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For very low-power systems, such as mobile phones, signal strength is usually expressed in dB-microvolts per metre (dBμV/m) or in decibels above a reference level of one milliwatt . In broadcasting terminology, 1 mV/m is 1000 μV/m or 60 dBμ (often written dBu). Examples. 100 dBμ or 100 mV/m: blanketing interference may occur on some receivers
Text messaging, or texting, is the act of composing and sending electronic messages, typically consisting of alphabetic and numeric characters, between two or more users of mobile phones, desktops / laptops, or another type of compatible computer. Text messages may be sent over a cellular network or may also be sent via satellite or Internet ...
The StingRay is an IMSI-catcher with both passive (digital analyzer) and active (cell-site simulator) capabilities. When operating in active mode, the device mimics a wireless carrier cell tower in order to force all nearby mobile phones and other cellular data devices to connect to it. [ 9][ 10][ 11] The StingRay family of devices can be ...
Mobile phone signal. A mobile phone signal (also known as reception and service) is the signal strength (measured in dBm) received by a mobile phone from a cellular network (on the downlink ). Depending on various factors, such as proximity to a tower, any obstructions such as buildings or trees, etc. this signal strength will vary.
According to the 9/11 Commission Report, 13 passengers from Flight 93 made a total of over 30 calls to both family and emergency personnel (twenty-two confirmed air phone calls, two confirmed cell phone and eight not specified in the report). Brenda Raney, Verizon Wireless spokesperson, said that Flight 93 was supported by several cell sites. [7]
There are 51 MTAs, 493 BTAs and 175 EAs in the United States. The Advanced Wireless Services (AWS) bands, auctioned in the summer of 2006, were for 1,710–1,755 MHz, and 2,110–2,155 MHz. The spectrum was divided into blocks: A blocks were for Cellular Market Areas, based on existing cellular (1G) licenses, and were 2 × 10 MHz.
GSM uses TDMA and FDMA for user and cell separation. UMTS, IS-95 and CDMA-2000 use CDMA. WiMAX and LTE use OFDM . Time-division multiple access (TDMA) provides multiuser access by chopping up the channel into sequential time slices. Each user of the channel takes turns to transmit and receive signals.
Currently, texting is the most widely used data service; 1.8 billion users generated $80 billion of revenue in 2006 (source ITU). Many phones offer Instant Messenger services for simple, easy texting. Mobile phones have Internet service (e.g. NTT DoCoMo's i-mode), offering text messaging via e-mail in Japan, South Korea, China, and India. Most ...