DECT Tuning

 

 

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!!! ACHTUNG !!! Es ist bei Strafe verboten Frequenzen zu stören bzw. zugelassene Geräte im HF Bereich zu verändern

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This is a special topic on the DECT Phone System. I like to tell about the possible

things to cover a larger area with our home cordless. There’s no easy way to ad

only some RF amplifier device.

 

Here are some reasons:     

*Pin Switch , hard to add external amps because antenna diversity

*Height Data Rate , tree times more than GSM

*Bad sensivity ,                      

  • no Interleaving or forward error correction

  • no Maximum Rate Combining   (Rake receiver)

  • no Spread Spectrum Gain                                                                            

 

But first some technical things....

 

The DECT System vs. GSM 1800

System DECT GSM 1800 (European)
Frequency 1880 ... 1900 Mhz 1710 ... 1785 Mhz (UL) 1805 ... 1800 Mhz (DL)
Band Space 20 Mhz 75 Mhz Up & 75 Mhz Down
Channels 120 2976 (Full Rate with Guard Space)
5952 (Half Rate with Guard Space)
Bandwich per Time Slot 1,72 Mhz in 24 Time Slots 2* 0,2 Mhz in 2*8 Time Slots
Modulation GMSK (Gaussian Minimum Shift Keying) GMSK (Gaussian Minimum Shift Keying)
Duplex Channels per Mhz 6  
Duplexing TDD Time Division Duplex TDD & FDD (Frequency Division Duplex)
DL/UL Space 12 Time Slots or 0,86 Mhz 95 Mhz
Data Rate 32 kBit/s unencoded (Base convert up to 64kbp/s for ISDN operation)
25,6kBit on save mode with 4*16 bits for error correction.  		13 kBit/s Full Rate with Error Correction
5,5 kBit/s Half Rate 
Tx Power MP (Mobile Part) 24 dbm (250mW) Peak EIRP 4 … 33 dbm (2,5mW…2W) Peak EIRP
Tx Power MP effective Ca. 10mW  (0,25W div. 24 Slots)  
Tx Power BST 
(Base Station Terminal)		 Like MP, no adjust 4 … 33 dbm (2,5mW…2W) EIRP
Power Control No usually 4 to 5 bit
Time Slots 24 (UL & DL) 16 (UP & DL)
Charrier 120 374
Range 50m Indoor 300m Outdoor Ca.10km
Range line of sight 1-5km much
Range WLL 
(Wireless Lokal Loop)		 up to 5km  
Max drive Speed MS Ca.25km/h Ca.130km/h
Bit Time 0,868 micro Sek. 3,7 micro Sek.
Bit Range   270kbit/s
Slot Lange 10ms 4,6ms
Reference Sensivity Ca. –87 dbm Ca. –104 dbm
Roundabout lange Ca.100m Ca.5km                                         
Handover Portable Part Base Station Sub-System
Frequency Planning Dynamic Channel Allocation DCA BST Frequency Planing
Diversity Yes (Siemens Gigaset) polarization & Room Diversity in BST Yes … polarization & Room Diversity in BST
Algorithms SSL-128bit for 3,4*10^38 comb. A5/2 Algorithms for EU 64bit – 10bit = 54bit for 1.8*10^16 comb.
Control Channels per Slot Ca.2 …left 10 CH Ca.2 … left 6 CH
Frequency Hopping No Yes
Costs Free non license Private Net
Roaming Yes ... Yes ,,, of curse
Code Rate no ½ for 6db of Gain
Maximum Radio Fixed Parts

7  for  Home Use 256 in Industry

 
Maximum Repeater 7  
Guard Period 2 Mhz – 1,72 Mhz = 280 kHz  

 


The amp. don't work as nice .... there's a problems with the negative gate voltage....

but still on progress ....

 

System frequencys Duplex FDD Space 
[Mhz]		 Frame time [ms] Timeslots per channel TDD space Duplex Channel per Mhz Duplex Channels Bandwich
CT2 (close down) 864 - 868 Mhz (UL+DL) TDD ... 2 2 1 10 40 4 Mhz
CT1plus (close down) 885 - 887 (UL)
930 - 932 (DL)		 FDD 45 Mhz analog analog analog 20 80 4 Mhz
DECT 1880 - 1900 Mhz (UL+DL)
1900 - 1920 Mhz (UL+DL)		 TDD ... 10 24 12 7 120 *100 20 Mhz
GSM900

(Europe)

 890 - 915 Mhz (UL)
935 - 960 Mhz (DL)		 FDD 45 Mhz 4.6 8 3 20 (FR)
40 (HR)		 1000 (FR)
(992 GS)
2000 (HR)
(1884 GS)		 25 Mhz
GSM900

(Europe)

Railway band

 876 - 880 Mhz (UL)

921 - 925 Mhz (DL)

 FDD 45 Mhz 4.6 8 3 20 (FR)

40 (HR)

   8 Mhz
GSM1800 1710 - 1785 Mhz (UL)

1805 - 1880 Mhz (DL)

 FDD 95 Mhz 4.6 8 3 20 (FR)

40 (HR)

 3000 (FR)
6000 (HR)		 150 Mhz
(D)AMPS
Digital American Mobile Phone System		 824 - 849 Mhz (UL)
869 - 894 Mhz (DL)		 FDD 45 Mhz  20 3   50 2500 50 Mhz
American Cordless 2400 - 2483 (UL+DL) FH ... ? ? FH ?  ? 83 Mhz
PCS Personal Communication System 1850 - 1910 Mhz (UL)
1930 - 1990 Mhz (DL)		 FDD 80 Mhz 20 3   50 6000 120 Mhz
JDC Japanese Digital Cellular 940 - 960 Mhz (UL)
810 - 930 Mhz (DL)		 FDD 130 Mhz 20 3   60 2400 40 Mhz

* with CCH Control Channel

----(UL = Upload)---- ... ----(DL = Download)----  ...  ----( FR = Full Rate)----  ...  ----(HR = Half Rate)----

 

UMTS CDMA Cellular        

System frequency Duplex FDD space Carrier space  Timeslots per carrier Spreizfaktor Chiprate [Mchip/s]
UMTS FDD 1920 - 1980 Mhz (DL)
2110 - 2170 Mhz (UL)		 FDD 190 Mhz 5 Mhz  / 4-512 (2'2-2'9) 3,84
UMTS TDD 1900 - 1920 Mhz (UL+DL)
2010 - 2025 Mhz (UL+DL)		 TDD / 5 Mhz 15 1,2,4,8,16 3,84
IS-95  1850 - 1910 Mhz (UL) 
1930 - 1990 Mhz (DL)		 FDD 80 Mhz 1.25 Mhz / 64 1,228