Technical References Collection now Avaliable on Scribd

Burning the Midnight has added a new section to its Scribd profile, called Technical References. It contains many useful documents and wall sheets for wireless, electronics and network technologies. Handy to have hanging in the laboratory or workshop for a quick reference: http://www.scribd.com/burningthemidnight

Publications include:

• Motorola Canopy Reset Default Plug
• Radio Transmitter Power dBm to Watt Conversion Table
• IP Subnet Reference Sheet
• JEDEC Coding System Table for Diodes and Transistors
• Serial Console Cable Howto and Wiring Diagram
• Ami Bios Beep Codes Reference
• Optical Fibre Connector Reference Sheet
• Electronic Formulas
• Resistor Colour Value Howto and Code Sheet
• Ceramic and Mylar Capacitor Value Howto and Code Sheet

Check them out at http://www.scribd.com/burningthemidnight in the Technical References section of the Burning the Midnight profile. Also, the Technical Reviews section on Scribd has a lot of information on wireless, networking and security hardware systems. Well worth a look.

Building an Industrial Robot - Part 1 - The Robot Brain and Body

Here's my project to make a universal platform for industrial robot experiments.

The requirements are to develop and construct an industrial grade tracked robot for under US$2000.

The robot has to be able to work in harsh environments, be net-workable and operate for long periods before recharging.


A series of blogs will follow the progress of the tracked robot project, and this part is focused on the base construction and layout of the robot's computer.


The Robot's Main Body

Before you mount a computer brains for a robot, you need a body to mount it, so I created a quick, cheap and strong assembly method.

Side of the robot without the hatch

Top of the robot without the hatch

The main body is made of poly carbonate panels with aluminium framing for lightness and strength.

The panels are glued to the aluminium frame with silicon, the same way you would build a fishtank.

This makes construction of a robot body easy, without too much drilling and reducing the number of bolts or rivets that might come lose during the robot's operation.

Also, construction makes the robot's main body water-proof, in case it has to operate in low level water.

The main body has been sprayed with a grey primer and matt black finishing paint to protect the polycarbonate body and increase water-proofing.

It also gives stealth or a black ops look to the robot.

Side view with the hatch on

Top view with the hatch on

With the top hatch and soft mounts on, the main body is sealed for protection of the robot's computer systems.

The GPS is mounted on the top, next to the 2.4 GHz omnidirectional antenna.

The pole mount at the other end of the main body is for the web cam.

In the centre, the main hatch opens to access the computer system for system reprogramming, battery maintenance and internal repairs.


The Robot's Computer

The main brain of the robot will be driven by a Mini-ITX system running Linux. The Mini-ITX system will be using a SSD to boot  and run, which removes the requirement for a hard drive that might be damaged when the robot is in motion. The idea behind the Mini-ITX is to reduce complexity from hardware into software tasks, and making the programming and design of the robot's brains much easier.

The main part of the robot lies in the PIC Micro-controller connected to the Mini-ITX by a RS232  connection.

This controller has 20 inputs and outputs for driving motors and reading sensors.

The PIC Micro-controller allows the software on the Mini-ITX to interface with the robot's outside world.

The 802.11g Linksys bridge is set to connect to the local access point for remote access to the robot via IP, either for the information of a remote user or for the robot to download new information and instructions. The network security is done by WAP encryption on the layer 2 as well as 256 AES VPNs from the Linux OS.

The Webcam and GPS are plugged straight into the Mini-ITX via USB cables.

This supplies the robot's computer with GPS positioning and a digital eye for navigation.

Computer Layout Components: Mini-ITX computer 802.11g Ethernet Bridge USB GPS USB Webcam 2.4 GHz Antenna Pic Micro-controller Board USB, RS232, Cat5 and Coax cabling

The Robot Computer Layout

The above diagram show the logic layout of the connections and hardware used for the computer controller.

The Mini-ITX connections use Cat5 to the 802.11 bridge, RS232 to the PIC Micro-controller and USB to the web cam and the GPS.

The 802.11 bridge is also connected to an antenna with shielded coaxial cable.

The choice of operating system for this robot project is Gentoo Linux. I have found this Linux distribution ideal for embedded and custom designed systems. It is very easy to make live images and small OS footprints with Gentoo Linux. I have tested Gentoo Linux on Mini-ITX systems before without any issues.

More to come in the next parts of this project, as we examine the power system, track design, motor systems and software applications required.

WiMAX 5.8Ghz vs Wi-Fi 5.8Ghz in Backhaul and Access Technologies

In today's wireless market, there are numerous  5.8Ghz Wi-Fi based products. Now wireless equipment vendors are releasing 5.8Ghz versions of their WiMAX products. It's tempting for small/medium ISP, businesses and governments to look at the new product offerings, but is it worth the switch to WiMAX from widely used Wi-Fi based products?

What is Wi-Fi and WiMax?

When comparing technologies for deployment applications, defining exactly what we are looking at is a good place to start.

Wi-Fi Definition:
Wi-Fi (pronounced /ˈwaɪfaɪ/) is a trademark of the Wi-Fi Alliance used with certified products that belong to a class of wireless local area network (WLAN) devices based on the IEEE 802.11 standards.

Because of the close relationship with its underlying standard, the term Wi-Fi is often used as a synonym for IEEE 802.11 technology, including the 802.11a/802.11b/802.11g standards.

WiMAX Definition:
WiMAX, means Worldwide Interoperability for Microwave Access.

It is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile Internet access.

The technology provides up to 10 Mbps broadband speed without the need for cables.

It is based on the IEEE 802.16 standard (also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard.

WiMAX and Wi-Fii standards

Standard	Family	Use	Radio/RF	Down Link	Uplink
Wi-Fi	802.11a/b/g (11n)	Fixed Internet/Fixed Data services	OFDM/MIMO TDD	288.9 Can support 600Mbps @ 40MHz channels
WiMAX	802.16d 802.16e  (802.16m developmental)	Fixed/Mobile Internet/Data services	OFDMA MIMO-SOFDMA TDD and FDD	144	35

As we can see from the standards information, there are distinct differences in both the WiMAX and Wi-Fi technologies and their possible applications.

Can 5.8GHz WiMAX can compete with 5.8GHz Wi-Fi for a Point to Point application?

For point to point applications, 5.8 Wi-Fi works fairly well and is widely used in Australia.

The main advantage in the WiMAX standard for PTP networks is FDD (full duplex communications) and QoS features. But, in many instances, it is difficult for point to point WiMAX to compete with 802.11 Wi-Fi in point to point systems. Wi-Fi has a better overall data-rate then WiMAX.

In the future, the 802.16m stardard for WiMAX will give point to point systems a better advantage over Wi-Fi point to point systems, offering rates at least 4x the current 802.16e rates.

5.8GHz Point to Multi-Point - WiMAX or Wi-Fi?

The WiMAX standard has many advantages over 802.11 Wi-Fi products in point to multipoint applications.

The hidden node effect is the biggest problem for Wi-Fi networks.

Hidden nodes in a wireless network refer to nodes that are out of range of other nodes or a collection of nodes.

Take a physical star topology with an access point and many nodes surrounding it in a circular fashion. Each node is within communication range of the AP, but some nodes may not be able to communicate with each other, as they do not have a physical connection to each other, thus producing a situation where nodes can not sense the carrier on the network.

Carrier sense multiple access with collision avoidance (CSMA/CA) does not work and collisions occur, scrambling data.

The Wi-Fi RF timing is less robust for long range transmissions and systems that have fixed the Wi-Fi timing problems risk incompatibility problems with the 802.11 standards. There are different versions of 802.11 from vendors including Alverion, Airaya and Skypilot. These companies use products with modified 802.11, but they only work with their own client subscriber units.

WiMAX wins hands down, and was designed to fix shortfalls in the Wi-Fi standard.

I have tried deploying larger Wi-Fi last mile access networks in the past and experienced a lot of problems.

I have never had a problem with WiMAX network deployments and reliability in access networks.

IT Technology Reviews Online

Technology reviews have been added to the Burning the Midnight site at http://sites.google.com/site/burningthemidnightproject, under the Online Library section of the site.

The topics include various IT equipment and software reviews for major brands.

Alvarion Breeze Access Ezy Airaya Wireless AI-108 Aximotek NA-806D Barracuda Networks Security Appliance Longreach Wireless IR+ ProofPoint Security Appliance Motorola Canopy Wireless Redline Communications AN-100, AN-80 and AN-50 SkyPilot Networks Trango Broadband Wireless Link-10

These are reviews and guides to setting up the systems.

Had a lot of fun with these products and still work with some of them.

Enjoy!