Satellite Based Augmentation System (SBAS)

Simplified the Satellite Based Augmentation Systems (SBAS) are satellite supported DGPS whereby the correction signals that improve the accuracy of the GNSS receivers are transmitted by satellite. WAAS (Wide Area Augmentation System), EGNOS (European Geostationary Navigation Overlay System), and MSAS (Multifunctional Satellite Augmentation System) together are designated as Satellite Based Augmentation Systems. The WAAS is available in America, EGNOS is the European equivalent, while MSAM operates in Asia. SBAS can help correct errors caused by distortion of GNSS signals as they pass through the ionosphere as well as clock and orbital variations associated with individual GNSS satellites. SBAS uses a network of ground-based stations that compare their precisely known location with locations calculated from GNSS satellite signals. Any differences found can be used to create correction data that is broadcast from SBAS satellites.

Satellite Signal

Raw data received from satellites in the context of a GNSS. In an ETC System they can be used for the calculation of a geoposition.


Support Beacon


Secure Chip Card

SCC Warning Limit

If the Value of Onboard Account falls below this limit, a warning about the decreasing of the Onboard Account will be displayed to the driver. Used for Registered Accounts and for Anonymous Accounts. Used on each SCC.


A political motivated programme, law or equivalent resulting in users being obliged to pay fees as defined in a tariff.


The displayable entity of OBU that is shown on the display at a time. The content of a screen might be larger than the physical display (the complete content of a screen can be viewed e.g. by scrolling).


An ordered string of vertices (x,y co-ordinate pairs) that begins at one location and end at another location connecting the segment to the (e.g. street-) network. The connecting points are called nodes.

Segment Charging

A tolling scheme that establishes fees for the usage of street segments.

Self Test

Verification of the hardware and software configuration item status.


The item is personalised by the user himself. The data is verified by online inquiring central systems or ex-post (if at all).

Sensor Fusion

A method to combine independent position or motion information into one result. Typically GNSS information is enhanced with data from inertial or odometer sensors to bridge situations with low or none satellite signals. The different sources are weighted by their inverse error and possibly additional model assumptions are made (like dead reckoning or Kalman filtering).

Service Level Agreement (SLA)

A contractual agreement between a service supplier and receiver about the definition of KPIs (their measurement) and the allowed value ranges as well as the consequences of violations.

Service Point

Abstract Role within the ETC System, in reality this could be a gas station, a retail shop, a checkout counter in a shop or a variable location where a transaction occurs or where users can get technical assistance with the mounting and maintenance of vehicle sided equipment (OBE/OBUs).

Service Provider

The Service Providers are offering (toll) Service by issuing OBUs, contracts and payment means to the road users. They will claim payment for the services consumed by their customers and guarantee to disburse this payment to the Toll Chargers. Each Service Provider (via its own methods, equipment and systems), insures functional and operational conformity of his OBUs. The OBU is able to exchange data (directly or via a proxy) with Toll Charger systems (including Enforcement functions) according to interface specifications mutually agreed by both Service Provider and Toll Charger. Within European standardization efforts it is named EETS Provider.


Service tool for OBU.


Technical devices such as [OBU], antenna or cables that can be merged to an article groups.


Standard deviation.


Subscriber Identity Module

Smart Client

An OBU implementing client centric toll event detection. Smart clients are believed to have a higher hard- and software complexity and costs than thin clients. Sometimes called "Thick Client", this term shall be avoided.


Short Message Service


Signal Noise Ratio

Stationary Enforcement

Enforcement by fixed installed equipment (which is typically only operated with a given duty-cycle).

Status Indicator

Status Indicator represents the readiness of OBU regarding participation for automatic schemes: ready or not ready ("green or red LED"). It is derived from Status Vector according to a well defined rule set.

Strict Personalisation

The personalised item is physically imprinted with specific personalisation data.

Subsequent Invoice

Invoice issued to a defaulting road user to make him pay the missing amount of road charge


Process of monitoring. An organisation unit (OU) and the associated systems responsible for the independent monitoring and documentation of the compliant operation of a system. Independent means that the supervision is only collecting and probing certain data in the production system, but processes these inputs organisationally and technically independent from the data sources.

Support Beacon

A special form of roadside equipment helping GNSS based positioning systems to resolve rare ambiguities.