Simply because of the band-width required to transmit and receive calls. If the channel spacing was narrower - they'd need to reduce the band-width - which would reduce the amount of data they could transmit.
How do you convert cellphone gsm frequency to another gsm frequency?"
GSM 900: Uplink frequency: 890 - 915 MHz GSM 1800 : Uplink frequency: 1710 - 1785 MHz GSM 1900: Uplink frequency: 1850 - 1910 MHz
maximum spacing assording to IS 456 = 300mm
System Specifications: 1. Tx Frequency; 1626.5-1646.5MHz 2. EIRPG33/25dBW 3. Rx Frequency; 1525.0-1545.0MHz 4. Channel Spacing; 20kHz
Allowable clearing spacing of bars = 3d where d is depth suppose d is 180 mm than clearing spacing is 3(180) =540mm note that clearing spacing of slab donot exceed upto 750mm
GSM Band 890 to 915= 25 MHz One GSM Channel BW= 200 KHz Total GSM channels=25MHz/200KHz=125
174 no ........ the uplink is 890-915 & down link is 935-960.....MHz each channel having band width of 200KHz & using by 8 subsciber.... so 25MHz/200Khz ......=125...so there are 125 channels present in GSM900 but one channel is use as a guard so only 124 channel present in GSM900
because we can use 99% of 270.5 kbps which is normally used for air interface in gsm, to get a minimum bit error rate of 1% and 8/1 db sn ratio.
WDM classification is based on channel spacing between two wavelengths * channel spacing greater than 200GHZ is called as CWDM * channel spacing greater than 100GHZ is called as WDM * channel spacing lesser than 100GHZ is called as DWDM * channel spacing lesser than 25GHZ is called as UDWDM 100GHZ = 0.8nm WDM classification is based on channel spacing between two wavelengths * channel spacing greater than 200GHZ is called as CWDM * channel spacing greater than 100GHZ is called as WDM * channel spacing lesser than 100GHZ is called as DWDM * channel spacing lesser than 25GHZ is called as UDWDM 100GHZ = 0.8nm
Channel spacing is the difference in the frequency allocation of the allocated frequency plan to avoid overlap between the channels or frequencies.
270.83 kbps
GSM-900 and GSM-1800 are used in most parts of the world: Europe, Middle East, Africa, Australia and most of Asia. In South and Central America the following countries use the following: : :* Costa Rica - GSM-1800 :* Brazil - GSM-850, 900 and 1800 :* Guatemala - GSM-850, GSM-900 and 1900 :* El Salvador - GSM-850, GSM-900 and 1900 GSM-900 uses 890-915 MHz to send information from the mobile station to the base station (uplink) and 935-960 MHz for the other direction (downlink), providing 124 RF channels (channel numbers 1 to 124) spaced at 200 kHz. Duplex spacing of 45 MHz is used. Guard bands 100 kHz wide are placed at either end of the range of frequencies[1]. : In some countries the GSM-900 band has been extended to cover a larger frequency range. This 'extended GSM', E-GSM, uses 880-915 MHz (uplink) and 925-960 MHz (downlink), adding 50 channels (channel numbers 975 to 1023 and 0) to the original GSM-900 band. The GSM specifications also describe 'railways GSM', GSM-R, which uses 876-915 MHz (uplink) and 921-960 MHz (downlink). Channel numbers 955 to 1023. GSM-R provides additional channels and specialized services for use by railway personnel. : All these variants are included in the GSM-900 specification. GSM-1800 uses 1710-1785 MHz to send information from the mobile station to the base tranceiver station (uplink) and 1805-1880 MHz for the other direction (downlink), providing 374 channels (channel numbers 512 to 885). Duplex spacing is 95 MHz. : GSM-1800 is also called DCS (Digital Cellular Service) in the United Kingdom, while being called PCS in Hong Kong[2] (not to mix up with GSM-1900 which is commonly called PCS in the rest of the world.)
Any time-slot on any GSM radio channel assigned to GPRS usage is defined as a Packet. Data CHannel(PDCH).
-- aeronautical mobile -- aeronautical radionavigation
link acess protocol for the D channel is used in the radio link between bts and ms
200KQ7W is the emission bandwidth of GSM 900/1800 network. 200K - 200KHz bandwidth Q - The carrier is angle-modulated during the period of the pulse 7 - Two or more channels containing quantized or digital information. W - Information to be transmitted- telegraphy, facsimile,telemetry, data transmission, telephony and television(video)
Yes it is possible to make an Electronic Pest Repellent using Arduino and possible to make ultrasound for 30khz to 200khz frequency; you must make a rectangle signal with a frequency and amplify it with transistors.