figure 2,

Since h = L tan θ, when L is constant, θ and h are in a one-to-one correspondence. Therefore, by marking the corresponding value of h at the θ position indicated on the vernier scale, it becomes possible to directly read the height on the altimeter.

(Figure 2) Schematic diagram of the height-measuring principle

(3) Dial Structure

To facilitate understanding of the dial structure of the SRC-Ⅰ/30 altimeter, we present it here side by side with the dial of the conventional Brüel altimeter (model CGQ-1) previously manufactured by our factory, as shown in Figures 3 and 4. A comparison reveals that the dial of the conventional Brüel altimeter (model CGQ-1) features two reading zones, whereas the dial of the SRC-Ⅰ/30 altimeter has three reading zones. The specific structural details are as follows:

1. Scale dial of the CGQ-1 altimeter (see Figure 3) as shown in the figure.

(1) Angle Reading Zone 1: This zone is located on the outer side of the dial and is used to read the horizontal inclination angle of the target position.

(2) Brulé height-measurement reading zone 2: This zone is equipped with four standard horizontal distances—15 m, 20 m, 30 m, and 40 m—which can be selected as needed during height measurement.

(Figure 3) Scale-division structure of the dial on a conventional Brüel height gauge

(Figure 4) Scale-division structure of the dial on the SRC-I/30 altimeter

2. Scale dial of the SRC-Ⅰ/30 altimeter (see Figure 4). As shown in the figure.

(1) Angle Reading Zone 1: This zone is located on the inner side of the graduated dial and is used to read the horizontal inclination angle of the target position.

(2) Quasi-continuous elevation measurement reading zone 2: In this zone, the horizontal distance range is 7 to 12 meters, with a step size of 1 meter; the elevation contour lines in the quasi-continuous elevation measurement reading zone are arranged in a “stepped” pattern as the distance varies, and the corresponding elevation values are marked at both ends of each stepped contour line.

(3) Brulé height-measurement reading zone 3: This zone includes two standard horizontal distances—15 m and 20 m—which are the most commonly used during height measurements and generally suffice for routine height-survey requirements.

(4) Explanation of the Distance-Multiplication Method

The back of the SRC-Ⅰ/30 altimeter is annotated with instructions on the double-distance method for height measurement, to facilitate height determination of exceptionally tall trees. The so-called double-distance method involves doubling the horizontal distance during measurement: for example, if the altimeter’s 20-m horizontal-distance scale is used to read the height, but the actual horizontal distance on site is 40 m (a two-fold relationship), then the recorded height value will also be doubled. Thus, if the tree height read using this method is 28.2 m, the actual tree height is 56.4 m.

III. Main Technical Parameters

IV. Instructions for Use

(1) Measuring Height (using tree height measurement as an example)

As shown in Figure 2, select a measurement point at a horizontal distance of L from the tree; press the start button to allow the plumb bob to swing freely; hold the height-measuring instrument and sight along the top of the tree; after a brief pause, once the plumb bob has come to rest, press the stop trigger; then read the height measurement from the position indicated by the plumb bob on the scale. An example of how to take a height reading is as follows:

Example: Figure 4 shows the situation when height is measured using the SRC-Ⅰ/30 quasi-continuous variable-range altimeter. When the horizontal distance L is 15 m, the height reading is 11.1 m; when L is 20 m, the height reading is 14.9 m; and when L is 7 m, 8 m, 10 m, or 12 m, the corresponding height readings are 5.1 m, 5.8 m, 7.4 m, and 8.8 m, respectively.

It should be noted that, to enhance measurement accuracy, the height-measurement procedure illustrated in Figure 2 of this manual is generally recommended. Specifically, when selecting measurement points, the line of sight should pass through the tree trunk (i.e., intersect the trunk), and situations where the line of sight lies below the base of the tree or above its crown should be avoided as much as possible, since this approach helps improve measurement precision. In addition, after measuring h, it is necessary to continue measuring h′; the total height of the tree is obtained by summing h and h′.

(2) Measuring Slope

Another application of the SRC-Ⅰ/30 altimeter is to measure slope steepness, as shown in Figure 5. During measurement, the observer stands at the foot of the slope and sights a specific height mark on the staff erected on the slope—this mark should be exactly at the observer’s eye level. Once the plumb bob comes to rest, the trigger is pressed, and the slope angle can then be read from the inclinometer scale (the reading procedure is illustrated in Figure 4; in that figure, the measured angle is 35.8°). In addition, when using this altimeter to measure slope, measurements may be taken either by sighting upward from the foot of the slope or by sighting downward from the top of the slope; the results obtained from either method are identical.

(Figure 5) Method for Measuring Slope Using a Leveling Instrument

V. Precautions for Use and Maintenance

1. Lock the plumb bob after use;

2. Handle with care and avoid applying pressure to prevent glass breakage;

3. The storage environment shall be clean, dry, and free of corrosive gases;

4. During use, avoid allowing rainwater and dust to enter.

Harbin Optical Instruments Factory Co., Ltd.

HARBIN OPTICAL INSTRUMENT FACTORY LTD.

ground   Address: Jingwei Third Road, Daoli District, Harbin City 32 Number

Post   Editor: 150010

Electricity   Words: 400-030-0319         0451-84286338      

network   Address: www.hrboptical.com           

E-mail： hopt@hopt.cn