Radio Systems for Machine Control

Contents

1. What are we trying to do and Why.

2. Physical Constraints of Mine Sites.

3. Data Flow Requirements.

4. Existing Radio Systems.

5. Security.

6. Where Will it End.

What are we trying to do and Why

What

•Optimize machine use.

•Maximize Mine resources.

•Simplify Communications to Field Operations.

Why

•To Save Money

•For Better Communications

•To Make Life Easier

Physical Constraints of Mines

•Large spoil piles.

•Deep pits.

•Large areas.

•Constant change of both operations and the mines topography.

•Constant blasting.

Data Flow Requirements

•General monitoring of production .0ne truck about 300 kilobytes/day

Draglines are heavy users

•Design files for operations to and from machines.Size can vary from 2meg to 20k per file

•RTK corrections. 1,550 kilobytes per day

CMR messages every second for 24 hours

Existing Radio Systems

UHF data radios

•450 to 520 mhz

•2400 baud rate

•240 characters per second

•These radios work with a tone di = 0, dr = 1

• UHF will reflect off walls ie it can bend around a pit

extented by multipath

•Narrow bandwith – High Power, Long Distance, minimal data

900 Mhz Spread Spectrum Data Radio

•915 to 928 mhz

•115200 baud rate

•11520 characters per second

•Data files are compressed by between 3 and 10 to 1

•The radio works on Time Division Multiple Access

•Each Link has a master and 2 slaves

•The Master synchronizes the signal so that hopping tables can be used

•One link can have a maximum of 40 machines

900 Mhz Spread Spectrum RTK Radio

•915 to 928 mhz

•115200 baud rate

•The RTK signal can be repeated 14 times .

•Each message takes up 330 milliseconds

•Security is provided by a lack of knowledge of the hopping tables

1 watt power output from radio allowable under ACA.

•Wide bandwidth – low power, short distance, large amounts of data

•Some multipath (Coal absorbs signal, hard rock does not)

TDMA

802.11 data radios

•2.4 Ghz

•115200 baud rate

•802.11 G has 54mhz band width

•802.11 B has 11mhz band width

•This system can work as a mesh where all radios are repeaters

•The radios know how to route the message to its destination

Approximate Throughput Comparison for 802.11a, 802.11b, and 802.11g

 Data Rate (Mbps) 

Approximate Throughput

(Mbps) 

Throughput as a Percentage of 802.11b Throughput  

802.11b 11 6 100%

802.11g (802.11b clients in cell) 54 8 133%

802.11g (no 802.11b clients in cell) 54 22 367%

802.11a 54 25 417%

802.11 data radios

•For security the system has an encryption key

•Any computer running a wireless link can be connected to the network if it has the encryption key.

•There will most likely be some other security measures put in place at the server end.

New systems for the future

• Where are we heading .

• What will our needs be.

• How many uses can we think of.

• Is it the best way to do it .