# IEC-61108-7 SBAS Standard for Shipborne Receivers: Preliminary Testing Validation Activities +
## 2 Setup Design and Realization  
JRC and ESSP prepared a testbed specifically designed to assess the implementation of the test scenarios and the assessment of the pass/fail criteria defined in [11]. All the tests were carried out--a subset of the tests at the EU Testing and Demonstration Hub for the GNSS Programmes of the JRC, in Ispra (Italy) [12], and the rest at the ESSP premises in Torrejon (Spain). A schematic representation of the setup used at the JRC is shown in Figure 1. The main elements of the setup are the following:  
* The GNSS simulator on which the scenarios specified in the standard were implemented. For these tests, a commercial GNSS simulator able to generate GPS L1 C/A and EGNOS signals was used. * An inline low-noise amplifier (LNA) with a 25 dB gain between the GNSS simulator and the SBAS receiver under test. This was employed to emulate the use of an active antenna, which is normally used in ships equipped with an SBAS receiver. * Interference signal generator used to externally generate the interfering signals that are then combined with the GNSS signals. The instrument can generate four classes of waveform: continuous wave; frequency, phase, and amplitude modulations; calibrated additive white Gaussian noise; and arbitrary digital waveforms with an instantaneous bandwidth up to 100 MHz. * A shipborne receiver or device under test (DUT) connected to the RF output of the LNA. This DUT outputs through one of its hardware interface NMEA messages or sentences according to the IEC 61162-1 standard [13]
* A data logger is used to collect the stream of NMEA messages from the hardware interface. A fundamental element of the test setup realization is the calibration of the insertion losses of the radio-frequency combiner and of the cables. In the specific setup, insertion losses of about 4 dB were estimated; for the test, interference signal insertion losses need to be considered by increasing the power level of both the GNSS and the interference signals. A test suite was developed on a host computer that managed the overall test execution in an automatic manner. First, it was able to interface with the DUTs via a virtual COMSB RS232 and also over the network via a TCP socket. The control software was based on a Python software tool running on an Ubuntu OS laptop. This software was used to configure the receivers to send specific commands (e.g., a configuration sentence or a cold start command) to interface with the GNSS simulator to load and execute the test scenario. In addition, the application received and collected the NMEA sentences from the DUTs and those logged by the GNSS simulator. The performance of the DUT was assessed by parsing and analyzing the logs of the NMEA messages output by the receiver during the tests and those from the GNSS simulator, which were taken as a reference to estimate the accuracy of the position velocity and timing (PVT) solution. Throughout the exercise, all the test cases outlined in the standard were carried out. A detailed description of these test cases can be found in Section 6.10 of [11]; a brief  
Figure 1: Schematic representation of the experimental setup developed for the testing campaign of the IEC 61108-7 standard. overview of the tests and their corresponding pass/fail criteria is provided below. The performance of the receiver under static conditions is evaluated in TC-001 and TC-002. The key difference between the two scenarios is the oscillatory movement of the antenna in TC-002 to simulate the vessel's roll movement due to waves. In addition, the accuracy of the position under dynamic conditions is assessed in TC-003 and TC-004. The pass/fail measure for these tests is based on a 95% acceptance rate for horizontal position error. The device's capability to deliver an accurate position fix within the warm start time limit (i.e., 5 min) is examined in TC-005.