Last updated on April 26th, 2024
The native positioning is an additional service on top of data uplink subscription, the data uplink service is thus required to activate the service.
| Service | Description | Specifications |
|---|---|---|
| Native positioning | 1 position every 4 received transmissions, on average |
|
Service Access Model
- Complementary service: on top of Data uplink service. Messages received for data uplink service can be used to compute native location
- Dedicated: Specific short messages. Native location is calculated with dedicated Low power short transmissions for longer autonomy
- A combination of both types of messages
Why use the native positioning?
- No need for GNSS receiver and antenna integration for smaller and less expensive devices
- Power saving solution for device positioning since it can be computed using messages containing useful data and thus does not require additional emissions
- 200m to 1km accuracy for static asset
- Insensitive to GNSS jamming
- Unforgeable Doppler based location
How does it work?
Basic principle
When a device transmits signals to the Kinéis satellites, it is possible to compute a position using the Doppler effect.
The Doppler Effect is the change in frequency of an electromagnetic wave that occurs when the source and observer are moving relative to each other.
In this case, the following hypotheses are made:
- the device is considered still in comparison of the satellite passing above at a speed of about 8km/s
- the frequency transmitted by the device is considered constant
A transmitter certification with good frequency stability is necessary to access this option.
The satellites measure the received frequencies of all messages, which allow to trace the evolution of the received frequency over time, called Doppler curve:
As a result, one position is computed from a cluster of several frequency measurements, performed thanks to the reception of several messages.
Native positioning has existed for 40 years! Argos has contributed to the knowledge of the migratory routes followed by animals thanks to the Doppler effect exploitation.
Step-by-step native positioning
