@proceedings {620, title = {On the Use of High Frequency Surface Wave Oceanographic Research Radars as Bistatic Single Frequency Oblique Ionospheric Sounders}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

We present an investigation demonstrating that passively collected high frequency coastal oceanographic radars, with suitable waveform characteristics, can be used as single frequency oblique ionospheric sounders. To our knowledge, this is one of the first demonstrations of dual purpose use of these HF coastal radars, in addition to their primary role as ocean current monitors.\ We present a technique for extracting the virtual height using the E-region as a time calibration; this technique is agnostic of the software defined radio used.\ The application of this investigation may be useful for expanding spatial coverage for traveling ionospheric disturbance studies, day-to-day variability studies, or within data-assimilation routines.\ Additionally, HF coastal radars may be used by the scientific community or radio amateur as an another suitable RF source. We performed an experiment in which we collected 10 days of data in March 2016 from a site in Maryland, USA (MSR) and 21 days of data collected in October 2020 from a site near Clemson, South Carolina, USA (CARL). For both experiments, we used a similar hardware setup utilizing an Ettus USRP N210 software defined radio, including the GPSDO unit.\ We performed radar signal processing to obtain the group delay time from the passively received signal of Coastal Ocean Dynamics Applications Radar (CODARs).\ Our observations for both intervals focused on one frequency band at 4.53718 MHz which included three CODAR transmitters located on the Coast of North Carolina and Virigina with callsigns: DUCK, CORE, and LISL. The digisonde located at Wallops Island, VA (WP937) was used as the diagnostic to compare and validate with the observations collected from oblique CODAR-MSR(CARL) paths.

}, author = {Stephen R. Kaeppler and Ethan Miller} } @conference {290, title = {IonTV: Using WWV Timing Reference Signals to Observe Ionospheric Variation}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

For decades, an AM modulated time signal has been broadcast at multiple HF frequencies by the National Institute of Standards and Technology (NIST).\  Shortwave radio stations WWV in Colorado and WWVH in Hawaii use these frequencies for the broad dissemination of accurate coordinated universal time information.\  As the HF signal traverses the ionosphere, propagation effects ensue, and the high temporal precision of the original transmitted signal provides an attractive potential for wide-sense monitoring of ionospheric variations.\  We present the results of an ongoing set of data collections and statistical analysis of the received variation in WWV timing signals aimed at extracting ionospheric propagation effects.\  The work includes design of a software defined receiver (SDR) for processing the amplitude modulated dual sideband (AM-DSB) timing signal. By observing the time shift between consecutive seconds of the 10MHz WWV timing signal, reflected from the ionosphere, the change in the effective height of the ionosphere can be estimated.\  Simultaneous measurements taken from different observation angles allow a more accurate sensing of ionospheric electron density variability as projected into refractive effects.\  The project also has a goal of creating a straightforward and reliable way for hobbyists and citizen scientists to demodulate and process their own NIST timing data. We describe a sample analysis of several blocks of WWV received data, both on remote paths and locally through groundwave propagation near the Colorado transmit array, including simultaneous collects. To process the timing data, several approaches will be described, including a heterodyne SDR with a digital phase-locked-loop (PLL).\  Carrier offset tracking using PLL techniques produce Doppler shifts that are associated with traveling ionospheric disturbances and inherent electron density variability.\  Demodulation and amplitude/phase analysis of the 100 Hz subcarrier of WWV can also provide precise delta-time information on ionospheric propagation through examination of variability in arrival of the leading edge of 1 pulse-per-second ticks.\  Results to date suggest that variation between consecutive second markers is a uniformly distributed Gaussian random variable with at least some of this variation due to ionospheric factors, although systematics must be addressed.

}, author = {Philip J. Erickson and William Liles and J. Dusenbury and K.C. Kerby-Patel and Ethan Miller and Gary Bust and Cathryn Mitchell} } @conference {329, title = {IonTV: Using WWV Timing Reference Signals to Observe Ionospheric Variation}, booktitle = {Hamvention HamSCI Forum}, year = {2019}, month = {05/2019}, publisher = {Dayton Amateur Radio Association}, organization = {Dayton Amateur Radio Association}, address = {Xenia, OH}, abstract = {

For decades, an AM modulated time signal has been broadcast at multiple HF frequencies by the National Institute of Standards and Technology (NIST).\  Shortwave radio stations WWV in Colorado and WWVH in Hawaii use these frequencies for the broad dissemination of accurate coordinated universal time information.\  As the HF signal traverses the ionosphere, propagation effects ensue, and the high temporal precision of the original transmitted signal provides an attractive potential for wide-sense monitoring of ionospheric variations.\  We present the results of an ongoing set of data collections and statistical analysis of the received variation in WWV timing signals aimed at extracting ionospheric propagation effects.\  The work includes design of a software defined receiver (SDR) for processing the amplitude modulated dual sideband (AM-DSB) timing signal. By observing the time shift between consecutive seconds of the 10MHz WWV timing signal, reflected from the ionosphere, the change in the effective height of the ionosphere can be estimated.\  Simultaneous measurements taken from different observation angles allow a more accurate sensing of ionospheric electron density variability as projected into refractive effects.\  The project also has a goal of creating a straightforward and reliable way for hobbyists and citizen scientists to demodulate and process their own NIST timing data. We describe a sample analysis of several blocks of WWV received data, both on remote paths and locally through groundwave propagation near the Colorado transmit array, including simultaneous collects. To process the timing data, several approaches will be described, including a heterodyne SDR with a digital phase-locked-loop (PLL).\  Carrier offset tracking using PLL techniques produce Doppler shifts that are associated with traveling ionospheric disturbances and inherent electron density variability.\  Demodulation and amplitude/phase analysis of the 100 Hz subcarrier of WWV can also provide precise delta-time information on ionospheric propagation through examination of variability in arrival of the leading edge of 1 pulse-per-second ticks.\  Results to date suggest that variation between consecutive second markers is a uniformly distributed Gaussian random variable with at least some of this variation due to ionospheric factors, although systematics must be addressed.

}, author = {Philip J. Erickson and William Liles and J. Dusenbury and K.C. Kerby-Patel and Ethan Miller and Gary Bust and Cathryn Mitchell} }