Communication System

•	Control from remote site (non line-of-sight).
•	Uninterrupted command and control.
•	2.5 Mbps from the rover to the control station during times the rover is operational.
•	500 Kbps from control station(s) to the rover during times the rover is operational.
•	Communication range up to 10 Kms between the rover and the relay station.

Requirements

Item	Data rate	Data rate with 
Compression	Comments	Total	
Uplink					
Rover Status	20 int at 4 Hz	1280 bps	Continuous	
2.5 Mbps
(with protocol overheads)	
Panospheric Camera	2k x 2k @10 bit, 6-8 Hz = 32 Mbps	1.88 Mbps (170:1 compression)	Continuous		
Front Camera	1k X 1k @ 8 bit 		Occasionally		
Back Camera	1k X 1k @ 8 bit		Occasionally		
Stereo Cameras			For Debugging only		
Downlink					
Command & Control	20 int + 20 floats at 4 Hz. 	3840 bps	Continuous	
500 Kbps available 	
Camera Control			Which camera, Compression Ratio, FOV		
Downloading code	-	-	Occasional		

Data Rate Requirements

Current Configuration

Block Diagram
•	8-10 Kms range at high data rate cannot be achieved with omnidirectional antennas.

•	The data rate drops rapidly with the pointing offset. 
Antenna Pointing- Why?

Item	Value	Comments	
Elevation range	-60 to + 60 deg		
Azimuth range	360 deg	Continuous	
Elevation Rate	60 deg/sec		
Azimuth Rate	30 deg/sec		
Elevation Acceleration	190 deg/sec^2		
Azimuth Acceleration	190 deg/sec^2		
Pointing Accuracy	2.5 deg 	Aggregate	
Pay Load Mass	2 kg 		
Payload Size	27.3 x 34.0 x 2 cm		
Target Mass	Approx. 6 kg	Flexible	
Target Power	Approx. 25 W	Flexible	
Environmental			

Antenna Pointing- Requirements
Configuration:
•	Azimuth/Elevation Configuration
•	Slip ring for elevation actuator
•	RF rotary joint to send RF signal from the transmitter to the antenna.

Sensing:
•	Differential GPS 
•	Incremental Encoders
•	Gyro Compass
•	Inclinometer
•	Inertial Measurement Unit

Antenna Pointing- Configuration

•	2.5 Mbps to Pittsburgh/ 0.5 Mbps to the Rover
•	3.4 m C-band dish mounted on a truck
•	Duplicate for each component (except the dish)
•	Modem capacity- 8 Mbps
•	Flexibility in link time/duration
•	Downlink in Miami
•	Landline to Pittsburgh (satellite vendor responsible for the landline)
Satellite Link
•	Tested high gain planar antenna (8dB gain) for long range. We were able to achieve 3.5 miles LOS communication with these antennas. 
•	Higher gain planar antennas and New bridge arrived yesterday. 
•	Satellite vendor have been identified and the formal contract would be signed soon. 
•	The design of the pointing mechanism is being finalized. 
•	The sensors needed for pointing are identified and some of the sensors (gyrostabilized compass, IMU) are acquired and being tested. 
•	The simulation of the pointing system are in progress and would be completed in next 2 weeks.

Status

•	Expected Data rate 2 Mbps continuous.
•	Range of 8-10 kms between the rover and the relay station is expected to be achieved.
•	Command and control is communicated via a lower bandwidth, higher reliability (non-LOS problems to a lesser extent) serial modem.
•	Same configuration as Ratler.
•	The high gain planar antennas are light weight and have wide beamwidth suitable for the application.
•	Antenna pointing is required, but the accuracy requirements are generous. 

Features

•	Non-LOS is a big issue
- Couldn’t identify a radio which would give non-LOS transmission over 8-10 miles range. 
- “Freewave radio” needs to be tested for longer range and non-LOS. 
- Worst case- use repeaters and/or choose the terrain accordingly. 
•	Antenna Pointing Mechanism development needs to speed up. 
•	Closing the feedback loop for antenna pointing is important, but we don’t have a proven/tested solution.

Issues

•	Test “freewave radio” for 8-10 miles LOS and non-LOS. If freewave doesn’t work, “Pacific Crest” which is a lower frequency radio might be better. What are the other options?
•	Test the “BR2040-EE” wireless ethernet bridge over longer range and various pointing offsets with the new antennas.
•	Speed up the development on the Antenna Pointing Mechanism.

Future Work

Communication- Block Diagram