�鶹��

This FNIRSI ERD-10 field detector is built like a professional multimeter. It has four fabric feet on the back (to stick to a hook-and-loop strip already on a work surface), a thick silicone bumper around the perimeter, four silicone buttons, and a high-resolution color display. For a modern touch, the device has a USB C port for recharging. This product looks right at home on an engineering workbench. The unit can show four instantaneous numbers on its default screen: temperature, magnetic field intensity, electromagnetic field intensity, and radiation power (for radio frequencies). An alternate screen omits radiation in favor of a history graph for either the EM or magnetic field; temperature is present again as just a number. The default screen scores EM and magnetic readings with up to eight bar segments, but the device never labels the vertical axis, much less the frequencies or direction of signals. The product has a Hold button which freezes all the numbers on the default screen. The second screen, with a constantly changing baseline, peaks and plateaus from the last 45 seconds, presents data in two dimensions. Despite the more informed analysis possible, that screen can not be frozen and the time axis is not labelled. The detector includes a temperature readout on its default screen and history screen.�� The temperature is not graphed, so you just see the current value or last value when Hold was pressed. Not a field measurement, this is the most basic of all the data the device displays. Magnetic field detection is rightfully zero in my home except when I place the unit close to AC transformers (found in wall power adapters and embedded power supplies), electric motors, and an operating microwave. Not surprisingly, the microwave yielded numbers (up to 30 microTeslas) that were over a thousand times higher than the minimum reading for weaker sources, at a distance roughly 10 cm away. Permanent magnets waved just millimetres away from the device also caused significant readings. Electric field numbers in open areas of my home are typically 0-15 V/m. When the device is 10 cm or closer to active electrical cords, wires in the wall for lights switched on, full-size LED light bulbs, or large appliances, numbers ranged from 20 to 140 V/m. I also noticed EM fields near dormant TV screens, dormant PC monitors (not all), and USB webcams. So the detector is definitely sensitive to EM from 60 Hz household AC, and maybe other internal frequencies in electronics. EM field readings rapidly fell to quiescent base levels when the distance from a source approached and exceeded 30 cm. Many spots in my home show radiation power at 0.025 microwatts per square cm. When I pushed Talk on an FRS walkie-talkie 10 cm away, the power jumped by over a hundred times. When an Android phone scanned for Bluetooth devices, a similar leap in radiation power occurred. Browsing by 2.4 GHz on the phone had a strong effect too, as did activity using LTE cellular. A dual-band wi-fi router 1 m away registered 0.800 microwatts per sq. cm. A 78mm halogen light tube almost touching the detector also produced a reading. Interestingly, a 5 GHz wi-fi connection on the phone did not elicit a radiation rise on the meter. The sources that caused radiation increases utilize frequency bands from about 400 Mhz to 2.6 GHz. The detector not responding to 5 GHz signals is disappointing. At least it can sense low frequency RF convincingly at 1 m and very dramatically at closer proximity. Radio frequencies are just EM fields within certain common bands modulated for communication. This field detector shows general EM values in big numbers and a graph, but relegates RF (radiation power) to a simple number on the default screen. A graph for RF would have been beneficial since home and office environments now abound with data transmissions. If you have walked past an FM radio or tried holding rabbit ear TV antennas in your hands, you will know the human body blocks, reflects, or conveys EM waves depending on the frequency. As a result, RF and especially EM numbers fluctuate constantly when my fingers are around the middle of the instrument. I find the most steady readings are achieved when I put the device on a table. When I want measurements near an appliance or specific point, grasping the unit with just a couple fingers at the bottom end reduces bodily interference.�� The manufacturer should have included labels to encourage holding the bottom. To their credit, they did include a wide plastic loop at the bottom for attaching a wrist strap. Using a strap will not really avoid EM and RF interference, but it makes carrying the device a bit easier. The audible alarms for EM and magnetic fields are quite distracting when numbers briefly and repeatedly go above and below the thresholds. I found silencing the instrument preserves sanity. You can still set thresholds to make the power button flash red, which is nicer than frequent beeping. I am sure checking industrial machinery, vehicles, and cell towers with this detector would be eye-opening. At home, this detector will tell you if you are near moving magnets, microwaves, powered electronics, active wires, transformers, walkie-talkies, 2.4 GHz wi-fi equipment, LTE cellular phones, and gadgets generating various EM, RF, and magnetic fields. When this instrument is touching or extremely close to those devices, it may sense multiple types of fields, and fewer will be detected as you move away. This instrument is both simple and confusing to read, so knowledge is definitely required to interpret the results. At the same time, the lack of frequency measurement, axis labelling, RF graphing, and other omissions prevent this product from being an engineering tool despite appearances. Even so, this product is competitive with other products in its price class. In the end, it provides enough insight to satisfy my curiosity about field safety and nominal operations for equipment.