1 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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2 | % Transmitting and Receiving Data using WARPLab with Automatic Gain Control |
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3 | % (SISO Configuration) |
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4 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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5 | % Before looking at this code we recommend getting familiar with the |
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6 | % warplab_siso_example_TxRx.m code which doesn't use AGC hence it is easier |
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7 | % to understand. |
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8 | |
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9 | % The specific steps implemented in this script are the following |
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10 | |
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11 | % 0. Initializaton and definition of parameters |
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12 | % 1. Generate a vector of samples to transmit and send the samples to the |
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13 | % WARP board (Sample Frequency is 40MHz) |
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14 | % 2. Prepare WARP boards for transmission and reception and send trigger to |
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15 | % start transmission and reception (trigger is the SYNC packet) |
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16 | % 3. Read the received samples from the WARP board |
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17 | % 4. Read values related to AGC |
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18 | % 5. Reset and disable the boards |
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19 | % 6. Plot the transmitted and received data and close sockets |
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20 | |
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21 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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22 | % 0. Initializaton and definition of parameters |
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23 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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24 | %Load some global definitions (packet types, etc.) |
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25 | warplab_defines |
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26 | |
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27 | % Create Socket handles and intialize nodes |
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28 | [socketHandles, packetNum] = warplab_initialize; |
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29 | |
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30 | % Separate the socket handles for easier access |
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31 | % The first socket handle is always the magic SYNC |
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32 | % The rest of the handles are the handles to the WARP nodes |
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33 | udp_Sync = socketHandles(1); |
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34 | udp_node1 = socketHandles(2); |
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35 | udp_node2 = socketHandles(3); |
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36 | |
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37 | % Define WARPLab parameters. |
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38 | % For this experiment node 1 will be set as the transmitter and node |
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39 | % 2 will be set as the receiver (this is done later in the code), hence, |
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40 | % there is no need to define receive gains for node 1 and there is no |
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41 | % need to define transmitter gains for node 2. |
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42 | TxDelay = 0; % Number of noise samples per Rx capture. In [0:2^14] |
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43 | TxLength = 2^14-1; % Length of transmission. In [0:2^14-1-TxDelay] |
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44 | CarrierChannel = 12; % Channel in the 2.4 GHz band. In [1:14] |
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45 | Node1_Radio2_TxGain_BB = 1; % Tx Baseband Gain. In [0:3] |
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46 | Node1_Radio2_TxGain_RF = 25; % Tx RF Gain. In [0:63] |
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47 | TxMode = 0; % Transmission mode. In [0:1] |
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48 | % 0: Single Transmission |
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49 | % 1: Continuous Transmission. Tx board will continue |
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50 | % transmitting the vector of samples until the user manually |
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51 | % disables the transmitter. |
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52 | Node2_MGC_AGC_Select = 1; % Set MGC_AGC_Select=1 to enable Automatic Gain Control (AGC). |
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53 | % Set MGC_AGC_Select=0 to enable Manual Gain Control (MGC). |
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54 | % By default, the nodes are set to MGC. |
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55 | Node2_TargetdBmAGC = -10; % AGC Target dBm. A larger target value will |
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56 | % result in larger Rx gains set by AGC. This is |
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57 | % the value we tune if AGC is not setting gains |
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58 | % correctly. |
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59 | Node2_NoiseEstdBmAGC = -95; % Noise power in dBm. -95dBm is a reasonable |
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60 | % value for wireless. If AGC is not setting gains correctly |
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61 | % this value may need to be modified. Usually we first try to |
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62 | % change the TargetdBmAGC before changing the NoiseEstdBmAGC |
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63 | Node2_Thresh1 = -90; |
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64 | Node2_Thresh2 = -53; |
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65 | Node2_Thresh3 = -43; |
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66 | % Change format of Thresholds so they can be correctly understood by |
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67 | % the FPGA: |
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68 | Node_2Thresholds = uint32(Node2_Thresh3+2^8)*2^16+uint32(Node2_Thresh2+2^8)*2^8+uint32(Node2_Thresh1+2^8); |
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69 | % The three thresholds above are used to set the Rx RF gain. If the RSSI in |
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70 | % dBm of the received signal is less than -90 then the AGC declares the |
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71 | % signal to be too low and quits. If the RSSI in dBm of the received signal |
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72 | % is between -53 and -90 then the AGC selects the largest RF gain : 3. If |
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73 | % the RSSI dBm is between -43 and -53 then the AGC sets medium RF gain : 2. If |
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74 | % the RSSI dBm is larger than -43 then the AGC sets low RF gain :1. |
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75 | % If AGC is no setting gains correctly then these three thresholds may need |
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76 | % to be modified. Usually we first try to change the TargetdBmAGC before |
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77 | % changing the Thresholds. |
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78 | % Remember there are 3 possible Rx RF gains: 1,2,3. Each step corresponds |
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79 | % to 15dB: Changing the gain from 2 to 3 increases the Rx gain by 15 dB. |
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80 | Node2_AGCTrigger_nsamps_delay = 100; % The AGC core should not be started before the |
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81 | % signal arrives. If TxDelay=0 then Tx and Rx should start at exactly the |
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82 | % same time (upon reception of magic sync) however, because of jitter in |
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83 | % reception of the magic sync, it may happed that the Rx gets the magic |
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84 | % sync before the Tx. If this is the case then the AGC will set wrong gains |
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85 | % because AGC will use RSSI values that are measured before reception of the signal. |
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86 | % To avoid this we can delay the trigger of the AGC core by |
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87 | % Node2_AGCTrigger_nsamps_delay samples relative to the reception of the |
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88 | % magic sync. We recommend to set this value between 0 and 50 samples. We |
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89 | % have not observed magic sync jitters greater than 50 samples. |
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90 | Node2_Enable_DCOffset_Correction = 1; % Enable/disable correction of DC Offsets (DCO). |
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91 | % Node2_Enable_DCOffset_Correction = 0; Disable correction of DC Offsets at |
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92 | % AGC |
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93 | % Node2_Enable_DCOffset_Correction = 1; Enable correction of DC Offsets at |
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94 | % AGC |
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95 | % Change of Rx gains by AGC may result in DC offsets. The AGC can correct |
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96 | % these offsets but the user must be very careful on the choice of preamble |
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97 | % used for AGC. For DCO correction at AGC to work properly the first 320 |
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98 | % samples must correspond to a periodic signal with an average (DC) of zero |
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99 | % over 32 consecutive samples, this will generate the right signal required |
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100 | % by AGC DCO correction for a sampling frequency of 40 MHz. AGC DCO |
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101 | % correction can be disabled by setting Node2_Enable_DCOffset_Correction=0, |
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102 | % in this case there is no requirement for the periodicity of the |
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103 | % preamble used for AGC. |
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104 | |
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105 | % NOTES ON AGC: |
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106 | % 1. As soon as AGC is triggered, it takes the AGC core |
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107 | % approximately 250 samples (at 40MHz sampling frequency) to set gains. If |
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108 | % DCO correction at AGC is enabled it takes the AGC an extra 32 samples to |
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109 | % filter DCO. This means that the first 250 samples received (282 when using DCO |
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110 | % correction) may not contain useful data because during reception of these |
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111 | % samples Rx gains (and DCO correction) were not set correctly. |
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112 | % 2. The first 250 samples must be representative of the rest of signal |
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113 | % being transmitted (similar bandwidth and amplitude), otherwise the gains |
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114 | % set by the AGC will work for the first 250 samples but will be wrong |
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115 | % (causing saturation or underflow) for the rest of the signal. |
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116 | |
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117 | % Download the WARPLab parameters to the WARP nodes. |
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118 | % The nodes store the TxDelay, TxLength, and TxMode parameters in |
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119 | % registers defined in the WARPLab sysgen model. The nodes set radio |
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120 | % related parameters CarrierChannel, TxGains, and RxGains, using the |
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121 | % radio controller functions. |
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122 | |
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123 | % The TxDelay, TxLength, and TxMode parameters need to be known at the transmitter; |
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124 | % the receiver doesn't require knowledge of these parameters (the receiver |
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125 | % will always capture 2^14 samples). For this exercise node 1 will be set as |
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126 | % the transmitter (this is done later in the code). Since TxDelay, TxLength and |
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127 | % TxMode are only required at the transmitter we download the TxDelay, TxLength and |
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128 | % TxMode parameters only to the transmitter node (node 1). |
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129 | warplab_writeRegister(udp_node1,TX_DELAY,TxDelay); |
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130 | warplab_writeRegister(udp_node1,TX_LENGTH,TxLength); |
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131 | warplab_writeRegister(udp_node1,TX_MODE,TxMode); |
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132 | % The CarrierChannel parameter must be downloaded to all nodes |
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133 | warplab_setRadioParameter(udp_node1,CARRIER_CHANNEL,CarrierChannel); |
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134 | warplab_setRadioParameter(udp_node2,CARRIER_CHANNEL,CarrierChannel); |
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135 | % Node 1 will be set as the transmitter so download Tx gains to node 1. |
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136 | warplab_setRadioParameter(udp_node1,RADIO2_TXGAINS,(Node1_Radio2_TxGain_RF + Node1_Radio2_TxGain_BB*2^16)); |
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137 | % Node 2 will be set as the receiver so download AGC related parameters to node 2. |
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138 | warplab_setAGCParameter(udp_node2,MGC_AGC_SEL, Node2_MGC_AGC_Select); % AGC mode is enabled when |
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139 | % Node2_MGC_AGC_Select = 1. THIS COMMAND RESETS AND INITIALIZES THE AGC. THIS COMMAND INITIALIZES |
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140 | % AGC PARAMETER TO DEFAULTS. Default values are hard coded in warplab C code. |
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141 | % The default values can be changed as is done in the 5 lines below. |
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142 | warplab_setAGCParameter(udp_node2,SET_AGC_TARGET_dBm, Node2_TargetdBmAGC); |
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143 | warplab_setAGCParameter(udp_node2,SET_AGC_NOISEEST_dBm, Node2_NoiseEstdBmAGC); |
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144 | warplab_setAGCParameter(udp_node2,SET_AGC_THRESHOLDS, Node_2Thresholds); |
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145 | warplab_setAGCParameter(udp_node2,SET_AGC_TRIG_DELAY, Node2_AGCTrigger_nsamps_delay); |
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146 | warplab_setAGCParameter(udp_node2,SET_AGC_DCO_EN_DIS, Node2_Enable_DCOffset_Correction); |
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147 | |
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148 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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149 | % 1. Generate a vector of samples to transmit and send the samples to the |
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150 | % WARP board (Sample Frequency is 40MHz) |
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151 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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152 | t = 0:(1/40e6):TxLength/40e6 - 1/40e6; % Create time vector. |
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153 | |
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154 | % Create a signal to transmit, the signal is a function of the time vector |
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155 | % 't' the signal can be real or complex. |
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156 | |
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157 | % The signal must meet the following requirements: |
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158 | % - Signal to transmit must be a row vector. |
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159 | % - The amplitude of the real part must be in [-1:1] and the amplitude |
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160 | % of the imaginary part must be in [-1:1]. |
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161 | % - Highest frequency component is limited to 9.5 MHz (signal bandwidth |
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162 | % is limited to 19 MHz) |
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163 | % - Lowest frequency component is limited to 30 kHz |
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164 | |
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165 | Node1_Radio2_TxData = exp(t*j*2*pi*2.5e6); % Generate 2.5 MHz signal. |
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166 | % Notice that with a sampling frequency of 40 MHz this signal is periodic |
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167 | % every 32 samples and has an average DC of zero. Hence, DC Offset |
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168 | % correction will work for this signal. |
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169 | |
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170 | % Download the samples to be transmitted |
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171 | warplab_writeSMWO(udp_node1, RADIO2_TXDATA, Node1_Radio2_TxData); |
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172 | |
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173 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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174 | % 2. Prepare WARP boards for transmission and reception and send trigger to |
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175 | % start transmission and reception (trigger is the SYNC packet) |
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176 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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177 | % The following lines of code set node 1 as transmitter and node 2 as |
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178 | % receiver; transmission and capture are triggered by sending the SYNC |
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179 | % packet. |
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180 | |
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181 | % Enable transmitter radio path in radio 2 in node 1 (enable radio 2 in |
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182 | % node 1 as transmitter) |
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183 | warplab_sendCmd(udp_node1, RADIO2_TXEN, packetNum); |
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184 | |
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185 | % Enable transmission of node1's radio 2 Tx buffer (enable transmission |
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186 | % of samples stored in radio 2 Tx Buffer in node 1) |
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187 | warplab_sendCmd(udp_node1, RADIO2TXBUFF_TXEN, packetNum); |
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188 | |
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189 | % Enable receiver radio path in radios 2 and 3 in node 2 (enable radio 2 |
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190 | % and radio 3 in node 2 as receiver) |
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191 | warplab_sendCmd(udp_node2, [RADIO2_RXEN RADIO3_RXEN], packetNum); |
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192 | |
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193 | % Enable capture in node2's radio 2 and radio 3 Rx Buffer (enable radio 2 rx buffer |
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194 | % and radio 3 rx buffer in node 2 for storage of samples) |
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195 | warplab_sendCmd(udp_node2, [RADIO2RXBUFF_RXEN RADIO3RXBUFF_RXEN], packetNum); |
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196 | |
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197 | % Prime transmitter state machine in node 1. Node 1 will be |
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198 | % waiting for the SYNC packet. Transmission from node 1 will be triggered |
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199 | % when node 1 receives the SYNC packet. |
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200 | warplab_sendCmd(udp_node1, TX_START, packetNum); |
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201 | |
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202 | % Prime receiver state machine in node 2. Node 2 will be waiting |
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203 | % for the SYNC packet. Capture at node 2 will be triggered when node 2 |
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204 | % receives the SYNC packet. |
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205 | warplab_sendCmd(udp_node2, RX_START, packetNum); |
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206 | |
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207 | % Send the SYNC packet |
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208 | warplab_sendSync(udp_Sync); |
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209 | |
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210 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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211 | % 3. Read the received samples from the WARP board |
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212 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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213 | % Read back the received samples |
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214 | [Node2_Radio2_RawRxData] = warplab_readSMRO(udp_node2, RADIO2_RXDATA, TxLength+TxDelay); |
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215 | [Node2_Radio3_RawRxData] = warplab_readSMRO(udp_node2, RADIO3_RXDATA, TxLength+TxDelay); |
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216 | % Process the received samples to obtain meaningful data |
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217 | [Node2_Radio2_RxData,Node2_Radio2_RxOTR] = warplab_processRawRxData(Node2_Radio2_RawRxData); |
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218 | [Node2_Radio3_RxData,Node2_Radio3_RxOTR] = warplab_processRawRxData(Node2_Radio3_RawRxData); |
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219 | |
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220 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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221 | % 4. Read values related to AGC |
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222 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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223 | % Read the sample number that corresponds to AGC being done setting gains |
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224 | [Node2_AGC_Set_Addr] = warplab_readAGCValue(udp_node2, READ_AGC_DONE_ADDR); |
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225 | % Received samples are stored in Received buffer, when AGC is done the |
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226 | % address of the sample being written at that moment is stored, this |
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227 | % address is Node2_AGC_Set_Addr. This means that samples after |
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228 | % Node2_AGC_Set_Addr sample are applied the Rx Gains computed by AGC. From |
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229 | % sample zero the Node2_AGC_Set_Addr the amplitude of the received signal |
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230 | % may vary a lot because during this time the AGC was not done setting |
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231 | % gains. |
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232 | |
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233 | % Read the value of the RSSI that corresponds to AGC being done setting |
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234 | % gains. When AGC is done the currrent RSSI value measured by node 2 radio2 |
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235 | % and radio 3 is stored in registers which can be read as shown below. |
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236 | [Node2_Radio2_AGC_Set_RSSI] = warplab_readAGCValue(udp_node2, READ_RADIO2AGCDONERSSI); |
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237 | [Node2_Radio3_AGC_Set_RSSI] = warplab_readAGCValue(udp_node2, READ_RADIO3AGCDONERSSI); |
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238 | |
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239 | % Read the gains set by AGC |
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240 | [Node2_Raw_AGC_Set_Gains] = warplab_readAGCValue(udp_node2, READ_AGC_GAINS); |
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241 | [Node2_GainsRF,Node2_GainsBB] = warplab_processRawAGCGainsData(Node2_Raw_AGC_Set_Gains); |
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242 | % Since only radio 2 and 3 were used then we only care about the second and third entries in |
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243 | % Node2_GainsRF and Node2_GainsBB vectors |
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244 | Node2_Radio2_GainsRF = Node2_GainsRF(2); |
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245 | Node2_Radio2_GainsBB = Node2_GainsBB(2); |
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246 | Node2_Radio3_GainsRF = Node2_GainsRF(3); |
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247 | Node2_Radio3_GainsBB = Node2_GainsBB(3); |
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248 | |
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249 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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250 | % 5. Reset and disable the boards |
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251 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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252 | % Set radio 2 Tx buffer in node 1 back to Tx disabled mode |
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253 | warplab_sendCmd(udp_node1, RADIO2TXBUFF_TXDIS, packetNum); |
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254 | |
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255 | % Disable the transmitter radio |
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256 | warplab_sendCmd(udp_node1, RADIO2_TXDIS, packetNum); |
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257 | |
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258 | % Set radio 2 and 3 Rx buffer in node 2 back to Rx disabled mode |
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259 | warplab_sendCmd(udp_node2, [RADIO2RXBUFF_RXDIS RADIO3RXBUFF_RXDIS], packetNum); |
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260 | |
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261 | % Disable the receiver radios |
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262 | warplab_sendCmd(udp_node2, [RADIO2_RXDIS RADIO3_RXDIS], packetNum); |
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263 | |
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264 | % Resets Rx gains to default values of RF Gain of 3 and Baseband gain of |
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265 | % 26. Sets AGC ready for a new capture. |
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266 | warplab_sendCmd(udp_node2, AGC_RESET, packetNum); |
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267 | |
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268 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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269 | % 6. Plot the transmitted and received data and close sockets |
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270 | %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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271 | figure; |
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272 | subplot(3,2,1); |
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273 | plot(real(Node1_Radio2_TxData)); |
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274 | title('Tx Node 1 Radio 2 I'); |
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275 | xlabel('n (samples)'); ylabel('Amplitude'); |
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276 | axis([0 2^14 -1 1]); % Set axis ranges. |
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277 | subplot(3,2,2); |
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278 | plot(imag(Node1_Radio2_TxData)); |
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279 | title('Tx Node 1 Radio 2 Q'); |
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280 | xlabel('n (samples)'); ylabel('Amplitude'); |
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281 | axis([0 2^14 -1 1]); % Set axis ranges. |
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282 | subplot(3,2,3); |
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283 | plot(real(Node2_Radio2_RxData)); |
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284 | title('Rx Node 2 Radio 2 I'); |
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285 | xlabel('n (samples)'); ylabel('Amplitude'); |
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286 | axis([0 2^14 -1 1]); % Set axis ranges. |
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287 | subplot(3,2,4); |
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288 | plot(imag(Node2_Radio2_RxData)); |
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289 | title('Rx Node 2 Radio 2 Q'); |
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290 | xlabel('n (samples)'); ylabel('Amplitude'); |
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291 | axis([0 2^14 -1 1]); % Set axis ranges. |
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292 | subplot(3,2,5); |
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293 | plot(real(Node2_Radio3_RxData)); |
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294 | title('Rx Node 2 Radio 3 I'); |
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295 | xlabel('n (samples)'); ylabel('Amplitude'); |
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296 | axis([0 2^14 -1 1]); % Set axis ranges. |
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297 | subplot(3,2,6); |
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298 | plot(imag(Node2_Radio3_RxData)); |
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299 | title('Rx Node 2 Radio 3 Q'); |
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300 | xlabel('n (samples)'); ylabel('Amplitude'); |
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301 | axis([0 2^14 -1 1]); % Set axis ranges. |
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302 | |
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303 | % Close sockets |
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304 | pnet('closeall'); |
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