Comms Research
- Logan Hartford
- Yuchen Lin
The first stage of figuring out how the comms system works is determining what we know now and then determining how we can get more information. @Yuchen Lin
Therefore the first steps are (check off as completed):
New:
Information Gained:
Write down anything you learn during your investigation here. Try and keep it organized as this document will eventually be turned into a formal piece of documentation.
URC Rules and Requirements for Radio Communications 2023
There will be a line of sight from the command station to the rover (Transmit and receive data without obstacles) during science, equipment servicing, and autonomous navigation.
Line of sight is not guaranteed 50% of the time during extreme delivery (distance: 1km+).
Global Navigation satellite system standard used (comms should transmit the data) [not clear: real-time transmitting or stored]
Tethered communications are not allowed (must be a single connected platform)
The antenna and any other system should be able to fold/ bend to fit into the transportation crate.
Wireless communication must be without delay.
Normal wireless INTERNET is not available, and cannot use satellite INTERNET.
The communication system can be powered off (no interference to other teams).
Communication methods must follow United States Federal Communication Commission standards and regulations.
Details on the communication system and the operator licenses before Apr 28, 2023.
Omnidirectional and directional antennae are both permitted. If the antenna moves it must be mechanized (no tracking by hand) to trace the signal from the ground station. (Can use Signal strength and relayed GNSS to track signal) (cannot use the camera for visual feedback)
Base station antenna height limit: 3m follow all the related regulation
The base station is located within 5 meters of the command station, with anchored rope within 10 meters
Should backup at least 25 meters of communication cable to reach the allowable antennae location given by the judge. (3.b.iv). i.e. the antenna and base station with not be in the same place.
The frequency bandwidth should not be greater than 8MHz.
3 levels of 900 MHz frequency are permitted: 900-low, 900-Mid, and 900-High. Should be operating exclusively in one of these bands. Sub-band will be notified before the competition and you must be able to switch from one to another. No channel number limit.
2.4 GHz frequency band: use center frequency channels 1-11 defined by IEEE 802.11 standard for 2.4 GHz.
No frequency greater than 22 MHz.
Must be able to shift to other channels based on the information given by the competition. Limited to a max of 3 channels in 2.4 GHz.
Rules 15-19 apply to both the rover and the base station.
Narrowband is allowed (fixed channel allocation or spread spectrum as long as fits the limit).
Anticipate other teams operating on different sub-bands, and must not interfere without communications. Must be able to deconflict the communications. 0.5 km minimum separation will be guaranteed.
Encouraged to use bands outside 900 MHz and 2.4 GHz but this requires a ham radio license. But interference outside 900MHz and 2.4GHz will not be granted with extra time or consideration.
Encouraged to use spread spectrum, automatic channel switching, frequency hopping, and interference tolerant protocols.
It is considered an intervention when it is required to move the rover in order to re-establish the connection with the rover. All the rules for intervention are applicable here.
URC Communications Advice 2023
The communications system requires proper design and testing (comms is the number one reason for failure during competition.)
The communication system should be firm and reliable.
In most tasks command station and rover are not far apart, but may experience wide angles for communication. Must be able to support wide-angle communications. There are tasks that require long-distance operations. Preparation for both.
Radio signals will not go through walls, Teams must mount the antenna outside the Hab, control station.
Design communication links in advance and testing in realistic cases. Test in a similar situation and test before the real competition.
RF/Comms Drive
900 MHz research:
File: 900 MHz base station antenna
Topic: Omnidirectional antenna selection
Requirement: 1km range + 900 MHz => adequate 6 DBi(concentration of the signal)
consideration:
Antenna Gain
Size
Weight
The shape of the transmission pattern reference where the antenna is pointed at
Weather application
Support Non-Line of sight for multipoint (if possible)
Lower DBi under the same range => better range cover.
File name: 900 MHz Routers research recommendations
Topic: Router replacement selection
Considerations:
Full dimension
Weight
Prize
Supporting distance and protocol use(normally TCP/IP)
Point to point or point to the multi-point application
Send & receive data period. Time division multiple access(TDMA).
Max supporting multi-input and multi-output
Performance through obstacles
Longest transmission distance
Note: Special antenna array design can create a better gain in DBi.
File name: 900 MHZ Base station proposal
Purpose: (base station = router + antenna) this file compare different solutions with different combination
consideration:
Prize
Dimensions
Directionality
Horizontal beam width
Vertical beam width
TX power (dBm) == device worst-case transmit power
Power consumed
Note: directional antenna may need a rotating base station to accommodate different ranges. And the perpendicular distance should be bigger than the estimated distance of the object.
File name: ALLAN-900MHz rover antenna set
Summary: each antenna is connected to a semi-rigid cable and therefore gives the ability to change the angle tilts. The document gave some of the available options in stock.
File name: robotics antennas
Summary: discusses the possible antennas that can be mounted onto the rover
Folder Name: Haiyi_s Folder of stuff
File name: Comms 13_10_18
Description: Meeting minutes
Note: The document may not be relevant to us anymore; because we are not permitted to use manpower.
File name: Comms overview. pptx
Key Points:
communication between rover and base station use protocols (not specified)
current setup:
900 MHz for control and data
2.4 GHz for video feed
900 MHz lower frequencies, fewer data send through, generally longer distance
Current setup: a base station and rover all use an omnidirectional antenna and wireless modem
2.4 GHz communication more data send through; more scattering off occurs. The closer the distance better the signal due to the scattering off.
Current setup: Base station and rover: directional antenna + commercial router/AP/ modem
The direction of the antenna is powered by the motor and potentiometer.
File: Wireless card notes
Description: some updates on the project
Key: ROS links for video compression
http://wiki.ros.org/image_transport
http://wiki.ros.org/image_transport/Tutorials/ExaminingImagePublisherSubscriber
http://wiki.ros.org/ROS/Tutorials/UnderstandingNodes
Folder name: Research
File: 900 MHz Channel map
Description: All the channels in the 900 MHz channel
File: Antenna Separation
Key Points:
There is a minimum horizontal distance and a maximum distance between the antenna sets.
1/4 of its wavelength < horizontal separation < 3-4 multiples of the distance
Useful document links:
900 MHz channel map.pdf
Antenna Separation length.docx
Current using antenna HGV-903U and HGV-906U datasheet
Nvidia Jetson Tx2 System on module documentation/data sheet manual
Jetson TX 2 developer Kit document.pdf
The current 2.4 GHz Router onboard setup
Copy of 2019 Wireless comms Basics
URL: https://docs.google.com/document/d/1diVcC8DwMZCG_oiZM34Dp_K7hfU9QQ5bv1IXBMVbixU/edit
Information From Other Leads
Austin: There is a comms testing board above the EE shelf.