GSM Voice Channel Research Articles

Remote monitoring of solar PV system for rural areas using GSM, V-F & F-V converters

The Small capacity photovoltaic (PV) systems like solar lantern and home lighting systems installed in remote rural area often fail without any prior warning due to lack of monitoring and maintenance. This paper describes implementation of remote monitoring for small capacity solar PV system that uses GSM voice channel for communication. Through GSM analog signal of sine wave with frequency range 300–3500 Hz and amplitude range 2.5–4 V is transmitted. Receiver is designed to work in the same frequency range. The voltage from solar PV system in range of 2 to 7.5 V can be converted to frequency directly at the transmitting end. The frequency range from 300–6000 Hz can be sensed and directly converted to voltage signal at receiving end. Testing of transmission and reception of analog signal through GSM voice channel is done for voltage to frequency (V-F) and frequency to voltage (F-V) conversions.

Low‐complexity leakage current acquisition system for transmission line insulators employing GSM voice channel

With the rapid advancements in electronics and in communication infrastructures, the deployment of low-complexity devices for power system monitoring has become an active area of research. For the large-scale deployment of monitoring devices, robust and economical remote data acquisition systems for power system monitoring are required. Keeping this in mind, the scheme of a remote leakage current acquisition system for high-voltage insulators that may be employed for remote monitoring purposes is described. A low-complexity method is adopted for the extraction of harmonic information from the leakage current signal. Unlike existing remote insulator-monitoring techniques that employ a dedicated fibre-optic network and satellite communication, the mobile communication voice channel is used to communicate the data to a central location for analysis. This provides an economical solution for the remote monitoring of insulators that may be used for large-scale deployment.

Remote Monitoring for Solar Photovoltaic Systems in Rural Application Using GSM Voice Channel

The health of the Solar PV systems should be monitored continuously for their better performance and maintenance. For PV systems installed at rural locations, remote monitoring capabilities provide the information in advance when system performance is degraded or is likely to fail. Based on this information, preventive maintenance can be carried out to improve the performance and life of the system, thereby reducing the overall operating cost.Advantages and disadvantages of several monitoring systems for rural application, based on the techniques of communication, such as, computer to computer communication (Ethernet), embedded system to computer (GSM) and embedded system to embedded system (GSM, GPRS) are discussed.A new technique is proposed as a solution to overcome the limitations of other techniques. The proposed technique uses GSM voice channel for the communication of data, in the form of analog signal between transmitter and receiver. In order to study and evaluate the performance of proposed technique, various experiments have been performed and impact of parameters like shape (sine, square and triangular), frequency (50 - 4000Hz) and amplitude (0 – 6V) of analog signal have been studied. It is observed that sine wave of frequency from 300Hz to 3300Hz with 4.5V maximum amplitude can be sent on voice channel of GSM network with less than 1% error. This technique has low initial as well as operating cost. The GSM network is readily available in rural areas; this technique can be used easily.

Reliable and Secure Voice Encryption over GSM Voice Channel

In this paper, we study and develope a special secure Dongle to be adapted in GSM SmartPhone for secure voice communication to the serial 20-pin connector in SmartPhone. We design and implement the Dongle module hardware, firmware, and software including cipher crypto-synchronization and cipher algorithm. Also we study and emulate the SmartPhone GUI software interface including communication software module to the Dongle. Finally, we analyze the performances of crypto-synchronization in some noisy environment and also we test the secure Dongle module.

Implementation of PCCD-OFDM-ASK Robust Data Transmission over GSM Speech Channel

This paper presents a novel data modulation scheme PCCD-OFDM-ASK: the phase continuous context dependent orthogonal frequency division multiplexing amplitude shift keying. The proposed modulation is successfully applied in the mobile payment system. It is used to transmit the digital data over the speech channel of the mobile communication system GSM, as well as CDMA. The main key points of the proposed modulation schemes are: precise signal synchronization between the modulator and demodulator, signal energy independent operation, on line adaptation of frequency characteristics of the transmission channel, and controlled frequency bandwidth thus enabling non-overlapped full duplex communication over the GSM's voice channel.

Data transmission over GSM voice channel using digital modulation technique based on autoregressive modeling of speech production

This paper presents a novel digital data modulation and demodulation algorithm ARDMA based on the principles of autoregressive modeling (AR) of speech production. In the first step a sustained voiced speech signal characteristics are analyzed using autoregressive modeling principle and then the two sets of linear prediction (LPC) coefficients are obtained and converted to linear spectrum frequencies (LSF). The input binary data stream drives the selection mechanism of LSF coefficients which are then applied as filter coefficients of the modulation signal synthesis filter. This filter is excited with specially designed excitation signal which corresponds to the basic characteristics of typical excitation signal of human vocal tract. Finally, a speech-alike modulation signal is produced. This modulation signal is then sent through the voice channel of the GSM system. The demodulator analyzes the incoming modulation signal using autoregressive modeling. The most likely LSF vector which modulated the particular symbol was determined by the demodulation process and converted to the respective string of binary data. The performance of proposed modulation scheme was compared to the regular frequency shift keying method (FSK). The performance improvement of ARDMA against FSK is observed at higher bit-rates in the case of three compared GSM speech coders.