dBm is the standard unit of measure for levels of power based on a one milliwatt (mW) reference signal. The dBm measurement is very similar to dB (decibel); however, dB is a relative measure of the power of an input signal while dBm is always an absolute value based on a single milliwatt. If there …
The military alphabet, or more properly the phonetic alphabet, exists in innumerable variants. If any military alphabet can be viewed as the most correct, it is the current NATO standard military alphabet. However, even with the NATO standard military alphabet, various member nations use numerous spelling variations. This version of the military alphabet is also …
A police scanner is basically a radio scanner that is also a receiver that receives wireless radio signals. A scanner identifies these wireless radio waves. A scanner can identify numerous radio signals and bands concurrently making it easy to keep track of many channels simultaneously. The phrase “police scanner” derives from the fact that the …
VSWR (Voltage Standing Wave Ratio) is a metric commonly used with antenna systems for ham or shortwave radio communication. VSWR is normally defined as a ratio with a 1:1 VSWR, indicating that there is an exact or perfect match between all antenna system elements. The VSWR can also be expressed by comparing Vmax with Vmin …
FCC ID stands for Federal Communications Commission Identification. An FCC ID is the number found in all computer hardware components. FCC ID numbers, usually found on the circuit boards, are helpful in finding information about the manufacturers of the hardware devices. An FCC ID has 2 elements. The first is a three-character Grantee Code which …
Radio-Frequency Identifier (RFID) technology has become really popular because of the various advantages it comes with. However, such as passports, national identity cards, credit cards etc have become a serious security concern. Two electrical engineering students (Ilan Kirschenbaum and Avishai Wool) from Tel Aviv University wrote a paper titled "How to Build a Low-Cost, …
A circulator is a box-shaped ferrite device that has three or four ports and allows energy from one port to transfer to the next port in line. Circulators are usually used with radio signals but can also be used with microwaves, light, and other electromagnetic waves. This means that a radio signal that is being …
Modulation is the process of varying some characteristic of a periodic wave with external signals. Modulation is utilized to send an information bearing signal over long distances. Radio communication superimposes this information bearing signal onto a carrier signal. These high frequency carrier signals can be transmitted over the air easily and are capable of traveling …
The Frequency-Hopping Spread Spectrum (FHSS) is a means of transmitting radio signals by shifting a carrier across a number of channels with a pseudorandom sequence that the sending and receiving station knows beforehand. The method is used as a multiple access process in the FH-CDMA (Frequency Hopping Code Division Multiple Access) transmission scheme. What Are …
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, …