GPS World

Tag: RF geolocation

  • Tiny clock meets big challenges

    Tiny clock meets big challenges

    chip-scale atomic clocks can supplement GNSS receivers to provide accurate and reliable time in GNSS-challenged environments. Photo: Microchip Technology
    Chip-scale atomic clocks can supplement GNSS receivers to provide accurate and reliable time in GNSS-challenged environments. Photo: Microchip Technology

    Accurate and reliable time is just as important as accurate and reliable location for a wide range of military and civilian applications — and GNSS receivers cannot provide either one when they are jammed. For timing, one solution is to supplement GNSS receivers with a miniature atomic clock. We asked Microchip Technology a few questions about their chip-scale atomic clock (CSAC) and Stewart Hampton, the company’s senior product line manager, responded.

    How long was your SA65 CSAC in development before you announced it in August 2021? Typically, how often do you launch a new CSAC?

    CSAC development started in 2001 under a contract from DARPA with Draper and Sandia laboratories. CSAC was first introduced to the commercial marketplace in 2011, and in 2016 we released an improved product design with an operating temperature range of –10 C° to +70 C°. Last year we released our CSAC SA65 with a wider operating temperature range, faster warm-up and improved frequency stability aimed at the defense and industrial marketplace. So, it has been about five years between major CSAC releases, but that may not be indicative of future products because we have also introduced specialized CSAC versions, such as the Low Noise CSAC (LNCSAC) in 2014 and the only commercially available radiation-tolerant CSAC (Space CSAC) in 2018.

    What is the CSAC SA65’s drift rate?

    Its typical drift rate is specified at <9 × 10–10 per month. Another key specification, particularly for many portable military applications, is total sensitivity of frequency to temperature (tempco) over a specified range. For the CSAC SA65, that specification is ±3 × 10–10 over the entire operating temperature range of –40 C° to +80 C °.

    What are a few specific military use cases?

    CSAC is designed into multiple military programs and used in a wide variety of military applications, particularly in GNSS-denied environments — including assured positioning, navigation and timing (APNT) modules, underwater unmanned and autonomous vehicles, software-defined radios, man-portable transceiver-based military communications, vehicle management computers, airborne reconnaissance/UAVs and GNSS-disciplined oscillators. It is also used in command, control, communications, computers, cyber, intelligence, surveillance and reconnaissance (C5ISR). The space CSAC variant is commonly used on low-Earth-orbit space defense payloads supporting such applications as low-latency communications networks, RF geolocation (geointelligence, or GEOINT), optical time transfer, alternative PNT satellites and Earth observation.

  • Trio of HawkEye 360 formation-flying microsatellites launched for RF geolocation

    Trio of HawkEye 360 formation-flying microsatellites launched for RF geolocation

    The HawkEye 360 constellation detects and geolocates RF signals for maritime situational awareness, emergency response, national security and spectrum analysis applications.

    Cluster 3 satellites fly in formation, joining Clusters 1 and 2. (Artist's rendering: Hawkeye 360)
    Cluster 3 satellites fly in formation, joining Clusters 1 and 2. (Artist’s rendering: Hawkeye 360)

    HawkEye 360 Inc. announced the successful launch of its Cluster 3 radio frequency geolocation microsatellites built by Space Flight Laboratory (SFL). Carried aboard the June 30 SpaceX Transporter 2 mission, the Cluster 3 formation-flying microsatellites quickly established communication with the company’s satellite operations center.  They join in orbit the HawkEye 360 Cluster 2 and Cluster 1 Pathfinder satellites.

    The HawkEye 360 Constellation detects and geolocates RF signals for maritime situational awareness, emergency response, national security and spectrum analysis applications. Cluster 3 significantly expands HawkEye 360’s capacity, and is part of its second generation of advanced RF-sensing satellites.

    “With the addition of our second-gen satellites, we’ll offer more frequent, timely and actionable data and insights to our government, commercial and humanitarian partners,” said CEO John Serafini.

    “The increased revisit frequency and capacity Cluster 3 brings to our constellation are essential to detecting, characterizing, and understanding the continuously changing RF activity important to our clients,” said Alex Fox, Executive Vice President for Sales and Marketing.

    Seven more clusters are fully funded and scheduled for launch in 2021 and 2022 to achieve collection revisits as frequent as every 20 minutes, Fox said. “Each cluster will offer new innovations to address a rapidly growing set of requirements needed by our defense, security and commerce clients. We plan on expanding the constellation past the initial 10 clusters to achieve near-persistent monitoring of global RF activity, which will drive even more value and ensure our continued dominance in the industry.”

    HawkEye 360 delivers a layer of intelligence to help understand human activity on Earth. The constellation detects, characterizes and precisely geolocates these RF signals from a broad range of emitters, including VHF marine radios, UHF push-to-talk radios, maritime and land-based radar systems, L-band satellite devices and emergency beacons.

    By processing and analyzing these RF data, the company delivers actionable insights for national, tactical and homeland security operations, maritime domain awareness, environmental protection and new applications in the commercial sector, the company said.

    The HawkEye 360 launch brings to 20 the total number of SFL satellites placed into orbit in less than a year. The Cluster 3 satellites were built on SFL’s 30-kg Defiant microsatellite bus.

    HawkEye 360 selected SFL due to the importance of formation flying by multiple satellites for successful RF geolocation. SFL is the acknowledged leader in developing and implementing high-performance attitude control systems that make it possible for relatively low-cost nanosatellites and microsatellites to fly in stable formations while in orbit.

    The previous HawkEye 360 satellite clusters built by SFL were the Pathfinder launched in 2018 and Cluster 2 in January. Each Cluster is comprised of three satellites.

    Other launches of SFL-built satellites in the past year include missions developed for the Norwegian Space Agency (NOSA) in Norway, the Dubai-based Mohammed Bin Rashid Space Centre (MBRSC) in the United Arab Emirates, GHGSat Inc. of Canada, Space-SI of Slovenia, and a Canada-based telecommunications company.