In December 2001, the authors started two kinds of experiments on the meteor burst communication (MBC) in Antarctica to study the ability of MBC as a communication medium for data collection systems in that region. In the first experiment, a continuous tone signal is transmitted from Zhongshan Station. The signal received at Syowa Station (about 1,400 km apart) is recorded and analyzed. This experiment is aimed to study basic properties of the meteor burst channel in that high latitude region. On the other hand, the second experiment is designed to estimate data throughput of a commercial MBC system in that region. A remote station at Zhongshan Station tries to transfer data packets each consisting of 10 data words to the master station at Syowa Station. Data packets are generated with five minutes interval. In this paper, we explain the experiments, briefly examine the results of the first year (from April 2002 to March 2003), and put forward the plan for the experiments in the second and third year. From the data available thus far, we can see that 1) the sinusoidal daily variation in the meteor activity typical in middle and low latitude regions can not be clearly seen, 2) non-meteoric propagations frequently dominate the channel especially during night hours, 3) about 60% of the generated data packets are successfully transferred to the master station within two hours delay even though we are now operating the data transfer system only for five minutes in each ten minutes interval, etc.

This paper presents a variable rate transmission scheme suitable for bandlimited meteor burst channel. Meteor Burst Communication (MBC) is a unique type of radio communication, which is primarily used for non-realtime remote data collection. In the paper, along with conventional BPSK and QPSK modulations, QAM and M-ary Bi-orthogonal modulations are analyzed for software modem implementation in an MBC system. Performance of the modulation methods is presented for both static AWGN channel and meteor burst channel. The proposed scheme for variable rate transmission dynamically estimates the MBC channel and varies the modulation type of a software modem, to control the transmission rate between bursts. The scheme dynamically selects a modulation type and packet length that will maximize the average throughput of the system. Performance of the scheme is analyzed and compared with conventional fixed rate modems. A practical implementation for software modem is suggested that uses a common core modulator/demodulator structure.

A new type of Meteor Burst Communication (MBC) network is developed. Each unit of the network is based on a DSP board running a modem software. All the fundamental blocks and functions of a modem are implemented in software. Unlike hardware modems, this software modem has flexibility of system configuration and operation. The system implements adaptability in terms of modulation type (number of phases in MPSK) using a unique dynamic channel estimation scheme appropriate for MBC channel. An MBC network protocol is implemented within the modem software. Some preliminary experiments were carried out for differential BPSK and differential QPSK modulations over a practical meteor burst link, and the results are presented.

This paper is a brief survey of mobile applications of meteor burst communications (MBC). Though the capacity of MBC systems is generally not large, this unique long distance communication method has at least two selling points when applied to mobiles. First of all, it is cheap. Secondly, it can easily offer nationwide seamless service. Thus, since the late 1980s, mobile MBC systems have been attracting interests of the industry. Although MBC is today a well established communication technique, there are some difficulties to be overcome before it is widely applied to mobile systems. Two most serious problems are the rather large antenna size and high transmitter power inherent to this beyond line of sight communication which relies on weak reflections of low VHF (typically 35 to 50 MHz) radio waves from ionized meteor trails. Some reduced sized antennas which can be mounted on the roofs of trucks have been tested. The problem of large peak power (a few hundred watts for mobile remotes) is much alleviated by the very low duty cycle (usually less than 1%) of remote transmitters due to their bursty transmissions responding to the probe signals from the master station via infrequent meteor reflections. In this paper, some land and maritime mobile MBC systems are brieflyintroduced.