Physical Layer Definition for a Long-Haul HF Antarctica to Spain Radio Link

Abstract

La Salle and the Observatori de l'Ebre (OE) have been involved in a remote sensing project in Antarctica for the last 11 years. The OE has been monitoring the geomagnetic activity for more than twenty years and also the ionospheric activity of the last ten years in the Spanish Antarctic Station Juan Carlos I (ASJI) (62.7 • S, 299.6 • E). La Salle is finishing the design and testing of a low-power communication system between the ASJI and Cambrils (41.0 • N, 1.0 • E) with a double goal: (i) the transmission of data from the sensors located at the ASJI and (ii) the performance of an oblique ionospheric sounding of a 12,760 km HF link. Previously, La Salle has already performed sounding and modulation tests to describe the channel performance in terms of availability, Signal-to-Noise Ratio (SNR), Doppler spread and delay spread. This paper closes the design of the physical layer, by means of the channel error study and the synchronization performance, and concludes with a new physical layer proposal for the Oblique Ionosphere Sounder. Narrowband and wideband frames have been defined to be used when the oblique sounder performs as an ionospheric sensor. Finally, two transmission modes have been defined for the modem performance: the High Robustness Mode (HRM) for low SNR hours and the High Throughput Mode (HTM) for the high SNR hours.

Vertical and oblique ionospheric soundings performance comparison over the 12,760 km transequatorial HF link between Antarctica and Spain

“…In the receiver, the inverted V antenna is used to feed the SDR platform that processes the signal. More details about the hardware can be found in Alsina‐Pagès et al [].…”

Advanced HF Communications for Remote Sensors in Antarctica

“…First, we started to sound the channel and estimate the main parameters of the channel [8][9][10][11][12]. Then, we have developed and tested a wide range of modulations, with its frame structure, the radiomodem, and several antennas for both the long range with oblique incidence and the near vertical incidence scenario [13][14][15][16][17]. We are also developing a self-organized network of NVIS nodes that can handle the delays and the unavailability of the ionospheric channel.…”

Polarization diversity in a long‐haul transequatorial HF link from Antarctica to Spain

“…The main goal of these works has been to study the highest possible bit rate with minimum bit error rate (BER). Once the transmission system has already taken advantage of frequency and time diversity by means of the optimum modulation technique, coding scheme, and time frame [ Alsina‐Pagès et al , ], the research focus has switched to a polarization diversity scenario to increase the SNR at the receiver. In this study we discarded the use of spatial diversity since long distances between antennas should be guaranteed throughout the whole HF band.…”