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Old 12-04-2013, 01:19 AM   #1
Dennis V
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Default Poor Mans 2.4 Ghz Spectrum Analyzer Update

Back two years ago, I originated a thread on a "Poor Mans" 2.4 Ghz Spectrum Analyzer that showed some of the things that is going on with our 2.4 Ghz radio systems. Below is a link to that thread.

Since that time, the original Spektrum analyzer has become extinct, and along with that, they absolutely do not work with Windows 8. So, if you should see one of the original analyzers in Ebay, or similar, word to the wise.

So, a birthday present to me included a new Spektrum Analyzer, as shown below: (The model I have is the 2.4 Ghz unit at $119.00)

So, do you need one of these for general flying on 2.4 Ghz? Absolutely NOT! But, if you're curious about these frequencies, this is one unit that will provide a lot of information. The RF Explorer is orders of magnitude more capable than the original unit listed above.

The unit has a built in LCD display in an aluminum case, with a built in battery that is good for hours of operation. Charging is by a USB cable. The analyzer can also interface with a PC, and display the information on your computer screen if desired.

Operating without a PC, this unit has a wide range of abilities, such as changing the frequencies scanned within the 2.4 Ghz band, showing the exact frequencies of any of the transmitted signals, accumulating scanned info, averaging scanned info, and quite a bit more.

One very nice thing, the operator can also change the "Sensitivity" of the unit for transmitters located a considerable distance away.

So, today I did a bit of testing with this unit, along with my Spektrum DX8 transmitter. The transmitter was placed about 50 feet behind my home, on top of a plastic garbage can. Its location was right along the line of sight of one wall of my home. Pacing off about 300 feet, the Spectrum Analyzer showed the normal signal level. And, stepping to the right about 5 feet put the home between the transmitter, and the Analyzer. The displayed signal dropped off. Really dropped off, as expected.

Next, the analyzer was put behind a 6S2P A123 battery pack, held in front of the analyzer by about 1/2 foot. The displayed signal level dropped completely to ZERO! Moving the analyzer closer to the battery pack, and some signal was picked up. Interesting.

The analyzer has a whip antenna, so the analyzer was rotated 90 degrees to see what would happen. Yup, the signal again dropped off noticeably. So, now you know why these 2.4 Ghz receivers require a second receiver with its antennas rotated from the master receiver. Or at least a single receiver with two antennas, one extended by perhaps 6 inches from the receiver. Those 2.4 Ghz signals are very definitely position and rotation sensitive.

Take a look at some photos of this unit, along with photos of the PC display when connected to the computer.

(Note, that wide band "Hump" on the left third of the DX7 display is from my computer modem, located about 15 feet away.)

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