User Manual

ManualsBrandsJapan Radio ManualsElectronicsGround Penetrating Rader

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4 Theory

4.1 Principle of Operation

The principle of this product is basically the same as for general radars widely used at present.

Electromagnetic waves are transmitted from the antenna toward the concrete as shown in Figure 4-1.

The electromagnetic waves are reflected by an interface with the reflecting objects (e.g., reinforcing steel

bars or cavities) whose electrical property is different from that of concrete. The waves are reflected back

onto the surface of concrete and received by the receiving antenna placed near the concrete surface. The

distance to the reflecting objects can be calculated from the time the reflected waves need to reach the

receiving antenna. The horizontal locations of the objects can be detected by moving the main unit on the

surface of concrete.

Since this product is designed to probe objects with high resolution that are near from the surface of

concrete, it transmits pulse waves having a width of only about one nanosecond (one-billionth of a

second) or less.

Figure 4-1 Diagram of Principle

Figure 4-2 shows a wave reflected by a reinforcing steel bar or the like in a concrete structure, which is

obtained by this product.

Figure 4-2 Sample of Reflected Waveform

Time

Reflected wave from rebar

Trans. wave

Reflection

Concrete surface

Inside concrete

Rebar

Trans antenna Rec. antenna

Trans. Rec.

Summary of content (10 pages)

PAGE 1
4 Theory 4.1 Principle of Operation The principle of this product is basically the same as for general radars widely used at present. Electromagnetic waves are transmitted from the antenna toward the concrete as shown in Figure 4-1. The electromagnetic waves are reflected by an interface with the reflecting objects (e.g., reinforcing steel bars or cavities) whose electrical property is different from that of concrete.
PAGE 2
Velocity V of electromagnetic waves in concrete is obtained from the following formula: Ｖ＝Ｃ εｒ（ｍ／ｓ） C: Velocity of electromagnetic waves in vacuum (in air) (3 × 108 m/s) εr: Relative dielectric constant of concrete (6 to 11 in the example) Distance D to the reflecting object is obtained from the following formula: １Ｄ＝ＶＴ（ｍ）２ 4.
PAGE 3
5 Maintenance Inspection WARNING Do not attempt to disassemble, modify, or repair this product. Doing so could cause fire, electric shock, or breakdown. When the power cord is damaged (exposed core wire, open circuit failure, or broken sheath), please contact our headquarters on Page 81 or our nearest branch office (See Section 9), sales outlet, or service station for a replacement power cord. Use of a damaged power cord could cause fire or electric shock.
PAGE 4
5.3 Troubleshooting This product's states listed below are not always a sign of trouble. Check for this product again before asking for repair. Main unit state Check Items and Response The main unit cannot be turned on. Nothing is displayed. • Check if the battery pack is mounted. →Mount a fully charged battery pack according to Section 3.1 Scan preparation. • Check if the battery pack is exhausted. →Mount a fully charged battery pack according to Section 3.1 Scan preparation.
PAGE 5
Main unit state No print out when pressing the OUTPUT key The message "Turn OFF/ON the printer" is displayed when the OUTPUT key is pressed. The message "Charge the printer's battery" is displayed when the OUTPUT key is pressed. The message "No printing paper" is displayed when the OUTPUT key is pressed. The message "Printer error" is displayed when the OUTPUT key is pressed.
PAGE 6
After-sales Service If this product malfunctions, read Section 5.3 Troubleshooting carefully, and check this product again. If this product still malfunctions, stop using it, and contact our nearest branch office, sales outlet, or service station.
PAGE 7
Disposal WARNING Before disposing of the used lithium ion battery, insulate the charging terminals by taping or the like. Otherwise, the battery could cause fire or explosion if short-circuited. 7.1 Disposal of Used Battery Pack ● Discharge the used battery pack (lithium ion battery) completely, insulate the charging terminals by a non-conductive tape or the equivalence, and then dispose of it as nonflammable refuse.
PAGE 8
Specification 8.1 Handy Search NJJ-105 Table 8-1 Specification of NJJ-105 item Functions and Performances Search method Electromagnetic wave radar method Search object Rebar (reinforcing steel bar), Polyvinyl-chloride pipe, Cavity, etc. Search depth 5 to 300mm for the concrete with a relative dielectric constant ＝ 6.2 everywhere and the top rebar of diameter 6mm Depth resolution Approx. 1 mm at the display range setting of Shallow Approx.
PAGE 9
Table 8-1 Specification of NJJ-105 (Continued) Item Specification Temperature range 0 to ＋50°C Power Battery pack or AC adapter (option) Continuous operation time Approx. 1.5 hour when using the fully charged battery. Structure Light splash proof Size Approx. 149(W)×147(H)×216(D)mm Weight Approx. 1.2kg 8.2 Battery pack BP-3007 series Table 8-2 Specification of battery pack BP-3007 series Item Specifications Battery Lithium ion battery Nominal capacity 1500 mAh Nominal voltage 7.
PAGE 10
9 Where to Contact For inquiries and repair about this product, contact our main office below, the nearest branch office, sales outlet, or service station. Japan Radio Co. Ltd. Section-I, International Business Department. Sales and Marketing Fjisawa bldg. 30-16,ogikubo 4-chome Suginami-ku, Tokyo 167-8540,Japan TEL:+81-3-6832-1721 FAX:+81-3-6832-1844 Web site: http://www.jrc.co.