Unique Signal Research Articles

Simultaneous Localization and Mapping for Pedestrians Using Radio Frequency Signals

Among various sensor measurements that are obtained through smartphones, the received signal strength indicator (RSSI) of a radio frequency (RF) signal is widely used to estimate a user’s location. In this study, we propose a novel RF-based simultaneous localization and mapping (SLAM) technology for robust map construction. Typically, building an indoor map using the SLAM requires accurate loop closure detection. However, it is generally difficult to accurately estimate the loop closure using RSSI owing to the large variance of RF RSSI in indoor environments. To address this, we utilize the user trajectory and RSSI sequence to identify the correct loop closure. The RSSI sequence accumulated in consecutive poses generates a unique signal pattern. Therefore, it is possible to accurately estimate the revisiting of a pedestrian to a specific position. To evaluate the performance of the proposed method, we performed a field test in a laboratory building. Moreover, SLAM was performed using only 25% of the received RF measurements to validate that the proposed method can perform accurate SLAM despite a poor RF infrastructure environment. The obtained experimental results verify that a mean error of less than 3 m can be achieved in various test scenarios.

Unique Signal System for Road Traffic

Abstract: The signal system designed here is intended to raise metal rods from the underground of road when red signal is energized. This scheme is adapted to restrict the road traffic strictly. When the red light turned in to green, automatically the metal rods will be lowered to below the road level. In addition after stopping the traffic, pedestrians are allowed to cross the road, for which an automatic announcement will be made to alert them. Since it is a prototype module, basic theme is presented for single road, but for real time applications it can be implemented for all sides of the cross roads . The demo module is constructed with single signal post which contains red, green & yellow signals. The main processing unit constructed with 89C2051 controller chip is programmed to energize indicators one after another automatically with specific timings. Once the system is energized, initially green indicator will be glow, after some time green indicator will be switched off and yellow indicator will be glown, and then red indicator will be energized. As long as red indicator remains in glowing condition, walking person symbol simulated with green LED’s will be flashed continuously until the green indicator glows. During red indicator on, metal rods remains above the road level, after that these rods will be lowered automatically. DC motor is used to raise and lower the metal rods moving mechanism. The moving mechanism is constructed with Rack & pinion. Voice record cum playback unit designed with ISD1820 chip is used to make an auto announcement such that during red signal condition “now pedestrians can cross the road” will be announced automatically. This message will be repeated until the red signal turned off. H Bridge IC is used to drive the DC motor. Especially this system is very useful for school zones.

FMRI form adaptation and size repetition enhancement in different subdivisions of the lateral occipital complex

Research findings on which brain areas demonstrate fMRI adaptation to the form, orientation, and size of visual stimuli has been mixed. Studies demonstrate effects in various subdivisions of the lateral occipital complex (LOC), including retinotopically tuned areas LO-1 and LO-2, and dorsal stream areas in the intraparietal sulcus (IPS). Therefore, we aimed to examine fMRI adaptation in four subdivisions of the LOC (LO-proper, posterior fusiform sulcus, LO-1, and LO-2) and three discrete regions in the IPS (caudal IPS, IPS-proper, and anterior IPS) to clarify the role that these structures play in form, orientation, and size processing. Participants performed three tasks which involved judging whether two serially presented novel objects shared the same form, orientation, or size. On each version of the task, one feature varied from trial-to-trial (e.g., form) while the other two features (e.g., orientation and size) were held constant. In this way, we were able to examine the unique fMRI signal changes in response to changes in form, orientation, and size in isolation. Form adaptation – a decrease in fMRI signal following repeated presentation of the same stimulus – was present in LO-proper and pFS, highlighting the role of LOC in form processing. Size repetition enhancement – an increase in fMRI signal following repeated presentations of the same stimulus – was observed in pFs. We propose that the latter result demonstrates the effects that top-down factors can have on visual areas, specifically when there is stimulus uncertainty. There was no evidence of orientation processing in any of the regions examined. Neither form adaptation nor size repetition enhancement was present in the three IPS regions-of-interest. Last, retinotopically defined LO1 and LO2 could not be reliably identified in participants and therefore we were unable to examine adaptation in these areas as we originally intended to do.

Toward Nanomolar Multi-Component Analysis by 19F NMR.

The widespread application of nuclear magnetic resonance (NMR) spectroscopy in detection is currently hampered by its inherently low sensitivity and complications resulting from the undesired signal overlap. Here, we report a detection scheme to address these challenges, where analytes are recognized by 19F-labeled probes to induce characteristic shifts of 19F resonances that can be used as "chromatographic" signatures to pin down each low-concentration analyte in complex mixtures. This unique signal transduction mechanism allows detection sensitivity to be enhanced by using massive chemically equivalent 19F atoms, which was achieved through the proper installation of nonafluoro-tert-butoxy groups on probes of high structural symmetry. It is revealed that the binding of an analyte to the probe can be sensed by as many as 72 chemically equivalent 19F atoms, allowing the quantification of analytes at nanomolar concentrations to be routinely performed by NMR. Applications on the detection of trace amounts of prohibited drug molecules and water contaminants were demonstrated. The high sensitivity and robust resolving ability of this approach represent a first step toward extending the application of NMR to scenarios that are now governed by chromatographic and mass spectrometry techniques. The detection scheme also makes possible the highly sensitive non-invasive multi-component analysis that is difficult to achieve by other analytical methods.

In Silico and In Vitro Analysis of Helicobacter pullorum Type Six Secretory Protein Hcp and Its Role in Bacterial Invasion and Pathogenesis.

Helicobacter pullorum is a human zoonotic pathogen transmitted through poultry where it is associated with vibrionic hepatitis and colitis. Hemolysin co-regulated protein (Hcp) is an important structural as well as effector protein of type six secretory system; however, its role in H. pullorum invasion and pathogenesis has not been elucidated. In this study, we predicted the Helicobacter pullorum Hcp (HpuHcp) structure and identified Campylobacter jejuni Hcp (CjHcp) as its nearest homologue. Analysis of the predicted structure shows several common bacterial Hcp motifs like Protein kinase C phosphorylation site, Casein kinase II phosphorylation site, N-myristoylation site, cAMP-and cCGMP-dependent protein kinase phosphorylation site, N-glycosylation site. The presence of unique microbodies C-terminal targeting signal domain was present in HpuHcp which was seen for the first time in CjHcp. This could indicate that Hcp is a structural protein as well as a secretory protein. Moreover, the presence of a deamidase domain, similar to the tecA of Burkholderia cenocepacia an opportunistic pathogen, may help in bacterial internalization as it depolymerises the membranous actin by deamidation of the host cell Rho GTPases cdc42 and Rac1, which was supported by increased invasion of hepatocytes by Hcp-positive isolates.

In Situ Detection of Kidney Organoid Generation From Stem Cells Using a Simple Electrochemical Method.

Organoids that mimic the structural and cellular characteristics of kidneys in vitro have recently emerged as a promising source for biomedical research. However, uncontrollable cellular heterogeneity after differentiation often results in the generation of off‐target cells, one of the most challenging issues in organoid research. This study proposes a new method that enables the real‐time assessment of kidney organoids derived from stem cells. When placed on a conductive surface, these organoids generate unique electrochemical signals at ≈0.3 V with intensities proportional to the amount of kidney‐specific cell types. Off‐target cells (i.e., non‐kidney cells) produce an electrical signature at 0 V that is distinguishable from other surrounding cell types, enabling non‐destructive assessment of both the differentiation, and maturation levels of kidney organoids. The developed platform can be applied to other types of organoids and is thus highly promising as a tool for organoid‐based drug screening, toxicity assessment, and therapeutics.

Biochemical Characterization of the Radical SAM Methylase Involved in Tetrahydromethanopterin Biosynthesis in Methanogenic Archaea

Tetrahydromethanopterin (H4MPT) is a tetrahydrofolate (H4F) analog that serves as a one‐carbon carrier cofactor in the methanogenesis pathway in methanogenic microorganisms. One major structural feature that distinguishes H4MPT from H4F and other pterin‐containing biomolecules is the presence of methyl groups at the C7 and C9 positions. Although the biosynthesis of H4MPT has been relatively well‐defined, the enzyme responsible for the methylation reactions at the unreactive carbon centers has remained unclear. Our previous work identified the radical S‐adenosyl‐L‐methionine (SAM) methylase, MjMptM, from Methanocaldococcus jannaschii that likely catalyzes the addition of both methyl groups during H4MPT biosynthesis. Our current data indicate that MjMptM does not utilize SAM as the methyl group donor and instead uses methylenetetrahydrofolate for this purpose, thus making MjMptM the founding member of “Class D” radical SAM methylases. Here, we describe our recent progress towards the biochemical and spectroscopic characterization of MjMptM. We demonstrated that the enzyme catalyzes two methylation reactions to produce a dimethylated folate species using methylenetetrahydrofolate as the C1 source for the in vitro methylation reactions and dihydrofolate as the in vitrosubstrate. Site‐directed mutagenesis and UV‐Vis spectroscopic analysis indicate that MjMptM harbors at least two [4Fe‐4S] clusters which reside in the two canonical CX3CX2C radical SAM motifs in the N‐terminus. This result was further confirmed by EPR spectroscopy, which shows the binding of at least two [4Fe‐4S] clusters with unique signals. Only one of the [4Fe‐4S] clusters catalyzes the reductive cleavage of SAM to produce 5’deoxyadenosine, the key first step in radical SAM enzyme catalysis, and thus the most N‐terminal auxiliary cluster is likely involved in electron transfer. Current work is focused on elucidating the details of the novel methylation reaction mechanism.

PD53-10 IDENTIFYING BLADDER UROTHELIAL CARCINOMAS USING FLUORESCENT SIGNAL INTENSITY OF PH LOW INSERTING PEPTIDES

You have accessJournal of UrologyCME1 May 2022PD53-10 IDENTIFYING BLADDER UROTHELIAL CARCINOMAS USING FLUORESCENT SIGNAL INTENSITY OF PH LOW INSERTING PEPTIDES Borivoj Golijanin, Michael DuPont, Ali Amin, Anna Moshnikova, Ohad Kott, Yana Reshetnyak, Oleg Andreev, and Dragan Golijanin Borivoj GolijaninBorivoj Golijanin More articles by this author , Michael DuPontMichael DuPont More articles by this author , Ali AminAli Amin More articles by this author , Anna MoshnikovaAnna Moshnikova More articles by this author , Ohad KottOhad Kott More articles by this author , Yana ReshetnyakYana Reshetnyak More articles by this author , Oleg AndreevOleg Andreev More articles by this author , and Dragan GolijaninDragan Golijanin More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002630.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Urothelial carcinomas (UC) are heterogenous malignancy with an acidic microenvironment. pH low insertion peptides (pHLIPs) are a class of pH specific transmembrane peptides that target the acidic microenvironment of cancer cells. pHLIP variant-3 (Var3-pHLIP) was conjugated to a near infrared fluorescent (NIRF) dye to evaluate the specificity and sensitivity as a UC targeting molecular probe. METHODS: After incubation for 15 minutes with Var3-pHLIP conjugated to indocyaninie green (ICG) or IRDye® 800CW, 38 ex-vivo bladder specimens from patients undergoing robotic assisted laparoscopic radical cystectomy for bladder cancer were placed under NIRF capable laser to excite the fluorophore. Peak signal intensity and the corrected mean intensity of malignant and nonmalignant cases were analyzed. The number of lesions visible under NIRF was compared with the number identified under white light. Paired-samples t-test was used to analyzed these data. Expression of NIRF signal and identification of lesions under white light by urologic oncology pathologist were compared to histopathology for specificity and sensitivity calculations. RESULTS: Of 58 lesions processed for histopathology, 47 (81%) were seen under white light and 57 (98.3%) were seen with Var3-pHLIP, representing an improved diagnosis by 17.3% (p=0.003). In NIRF, Var3-pHLIP demonstrated an average peak signal intensity of 116.4 relative fluorescent units (RFU) in malignant cases, and nonmalignant cases demonstrated an average of 44.3 RFU (p <0.001). Corrected average signal intensity of malignant cases demonstrated an average of 52.9 RFU/μm2 and nonmalignant cases demonstrated an average of 25 RFU/μm2 (p <0.001). Var3-pHLIP demonstrated 98% sensitivity and 100% specificity in identification of UC. CONCLUSIONS: NIRF of Var3-pHLIP enhanced visualization and improved diagnosis of UC. Categorizing into the borader categories of malignant and nonmalignant, the unique Var3-pHLIP NIRF signal can be used to differentiate the two groups on both peak signal intensity and mean intensity per unit area of lesion. NIRF of Var3-pHLIP identified UC irrespective of subtype, previous treatment, and stage. All CIS cases missed by white light cystoscopy were diagnosed using Var3-pHLIP NIRF imaging. Additional work into digital, automated analysis of Var3-pHLIP NIRF signal and development of a fluorescent signal analysis capable cystoscope can lead to diagnosis of bladder cancer at the time of cystoscopy. Source of Funding: This study was funded by internal departmental funds allocated to DG, OA, and YK © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e913 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Borivoj Golijanin More articles by this author Michael DuPont More articles by this author Ali Amin More articles by this author Anna Moshnikova More articles by this author Ohad Kott More articles by this author Yana Reshetnyak More articles by this author Oleg Andreev More articles by this author Dragan Golijanin More articles by this author Expand All Advertisement PDF DownloadLoading ...

The Potential for a Networked Ionospheric Sounding Constellation

AbstractA novel networked sounding constellation mission concept is proposed. Radio sounding is the original sensing method that proved the existence of the ionosphere. Satellite‐borne sounders provided the first global observations of the terrestrial ionosphere and plasmasphere, as well as the Martian ionosphere. Networked sounding, where signals are transmitted and received across multiple instruments, has been used on the ground since the first days of ionospheric observation. This paper proposes networked sounding from space, to produce measurements of the F‐layer peak, enhanced E‐layers, regions of turbulent structuring, the topside scale height (or transition height) and potentially the plasmapause. The principal advantage of sounding over other methods is direct measurement of the peak density, where a networked implementation greatly increases spatial data coverage because it provides multiple unique signal paths through the ionosphere at different frequencies. Major advances in satellite software‐defined radio, deployable antennas, signal processing and data analysis have been made in recent years, such that a networked sounding constellation could be built at realistic cost—either as a hosted payload on commercial buses or on dedicated CubeSats.

AIEgen based turn-on fluorescent probes of histone deacetylase 6 via restriction of molecular motion

Extensive attention has been attracted to blocking histone deacetylases (HDACs) due to its significant over-expressing in various types of tumors. Herein, we presented two AIEgen-based water-soluble fluorescent probes, TPAsaha and TPEsaha, capable of monitoring the expression of a single HDAC isoform (HDAC6) in living cells. These two probes hardly emitted in water, and showed bright fluorescence towards HDAC6 with a very fast response time and very low interference. The fluorescence enhancement aroused from the restriction of intramolecular motion upon strong interaction with HDAC6, as proved by molecular dynamics simulations. The unique signal response mechanism makes TPAsaha and TPEsaha highly attractive in early cancer diagnosis, treatment monitoring, and prognosis assessment.

Heavy QCD axion at Belle II: Displaced and prompt signals

The QCD axion is a well-motivated addition to the standard model to solve the strong $CP$ problem. If the axion acquires mass dominantly from a hidden sector, it can be as heavy as $O(1)\text{ }\text{ }\mathrm{GeV}$, and the decay constant can be as low as $O(100)\text{ }\text{ }\mathrm{GeV}$ without running into the axion quality problem. We propose new search strategies for such heavy QCD axions at the Belle II experiment, where the axions are expected to be produced via $B\ensuremath{\rightarrow}Ka$. We find that a subsequent decay $a\ensuremath{\rightarrow}3\ensuremath{\pi}$ with a displaced vertex leads to a unique signal with essentially no background, and that a dedicated search can explore the range $O(1--10)\text{ }\text{ }\mathrm{TeV}$ of decay-constant values. We also show that $a\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ can cover a significant portion of currently unexplored region of $150\ensuremath{\lesssim}{m}_{a}\ensuremath{\lesssim}500\text{ }\text{ }\mathrm{MeV}$.

THE VERSATILE USES OF THE 14C BOMB PEAK

ABSTRACTA concise review is presented of applying 14C produced in the atmospheric nuclear weapons testing program (1950 to 1963), subsequently forming the so-called 14C bomb peak. In order to convey the versatility of this unique isotope signal, selected applications from a variety of different fields are discussed touching on environmental, archaeological, biological, and forensic issues. A comprehensive list of references is supplied for in-depth studies of the respective fields.

Design of an electronic radiological clip for improved breast cancer imaging with ultrasound

Radiological clips are commonly used to track and identify lesions in breast cancer patients receiving neoadjuvant chemotherapy. Available radiological clips often suffer degradation of visibility in ultrasound during the course of treatment, thus requiring more involved localization procedures to identify regions prior to resection. Furthermore, upon localization, additional markers are placed to aid surgeons during resection. We describe a biocompatible electronic device which transmits a unique identification signal when imaged with ultrasound pulse inversion,i.e., ultrasound identification (USID). The USID clip provides better localization and visualization of the clip compared to passive clips. Furthermore, the ultrasound systems can be programmed to produce an audible indicator of a specific clip’s presence and proximity to the probe, thereby eliminating the need for insertion of additional markers. This concept is tested using a microcontroller and a direct digital synthesis board connected to two sonomicrocrystals, a Verasonics research system, and tissue mimicking phantoms. Clips with six different USID tags were successfully visualized at 10 dB above the background signal. Localization and identification are demonstrated using pulse inversion and image processing techniques.

Channel Attention Networks for Robust MR Fingerprint Matching.

Magnetic Resonance Fingerprinting (MRF) enables simultaneous mapping of multiple tissue parameters such as T1 and T2 relaxation times. The working principle of MRF relies on varying acquisition parameters pseudo-randomly, so that each tissue generates its unique signal evolution during scanning. Even though MRF provides faster scanning, it has disadvantages such as erroneous and slow generation of the corresponding parametric maps, which needs to be improved. Moreover, there is a need for explainable architectures for understanding the guiding signals to generate accurate parametric maps. In this paper, we addressed both of these shortcomings by proposing a novel neural network architecture (CONV-ICA) consisting of a channel-wise attention module and a fully convolutional network. Another contribution of this study is a new channel selection method: attention-based channel selection. Furthermore, the effect of patch size and temporal frames of MRF signal on channel reduction are analyzed by employing a channel-wise attention. The proposed approach, evaluated over 3 simulated MRF signals, reduces error in the reconstruction of tissue parameters by 8.88% for T1 and 75.44% for T2 with respect to state-of-the-art methods. It is demonstrated that channel attention mechanism helps to focus on informative channels and fully convolutional network extracts spatial information achieve the best reconstruction performance. As a consequence of improvement in fast and accurate manner, presented work can contribute to make MRF appropriate for clinical use.

Programmable Multiwavelength Radio Frequency Spectrometry of Chemophysical Environments through an Adaptable Network of Flexible and Environmentally Responsive, Passive Wireless Elements

Readout of multiparametric environmental signals typically uses discrete sensing formats that individually require unique signal conditioning circuitry and/or processing pathways. Here, adaptable sensor networks composed exclusively of passive material architectures that enable spectrometric comonitoring of chemical or physical environmental signals are proposed. Herein, a single radio frequency (RF) reader wirelessly interacts first with an intermediate wireless relay coil—this is tunable in length and can be designed to conform around surfaces. This relay (that is fused on textiles or surfaces) is then wirelessly coupled to arrays of passive RF sensors with individually programmable flexibility/reactivity to environmental signals. Multiple chemical and physical signals can then be monitored within the single spectral readout of a wearable reader. This technique can probe over tunable length scales, and is robust to mechanical disturbances that limit present techniques. As a proof of concept, this approach is used to comonitor chemophysical metrics such as nutrients, temperature, pressure, pH, and more on the skin or in utensils with a single readout. This technique may form a cornerstone of zero‐microelectronic sensor networks.

Reconstructing Binary Signals from Local Histograms.

In this paper, we considered the representation power of local overlapping histograms for discrete binary signals. We give an algorithm that is linear in signal size and factorial in window size for producing the set of signals, which share a sequence of densely overlapping histograms, and we state the values for the sizes of the number of unique signals for a given set of histograms, as well as give bounds on the number of metameric classes, where a metameric class is a set of signals larger than one, which has the same set of densely overlapping histograms.

A novel lipase with dual localisation in Trypanosoma brucei

Phospholipases are esterases involved in lipid catabolism. In pathogenic micro-organisms (bacteria, fungi, parasites) they often play a critical role in virulence and pathogenicity. A few phospholipases (PL) have been characterised so far at the gene and protein level in unicellular parasites including African trypanosomes (AT). They could play a role in different processes such as host–pathogen interaction, antigenic variation, intermediary metabolism. By mining the genome database of AT we found putative new phospholipase candidate genes and here we provided biochemical evidence that one of these has lipolytic activity. This protein has a unique non-canonical glycosome targeting signal responsible for its dual localisation in the cytosol and the peroxisomes-related organelles named glycosomes. We also show that this new phospholipase is excreted by these pathogens and that antibodies directed against this protein are generated during an experimental infection with T. brucei gambiense, a subspecies responsible for infection in humans. This feature makes this protein a possible tool for diagnosis.

Multi-channel optical sensing system with a BP-ANN for heavy metal detection.

A multi-channel optical sensing system for heavy metal concentration detection is presented in this paper. The system utilizes a multi-channel optical path combined with a unique circuit design and BP neural network (BP-ANN) to perform the online analysis of multi-wavelength signals, achieving accurate concentration detection of a heavy metal solution. An array photodiode is used to detect the transmission light intensities at multiple wavelengths through the optical path of the system, which enables the collection of useful spectral information of the solution. The system uses a unique signal acquisition method to effectively improve the efficiency of both signal acquisition and operation. BP-ANN is applied to the online analysis of multi-channel information, which overcomes the influential issue of nonlinear effect on data detection, optimizes the anti-interference ability, and lowers the detection limit of the system. This system eliminates the necessary employment of the expensive and large spectrometers and therefore greatly reduces the instrument cost and occupying space. Additionally, the detection limit of the system is extended lower than that of the conventional spectrophotometer. Compared with the detection limits of heavy metal solution obtained by using a single characteristic light wavelength, the detection limits of Cd2+, Cu2+ and Cr6+ achieved through using multi-channel detection system can be reduced by 42.64%, 38.12%, and 20.62%, respectively, and these detection limits are found as 0.0041mg/L, 0.0091mg/L, and 0.0112mg/L, respectively.

A Fingerprint in a Fingerprint: A Raman Spectral Analysis of Pharmaceutical Ingredients

The fingerprint region in mid-infrared (IR) and Raman spectroscopy, typically between 300 to 1900 cm-1, is used to characterize molecules by utilizing their vibrational and rotational changes in this region. In this study, a smaller subset of this Raman spectral region was evaluated for its significance in characterizing pharmaceutical products. This narrower region from 1550 to 1900 cm-1 in the Raman spectrum will further be defined as the “fingerprint in the fingerprint” region. A spectral evaluation was conducted on active pharmaceutical ingredients (APIs) in prescription drugs, over-the-counter drugs, and pharmaceutical drug products. Qualitative and quantitative analysis was performed on these products to gain an understanding of this spectral region. The qualitative results showed no Raman spectral signals in this region for any of the common excipients. Additionally, all APIs evaluated had unique Raman vibrations and spectral signals in this region. This data indicates that the 1550–1900 cm-1 Raman spectral region is ideal for API identity testing. Furthermore, the data indicate the potential of this spectral region for differentiation and classification of API content in different strengths of a given drug product.

GNSS Time Signal Spoofing Detector for Electrical Substations

This paper introduces a novel method of GNSS spoofing detection with applications in electrical substations. Time sensitive applications in electricity substations, including Phasor Measurement Units (PMU) and Merging Units (MU), rely on Global Navigation Satellite Signals (GNSS), often GPS, for time transfer. Recently, sophisticated ‘spoofing’ attacks have become feasible due to the availability of low cost Software Defined Radio (SDR) systems. The proposed method uses multiple GNSS receive antennas placed in close proximity at the electricity substation, such that it is not possible for an attacker to target a unique spoofing signal towards each antenna. In a system employing three or more receive antennas, during a spoofing attack two or more of the GNSS receive antennas will return an estimated position in impossible locations. This is sufficient to raise alarm that time sensitive applications should use an alternative time source or holdover clock. The contributions of this paper include a detailed description of the proposed method, an experimental assessment of GNSS receiver and substation clock position estimation variance to establish the minimum separation required between receive antennas, and a validation of the method by experimental demonstration. A further benefit of the authors’ method is that it may be put into practice immediately using commercial-off-the-shelf (COTS) substation clock equipment.