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Demo the wireless communication distance for RFBee, both 433MHz and 434MHz, outdoor and indoor.

This tutorial is to show the demo of wireless communication distance for RFBee, both 433MHz and 434MHz, outdoor and indoor. There are two types of RFBee available in Cytron, they are RFBee 434MHz UART Wireless Module (100m) and RFBee 433MHz UART Wireless Module (1km):

RFBEE-434MHZ(V2)-800x800

RFBee 434MHz UART Wireless Module (100m):Having operating frequency of 434 MHz and wireless range of 100 m. This wireless range is measured under open space, the wireless range may reduce if we use it in indoor

RFBEE-433MHZ(V2)-800x800

RFBee 433MHz UART Wireless Module (1km): Having operating frequency of 433 MHz and wireless range of 1 km. Again, this specification is measured under open space, and it should be shorter when it is used in indoor

Since they have different wireless frequencies, both these modules are not compatible with each other. We need same frequency module in order to get wireless communication. Also, they are not compatible to the low cost RF transmitter and receiver.

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Today, I am going to test the wireless communication range with different type of antenna for both 433MHz and 434MHz, outdoor and indoor. Its is really important to know about antenna when we communicates using RFBee modules.

What is an antenna ?

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The antenna is a very important element of radio equipment. The antenna of the transmitter emits high frequency energy into space while the antenna of the receiver catches this and converts it into electricity. If the antenna is not precisely the correct length for the frequency used, the radio waves cannot be emitted or captured efficiently. It should neither be too long, nor too short. A good transmitting antenna can be a good receiving antenna, and for ordinary uses, one antenna serves both functions.

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To start test range distance, we need a pair of RFBee. Please read user’s manual of particular RFBee to configure the module. Make sure each pair of RFBee have same configuration. In this experiment, each node of RFBee will consist of RFBee module + CT-UNO + XBee shield. A master node and another slave node. 

I am not expert in range test, but I guess we need data communication between two nodes, right? So, my experiment setup is for the master node to send a byte of data to slave node, and within certain period of time (timeout) it will check the receiving buffer and verify if the data receive is same as data sent our earlier. The data will loop from 0 to 255 and repeat. That is master node task. The slave node will receive data and transmit out, this is some time call echo test. Simple!

In case the data that send and receive is not same or no data before timeout, it means data lost happen. Master node will display the result on LCD.

 

Setup master node:

a) Stack XBee Shield onto CT-UNO.

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b) Connect the CT-UNO to computer using USB micro-B cable and install the necessary driver.  If you are new to CT-UNO, please check the User’s Manual to get started. Open ARDUINO IDE, go to Tools -> Serial Port -> COM (that connected with CT-UNO). In my case, the COM is 5.

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c) Load this Range_RFBee_Test into CT-UNO. *Before uploading sketch into CT-UNO, please remove the mini jumpers on XBee shield to D2 and D3. This is to avoid the bootloading process being interfered by XBee shield.

d) Now, stack LCD shield and RFBee module onto XBee shield. Since RFBee’s antenna might be blocked by the LCD shield, I added Arduino female header to extend the LCD shield height. *Do not solder Antenna at Horizontally. Soldering Antenna vertically works much better than soldering antenna horizontally.

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Setup Slave Node:

a) Stack XBee Shield onto CT-UNO.

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b) Connect the CT-UNO to computer using USB micro-B cable and install the necessary driver.  If you are new to CT-UNO, please check the User’s Manual to get started. Open ARDUINO IDE, go to Tools -> Serial Port -> COM (that connected with CT-UNO). In my case, the COM is 7.

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c) Load this RFBee_Distance_Test_Slave_Node sketch into CT-UNO. *Before uploading sketch into CT-UNO, please remove the mini jumpers on XBee shield to D2 and D3. This is to avoid the bootloading process interfered by XBee shield.

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1st range test, I am going to test wireless communication between RFBee without antenna. Yes, the same RFBee module can communicate even without antenna but the range will be very short. Since the distance of communication is very short, I test at indoor only.

Testing distance without Antenna.

1) Stack in RFBee module without antenna onto both XBee shield.

2) Plug in 12V DC.

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3) Put slave node at one place.

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4) Move master node farther from slave node.
5) Monitor the LCD, continue to move until LCD displays “Data lost”.

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6) Exchange both RFBee (100m, 434MHz) module with RFBee (1km, 433MHz).
7) Repeat step 1 to 5 with RFBee (1km, 433MHz) module.

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Here the result after the test indoor.

As I mention before, the wireless communication distance of RFBee module without antenna would be too short. This result shows that the wireless communication distance without antenna is very short. I think we should solder spring antenna that come with RFBee. This time I will test at both indoor and outdoor.

Testing wireless communication distance of RFBee module with spring antenna.

Procedure :

1) Solder spring antenna onto RFBee (100m) modules. *Spring Antenna should solder Vertically for better wireless range.

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2) Stack on RFBee (100m) module with spring antenna onto both XBee shield of master node and slave node.

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3) Plug in power supply.

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4) Put slave node at one place.

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5) Bring master node and move far from slave node.

6) Take note of the distance until LCD shield on master node displays the ” Data  lost “. 

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7) Bring slave node to outdoor. Repeat step 4 to 6 at outdoor. *If measuring distance at outdoor, measure  distance using google map.

8) Remove both RFBee (100m) module.

9) Repeat step 1 to 7 with RFBee (1km) module.

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Here are the results of testing, the communication range with spring antenna, outdoor near Cytron’s office.

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Seems the wireless communication distance of the both RFBee module is actually shorter than I expected. I believe one of the reasons is the antenna, not to forget the environment too. The Antenna comes with RFBee packet is made of steel. Steel metal have low conductivity level.

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Table from the Electrical Conductivity of Metals.

Based on table above, we can conclude that spring antenna is steel metal that have low electrical conductivity level. Lets replace spring antenna with copper wire antenna. Why copper wire? Because, copper wire is cheap and easy to get and have good electrical conductivity. I will show you how the different design of copper wire antenna effects the wireless communication distance. Later, I will show you testing using straight copper wire antenna and spiral copper wire antenna. Before we solder copper wire antenna onto RFBee module, we should calculate the antenna length for its frequency because each frequency module have different length and difference type of antenna. For example; radio, tv, wifi and mobile phone. The length of the antenna is determined by the wavelength of the radio waves it is used with. 

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Calculate the length of antenna

To know how to calculate length of antenna, just follow these steps.
We need to get the wavelength of the wireless signal. The formula for calculating wavelength is:

670px-Calculate-Wavelength-Step-1-Version-2 

 

670px-Calculate-Wavelength-Step-2-Version-2

The length of antenna = Wavelength = Wave speed/Frequency.
The length of antenna is also the Wavelength. Wavelength is commonly represented by the Greek letter lambda (λ). Speed of light is commonly represented by the letter c (3×10^8 m/s ). Frequency is commonly represented by the letter f. Determent the frequency of RFBee module. For example the frequency of RFBee (100m) module is 434 MHz.

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Now you already have Frequency,f and speed of light,c. 
All you have to do is plug them into the original formula and manipulate it to solve for the Wavelength (λ).
Solve the following problem: Find the Wavelength (λ). Here’s how:

 

a

 

The answer for  Wavelength (λ)  for RFBee module

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The answer for  Wavelength (λ)  for RFBee module

 

0.69 m is length of Wavelength (λ) and also the length of antenna for 434Mhz frequency module and also for 433Mhz frequency module. Divide Wavelength (λ) by 4. Why divide with four ? The most common form is the quarter-wave monopole, in which the antenna is approximately 1/4 of a wavelength of the radio waves. Of course the longer length of antenna is better but its not practical to get longest antenna length. So by 1/4 length of antenna the communication still able to work nicely. Convert meter to millimeter and the length antenna should be 173 mm.

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The length of antenna for both RFBee is module is quite same. So, the length of both RFBee module is 173 mm.

 

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Testing wireless communication distance for RFBee modules with copper wire antenna divided into two part.

Part A : Testing wireless communication distance for RFBee modules with spiral copper wire antenna.

1) Cut copper wire  with length of 173 mm and plug out 1 cm insulator from both end.

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2) Make copper wire turns using pen or screwdriver.

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3) Solder spiral copper wire antenna onto both RFBee (100m) modules. *Spring Antenna should solder Vertically for better wireless communication range

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4) Stack in RFBee module with spiral copper wire antenna onto both XBee shield.

5) Plug in Power supply.

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6) Put slave node at one place.

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7) Bring master node and move far from slave node.
8) Take note of the distance until LCD shield on master node displays the “Data lost”.

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9) Bring slave node to outdoor. Repeat step 6 to 8. *If measuring distance at outdoor, measure distance using google map.

10) Remove both RFBee (100m) module.

11) Repeat same step 1 to 9 with RFBee (1km) module.

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Here the result of testing wireless communication distance using RFBee modules with straight copper wire antenna at outdoor near to my office.

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The result shows the wireless communication distance using copper wire antenna is better than using spring antenna. The wireless communication distance result still not as I expected because we actually reduced the height of antenna by make turns to make spiral antenna. Let try with straight copper wire antenna. The straight copper wire antenna should work much better.

PART B

Testing wireless communication distance for RFBee modules with straight copper wire antenna.

1) Cut copper wire with length of 173 mm and plug out 1 cm insulator from both end.

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2) Solder straight copper wire antenna onto both RFBee (100m) modules. *Spring Antenna should solder vertically for better wireless communication range

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3) Stack in RFBee module with straight copper wire antenna onto both XBee shield.

4) Plug in Power supply.

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5) Put slave node at one place.

6) Bring master node and move far from slave node.

7) Take note of the distance until LCD shield on master node displays the ” Data lost “.

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8) Bring slave node to outdoor. Repeat step 5 to 7. *If measuring distance at outdoor, measure distance using google map.

9) Remove both RFBee (100m) module.

10) Repeat same step 1 to 8 with RFBee (1km) module.

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Here the result of testing wireless communication distance using RFBee modules with straight copper wire antenna at outdoor near to my office.

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This result show straight copper wire antenna able to communicate at longer distance. It is is more than I expected.

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In the Conclusion, the straight copper wire Antenna able to give excellent wireless  communication distance for RFBee module.

Attachment:

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2 thoughts on “Demo the wireless communication distance for RFBee, both 433MHz and 434MHz, outdoor and indoor.

  1. what is the different between the xbee and the Rfbee , can I use the xbee module as an alternative for the Rfbee module in the relay shield v.1

  2. Well, there are quite a number of differences between XBee and RFBee. It depends on your requirement. Both are wireless device that provide wireless communication. Since you have XBee already, just go ahead and use it.

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