Communications System (2021-2022)
- Jasmine Milan
This page is currently in progress. Eventually it will indicate the current communication system, summaries the past communication system and outline and mechanical requirements
Current Communications System - (2021-09-09)
TLDR
- 900MHz antenna -> M900 router (Rocket)
- 2.4 GHz antenna -> M2 router (Rocket)
- 5 GHz antenna -> M5 router (Rocket)
System Summary
There are six total small rover-side antennas, divided into three types: 900 MHz, 2.4GHz and 5GHz. Each type of antenna connects to a particular router: M900, M2 and M5 respectively. The two 900 megahertz Bluebeam antennas (the blue spiral ones) connect to the Rocket M900 router. The two 2.4 gigahertz antennas are Hyperlink HGV-2406Us, they're the longer ones. They connect to the Rocket M2 router. The two 5 gigahertz antenna are Hyperlink HGV-4958-06Us, they're the longer ones. They connect to the Rocket M5 router. Each router is connected through ethernet to the switch (the Ubiquiti edge router). The switch is located to the electrical box and connected to power.
Wire Diagrams
Datasheets
Rocket M900 / M2 / M6 (Routers): https://drive.google.com/open?id=1re80kG7bs59b6KeSXt-gQb1Q-SbUkHl8 (Updated: https://dl.ubnt.com/datasheets/rocketm/RocketM_DS.pdf )
Hyperlink HGV-4958-06U (Antenna): HGV-4958-06U (l-com.com)
Hyperlink HGV-2406U (Antenna): https://www.farnell.com/datasheets/2628765.pdf
900MHz Blue beam Ultra (Antenna): I couldn't find the data sheet but here's a website link ->https://hobbywireless.com/800900-mhz-antennas-c-179_73_74/900mhz-blue-beam-ultra-antenna-set-rhcp-p-1007.html?language=en
Ubiquiti Edge Router (Switch): https://dl.ubnt.com/datasheets/edgemax/EdgeRouter_DS.pdf
Prior Communication System (2020-05-29)
This information is pulled from this document from the google drive. Created by Christopher Arjune on May 29th 2020.
TLDR
900MHz
Rover status sent to base station, commands sent to rover
HGV-906U antennas + Rocket M900 routers used on base station, Bluebeam antennas + Rocket M900 on rover
2.4GHz
Only rover video feed to base station
Integrated Jetson wireless card and default antennae on rover, directional Yagi antenna + Asus RT-N13 D1 router at base station
Directional antenna at base station tracks and points to rover
Datasheets
Rocket M900: https://drive.google.com/open?id=1re80kG7bs59b6KeSXt-gQb1Q-SbUkHl8
HGV-906U: https://drive.google.com/open?id=1w8MaTKccprmBUwlwNGX035lWf5a-_n9f
Tupavco Yagi: https://drive.google.com/open?id=1QM-I7qOnkPHVuB5dKcVT7ofXfDeJYlCD
Jetson TX2: https://drive.google.com/open?id=15ZsqxhrSBD7LPu8D6NIBwL9_dbkmHPGf
System Summary
Overall, there will be a base station situated with the human controllers, and a smaller RF module on the rover that we will communicate with. This will consist of both 900MHz and 2.4GHz systems.
900MHz
The connection is bidirectional, with important rover status information being sent from the rover to the base station and movement commands sent from the base station to the rover. As of S2019, the old setup being used was an omnidirectional HGV-906U[1] antenna connected to a Spectra 920[2] router on both the rover and base station. No additional hardware is necessary to facilitate a stable connection, given the nature of the lower frequency signal.
The new setup uses Ubiquiti Rocket M900s as the routers on both sides of the system, with the antenna connections tentatively set as omnidirectional Bluebeams[7] on the rover side, and one or two omnidirectional HGV-906U[1] antennas on the base station.
2.4GHz
The main purpose of this connection is to transmit video feed data from the camera(s) mounted on the rover to the control team as a primary means of navigation and sensory data. Therefore, to maximise reception the base station antenna is directional and must be faced towards the rover for the best signal reception.
On the old (2017) setup, we used VIP 2400 routers, a rubber duck antenna on the rover, and a HG2415U-PRO[3] omnidirectional antenna for the base station. This year, the rover antenna is an omnidirectional rubber duck antenna for weight and technology constraints; and the base station is a rotating directional antenna that will track the rover’s relative location and move accordingly. The routers we are using is an Asus RT-N13 D1[4] on the base station side, and an integrated WLAN module on the Jetson TX2[5] on the rover side, and will be connected to the antenna using coaxial cables[6]. Due to the relatively inflexible nature of the cables, care will need to be taken to ensure the cables don’t bend too much and that rotation won’t cause any pinching, and allow for at least 180° horizontal rotation during competition and adjustable vertical angle of about +/- 20° in 5° increments during setup. Attached to the router on the base station will also be a controller unit for the rover tracking and rotation control, specified by the software team.