1B Processor Research Articles

Swarm Thermal Ion Imager measurement performance

We assess the performance of the thermal ion imaging (TII) technique as conceived for the Swarm Earth Explorer satellites. Analysis, simulation, and laboratory testing performed prior to flight provided estimates of systematic and random error sources of the electric field instrument’s vector ion drift, electric field, and ion kinetic temperature measurements. An end-to-end instrument simulator, consisting of models of the TIIs on a prototypical Swarm satellite orbiting Earth with ionospheric plasma, electric field, and magnetic field inputs, was used to generate TII sensor data (level 0 instrument data). These data were processed with a prototype processor (the level 1b processor) to characterize theoretical measurement performance. We describe the methodology used to assess TII measurement uncertainty and present the main findings of the end-to-end measurement performance study. In addition, we assess the measurement performance achieved during approximately eight years of orbital operations. Example measurements demonstrate the quality of ion drift velocity. Unprocessed TII imagery reveals spurious signals which can affect measurement performance. Availability of such imagery has proven vital for diagnosing measurement anomalies associated with sensor operation and spacecraft–plasma interactions.Graphical

In-flight calibration results of the TROPOMI payload on board the Sentinel-5 Precursor satellite

Abstract. After the launch of the Sentinel-5 Precursor satellite on 13 October 2017, its single payload, the TROPOspheric Monitoring Instrument (TROPOMI), was commissioned for 6 months. In this time the instrument was tested and calibrated extensively. During this phase the geolocation calibration was validated using a dedicated measurement zoom mode. With the help of spacecraft manoeuvres the solar angle dependence of the irradiance radiometry was calibrated for both internal diffusers. This improved the results that were obtained on the ground significantly. Furthermore the orbital and long-term stability was tested for electronic gains, offsets, non-linearity, the dark current and the output of the internal light sources. The CCD output gain of the UV, UVIS and NIR detectors shows drifts over time which can be corrected in the Level 1b (L1b) processor. In-flight measurements also revealed inconsistencies in the radiometric calibration and degradation of the UV spectrometer. Degradation was also detected for the internal solar diffusers. Since the start of the nominal operations (E2) phase in orbit 2818 on 30 April 2018, regularly scheduled calibration measurements on the eclipse side of the orbit are used for monitoring and updates to calibration key data. This article reports on the main results of the commissioning phase, the in-flight calibration and the instrument's stability since launch. Insights from commissioning and in-flight monitoring have led to updates to the L1b processor and its calibration key data. The updated processor is planned to be used for nominal processing from late 2020 on.

CryoSat-2 range, datation and interferometer calibration with Svalbard transponder

Transponders are commonly used to calibrate absolute range from conventional altimeter waveforms because of their characteristic point target radar reflection. The waveforms corresponding to the transponder distinguish themselves from the other waveforms resulting from natural targets, in power and shape. ESA deployed a transponder available for the CryoSat mission (a refurbished ESA transponder developed for the ERS-1 altimeter calibration). It is deployed at the KSAT Svalbard station: SvalSAT. The transponder is used to calibrate SIRAL’s range, datation, and interferometric phase (or angle of arrival) to meet the mission requirements. In these calibrations, 3 different types of data have been used: the raw Full Bit Rate data, the stack beams before they are multi-looked (stack data) in the Level 1b processor, and the Level 1b data itself. Ideally, the comparison between the theoretical values provided by the well-known target, and the measurement by the instrument to be calibrated provides us with the error that the instrument is introducing when performing its measurement. When this error can be assumed to be constant regardless the conditions, it will provide the bias of the instrument. If the measurements can be repeated after a certain period of time, it can also provide an indication of the instrument drift. This paper presents the method to estimate the range, datation and angle-of-arrival errors from the transponder data and applies it to six years of Baseline C data to derive potential biases and drifts.

MIPAS Level 1B algorithms overview: operational processing and characterization

Abstract. This paper gives an overview of the MIPAS Level 1B (L1B) processor whose main objective is to calibrate atmospheric measurements radiometrically, spectrally and geo-located. It presents also the results of instrument characterization done on ground and during the first years in-flight. An accurate calibration is mandatory for high quality atmospheric retrievals. MIPAS has shown very good performance and stability. The noise equivalent spectral radiance ranges from 3 to 50 nW/(cm2 sr cm−1) and is well within the requirements over nearly the whole spetral range. The systematic radiometric error is estimated to be within 1 or 2% in most situations.

Foreword

In the May 1995 issue of the AT&T Technical Journal, which focused on the 1B processor. I wrote about the importance of sharing success stories across the R&D community. Nowhere is this more important than in the area of software development. Software is part of virtually all of AT&T's products and services and is the preeminent integrating technology.

1B Processor Deployment: Leading the Way to Flawless Execution

Deploying the 1B processor involved installing and retrofitting it in a live, fully operational 4ESS™ switch. The customer requirements for deploying the 1B processor were simple, clear, and stark: “flawless execution with no interruption to service.” To accomplish this, special bus switches were designed to allow peripheral units to be switched from the 1A to the 1B processor as part of the retrofit. The aggressive schedule called for installing the 1B processor in 134 AT&T switches in only 16 months. This paper describes the unique customer-supplier partnering approach used to meet the customer requirement of “flawless execution.” It also discusses the major leadership-based procedures used to improve processes and eliminate risks.

The Evolution of Switch Intelligence: An AT&T Network Perspective

Since the mid-1970s, the 4ESS™ switch has been the principal switching system — first in the AT&T Long Lines network, and today in the AT&T network as a whole. Until now, its main call-processing engine has been the 1A processor. The 1A is an ultra-reliable central controller designed to support high-volume electronic switching of simple phone calls having few if any special service features, like those in AT&T 800 service. In recent years, however, rising call volumes and sophisticated new long-distance service features have created the need for much more processing capacity and “intelligence” in the 4ESS switch. To meet this need, the AT&T Network Services Division — which manages the AT&T network-chose AT&T Network Systems Group's 1B processor to replace the 1A processor in 135 4ESS switches. The 1B processor more than doubles the call-handling capacity of the 4ESS switch while performing at least as reliably as the 1A processor. Not only that — the 1B processor can connect to a community of other processors, databases, and switch fabrics.

The AT&T Switching Evolution Challenge

The 1B processor represents one of the largest single investments in new network technology ever made by AT&T. The effort to make the 1B processor a reality encompassed organizations throughout AT&T, requiring, from all involved, the highest levels of commitment and teamwork to meet an aggressive schedule. This paper provides an overview of the scope and complexity of the entire project, from requirements through field deployment. It focuses on the significant role that the 1B processor plays in the long distance network, the stringent reliability requirements imposed on it, and the technical and organizational challenges that were successfully met. Also included are a high-level summary of the 1B processor's capabilities, and a discussion of the business directions that helped to define them. Finally, this paper sets the stage for the detailed papers that follow, providing perspective on how each effort fits into the overall scheme.

Manufacturing Issues of the 1B Processor

This paper outlines the critical strategies, facilities, and processes put in place to meet the high reliability and quick ramp-up requirements of manufacturing the 1B24 processor. The intent is to provide insight into several of the functions necessary to support the project objectives, including organization, vendor involvement, contingency planning, stocking, testing, and processes.

Requirements for a Brain Transplant for the New 1B Processor

Generating the system requirements for the 1B processor, the new “brain” of the 4ESS™ switch, was a critical step in the front-end process. The set of requirements, prepared by cross-functional teams, was used both to specify hardware and software development and to guide verification. To shorten the overall cycle time, the production of these specifications also overlapped the hardware and software development processes. This paper describes the customer-supplier interaction model used, the approach chosen to facilitate productivity during requirements production, a high-level perspective of the requirements, the process used to generate these requirements, the challenges encountered, and the teamwork solutions via process optimization that helped make this project a success.

An Improved Approach to Product Quality Through Testing

Due to the crucial importance of the 1B processor project, AT&T Network Systems (NS) implemented extensive testing programs to ensure that the product delivered was of the highest quality and met customers' needs. In addition to normal customer acceptance testing, the AT&T Network Services Division (NSD) introduced an innovative new strategy called the accelerated life-cycle test program (ALTP) to facilitate the identification and repair of defects. NSD used a 4ESS™ switch having 100-percent reversible traffic to test the retrofit process and to ensure that customer service would not be adversely affected by the introduction of the 1B into the AT&T network. This paper describes the final product integration and verification processes performed by NS, along with the special testing programs established by NSD customers.

Improving on the Best: “Like a 1A, Only Better”

Since 1976 the 4ESS™ switch and its 1A processor had been the workhorse of the network. As technology advanced and customers required new services, the capacity of the 4ESS switch came close to being exhausted, making it necessary to develop a successor to the 1A processor. Developers of the 1B processor were presented with the challenge of designing and implementing a system that could accommodate the new network demands, that would be “like a 1A, only better.” This paper describes several problems encountered during that project and how they were solved.