Consumer-grade Receivers Research Articles

Precise GNSS Time Synchronization With Experimental Validation in Vehicular Networks

Time synchronization utilizing the Global Navigation Satellite System (GNSS) is being increasingly investigated for vehicular networks. Due to GNSS signal blockages, the availability and accuracy of GNSS timing solutions in various road settings is a recognized challenge. With the recent improvement of Multi-GNSS technology and the increased capacity of consumer-grade receivers, the application of GNSS in vehicular environments has brightened up. This paper systematically analyzes the required time synchronization of vehicular networks and presents a GNSS-based time synchronization solution. It also experimentally demonstrates the availability and capabilities of GNSS time synchronization using commercial-grade GNSS receivers and off-the-shelf communication devices. Our experiments show that the timing accuracy of an individual vehicular node can be as good as ±2 microseconds, resulting in synchronization accuracy of sub-10 microseconds among nodes. A momentary complete outage of the GNSS time solution due to signal blockage on the road adds clock error, leading to synchronization inaccuracy of up to sub-20 microseconds. This level of inaccuracy still meets the desired requirement for most applications in vehicular communication.

The Impact of Receivers on Spectrum Management

On April 21, 2022, the U.S. national spectrum regulator for the private sector, the Federal Communications Commission/FCC, formally asked for input on the issue of “the role of receiver performance in (its) spectrum management responsibilities” [1]. A previous issue of this column addressed related issues and the enigmatic question “Which uses the most spectrum: transmitters or receivers?” [2]. That issue described the classic example of early U.S. market UHF TV receivers in the 1950s when UHF technology was first being introduced to consumer electronics. FCC decided at the time that the selectivity and intermodulation issues in consumer grade receivers would limit the use of UHF TV channels to channels spaced six channels apart to avoid interference [3]. Thus, only 1/6 of the apparent number of UHF channels could be used in a given city even if there were no other cities nearby. (With improved electronics and digital television modulation, television channels can now be used with a much higher density.)

An Experiment for Outdoor GPS Localization Enhancement using Kalman Filter with Multiantenna Consumer-Grade Sensors

Consumer-Grade global positioning system (GPS) is widely used in many domains. The obvious issue of this consumer-grade device is low accuracy and reading fluctuation results. In terms of using an application that requires a more precise location, the output could be difficult. In this study, the authors deploy various methods to reduce the global positioning system data fluctuation and present field test results. Two main types of the device worked together to collect data from global positioning systems, such as Microcontroller for algorithm processing and presenting data and global positioning system receivers for receiving data from a satellite. We combine three global positioning system modules to received signals in a single device and test calculated data compared with the Kalman filtering methods in many cases, including moving and static devices. Implementing the Standard Kalman Filter to multiple global positioning system Modules has improved the constancy of cheap global positioning system equipment. The experiment algorithm is presented significant improvement to overcome the retrieved data fluctuation problem. This study's contribution will enable creating a cheap global positioning system locator device for various applications that require more accuracy than the standard consumer-grade receiver.

RETRACTED ARTICLE: Likelihood-based GNSS positioning using LOS/NLOS predictions from 3D mapping and pseudoranges

The accuracy of conventional global navigation satellite systems (GNSS) positioning in dense urban areas is severely degraded due to blockage and reflection of the signals by the surrounding buildings. By using 3D mapping of the buildings to aid GNSS positioning, the accuracy can be substantially improved. However, positioning performance must be balanced against computational load. Here, a likelihood-based 3D-mapping-aided (3DMA) GNSS ranging algorithm is demonstrated that enables signals predicted to be non-line-of-sight (NLOS) to contribute to the position solution without explicitly computing the additional path delay due to NLOS reception, which is computationally expensive. Likelihoods for an array of candidate positions are computed based on the difference between the measured and predicted pseudoranges. However, a skewed distribution is assumed for those signals predicted to be NLOS on the basis that the ensuing ranging errors are always positive. An overall position solution is then extracted from the likelihood surface. GNSS measurement data have been collected at several locations in both traditional and modern dense urban environments. Horizontal root-mean-square single-epoch position accuracies of 4.7, 5.6 and 6.5 m are obtained using, respectively, a Leica Viva geodetic receiver, a u-blox EVK M8T consumer-grade receiver and a Nexus 9 tablet incorporating a smartphone GNSS antenna and a GNSS chipset that outputs pseudoranges. The corresponding accuracies using single-epoch conventional GNSS positioning are 20.5, 23.0 and 28.4 m, about a factor of four larger. The 3DMA GNSS algorithms have also been implemented in real time on a Raspberry Pi 3 at a 1-Hz update rate.

New decision variables for GNSS acquisition in the presence of CW interference

This paper investigates the problem of Global Navigation Satellite System signal acquisition using a consumer-grade receiver in the presence of continuous wave interference. By examining in detail the impact of interference on the acquisition search space, a set decision variables are developed. These decision variables leverage the systematic properties of the interference observed in the search space, manipulating or differencing portions of it to achieve improved detection performance. Strategies based on these variables are examined under a selection of operating scenarios including acquisition in the presence of interference when the receiver has some, or has no, a priori information regarding the interference. It is shown that a receiver employing these new schemes can tolerate up to 10 dB more interference power than a traditional receiver.

Digital GNSS PLL Design Conditioned on Thermal and Oscillator Phase Noise

Both thermal and oscillator phase noise pose significant difficulties for phase-lock loops (PLLs) in consumer grade GNSS receivers employing low quality oscillators. Unfortunately, these phenomena impose conflicting constraints on the PLL design and so a trade-off between noise rejection and tracking error must be made. Design rules are developed for optimal, Wiener filter based PLLs conditioned on the influence of the oscillator and thermal noise on consumer-grade receivers. The performance of these PLLs is examined through both simulation and the use of actual GPS signals.

Positional accuracy of the Wide Area Augmentation System in consumer-grade GPS units

Global Positioning System devices are increasingly being used for data collection in many fields. Consumer-grade GPS units without differential correction have a published horizontal positional accuracy of approximately 10–15 m (average positional accuracy). An attractive option for differential correction for these GPS units is the Wide Area Augmentation System (WAAS). Most consumer-grade GPS units on the market are WAAS capable. According to the Federal Aviation Authority (FAA), the WAAS broadcast message provides integrity information about the GPS signal as well as accuracy improvements, which are reported to improve accuracy to 3–5 m. Limited empirical evidence has been published on the accuracy of WAAS-enabled GPS compared to autonomous GPS. An empirical study was conducted comparing the horizontal and vertical accuracy of WAAS-corrected GPS and autonomous GPS under ideal conditions using consumer-grade receivers. Data were collected for 30-min time spans over accurately surveyed control points. Metrics of median, 68th and 95th percentile, Root Mean Squared Error (RMSE), and average positional accuracy in the horizontal and vertical dimensions were computed and statistically compared. No statistically significant difference was found between WAAS and autonomous position fixes when using two different consumer-grade units. When using WAAS, a third unit type exhibited a statistically significant improvement in positional accuracy. Analysis of data collected for a 27-h time span indicates that while WAAS is altering the estimated position of a point compared to an autonomous position estimate, WAAS augmentation actually appears to decrease the positional accuracy.

RF Replay System for Narrowband GNSS IF Signals

Although global navigation satellite systems (GNSS) radio frequency (RF) signal simulators have long possessed the capability to generate scenarios, they are, for example, not yet able to model a specific realistic scenario with complex multipath. Software-defined receivers bridge the gap between simulated and real data to the extent that they may offer a replay capability, where a data set is first recorded to disk and later can be processed several times. Unfortunately the recorded data generally cannot be used by hardware-based GNSS receivers, making receiver-to-receiver comparisons difficult and time consuming. A system capable of replaying recorded IF data into any narrow bandwidth L1 (the frequency band of the traditional civilian GPS signal) GNSS receiver is described here, including an evaluation of the difference (position, timing, and signal-to-noise ratio (SNR)) between live and replayed data using a high sensitivity, consumer-grade receiver. The performance of the replayed data set was, with regards to the position and timing, found to match that of the live data.

“AQUA”: A New Audio Quality Monitoring Algorithm for the Performance of DRM Receivers in Fading Channels

This paper presents a new audio quality monitoring algorithm: ldquoAQUArdquo for assessing the performance of Digital Radio Mondiale (DRM) receivers. AQUA targets performance evaluation of consumer grade receivers in fading channels objectively. Consumer grade DRM receivers do not generally possess a Receiver Status and Control Interface (RSCI), which prohibits the possibility of analysing digitally decoded audio bit stream after reception. AQUA relies on the analysis of the received analog audio output signal instead. The paper describes the development of the AQUA algorithm and the measurement system used for receiver audio quality testing. The performance of AQUA is compared to conventional RSCI derived metrics like Bit Error Rate (BER) and Frame Error Rate (FER) of the decoded audio data. A series of tests are conducted in a variety of propagation conditions using a DRM dedicated testing system with a fading channel emulator. It is shown that FER estimates using AQUA are in good agreement with conventional FER figures derived from RSCI in different fading channel scenarios. This allows AQUA to be used as a reliable alternative to conventional FER performance analysis for automated objective testing of DRM receivers.

A Comparison of GPS Performance in a Southern Hardwood Forest: Exploring Low-Cost Solutions for Forestry Applications

Abstract The global positioning system (GPS) exhibits much potential for forestry applications, where traditional methods of position determination still dominate. Recent advances in GPS technology may offer improved performance of GPS in forested conditions, and at a considerable cost advantage compared with previous GPS alternatives. We examined the use of several mapping- to recreation-grade GPS receivers across a topographic gradient and the influence of using the Wide Area Augmentation System (WAAS) to their performance under leaf-on and leaf-off conditions. Generally, the mapping-grade receiver with postprocessed differential correction offered the highest position accuracies, which improved root mean squared error (RMSE95) from 3.64 to 5.32 m across leaf conditions, compared with recreation-grade receiver performance, which ranged in RMSE95 from 12.76 to 38.74 m under leaf-on conditions to 8.22 to 36.81 m under leaf-off conditions. Users of this information should keep in mind that RMSE95 equals actual RMSE × 1.7308. These results are consistent with the general thoughts that (a) mapping-grade receivers should provide higher horizontal position accuracy than consumer-grade receivers, (b) better horizontal position accuracy is obtained during leaf-off forest conditions (i.e., winter), (c) differential correction can improve horizontal position accuracy, and (d) WAAS, when available, can improve horizontal position accuracy. Results also indicate that slope position and the number of position fixes acquired may influence the performance of the GPS units.

Blind Compensation of Linear Amplitude Distortions

The estimation and the compensation of particular amplitude distortions, typically affecting the consumer-grade receivers in broadband satellite communications, are considered. The distortion filter is modeled as a linear function of the frequency with unknown slope. We present a novel slope estimator, analytically derived by exploiting the spectral properties of the distorted signal, which results to be unbiased and does not exhibit false locks in the scenarios of practical interest. Since an ideal slope compensator would require an unmanageable filtering, we focus on a low-complexity compensation filter that ensures nearly the same performance. Extensive simulation results prove the effectiveness and the robustness of the proposed solution, which can also work blindly at very low values of the signal-to-noise ratio.

GPS after Selective Availability: How Accurate Is Accurate Enough?

Abstract Global positioning systems (GPS) without differential correction may now be accurate enough for many forestry applications. We present accuracy estimates for point locations and a method of stating area accuracy so that potential GPS users can decide whether the accuracy is sufficient. The results show that GPS without differential correction is more accurate than traditional methods of location and area calculation, short of actual surveying. Compass-and-pace is less accurate than GPS, and lines and points at customary map scales are as wide as typical GPS errors. If differential correction is not necessary, practitioners can use the inexpensive, light, and easily operated consumer-grade receivers and simple software.