Concept of Operations

Using for store and forwarding, and remote sensing concepts form the backbone of ASAL-SAT 1. The ground segment will comprise of a cheap but advanced network of ground sensors based on LoRa (Long Range) technology for remote sensing and the ground station . The space segment will include the store and forward functionality and the payloads for pasture identification and vegetation cover investigations. Low Power Long Range (LoRa) modulation technique implemented across many RF chips offers low cost solutions to end users. Such products are extremely admirable for offering solutions in the developing countries. Combining with a satellite service would make such solutions as the one being proposed here economically viable. Though this solution is not offered as a business model, its social impact is great and the governments of the involved countries can quite cheaply and effectively provide it as a service to its citizens to improve their lives and also to serve other national interests such as monitoring desertification, climate change and natural events such as the evolving Rift Valley split and flash floods.

Overall System Configuration

Ground Segment: Collecting data from such areas and relaying it to central databases has always been a challenge. However, with a combination of LoRa devices and nano/micro satellites, this feat can be cost effectively achieved . Use of Long Range (LoRa) Technology has the following admirable characteristics suitable for remote areas.

· Low-throughput communications with data rates ranging from 0.3kbps to 50 Kbps

· Operates on the 433-, 868- or 915-MHz ISM bands and Low power consumption

· Connects to sensors 15-30 miles away in rural areas.

Since for the proposed ground sensor network, the data is quite small in the order of a few bytes per node, the LoRa is extremely suitable. Due to few obstacles in the vast savanna lands, the LoRa nodes can transmit over 15 kms. Thus the gateways can be spaced 30 kms apart such that each gateway covers a radius of 15 Kms. The gateways will augment the data collected from the different sensors within its 15 Kms radius and store this data till a satellite pass occurs. It will then transmit this data to the satellite.

a)Livestock and wildlife population mapping, enumeration and tracking

Livestock and Wildlife Monitoring

For cattle tracking,only a few of the livestock need to have LoRa-tracking collars. Their movement will generally indicate the movement of the whole herd of cattle. Livestock and Wildlife Monitoring will have a rough estimate of the livestock keeping patterns and mapping of their population to help curb overgrazing that leads to desertification and communal conflicts as a result of sparse pasture. The pastoralists will benefit in keeping track of their livestock especially in the case of cattle rustling that is quite rampant across the Sahara among the cattle keeping communities. Consequently, with the knowledge that the livestock will be easily tracked, people will be discouraged from engaging in cattle rustling.

For wildlife tracking, there are numerous game reserves, national parks and ranches across the Sub-Saharan AfricaThe use of LoRa trackers will be appropriate as they are cheap, low power and the batteries will last for years before they need replacement.

The LoRa-enabled trackers will be randomly strapped on various parts of a given livestock. The rest of will have similar but dummy straps that will make it hard for a potential rustler to pick out non-tracked humans. End node will be a LoRa human tracker – TM900-N1C1. This is a low-cost tracker that meets all the requirements for human tracking in remote areas:

·Standby battery lifespan of more than 10 years

·Light weight and small in size- 3grams

·Transmission distances of over 10 Km

·Transmitting Power up to +20 dBm

LoRa Human tracker

b)Flash floods/ Water Level monitoring and warning system

In the remote and pastoral areas, many of the rivers are seasonal. During the rainy season, the rivers suddenly get swollen and the residents downstream are always caught off-guard resulting in loss of lives and property. Incorporation of water level sensors and LoRa transceivers along such seasonal rivers can form a cheap yet expansive floods monitoring system. Water level sensors interfaced with LoRa transmitters (nodes) can be located at various points upstream of a major road/route or known hotspots. The LoRa nodes will then transmit to the LoRa gateway in their vicinity. The LoRa gateway will then transmit to the satellite.

River and water level monitoring

A non-contact LoRa-enabled water level sensor shown below is quite suitable.

·Maximum range of 10 meters (394 inches)

·Real-time automatic calibration (voltage, humidity, and ambient noise)

·42kHz ultrasonic sensor measures distance to objects.

LoRa based water level sensor

c) Pasture and water identification and vegetation cover surveillance Majority of the pastoralists’ communities across the Sub-Sahara, including in Kenya, are nomadic in nature. This means that they move from place to place in search of water and green pastures for their livestock. Such lifestyles would greatly benefit from a system that can help the nomads identify pastures and water points closest to their present locations. This can be achieved by use of a cheap yet high resolution imaging equipment. The High Precision Telescope (HPT) is a prime candidate for this mission. It will be presented in detail in the Space Segment.

Key Performance Parameters

i) Tracking updates at 30 minutes intervals The livestock and wildlife tracking function should receive location updates at intervals of approximately 30 minutes. A minimum of 3 satellites placed on the equatorial plane 120° apart will achieve a revisit time of about 30 minutes.

ii)  Ground resolution of 5 meters for pasture and water identification. The nomadic lifestyle is informed by search of pasture and water. The ASAL-SAT should provide imagery capable of making this identification. The High Precision Telescope (HPT) will deliver this high resolution.

iii) Flash floods warning system updates of at least 15 minutes’ intervals. The minimum success level for flash floods data update is 15 minutes updates. For a near-real time update, 5 minutes will be an acceptable interval.

Space Segment Description

The ASAL-SAT 1 will contain two main payload subsystems: LoRa Gateways and a High Precision Telescope

a)LoRa Gateways

The novel part of the proposed solution is that the individual sensors on the ground don’t need to establish a link with the satellites. Instead, the individual sensors (LoRa nodes) will transmit to the LoRa gateways in their vicinities. These gateways will augment data from different nodes and transmit to the satellite. Since LoRa is a modulation technique based on the Spread Spectrum, both the receiver and transmitter need to implement the same protocol. Hence on the satellite, a LoRa transceiver (which is another gateway) has to be implemented. This gateway will form a link with the various gateways on the ground during a satellite pass.

·More than 1 gateway can be deployed to serve several channel settings.

·Capable of simultaneous reception on several channels and implementing the LoRaWAN specification

·Sensitivity of up to -142 dBm

 LoRa Gateway

b) High Precision Telescope (HPT)

This imager has a ground resolution of about 3 meters. It has been successfully implemented in Philippines Diwata-1 and Japanese Rising-2 microsatellites. The Rising-2 microsatellite HPT has an observation area of about 3.2 km x 2.2 km. Its imaging system took high resolution images in 400 spectral bands with 5m GSD [6].