Digital Enhanced Cordless System  DECT


    DECT Channels: FR carriers shall be placed from 1880 - 1900 Mhz. Center Frequency is calculated 
    by Fo=1897.344 Mhz , and the     frequency channel number c= (0,1,2....9) shown on the left side.

    Fc=Fo- (C x 1,728 Mhz)

    Let's calculate the X in the Downlink (channel number 4 , slot 5)

     1897.344 Mhz - (4 x 1,728 Mhz) = 1890.432 Mhz

               Downlink ,,,, or 5ms                                                                                            Uplink ,,, also 5ms

    GS2 1800,000

    928 khz

    1880,928

    		                                                
    9 1881,792                                                
    8 1883,520                     Y                       Y  
    7 1885,248                                                
    6 1886,976                                                
    5 1888,704                                                
    4 1890,432           X                       X            
    3 1892,160                                                
    2 1893,888                                                
    1 1895,616                                                
    0 1897,344                                                
    GS1 1898,208

    1792 khz

    1900,000

    		                                                
      Timeslot  0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

    Duplex Method: DECT use TDD .... Time Division Duplex to separate Downlink & Uplink information. 
    So Downlink  receive 5ms after Uplink transmit last information.

    Bandwich per duplex channel: DECT bandwich is 1,728 Mhz into 24 Timeslots or one frame. 

     

     

    Guard Space DECT Europe

     

       GS1 to the upper band =  Center of CH 0 is 1897,344  MHz - Bandwich/2 = 1898,208

    1900,000 - 1898,208 Mhz = 1792 khz

        GS2 to the lower band  =  Center of CH 9 is 1881,792 Mhz - Bandwich/2 = 1880,928

    1880,928 - 1800,000 Mhz = 928 khz

     

     

     

    Guard Periode: During GP on end of a frame no bits were send to avoid bit collision.

    GP in GSM = 8.25 bits or 30.5 micro seconds 

    GP in DECT = 60 bits or 1.2 ms (10ms/480bps * 60bits)

    Maximum peak power transmitted: DECT based device normally radiated 250mW EIRP  

    in one of the 24 timeslots .....

    so average power is ....

    Maximum Radiated Power divide by 1 of  the 24 timeslots ...

     if one slot is used :        250mW : 24 slots = 10.4mW

     

    if six slots are used (RFP) :        250mW : 24 slots x 6 = 62.5mW