A satellite phone is a mobile telephone which communicates using satellites instead of using cell towers. Three major satellite phone networks are currently in operation: Iridium Globalstar Thuraya Iridium The Iridium network uses 66 low earth orbit satellites in polar orbits 485 miles above sea level. The use of low earth orbit satellites helps minimize round-trip-time, which greatly improves the perceived quality of the phone call. The Iridum network is able to provide complete global coverage. There is no spot on the Earth where you will not be able to Read More

PC Based Machine controls are fairly new to industrial environments, however, within the last two decades, PC based machine controls have overtaken the once standard PLC (programmable logic controllers) to run many industrial processes. A machine control is an essential part of modern industrial processes and automation. If you have never visited a factory or assembly line, many of today’s vital components of manufacturing no longer require a human, they are instead computer controlled. While each manufacturer and sometimes each industrial process once required a special PLC with specific hardware Read More

VSAT (Very Small Aperture Terminal) is basically a two-way satellite ground station with a less than 3 meters tall (most of them are about 0.75 m to 1.2 m tall) dish antenna stationed. The transmission rates of VSATs are usually from very low up to 4 Mbit/s. These VSATs’ primary job is to access the satellites in the geosynchronous orbit and relay data from terminals on earth to other terminals and hubs. They often transmit narrow-band data such as credit card transactions, polling, RFID (radio frequency identification) data, and SCADA Read More

A phototransistor is a device that converts light energy into electric energy. Phototransistors are similar to photoresistors but produce both current and voltage, while photoresistors only produce current. This is because a phototransistor is made of a bipolar semiconductor and focuses the energy that is passed through it. Photons (light particles) activate phototransistors and are used in virtually all electronic devices that depend on light in some way. How a Phototransistor Works A phototransistor is a bipolar device that is completely made of silicon or another semi-conductive material and is Read More

Frequency modulation is a type of modulation where the frequency of the carrier is varied in accordance with the modulating signal. The amplitude of the carrier remains constant. The information-bearing signal (the modulating signal) changes the instantaneous frequency of the carrier. Since the amplitude is kept constant, FM modulation is a low-noise process and provides a high quality modulation technique which is used for music and speech in hi-fidelity broadcasts. In addition to hi-fidelity radio transmission, FM techniques are used for other important consumer applications such as audio synthesis and Read More

A dielectric is a material that restricts the flow of current. Dielectrics are defined by their dielectric constant, current leakage, and breakdown voltage. They are mainly used in capacitors, allowing charge to build up on the conductive plates. An insulator is a dielectric than can withstand a high electric field without letting current flow through it. Permittivity When the material is surrounded by an electrostatic field, the electrons in each atom shift towards the positive side and away from the nucleus. This creates a dipole moment in the atom and Read More

Satellite radio refers to a number of subscription-based radio broadcasting programs that are available in the US, Europe, and elsewhere that are dependent on satellites to provide mobile users with constant radio access. While terrestrial-based FM radio stations only provide radio broadcasts to a specific area, usually confined to the city they are located in, satellite radio is available even while the listener is moving between cities, states, and even countries. Satellite radio has been available for just over a decade, with the first artist ever broadcasted on satellite radio Read More

A field-effect transistor (FET) is a semi-conductive device that is used in integrated circuits to control the conductivity of a conductive channel. FETs are highly dependent on negative and positive charges. They have many purposes, including limiting a device’s power levels, storing data, and being used as a switch for a wide variety of electronic devices. Various FET designs have been presented and produced since 1925 and have collectively allowed modern electronics to be possible. How Field-Effect Transistors Work FETs are dependent on four essential components: the base, the source, Read More

A spark gap consists of two electrodes separated by a small gap that is filled by a gas, usually air. The potential difference across the gap increases until it reaches the level where the gas ionizes and current flows across it for a brief time. The two types of spark gap are the static and rotary. Static spark gaps require the use of high voltage which causes their electrodes to erode. Spark gaps also create interference which causes noise in nearby radios and televisions. Rotary Spark Gap The rotary spark Read More

The decibel is a standard unit for measuring relative levels of current, voltage, or power. The decibel shows the ratio between the input and the output. Decibel is abbreviated dB. A minus sign before the dB indicates a loss and a plus sign or no sign at all before the dB indicates a gain. The Decibel Formula The decibel value of a change between input and output can be expressed utilizing the following algorithm: db = log10 Input / Output A Decibel Table Decibel Gain Ratio of Gain 1 1.3 Read More