Project Communication system

System Architecture:

Previous system:

Open

Figure 1.0: Original communication system using TCP/IP

System Highlights:

• High data rate transmission

• Support TCP/IP communication

• 28 dBm Transmission power (radio datasheet)

Challenges in the Original System:

• Knowledge Gap

• Complicated system for coordinating between multiple links

• heavyweight

• Ground station setup time and transportation

• The omnidirectional antenna is not ideal for competition requirement

New Design Philosophy:

• Modular

• Decouple different radio link

• One radio link only dedicated to one specific use case

• Simplicity

• Lightweight communication protocol

• Portability

System Architecture:

Open

Figure 1.1 Current System Architecture using UART

Note: This communication link aims to ensure reliable communication at all times and to contain only limited critical information (Control input and GPS coordinate output) under limited bandwidth.

Key Feature:

Hardware:

• MAX power output: 27 dBm(~500mW)

• Configurable Frequency Range(REQUIRED BY COMPETITION): Narrow Band

• Error Correction Code (Eliminate error during transmission)

• RSSI monitoring(Radio Strength Indicator)

• Baud Rate: 115200

• Improved Omni-directional Antenna

• UART data port with JST-GH connector compatible with any similar radio

Software:

• Available SIK Radio Configuration Tool

• Handshake before transmission

• Custom lightweight Protocol: Device ID + Message Type + payload

• Support MAX 127 device using the communication link(Unique Device ID)

• Non-blocking UART listener

• Timeout detection plus device reset

Future Roadmap

Antenna:

• Advertise on the SILK Radio, patch antenna can provide significant range improvement

  • https://www.l-com.com/wireless-antenna-900-mhz-8-dbi-flat-patch-antenna-4ft-sma-male-connector

Radio Hardware:

• https://www.digi.com/products/embedded-systems/digi-xbee/digi-xbee-gateways/digi-xbee-modems/xtend-900mhz-rf-modems Using Off-the-shelf RF modems designed for long range use cases

• https://holybro.com/products/microhard-radio?variant=42522025590973 another suggested off-the-shelf hardware

Note: these hardware are ideal after the whole communication system is solidified and the limitation of the current radio system is observed and cannot solved easily. Because the cost of replacing a radio like this is extremely high.

Radio Software:

• TCP/IP through UART using ROS 2 middleware

More Communication Link:

• 2.4/5.8 GHz for High data rate Middle Range Communication (additional for higher bandwidth not critical for rover communication system)

  • Extended Radio Status Information

  • 2 x Video Feed for Driver Control

Canada Legal requirement:

• Operate radio under unrestricted frequency Band

• Operate radio under 1 Watt power output

Note: potentially considering obtaining a Canada Ham Radio license and operating a 2 Watt radio for better range performance.