Microwave Telemetry Research Articles

Development and parameterization of a data likelihood model for geolocation of a bentho-pelagic fish in the North Pacific Ocean

State-space geolocation models feature coupled process (movement) and observation (data likelihood) models to reconstruct fish movement trajectories using electronic tag data. Development of the data likelihood model is therefore a key step in adapting a state-space geolocation model for use with different fish species, geographical regions, or types of electronic data. Here we adapt a discrete hidden Markov model for the geolocation of Pacific spiny dogfish (Squalus suckleyi, n = 154) in the North Pacific Ocean by developing a data likelihood model based on Microwave Telemetry X-tag Pop-up Satellite Archival Tag (PSAT) data. The data likelihood model consists of light-based longitude, light-based latitude, sea surface temperature (SST), temperature-depth profile (TDP), and maximum daily depth. Pacific spiny dogfish tend to occupy coastal waters where small-scale local currents and freshwater inputs make SST and TDP variables difficult to map. To address this issue, we introduce an empirical method for parameterizing SST and TDP likelihoods by calculating root mean square difference between PSAT temperature and depth values recorded at known locations (day of tag deployment and tag pop-up) and mapped values at those locations. For SST observations (n = 85), the difference between measured and mapped values did not vary seasonally or monthly and the overall root mean square error (RMSE) used to parameterize the SST likelihood was 0.9 °C. Likelihood values for SST at known locations were higher for likelihoods parameterized with the empirical value compared to variance specification methods from previous studies. For TDP, measured values differed from mapped values (n = 89) by depth, season, and month. Therefore, RMSE values used to parameterize the TDP likelihood were calculated for each depth bin (n = 27) and month. RMSE values were low (< 1 °C) for all depths during the winter but increased for depths < 100 m during the summer months. Our work provides an example of adapting state-space geolocation models for specific applications. It demonstrates the value of large numbers of tagged animals for parameterizing the data likelihood model in coastal waters as well as flexible data likelihood models with component likelihoods that can be switched on or off depending on geolocation quality.

Striped marlin in their Pacific Ocean milieu: Vertical movements and habitats vary with time and place

Striped marlin, Kajikia audax, a top bycatch of the longline fishery, has been designated as being in overfished condition in the Western and Central North Pacific, and overfishing is still occurring. This prompts an urgent need to devise conservation and management measures based on the best, current information on the biology and ecology of this species. Despite decades of conventional tagging around the Hawaiian waters, ecological research on striped marlin in the Central North Pacific has been lacking since 2005, and little is known about striped marlin’s vertical habitat, diving behavior and bycatch vulnerability in this area. To address this knowledge void, 31 popup satellite archival tags (4 X-Tags; Microwave Telemetry, Inc. and 27 MiniPATs; Wildlife Computers Inc.) were deployed on striped marlin (138-192 cm eye fork length) between 2016 and 2019 via the Hawaii-based longline fleet. Transmitted time series records revealed striped marlin spent 38 and 81% of their day and night in the top 5 m, with median daytime and night depths of 44 m and 2 m, respectively. Temperatures experienced were 23.3°C, daytime median, and 24.6°C, nighttime median, to a minimum of 7.6°C at the deepest depth logged, 472 m. Striped marlin exhibited distinct swimming behaviors, including diel depth distributions, excursions around the top of the thermocline, and extended time at the surface, most likely reflecting the dynamic biophysical environment and intrinsic life history of this highly migratory predator. High post-release survivorship (86%) in tagged striped marlin, and their predominant use of the sea surface and mixed layer indicate that live release measures can be a viable bycatch reduction strategy.

Design of 8-port compact hybrid fractal UWB MIMO antenna with a conjoined reflector-ground integration for isolation improvement

In this article, a compact 8-port UWB MIMO antenna was proposed to operate from (2.5–24) GHz with 162.2% impedance bandwidth. To achieve space diversity, i.e., maximum antenna elements accomodated in a premium foot-print, each radiating pairs are designed with self-similar hybrid geometry and oriented in side-by-side orthogonal configuration. The substrate corners are cut-out for maximum free space radiation and volumetric reduction. The isolation improvement mechanism is achieved by conjoining an annular reflector at top with the ground plane via metallic vias. The metal vias magnetically couple reflector and the ground plane into a connected topology. The annular reflector has dual-purpose, firstly, the contra-cyclic surface current symmetry improves the lower mode impedance matching and secondly, port-isolation is achieved (>22 dB) by electrically self-neutralize near-field radiated currents due to contra-rotational E-field NULL distributions. The antenna MIMO diversity performances show good attributes for indoor and outdoor wireless environments. To validate, a prototype antenna of size 48 mm × 48 mm (0.4λ×0.4λ,λ = operating wavelength at 2.5 GHz) was fabricated and measured. The simulated and measured results has good agreements to be explored in UWB MIMO systems, microwave telemetry, tracking and RF doppler sensor applications.

Radiowave technology of resonant gas-sensor microwave telemetry

The possibility of using microstrip reflector microwave resonators in solving problems of resonant gas-sensor telemetry on layered dielectric substrates with gas-sensitive sputtering was investigated. It is noted that the use of chemically active sputtering, for example, on the basis of zeolites having a high selective gas adsorbent kinetics in terms of speed, makes it possible to create radiosensor materials capable of changing the dielectric constant in the process of absorbing gases, as well as of sublimated vapors of solid and liquid phases of various compounds. As an alternative approach in the field of dosimetric gas monitoring, a modification of radiosensor applications based on microwave sensors is proposed, which allows using microwave solutions based on microstrip microwave resonators with active gas-sensitive sorption zeolite sputtering on a dielectric substrate to conduct gas analysis in real time. The radio-wave principle of the microstrip gas sensor analyzer was formulated. An electrodynamic model of a microstrip gas sensor analyzer in the Altair Feko environment was developed. An experiment was planned, and gas-sensor telemetry tests of ammonia vapors dissolved in water were carried out. It was established that the amount of sorbed water and ammonia in the zeolite unambiguously conforms both to the absolute value of the reflection coefficient at resonance and to the resonant frequency itself. Using the example of recording hydrogen nitride vapors it was shown that the reflection coefficient and frequency shift in the resonator, which depend on the concentration of the adsorbed gas, correspond to the saturation characteristics of the gas sensor and make it possible to repeatedly measure small concentrations of a gas that can be absorbed by zeolite at a temperature corresponding to the condition of rapid evaporation of controlled gas from the active dielectric layer, which guarantees desorption of the sensor. It was established that in order to increase the speed of the gas sensor response it is advisable to create a microstrip resonator for the resonance region of 8...10 GHz and to use a microstrip sensor substrate material with a high dielectric constant. This is due to the fact that the transition to the upper microwave frequencies will allow reducing the size of the topology of the microstrip resonator and reducing the effective area of the zeolite deposition, and, consequently, increasing the adsorption rate of the gas-sensitive layer of the active dielectric.

Nevada Seismological Laboratory Rapid Seismic Monitoring Deployment and Data Availability for the 2020 Mww 6.5 Monte Cristo Range, Nevada, Earthquake Sequence

Abstract The Nevada Seismological Laboratory (NSL) at the University of Nevada, Reno, installed eight temporary seismic stations following the 15 May 2020 Mww 6.5 Monte Cristo Range earthquake. The mainshock and resulting aftershock sequence occurred in an unpopulated and sparsely instrumented region of the Mina deflection in the central Walker Lane, approximately 55 km west of Tonopah, Nevada. The temporary stations supplement NSL’s permanent seismic network, providing azimuthal coverage and near-field recording of the aftershock sequence beginning 1–3 days after the mainshock. We expect the deployment to remain in the field until May 2021. NSL initially attempted to acquire the Monte Cristo Range deployment data in real time via cellular telemetry; however, unreliable cellular coverage forced NSL to convert to microwave telemetry within the first week of the sequence to achieve continuous real-time acquisition. Through 31 August 2020, the temporary deployment has captured near-field records of three aftershocks ML≥5 and 25 ML 4–4.9 events. Here, we present details regarding the Monte Cristo Range deployment, instrumentation, and waveform availability. We combine this information with waveform availability and data access details from NSL’s permanent seismic network and partner regional seismic networks to create a comprehensive summary of Monte Cristo Range sequence data. NSL’s Monte Cristo Range temporary and permanent station waveform data are available in near-real time via the Incorporated Research Institutions for Seismology Data Management Center. Derived earthquake products, including NSL’s earthquake catalog and phase picks, are available via the Advanced National Seismic System Comprehensive Earthquake Catalog. The temporary deployment improved catalog completeness and location quality for the Monte Cristo Range sequence. We expect these data to be useful for continued study of the Monte Cristo Range sequence and constraining crustal and seismogenic properties of the Mina deflection and central Walker Lane.

The use of satellite tags to redefine movement patterns of spiny dogfish (Squalus acanthias) along the U.S. east coast: implications for fisheries management.

Spiny dogfish (Squalus acanthias) are assumed to be a highly migratory species, making habitual north-south migrations throughout their northwestern Atlantic United States (U.S.) range. Also assumed to be a benthic species, spiny dogfish stock structure is estimated through Northeast Fisheries Science Center (NEFSC) bottom-trawl surveys. Recent anomalies in population trends, including a recent four-fold increase in estimated spawning stock biomass, suggest alternative movement patterns could exist for this shark species. To obtain a better understanding of the horizontal and vertical movement dynamics of this species, Microwave Telemetry pop-up satellite archival X-Tags were attached to forty adult spiny dogfish at the northern (Gulf of Maine) and southern (North Carolina) extents of their core U.S. geographic range. Reconstructed geolocation tracks ranging in lengths from two to 12 months suggest that the seasonal migration patterns appear to be local in nature to each respective northern and southern deployment site, differing from previously published migration paradigms. Differences in distance and direction traveled between seasonal geolocations possibly indicate separate migratory patterns between groups. Kernel utilization distribution models also suggest strong separate core home ranges. Significant differences in seasonal temperature and depths between the two regions further substantiate the possibility of separate regional movement patterns between the two groups. Vertical utilization also suggests distinct diel patterns and that this species may not utilize the benthos as previously thought, potentially decreasing availability to benthic gear.

East with the Night: Longitudinal Migration of the Orinoco Goose (Neochen jubata) between Manú National Park, Peru and the Llanos de Moxos, Bolivia

We report on the intra-Amazonian migration of a pair of Orinoco Geese (Neochen jubata) from Manú National Park, Peru. The species is Critically Endangered in Peru, so a major aim of the study was to aid conservation planning by learning the wet season location of the country's last known breeding population. We captured a breeding pair on October 27, 2010, and fitted the birds with Microwave Telemetry, Inc. GPS/Argos satellite PTT's. The pair migrated ∼655 km from Manú National Park to the Llanos de Moxos, Bolivia (Dept. of Bení) in a predominantly longitudinal migration, reaching their final destination on December 23, 2010. Major movements (>5 km per time period) were almost exclusively at night and were undertaken with and without moonlight. Foraging areas used at stopovers in the Llanos de Moxos were remarkably limited, suggesting the importance of grazing lawns maintained by the geese and other herbivores, possibly including cattle. Orinoco Geese are resident in the Llanos de Moxos year-round, so the Manú geese represent a partial migration from the Bení region. We hypothesize that cavity nest limitation explains the partial migration of Orinoco Geese from the Llanos de Moxos.

A Wireless Microwave Telemetry Data Transfer Technique for Reciprocating and Rotating Components

Wireless microwave telemetry addresses the difficult issue of obtaining transducer outputs from reciprocating and rotating components through the use of advanced electronic components. This eliminates the requirements of a direct link between the transducer and the acquisition system. Accuracy of the transducer signal is maintained through the use of a double frequency modulation technique which provides temperature stability and a 20 point calibration of the complete system. Multiple transmitters can be used for larger applications and multiple antennas can be used to improve the signal strength and reduce the possibility of dropouts. Examples of automotive torque converter and piston temperature measurements are provided, showing the effectiveness of the wireless measuring technique.

Reflectenna: a quasi passive on–off keyed microwave telemetry system for remote sensor applications

A method to transmit one-directional wireless data with low power consumption has been investigated. This system, called the ‘reflectenna’, works on the principle of transmitting information by modulating an incident continuous wave carrier signal prior to re-transmission and consists of two orthogonally linear polarised, micromachined microstrip patch antennas and a single-pole-single-throw switch that modulates the carrier signal. This quasi-passive method to transmit data has been tested with a transceiver system that transmits a 10 GHz carrier signal and demodulates the received signal reflected back from the reflectenna. The carrier signal was modulated with a 2 kHz square wave and a link with a range up to 25 m was achieved.

Declining Extent of Open-water Refugia for Top Predators in Baffin Bay and Adjacent Waters

Global climate change is expected to severely impact Arctic ecosystems, yet predictions of impacts are complicated by region-specific patterns and nonuniform trends. Twentyfour open-water overwintering areas (or "microhabitats") were identified to be of particular importance for eight seabird and marine mammal species in the eastern Canadian High Arctic and Baffin Bay. Localized trends in the available fraction of open-water were examined in March during 1979--2001, derived from approximate sea ice concentrations from satellite-based microwave telemetry. Declines in the fraction of open-water were identified at microhabitats in Baffin Bay, Davis Strait, coastal West Greenland, and Lancaster Sound. Increases in open-water were observed in Hudson Bay, Hudson Strait, and Foxe Basin. The biological importance of each microhabitat was examined based on species distribution and abundance. Potential consequences of reduced open-water for top marine predators include impacts on foraging efficiency and oxygen and prey availability.

Measurements of Strain on 310 mm Torque Converter Turbine Blades

An automotive torque converter was tested in order to determine the effect of converter operating condition and turbine blade design on turbine blade strain in the region of the inlet core tab restraint. The converter was operated over a wide range of speed ratios (0 to 0.95) at constant input torque and a stall condition for two input torques. Foil‐type strain gages in combination with wireless microwave telemetry were used to measure surface strain on the turbine blade. Strain measurements were made on two turbine blade designs.The steady component of strain over the range of speed ratios suggests the effect of both torque loading and centrifugal loading on the turbine blade tip. The unsteady strain was greatest at stall condition and diminished as speed ratio increased. Greater input torque at stall condition resulted in both greater steady strain and greater unsteady strain. The spectral distribution of strain over the range of tested speed ratios displayed an increase in low‐frequency broadband fluctuations near stall condition. A blade‐periodic event is observed which correlates to the pump‐blade passing frequency relative to the turbine rotating frame. Reducing the blade‐tip surface area and increasing the inlet‐tab root radius reduced the range of steady strain and magnitude of unsteady strain imposed near the inlet core tab restraint over the range of operating conditions.

Preliminary investigation of microwave telemetry on an EML projectile

This paper describes a preliminary experimental investigation to convey acceleration measurements, made on-board an electromagnetic (EM) launched projectile, using microwave telemetry techniques. The focus of the investigation is to extend the Hardened Subminiature Telemetry and Sensor Systems (HSTSS) technology for use in EM launch environments. Many aspects of the HSTSS technology have already been successfully demonstrated in high-G, high-pressure launch environments in conventional gun systems. In addition, microwave transmission in stationary experiments, where the telemetry package was exposed to relatively high magnetic fields and EM transients in a railgun launcher, has been demonstrated. However, microwave telemetry during an EM launch has not been demonstrated until now. In this work, setback acceleration measurements obtained with an on-board accelerometer were processed by HSTSS electronics and transmitted simultaneously during launch via an antenna located in front of the EM launch package. While only the test conducted at 9-kG peak acceleration provided the most useful data, detailed analyses suggest that mechanical problems-rather than the microwave telemetry process itself-were probably responsible for difficulties experienced at higher accelerations. This paper reviews the experimental methodology and discusses the results of the investigation.

The development and use of an implantable radio whale tag from 1970 to the present

William A. Watkins, Woods Hole Oceanographic Institution (WHOI), led the development and refinement of the WHOI Radio Whale Tag. The initial tags were developed in the 1960s at WHOI, improved in the 1970s and 1980s by Ocean Applied Research, Inc., and adapted to satellite telemetry in the 1990s by Microwave Telemetry, Inc. Through this entire period, the tag delivery and attachment methods were continually refined. The same delivery and attachment methods were used with acoustic tags, radio tags, combined radio and acoustic tags, and satellite tags. Scientific studies using these tags have been conducted on finback, humpback, Brydes, bowhead, and sperm whales. These field studies have ranged from Venezuela to the Canadian arctic and Alaska, and from the Pacific to the Mediterranean. Every tagging experiment led to new information about the animals, and in most cases the information from radio and acoustic tagged whales showed that the best available data based on surface observations of untagged animals were deficient. Highlights from some of these findings will be presented.

Autodyne effect in weak-resonant BWO with chaotic dynamics

An autodyne phenomenon in the O-type Weak-Resonant Backward Wave Oscillator of Ka-band working in chaotic oscillatory regime is under investigation. The main attention is paid to the studying of the action of decorrelated reflected signals on the modulation of the power spectral density of the chaotic oscillations. Physical mechanisms are revealed and phenomenological model is suggested to explain the strong PSD modulation observed under the affect of the small refelected signal. The PSD modulation index has been introduced and its anomalous increase with the enlargement of the distance to the load is revealed experimentally, as well as the physical explanation for that effect is presented. All physical results obtained are valid for the autodyne effect in any chaotic oscillator. The results obtained can be used for the design of different autodyne based devices for the remote sensing, microwave telemetry and control systems.

Migrating Whooper Swans Cygnus cygnus: Satellite Tracks and Flight Performance Calculations

The ARGOS satellite system was used to follow seven migratory flights of six Whooper Swans, comprising five autumn flights from Iceland to Scotland in 1994 and 1995, and two spring flights in the opposite direction in 1995. We monitored the wind and weather in detail at migration times. The transmitters were type PTT-100 from Microwave Telemetry, equipped with air pressure and temperature sensors for altitude telemetry, and were attached by a harness made from neoprene tape. None of the swans flew any higher than necessary for terrain clearance when crossing land. Two swans migrating on 27 October 1995 flew at heights between 500 and 1700 m ASL when crossing the ocean, with evidence of small climbs in lee waves downwind of Iceland. Otherwise, the swans flew very low, with frequent, and sometimes prolonged stops on the water. The swans flew by day, or at night when there was moonlight or clear sky without moon, but landed in conditions of low cloud and poor visibility, and also in darkness when there was heavy cloud cover and no moon. The southbound swans flew straight tracks across the ocean, three making landfall in the Outer Hebrides, one on the north coast of Scotland, and one in Donegal Bay after a direct crossing from northeastern Iceland. The two northbound swans were both forced away from the direct track by contrary gales, but eventually made their landfalls near their respective staging areas on the south coast of Iceland. One was four days at sea, and the other over 30 hours. Flight performance calculations indicated that an amount of fat equivalent to 25% of the lean mass should suffice for the crossing with adequate reserves. A medium-sized female should have sufficient muscle power to fly with 25% of her lean mass as added fat, whereas this would be marginal for a large male. Females, being smaller, would be able to arrive in: Iceland in spring with more reserve fat. Little or no excess power would be available for climbing, even at sea level. It is not credible that these swans could climb by muscle power alone to the great heights previously reported, although this might be possible if they can indeed soar in lee waves.

A computerized approach to select the most cost-effective telemetry system

Large water utilities adopt various levels of automation involving digital computer technology and modern instrumentation that provide the capability of controlling most operations in the water treatment and distribution system. One of the major components of water system automation is telemetering of information to and from a central control centre. Most water utility systems currently use leased telephone lines for telemetry requirement. An alternative approach is microwave telemetry. Concern about recent increases in leased-line tariff rates, the apparent tendency for further increases, and the degree of service provided by local telephone systems led to a study which showed that overall water distribution system telemetry cost can be minimized by adopting a hybrid telemetry system composed of both radio links and telephone links. A need arises to determine the transmission links for which each alternative method is economically more suitable. This paper presents an interactive computer program which performs an economic analysis of the transmission links in a water distribution system to determine the hybrid configuration of radio and leased phone lines that provide the most cost-effective telemetry system. A typical phone tariff structure is presented. The set of input variables can be altered interactively, and the effect of the change on system telemetry cost can be examined, allowing a resolution of a series of ‘what if’ questions of interest to a water utility manager. A case example is presented.

Computer simulation of the Pioneer 10 Microwave Occultation Experiment

As Pioneer 10 approaches the planet Jupiter, its trajectory will carry it behind the planet, as seen from the earth. The microwave telemetry signal from the spacecraft will then pass through the Jovian atmosphere on its way to the earth, and analysis of the effects of the atmosphere on the signal should yield information on the atmospheric structure. To help define the capabilities of this experiment and to aid the analysis of the real data, we have simulated the occultation experiment on a computer by using model Jovian atmospheres and a predicted trajectory. The results indicate that the useful depth of penetration of the microwave signal will be governed by ammonia absorption rather than superrefractivity. The experiment is apparently far more sensitive to variations in cloud-top temperature than to variations in the hydrogen-helium ratio. Characteristic 'flashes' in the attenuation record of the signal may yield information on the location of the top of the Jovian convective zone.

Lasers Offer Satellites Better Ways to Communicate

What happens to the wavefront of a beam of coherent light as it is propagated through the atmosphere? The question has become one of vital interest to space scientists, and is answerable now that we can study, for the first time, light sent out into space by lasers, as well as that originating from an external source such as a star. The answer will affect the development of optical space‐communication systems (destined to supplement present microwave telemetry channels) and precision laser tracking for satellite‐orbit determination, geodesy and lunar‐motion studies.

A 10-watt electrostatically-focused traveling-wave tube for satellite telemetry

Satellite environments impose several special requirements on microwave telemetry transmitting tubes, such as long life, high efficiency, and light weight. A microwave amplifier will be described which is designed to meet the following requirements: 10 watts power output, life greater than 10,000 hours, efficiency greater than 30%, weight less than 1.0 pound, and rugged construction to meet shock and vibration requirements. The basic tube is a forward-wave S-band traveling-wave tube amplifier which accomplishes electron-beam focusing by electrostatic means. The tube exhibits greater than 30 db gain so that it requires only a few milliwatts of r-f input to drive it to saturation power output. To achieve high efficiency, the electron beam is collected at a beam potential below that of the average helix potential. Whn the tube is used as an oscillator, feedback is accomplished by passing a fraction of the power output through a tuned cavity to drive the input, thus achieving high frequency stability. By adjusting the loaded Q of the cavity, the tube can be made electrically tunable over a range of ± 10 mcs by varying the cathode-helix voltage.