Dimetra EBTS » History » Version 1
laforge, 02/19/2016 10:52 PM
add some graphs
1 | 1 | laforge | The Motorola Dimetra EBTS is a TETRA Base Station design. |
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3 | We have been able to get our hands on some of them. This page documents our knowledge about the units, their configuration and how to use them. |
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4 | |||
5 | == Hardware == |
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6 | |||
7 | === Motorola Dimetra Base Radio (T5931A) === |
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8 | |||
9 | The Base Radio (BR) is a modular design in a 4U case, consisting of the following modules: |
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10 | |||
11 | ==== Power Supply (CPN1031B) ==== |
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12 | |||
13 | As the name suggests, it is merely a power supply, converting from the 48 V input to the various voltages required within the radio |
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14 | |||
15 | ==== Controller (CAE010CMX) ==== |
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16 | |||
17 | This is s small PowerPC based embedded system. It communicates with the TETRA Site Controller (TSC) over 10-Base-2 Ethernet |
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18 | and controls all the other units of the Base Radio via the backplane of the BR cabinet. |
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19 | |||
20 | It has the following connections: |
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21 | * RS-232 on the back of the BR |
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22 | * RS-232 on the front of the BR |
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23 | * Site Alarm I/O on the back of the BR |
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24 | * 10-Base-2 Ethernet on the back of the BR (BNC) |
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25 | * Clock input on the back of the BR (BNC) |
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26 | |||
27 | ==== 3x Diversity Receiver (CTX1090A) ==== |
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28 | |||
29 | This is the receiver. It has three antenna inputs in order to use antenna diversity for additional signal gain. |
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30 | |||
31 | The received and demodulated TETRA bursts are forwarded to the Controller via the BR backplane. |
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32 | |||
33 | ==== Exciter (CLN1510A) ==== |
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34 | |||
35 | This is the transmitter. It receives TETRA frames from the Controler via the backplane and encodes/modulates them. The output |
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36 | is fed into the power amplifier over a SMA jumper connection on the back of the base radio. |
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37 | |||
38 | ==== Power Amplifier (CTX1030A) ==== |
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39 | |||
40 | This is a RF power amplifier, used to generate a high-power signal from the output of the exciter. |
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41 | |||
42 | It has three coaxial connections on the back, which are used as follows: |
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43 | * input from the exciter |
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44 | * feedback from PA into the exciter |
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45 | * actual RF power output (towards antenna) |
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46 | |||
47 | === Integrated Site Controller (CLN1480A) === |
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48 | |||
49 | This is a unit that interfaces up to 8 Base Radios with the core network of the Dimetra TETRA network (SwMI). |
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50 | |||
51 | Hardware-wise, it is a PowerPC based system, looking very much like an old-fashioned PC mainboard with |
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52 | both ISA and PCI slots. |
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53 | |||
54 | The mainboard houses the PowerPC CPU and it has slots for RAM. |
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55 | |||
56 | There are some extension cards plugged into the system: |
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57 | * Clock generation card (ISA, full length). |
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58 | * has an integrated GPS receiver, to which you attach a GPS antenna |
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59 | * generates the reference 5MHz clock distributed over Coaxial cable to the Base Radios |
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60 | * Ethernet Card using DEC tulip chipset (PCI) |
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61 | * This card is what talks to the Base Radios (BR) via 10-Base-2 |
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62 | * Unknown card with RJ-45 jack (REDUND) on the back. Might be E1 |
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63 | |||
64 | There are further inputs and outputs on the system: |
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65 | * A DB-15 jack for X.21 synchronous serial backhaul (2048Mbps) |
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66 | * FIXME |
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67 | * A RS-232 serial port for local configuration |
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68 | |||
69 | === RF Distribution System (CFX4041A) === |
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70 | |||
71 | This is a sophisticated combiner for the high-power output signals of the PA of up to 4 Base Radios. |
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72 | |||
73 | In order to ensure optimal impedance matching, the combiner is mechanically tuned by electrical motors |
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74 | which are controlled by some control logic. |
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75 | |||
76 | The combiner inside the system has the following connections (external connections in '''bold'''): |
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77 | * '''4 high-power radio input ports''' (N socket on the front, one close to each motor) |
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78 | * this is where the RF signal emitted by the PA of the BR enters |
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79 | * 4 RF taps, one for each of the high-power radio inputs |
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80 | * they are connected to the controller unit attached to the inside of the front lid |
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81 | * 1 high-power radio output port (N socket) |
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82 | * this output is connected to a power meter inside the same cabinet |
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83 | * 4 stepper motor electrical connections |
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84 | * connected to the controller unit attached to the inside of the front lid |
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85 | * RS-232 serial line for control+monitoring |
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86 | * this is a DB-9 port of the controller unit attached to the inside of the front lid |
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87 | * interconnected to one of the Base Radios (typically BR1) inside the rack |
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88 | |||
89 | The flow of the signals is as follows: |
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90 | * RF from the PA enters at the four combiner inputs |
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91 | * combined RF output leaves through central output of the combiner, from where |
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92 | * it is routed to the FR power meter |
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93 | * whose output socket is routed to the transmit antenna (or a duplexer in case of a shared Rx/Tx antenna) |
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94 | |||
95 | {{{ |
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96 | #!graphviz |
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97 | digraph G { |
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98 | graph [ rankdir = LR ]; |
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99 | |||
100 | //{ rank=same; combiner; controller; }; |
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101 | |||
102 | br1_pa_out -> combiner |
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103 | br2_pa_out -> combiner |
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104 | br3_pa_out -> combiner |
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105 | br4_pa_out -> combiner |
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106 | |||
107 | combiner -> power_meter |
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108 | power_meter -> tx_antenna |
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109 | |||
110 | combiner -> controller [ dir=both color=red ] |
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111 | power_meter -> controller [ color=red ] |
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112 | |||
113 | power_meter [ shape=box ]; |
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114 | combiner [ shape=box ]; |
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115 | controller [ shape=box ]; |
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116 | |||
117 | |||
118 | |||
119 | } |
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120 | }}} |
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121 | === Rx LNA Multicoupler (CRX102A) === |
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122 | |||
123 | The purpose of the Rx LNA multicoupler is to amplify the received signal from the antennas, and split |
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124 | the signal so each Base Radio is attached to each antenna: |
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125 | |||
126 | {{{ |
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127 | #!graphviz |
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128 | digraph G { |
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129 | graph [ rankdir = LR ]; |
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130 | |||
131 | antenna1 -> lna1 |
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132 | antenna2 -> lna2 |
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133 | antenna3 -> lna3 |
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134 | |||
135 | lna1 -> multicoupler1 |
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136 | lna2 -> multicoupler2 |
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137 | lna3 -> multicoupler3 |
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138 | |||
139 | multicoupler1 -> br1_rx1 |
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140 | multicoupler1 -> br2_rx1 |
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141 | multicoupler1 -> br3_rx1 |
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142 | multicoupler1 -> br4_rx1 |
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143 | |||
144 | multicoupler2 -> br1_rx2 |
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145 | multicoupler2 -> br2_rx2 |
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146 | multicoupler2 -> br3_rx2 |
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147 | multicoupler2 -> br4_rx2 |
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148 | |||
149 | multicoupler3 -> br1_rx3 |
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150 | multicoupler3 -> br2_rx3 |
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151 | multicoupler3 -> br3_rx3 |
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152 | multicoupler3 -> br4_rx3 |
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153 | |||
154 | lna1 [ shape=box label="LNA 1" ]; |
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155 | lna2 [ shape=box label="LNA 2" ]; |
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156 | lna3 [ shape=box label="LNA 3" ]; |
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157 | multicoupler1 [ shape=box ]; |
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158 | multicoupler2 [ shape=box ]; |
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159 | multicoupler3 [ shape=box ]; |
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160 | } |
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161 | }}} |