Norwegian Metrology Service

Jammertest is the largest known GNSS jamming, meaconing, and spoofing test event in the world, which has an open policy towards both user participation and user communication with no restrictions on the sharing of data or publication of results. The organizers implemented several changes and enhancements within the 2023 test campaign to further broaden the appeal and applicability of the tests for as many demographics of GNSS users as possible. More than 200 participants from 19 nations took part in person from 18 to 22 September at the test sites along the west coast of the Andøy island. This paper summarizes the design and motivation of the tests and test venue with particular attention to the efforts taken to provide users with precision timing and frequency references independent of the denied and disrupted GNSS signals. Aspects of surveilling and enforcing unintentional emissions, and real-time communication and coordination to the large number of distributed participants are also discussed.

The room temperature dual-mode self-calibrating detector combines low-loss photodiodes with electrical substitution radiometry for determination of optical power. By using thermal detection as a built-in reference in the detector, the internal losses of the photodiode can be determined directly, without the need of an external reference. Computer simulations were used to develop a thermal design that minimises the electro-optical non-equivalence in electrical substitution. Based on this thermal design, we produced detector modules that we mounted in a trap structure for minimised reflection loss. The thermal simulations predicted a change in response of around 280 parts per million per millimeter when changing the position of the beam along the centre line of the photodiode, and we were able to reproduce this change experimentally. We report on dual-mode internal loss estimation measurements with radiation of 488 nm at power levels of 500 μW, 875 μW and 1250 μW, using two different methods of electrical substitution. In addition, we present three different calculation algorithms for determining the optical power in thermal mode, all three showing consistent results. We present room temperature optical power measurements at an uncertainty level approaching that of the cryogenic radiometer with 400 ppm (k = 2), where the type A standard uncertainty in the thermal measurement only contributed with 26 ppm at 1250 μW in a 6 hour long measurement sequence.

We report proof-of-concept experiments on an optically driven Josephson voltage standard based on a mode-locked laser (MLL), a time-division multiplexer, and a cryogenic ultrafast photodiode driving an overdamped Josephson junction array (JJA). Our optical pulse pattern generator (PPG) concept builds on the capability of MLLs to produce trains of picosecond-wide optical pulses with little amplitude and temporal spread. Our present setup enables multiplication of the original 2.3 GHz pulse repetition frequency by a factor of 8. A commercial photodiode converts the optical pulses into about 25 ps wide electrical pulses in liquid helium several cm from the JJA. Using a custom-made MLL, we can drive a JJA with a low critical current of 360 μA at multiple Shapiro steps. We have performed experiments with pulse pairs whose time interval can be set freely without distorting the shapes of individual pulses. Experimental results are in qualitative agreement with theoretical simulations, and they demonstrate, e.g., crossover in the Shapiro step pattern when the time interval between the pulses is approximately equal to the inverse of the characteristic frequency of the JJA. However, there are quantitative discrepancies, which motivate an improved integration of photodiodes and JJAs to improve both the understanding and fidelity of Josephson Arbitrary Waveform Synthesizers. Considering future quantum technologies in a wider perspective, our optical approach is a potential enabler for fast and energy-efficient pulse drive without an expensive high-bandwidth electrical PPG and without high-bandwidth electrical cables that yield too high thermal conductance between cryogenic and room temperatures.

In this paper, we investigate three different passivating films for use in predictable quantum efficient detectors: two monolayer films of SiNx with different compositions and one double-layer stack of SiNxOy capped with SiNx, all deposited on very high resistivity silicon substrates. In addition to the conventional characterization methods, we also utilize the novel method of photoluminescence imaging under applied bias (PL-V) and high voltage soaking to modulate the fixed charge density Qf in the layers. All films exhibit very good passivating properties after deposition and annealing, with the oxynitride stack providing the best passivation, resulting in an effective carrier lifetime close to 20 ms. This value is explained by a relatively high fixed charge density of Qf = 1.12 × 1012 cm−2 and low interface defect density (S0,n = 6.0 × 102 cm/s), giving a chemical passivation which is an order of magnitude better than the investigated nitrides. Both nitride films were readily charged by voltage soaking, increasing the effective carrier lifetime by about 20%. Based on the passivating properties, photodetector device simulations predict that self-induced photodiodes made with any of these passivation layers will have an internal quantum deficiency well below 1 ppm for selected wavelengths at room temperature, and all the investigated materials are thus good candidates for use as passivating layers in such photodiodes.

A very promising alternative to the state-of-the-art static volume measurements for liquefied natural gas (LNG) custody transfer processes is the dynamic principle of flow metering. As the Designated Institute (DI) of the LNE (‘Laboratoire National de métrologie et d’Essais’, being the French National Metrology Institute) for high-pressure gas flow metering, Cesame–Exadebit is involved in various research and development programs. Within the framework of the first (2010–2013) and second (2014–2017) EURAMET Joint Research Project (JRP), named ‘Metrological support for LNG custody transfer and transport fuel applications’, Cesame–Exadebit explored a novel cryogenic flow metering technology using laser Doppler velocimetry (LDV) as an alternative to ultrasonic and Coriolis flow metering.Cesame–Exadebit is trying to develop this technique as a primary standard for cryogenic flow meters. Currently, cryogenic flow meters are calibrated at ambient temperatures with water. Results are then extrapolated to be in the Reynolds number range of real applications. The LDV standard offers a unique capability to perform online calibration of cryogenic flow meters in real conditions (temperature, pressure, piping and real flow disturbances). The primary reference has been tested on an industrial process in a LNG terminal during truck refuelling. The reference can calibrate Coriolis flow meters being used daily with all the real environmental constraints, and its utilisation is transparent for LNG terminal operators.The standard is traceable to Standard International units and the combined extended uncertainties have been determined and estimated to be lower than 0.6% (an ongoing improvement to reducing the correlation function uncertainty, which has a major impact in the uncertainty estimation).

Our dual-mode optical power detector combines the principles of electrical substitution with measuring photocurrent. We present a new detector design, which shows a considerable reduction in non-equivalence between optical and electrical heating during electrical substitution.

The AC-DC difference of a set of current shunts produced by the Norwegian Metrology Service (Justervesenet), were measured by PTB and Justervesenet, in a bilateral comparison, where Justervesenet acted as the organizer and pilot laboratory. The nominal values of the current shunts are 30 mA, 100 mA, 300 mA, 1 A, 3 A, 5 A, 10 A and 20 A, which were measured at their nominal values for the frequencies 10 Hz, 20 Hz, 55 Hz, 110 Hz, 400 Hz, 1 kHz, 5 kHz, 10 kHz, 20 kHz, 50 kHz and 100 kHz. All current shunts were measured in combination with Planar Multi-junction Thermal Converters produced by PTB.The results show that there is a degree of equivalence within 0.4 for all measured values, and that for frequencies below 10 kHz, the value is typically below 0.2. Hence, there is a very close agreement between the measurements, which are not correlated by traceability chains, and the properties of the current shunts have been documented by the comparison. Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).