Oi Habr.
Em um artigo anterior sobre o Software Defined Radio, me perguntaram como decodificar o RDS usando o GNU Radio. O decodificador RDS não é tão fácil de criar a partir do zero, mas felizmente para nós, ele já está embutido no GNU Radio, portanto é fácil ver como ele funciona sem escrever uma única linha de código, apenas o receptor RTL-SDR.
Como funciona, continuou sob o corte.
Não vou repetir sobre o GNU Radio e sua instalação, ele já foi descrito
anteriormente . Em resumo, uma distribuição para Windows pode ser encontrada
aqui . Vamos para o RDS.
Se alguém de repente não estiver atualizado, o
RDS (Radio Data System) é um protocolo usado na transmissão convencional de FM para transmitir informações digitais adicionais (hora, taxas de câmbio, clima etc.). A transmissão está a uma velocidade de 1187,5bps a uma frequência de 57KHz (terceiro harmônico do tom piloto), minimização de fase usando a codificação de fase BPSK (Chamada de deslocamento de fase binária). O RDS em nível de bit já foi considerado no hub
antes de passarmos para o GNU Radio.
O decodificador da GNU Radio foi fabricado há cerca de
10 anos , mas é inútil assistir a essa versão, os nomes de muitos blocos foram alterados e os exemplos dados lá não funcionam mais. Garfo atualizado pode ser retirado
daqui .
A propósito, não funcionou para coletar gr-rds da fonte para Windows - o cmake dá erros pela ausência do Boost, embora esteja instalado. É incompreensível, a propósito, que ao longo dos anos de existência cmake and boost, cmake não tenha sido ensinado a encontrar caminhos no Windows - como encontrar uma pasta em um disco não é ciência do foguete (se alguém conhece a solução, escreva nos comentários, embora a julgar pelo Stack Overflow, o problema
existe há anos e todos não se importam). Mas, como se viu, não precisamos disso - o decodificador RDS já foi adicionado ao GNU Radio; portanto, no projeto no github, precisamos apenas de exemplos que estejam na pasta
apps .
O diagrama de blocos incluído nos exemplos é bastante monstruoso e, além disso, são gerados erros quando é aberto (os blocos são marcados em vermelho).
Na vida real, porém, tudo é mais simples - 2/3 do circuito é um aparelho de som para FM, onde os canais L + R e LR são extraídos do sinal original, processados e alimentados na placa de som. Isso não é relevante para nós agora, portanto, esses blocos podem ser removidos (ainda mais porque, por algum motivo, não funcionou imediatamente, mas era muito preguiçoso para entender). Os erros surgem devido ao parâmetro Grid Position, que, aparentemente, não é suportado pela versão do Windows, mas pode ser removido sem problemas, sem afetar a funcionalidade.
Depois de remover "tudo o que é supérfluo", o circuito decodificador RDS em funcionamento fica assim:
Vamos ver o que há lá.
O sinal inicial vem da fonte RTL-SDR, a frequência é definida pelo parâmetro freq, que é do tipo WX GUI Slider (sim, você pode criar sua própria interface no GNU Radio, e há controles básicos). Para evitar um pico na frequência zero no centro, o parâmetro freq_offset é usado, o bloco Frequency Xlating muda a frequência por esse valor. O bloco WBFM Receive, como o nome indica, executa a desmodulação de FM e a frequência é alterada novamente para destacar o próprio RDS a 57KHz. O bloco Filtro Cosinado Raiz seleciona uma frequência estreita, mas o decodificador MPSK com o parâmetro 2 executa a decodificação BPSK (o próprio RDS é transmitido usando
modulação de fase com dois estados). O RDS usa
codificação diferencial ; portanto, o decodificador diferencial correspondente é chamado e, finalmente, o fluxo binário final é enviado ao bloco do decodificador RDS (suas fontes podem ser visualizadas no
github ). Após o decodificador, uma parte igualmente importante é o
analisador RDS - existem muitos tipos de pacotes no RDS, e o analisador faz todo o trabalho para descriptografá-los.
Na verdade isso é tudo. Os resultados do decodificador no KDPV e capturas de tela.
Se alguém precisar usar o programa no modo sem interface do usuário, você pode usar o bloco FR Tap, uma descrição mais detalhada
aqui , pessoalmente não o experimentei. Se o RDS de nível de bit mais baixo é interessante, considerei-o
anteriormente , por interesse geral, também pode ser útil.
Como sempre, todas as experiências bem-sucedidas.
O arquivo GRC original em execução no Windows está sob um spoiler (basta alterar a frequência da estação de rádio).
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<key>_coordinate</key> <value>(184, 6)</value> </param> <param> <key>_rotation</key> <value>0</value> </param> <param> <key>grid_pos</key> <value></value> </param> <param> <key>id</key> <value>nb</value> </param> <param> <key>labels</key> <value>['BB', 'Demod', 'L+R', 'Pilot', 'DSBSC', 'RDS', 'L-R', 'RDS constellation','Waterfall']</value> </param> <param> <key>notebook</key> <value></value> </param> <param> <key>style</key> <value>wx.NB_TOP</value> </param> </block> <block> <key>root_raised_cosine_filter</key> <param> <key>alpha</key> <value>1</value> </param> <param> <key>alias</key> <value></value> </param> <param> <key>comment</key> <value></value> </param> <param> <key>affinity</key> <value></value> </param> <param> <key>decim</key> <value>1</value> </param> <param> <key>_enabled</key> <value>True</value> </param> <param> <key>type</key> <value>fir_filter_ccf</value> </param> <param> <key>_coordinate</key> <value>(304, 516)</value> </param> <param> <key>_rotation</key> <value>0</value> </param> <param> <key>gain</key> <value>1</value> </param> <param> <key>id</key> <value>root_raised_cosine_filter_0</value> </param> <param> <key>interp</key> <value>1</value> </param> <param> <key>maxoutbuf</key> <value>0</value> </param> <param> <key>minoutbuf</key> <value>0</value> </param> <param> <key>ntaps</key> <value>100</value> </param> <param> <key>samp_rate</key> <value>samp_rate/bb_decim/audio_decim</value> </param> <param> <key>sym_rate</key> <value>2375</value> </param> </block> <block> <key>rtlsdr_source</key> <param> <key>alias</key> <value></value> </param> <param> <key>ant0</key> <value></value> </param> <param> <key>bb_gain0</key> <value>20</value> </param> <param> <key>bw0</key> <value>0</value> </param> <param> <key>dc_offset_mode0</key> <value>0</value> </param> <param> <key>corr0</key> <value>0</value> </param> <param> <key>freq0</key> <value>freq_tune</value> </param> <param> <key>gain_mode0</key> <value>False</value> </param> <param> <key>if_gain0</key> <value>20</value> </param> <param> <key>iq_balance_mode0</key> <value>0</value> </param> <param> <key>gain0</key> <value>gain</value> </param> <param> <key>ant10</key> <value></value> </param> <param> <key>bb_gain10</key> <value>20</value> </param> <param> <key>bw10</key> <value>0</value> </param> <param> <key>dc_offset_mode10</key> <value>0</value> </param> <param> <key>corr10</key> <value>0</value> </param> <param> <key>freq10</key> <value>100e6</value> </param> <param> <key>gain_mode10</key> <value>False</value> </param> <param> <key>if_gain10</key> <value>20</value> </param> <param> <key>iq_balance_mode10</key> <value>0</value> </param> <param> <key>gain10</key> <value>10</value> </param> <param> <key>ant11</key> <value></value> </param> <param> <key>bb_gain11</key> <value>20</value> </param> <param> <key>bw11</key> <value>0</value> </param> <param> <key>dc_offset_mode11</key> <value>0</value> </param> <param> <key>corr11</key> <value>0</value> </param> <param> <key>freq11</key> <value>100e6</value> </param> <param> <key>gain_mode11</key> <value>False</value> </param> <param> <key>if_gain11</key> <value>20</value> </param> <param> <key>iq_balance_mode11</key> <value>0</value> </param> <param> <key>gain11</key> <value>10</value> </param> <param> <key>ant12</key> <value></value> </param> <param> <key>bb_gain12</key> <value>20</value> </param> <param> <key>bw12</key> <value>0</value> </param> <param> <key>dc_offset_mode12</key> <value>0</value> </param> <param> <key>corr12</key> <value>0</value> </param> <param> <key>freq12</key> <value>100e6</value> </param> <param> <key>gain_mode12</key> <value>False</value> </param> <param> <key>if_gain12</key> <value>20</value> </param> <param> <key>iq_balance_mode12</key> <value>0</value> </param> <param> <key>gain12</key> <value>10</value> </param> <param> <key>ant13</key> <value></value> </param> <param> <key>bb_gain13</key> <value>20</value> </param> <param> <key>bw13</key> <value>0</value> </param> <param> <key>dc_offset_mode13</key> <value>0</value> </param> <param> <key>corr13</key> <value>0</value> </param> <param> <key>freq13</key> <value>100e6</value> </param> <param> <key>gain_mode13</key> <value>False</value> </param> <param> <key>if_gain13</key> <value>20</value> </param> <param> <key>iq_balance_mode13</key> <value>0</value> </param> <param> <key>gain13</key> <value>10</value> </param> <param> <key>ant14</key> <value></value> </param> <param> <key>bb_gain14</key> <value>20</value> </param> <param> <key>bw14</key> <value>0</value> </param> <param> <key>dc_offset_mode14</key> <value>0</value> </param> <param> <key>corr14</key> <value>0</value> </param> <param> <key>freq14</key> <value>100e6</value> </param> <param> <key>gain_mode14</key> <value>False</value> </param> <param> <key>if_gain14</key> <value>20</value> </param> <param> <key>iq_balance_mode14</key> <value>0</value> </param> <param> <key>gain14</key> <value>10</value> </param> <param> <key>ant15</key> <value></value> </param> <param> <key>bb_gain15</key> <value>20</value> </param> <param> <key>bw15</key> <value>0</value> </param> <param> <key>dc_offset_mode15</key> <value>0</value> </param> <param> <key>corr15</key> <value>0</value> </param> <param> <key>freq15</key> <value>100e6</value> </param> <param> <key>gain_mode15</key> <value>False</value> </param> <param> <key>if_gain15</key> <value>20</value> </param> <param> <key>iq_balance_mode15</key> <value>0</value> </param> <param> <key>gain15</key> <value>10</value> </param> <param> <key>ant16</key> <value></value> </param> <param> <key>bb_gain16</key> <value>20</value> </param> <param> <key>bw16</key> <value>0</value> </param> <param> <key>dc_offset_mode16</key> <value>0</value> </param> <param> <key>corr16</key> <value>0</value> </param> <param> <key>freq16</key> <value>100e6</value> </param> <param> <key>gain_mode16</key> <value>False</value> </param> <param> <key>if_gain16</key> <value>20</value> </param> <param> <key>iq_balance_mode16</key> <value>0</value> </param> <param> <key>gain16</key> <value>10</value> </param> <param> <key>ant17</key> <value></value> </param> <param> <key>bb_gain17</key> <value>20</value> </param> <param> <key>bw17</key> <value>0</value> </param> <param> <key>dc_offset_mode17</key> <value>0</value> </param> <param> <key>corr17</key> <value>0</value> </param> <param> <key>freq17</key> <value>100e6</value> </param> <param> <key>gain_mode17</key> <value>False</value> </param> <param> <key>if_gain17</key> <value>20</value> </param> <param> <key>iq_balance_mode17</key> <value>0</value> </param> <param> <key>gain17</key> <value>10</value> </param> <param> <key>ant18</key> <value></value> </param> <param> <key>bb_gain18</key> <value>20</value> </param> <param> <key>bw18</key> <value>0</value> </param> <param> <key>dc_offset_mode18</key> <value>0</value> </param> <param> <key>corr18</key> <value>0</value> </param> <param> <key>freq18</key> <value>100e6</value> </param> <param> <key>gain_mode18</key> <value>False</value> </param> <param> <key>if_gain18</key> <value>20</value> </param> <param> <key>iq_balance_mode18</key> <value>0</value> </param> <param> <key>gain18</key> <value>10</value> </param> <param> <key>ant19</key> <value></value> </param> <param> <key>bb_gain19</key> <value>20</value> </param> <param> <key>bw19</key> <value>0</value> </param> <param> <key>dc_offset_mode19</key> <value>0</value> </param> <param> <key>corr19</key> <value>0</value> </param> <param> <key>freq19</key> <value>100e6</value> </param> <param> <key>gain_mode19</key> <value>False</value> </param> <param> <key>if_gain19</key> <value>20</value> </param> <param> <key>iq_balance_mode19</key> <value>0</value> </param> <param> <key>gain19</key> <value>10</value> </param> <param> <key>ant1</key> <value></value> </param> <param> <key>bb_gain1</key> <value>20</value> </param> <param> <key>bw1</key> <value>0</value> </param> <param> <key>dc_offset_mode1</key> <value>0</value> </param> <param> <key>corr1</key> <value>0</value> </param> <param> <key>freq1</key> <value>100e6</value> </param> <param> <key>gain_mode1</key> <value>False</value> </param> <param> <key>if_gain1</key> <value>20</value> </param> <param> <key>iq_balance_mode1</key> <value>0</value> </param> <param> <key>gain1</key> <value>10</value> </param> <param> <key>ant20</key> <value></value> </param> <param> <key>bb_gain20</key> <value>20</value> </param> <param> <key>bw20</key> <value>0</value> </param> <param> <key>dc_offset_mode20</key> <value>0</value> </param> <param> <key>corr20</key> <value>0</value> </param> <param> <key>freq20</key> <value>100e6</value> </param> <param> <key>gain_mode20</key> <value>False</value> </param> <param> <key>if_gain20</key> <value>20</value> </param> <param> <key>iq_balance_mode20</key> <value>0</value> </param> <param> <key>gain20</key> <value>10</value> </param> <param> <key>ant21</key> <value></value> </param> <param> <key>bb_gain21</key> <value>20</value> </param> <param> <key>bw21</key> <value>0</value> </param> <param> <key>dc_offset_mode21</key> <value>0</value> </param> <param> <key>corr21</key> <value>0</value> </param> <param> <key>freq21</key> <value>100e6</value> </param> <param> <key>gain_mode21</key> <value>False</value> </param> <param> <key>if_gain21</key> <value>20</value> </param> <param> <key>iq_balance_mode21</key> <value>0</value> </param> <param> <key>gain21</key> <value>10</value> </param> <param> <key>ant22</key> <value></value> </param> <param> <key>bb_gain22</key> <value>20</value> </param> <param> <key>bw22</key> <value>0</value> </param> <param> <key>dc_offset_mode22</key> <value>0</value> </param> <param> <key>corr22</key> <value>0</value> </param> <param> <key>freq22</key> <value>100e6</value> </param> <param> <key>gain_mode22</key> <value>False</value> </param> <param> <key>if_gain22</key> <value>20</value> </param> <param> <key>iq_balance_mode22</key> <value>0</value> </param> <param> <key>gain22</key> <value>10</value> </param> <param> <key>ant23</key> <value></value> </param> <param> <key>bb_gain23</key> <value>20</value> </param> <param> <key>bw23</key> <value>0</value> </param> <param> <key>dc_offset_mode23</key> <value>0</value> </param> <param> <key>corr23</key> <value>0</value> </param> <param> <key>freq23</key> <value>100e6</value> </param> <param> <key>gain_mode23</key> <value>False</value> </param> <param> <key>if_gain23</key> <value>20</value> </param> <param> <key>iq_balance_mode23</key> <value>0</value> </param> <param> <key>gain23</key> <value>10</value> </param> <param> <key>ant24</key> <value></value> </param> <param> <key>bb_gain24</key> <value>20</value> </param> <param> <key>bw24</key> <value>0</value> </param> <param> <key>dc_offset_mode24</key> <value>0</value> </param> <param> <key>corr24</key> <value>0</value> </param> <param> <key>freq24</key> <value>100e6</value> </param> <param> <key>gain_mode24</key> <value>False</value> </param> <param> <key>if_gain24</key> <value>20</value> </param> <param> <key>iq_balance_mode24</key> <value>0</value> </param> <param> <key>gain24</key> <value>10</value> </param> <param> <key>ant25</key> <value></value> </param> <param> <key>bb_gain25</key> <value>20</value> </param> <param> <key>bw25</key> <value>0</value> </param> <param> <key>dc_offset_mode25</key> <value>0</value> </param> <param> <key>corr25</key> <value>0</value> </param> <param> <key>freq25</key> <value>100e6</value> </param> <param> <key>gain_mode25</key> <value>False</value> </param> <param> <key>if_gain25</key> <value>20</value> </param> <param> <key>iq_balance_mode25</key> <value>0</value> </param> <param> <key>gain25</key> <value>10</value> </param> <param> <key>ant26</key> <value></value> </param> <param> <key>bb_gain26</key> <value>20</value> </param> <param> <key>bw26</key> <value>0</value> </param> <param> <key>dc_offset_mode26</key> <value>0</value> </param> <param> <key>corr26</key> <value>0</value> </param> <param> <key>freq26</key> <value>100e6</value> </param> <param> <key>gain_mode26</key> <value>False</value> </param> <param> <key>if_gain26</key> <value>20</value> </param> <param> <key>iq_balance_mode26</key> <value>0</value> </param> <param> <key>gain26</key> <value>10</value> </param> <param> <key>ant27</key> <value></value> </param> <param> <key>bb_gain27</key> <value>20</value> </param> <param> <key>bw27</key> <value>0</value> </param> <param> <key>dc_offset_mode27</key> <value>0</value> </param> <param> <key>corr27</key> <value>0</value> </param> <param> <key>freq27</key> <value>100e6</value> </param> <param> <key>gain_mode27</key> <value>False</value> </param> <param> <key>if_gain27</key> <value>20</value> </param> <param> <key>iq_balance_mode27</key> <value>0</value> </param> <param> <key>gain27</key> <value>10</value> </param> <param> <key>ant28</key> <value></value> </param> <param> <key>bb_gain28</key> <value>20</value> </param> <param> <key>bw28</key> <value>0</value> </param> <param> <key>dc_offset_mode28</key> <value>0</value> </param> <param> <key>corr28</key> <value>0</value> </param> <param> <key>freq28</key> <value>100e6</value> </param> <param> <key>gain_mode28</key> <value>False</value> </param> <param> <key>if_gain28</key> <value>20</value> </param> <param> <key>iq_balance_mode28</key> <value>0</value> </param> <param> <key>gain28</key> <value>10</value> </param> <param> <key>ant29</key> <value></value> </param> <param> <key>bb_gain29</key> <value>20</value> </param> <param> <key>bw29</key> <value>0</value> </param> <param> <key>dc_offset_mode29</key> <value>0</value> </param> <param> <key>corr29</key> <value>0</value> </param> <param> <key>freq29</key> <value>100e6</value> </param> <param> <key>gain_mode29</key> <value>False</value> </param> <param> <key>if_gain29</key> <value>20</value> </param> <param> <key>iq_balance_mode29</key> <value>0</value> </param> <param> <key>gain29</key> <value>10</value> </param> <param> <key>ant2</key> <value></value> </param> <param> <key>bb_gain2</key> <value>20</value> </param> <param> <key>bw2</key> <value>0</value> </param> <param> <key>dc_offset_mode2</key> <value>0</value> </param> <param> <key>corr2</key> <value>0</value> </param> <param> <key>freq2</key> <value>100e6</value> </param> <param> <key>gain_mode2</key> <value>False</value> </param> <param> <key>if_gain2</key> <value>20</value> </param> <param> <key>iq_balance_mode2</key> <value>0</value> </param> <param> <key>gain2</key> <value>10</value> </param> <param> <key>ant30</key> <value></value> </param> <param> <key>bb_gain30</key> <value>20</value> </param> <param> <key>bw30</key> <value>0</value> </param> <param> <key>dc_offset_mode30</key> <value>0</value> </param> <param> <key>corr30</key> <value>0</value> </param> <param> <key>freq30</key> <value>100e6</value> </param> <param> <key>gain_mode30</key> <value>False</value> </param> <param> <key>if_gain30</key> <value>20</value> </param> <param> <key>iq_balance_mode30</key> <value>0</value> </param> <param> <key>gain30</key> <value>10</value> </param> <param> <key>ant31</key> <value></value> </param> <param> <key>bb_gain31</key> <value>20</value> </param> <param> <key>bw31</key> <value>0</value> </param> <param> <key>dc_offset_mode31</key> <value>0</value> </param> <param> <key>corr31</key> <value>0</value> </param> <param> <key>freq31</key> <value>100e6</value> </param> <param> <key>gain_mode31</key> <value>False</value> </param> <param> <key>if_gain31</key> <value>20</value> </param> <param> <key>iq_balance_mode31</key> <value>0</value> </param> <param> <key>gain31</key> <value>10</value> </param> <param> <key>ant3</key> <value></value> </param> <param> <key>bb_gain3</key> <value>20</value> </param> <param> <key>bw3</key> <value>0</value> </param> <param> <key>dc_offset_mode3</key> <value>0</value> </param> <param> <key>corr3</key> <value>0</value> </param> <param> <key>freq3</key> <value>100e6</value> </param> <param> <key>gain_mode3</key> <value>False</value> </param> <param> <key>if_gain3</key> <value>20</value> </param> <param> <key>iq_balance_mode3</key> <value>0</value> </param> <param> <key>gain3</key> <value>10</value> </param> <param> <key>ant4</key> <value></value> </param> <param> <key>bb_gain4</key> <value>20</value> </param> <param> <key>bw4</key> <value>0</value> </param> <param> <key>dc_offset_mode4</key> <value>0</value> </param> <param> <key>corr4</key> <value>0</value> </param> <param> <key>freq4</key> <value>100e6</value> </param> <param> <key>gain_mode4</key> <value>False</value> </param> <param> <key>if_gain4</key> <value>20</value> </param> <param> <key>iq_balance_mode4</key> <value>0</value> </param> <param> <key>gain4</key> <value>10</value> </param> <param> <key>ant5</key> <value></value> </param> <param> <key>bb_gain5</key> <value>20</value> </param> <param> <key>bw5</key> <value>0</value> </param> <param> <key>dc_offset_mode5</key> <value>0</value> </param> <param> <key>corr5</key> <value>0</value> </param> <param> <key>freq5</key> <value>100e6</value> </param> <param> <key>gain_mode5</key> <value>False</value> </param> <param> <key>if_gain5</key> <value>20</value> </param> <param> <key>iq_balance_mode5</key> <value>0</value> </param> <param> <key>gain5</key> <value>10</value> </param> <param> <key>ant6</key> <value></value> </param> <param> <key>bb_gain6</key> <value>20</value> </param> <param> <key>bw6</key> <value>0</value> </param> <param> <key>dc_offset_mode6</key> <value>0</value> </param> <param> <key>corr6</key> <value>0</value> </param> <param> <key>freq6</key> <value>100e6</value> </param> <param> <key>gain_mode6</key> <value>False</value> </param> <param> <key>if_gain6</key> <value>20</value> </param> <param> <key>iq_balance_mode6</key> <value>0</value> </param> <param> <key>gain6</key> <value>10</value> </param> <param> <key>ant7</key> <value></value> </param> <param> <key>bb_gain7</key> <value>20</value> </param> <param> <key>bw7</key> <value>0</value> </param> <param> <key>dc_offset_mode7</key> <value>0</value> </param> <param> <key>corr7</key> <value>0</value> </param> <param> <key>freq7</key> <value>100e6</value> </param> <param> <key>gain_mode7</key> <value>False</value> </param> <param> <key>if_gain7</key> <value>20</value> </param> <param> <key>iq_balance_mode7</key> <value>0</value> </param> <param> <key>gain7</key> <value>10</value> </param> <param> <key>ant8</key> <value></value> </param> <param> <key>bb_gain8</key> <value>20</value> </param> <param> <key>bw8</key> <value>0</value> </param> <param> <key>dc_offset_mode8</key> <value>0</value> </param> <param> <key>corr8</key> <value>0</value> </param> <param> <key>freq8</key> <value>100e6</value> </param> <param> <key>gain_mode8</key> <value>False</value> </param> <param> <key>if_gain8</key> <value>20</value> </param> <param> <key>iq_balance_mode8</key> <value>0</value> </param> <param> <key>gain8</key> <value>10</value> </param> <param> <key>ant9</key> <value></value> </param> <param> <key>bb_gain9</key> <value>20</value> </param> <param> <key>bw9</key> <value>0</value> </param> <param> <key>dc_offset_mode9</key> <value>0</value> </param> <param> <key>corr9</key> <value>0</value> </param> <param> <key>freq9</key> <value>100e6</value> </param> <param> <key>gain_mode9</key> <value>False</value> </param> <param> <key>if_gain9</key> <value>20</value> </param> <param> <key>iq_balance_mode9</key> <value>0</value> </param> <param> <key>gain9</key> <value>10</value> </param> <param> <key>comment</key> <value></value> </param> <param> <key>affinity</key> <value></value> </param> <param> <key>args</key> <value></value> </param> <param> <key>_enabled</key> <value>1</value> </param> <param> <key>_coordinate</key> <value>(24, 272)</value> </param> <param> <key>_rotation</key> <value>0</value> </param> <param> <key>id</key> <value>rtlsdr_source_0</value> </param> <param> <key>maxoutbuf</key> <value>0</value> </param> <param> <key>clock_source0</key> <value></value> </param> <param> <key>time_source0</key> <value></value> </param> <param> <key>clock_source1</key> <value></value> </param> <param> <key>time_source1</key> <value></value> </param> <param> <key>clock_source2</key> <value></value> </param> <param> <key>time_source2</key> <value></value> </param> <param> <key>clock_source3</key> <value></value> </param> <param> <key>time_source3</key> <value></value> </param> <param> <key>clock_source4</key> <value></value> </param> <param> <key>time_source4</key> <value></value> </param> <param> <key>clock_source5</key> <value></value> </param> <param> <key>time_source5</key> <value></value> </param> <param> <key>clock_source6</key> <value></value> </param> <param> <key>time_source6</key> <value></value> </param> <param> <key>clock_source7</key> <value></value> </param> <param> <key>time_source7</key> <value></value> </param> <param> <key>minoutbuf</key> <value>0</value> </param> <param> <key>nchan</key> <value>1</value> </param> <param> <key>num_mboards</key> <value>1</value> </param> <param> <key>type</key> <value>fc32</value> </param> <param> <key>sample_rate</key> <value>samp_rate</value> </param> <param> <key>sync</key> <value></value> </param> </block> <block> <key>wxgui_fftsink2</key> <param> <key>avg_alpha</key> <value>0.8</value> </param> <param> <key>average</key> <value>True</value> </param> <param> <key>baseband_freq</key> <value>0</value> </param> <param> <key>alias</key> <value></value> </param> <param> <key>comment</key> <value></value> </param> <param> <key>affinity</key> <value></value> </param> <param> <key>_enabled</key> <value>True</value> </param> <param> <key>fft_size</key> <value>1024</value> </param> <param> <key>freqvar</key> <value>None</value> </param> <param> <key>_coordinate</key> <value>(1056, 56)</value> </param> <param> <key>_rotation</key> <value>0</value> </param> <param> <key>grid_pos</key> <value></value> </param> <param> <key>id</key> <value>wxgui_fftsink2_0</value> </param> <param> <key>notebook</key> <value>nb, 0</value> </param> <param> <key>peak_hold</key> <value>False</value> </param> <param> <key>ref_level</key> <value>-30</value> </param> <param> <key>ref_scale</key> <value>2.0</value> </param> <param> <key>fft_rate</key> <value>15</value> </param> <param> <key>samp_rate</key> <value>samp_rate</value> </param> <param> <key>title</key> <value>Baseband</value> </param> <param> <key>type</key> <value>complex</value> </param> <param> <key>win_size</key> <value></value> </param> <param> <key>win</key> <value>None</value> </param> <param> <key>y_divs</key> <value>10</value> </param> <param> <key>y_per_div</key> <value>10</value> </param> </block> <block> <key>wxgui_fftsink2</key> <param> <key>avg_alpha</key> <value>0.8</value> </param> <param> <key>average</key> <value>True</value> </param> <param> <key>baseband_freq</key> <value>0</value> </param> <param> <key>alias</key> <value></value> </param> <param> <key>comment</key> <value></value> </param> <param> <key>affinity</key> <value></value> </param> <param> <key>_enabled</key> <value>True</value> </param> <param> <key>fft_size</key> <value>1024</value> </param> <param> <key>freqvar</key> <value>None</value> </param> <param> <key>_coordinate</key> <value>(1056, 280)</value> </param> <param> <key>_rotation</key> <value>0</value> </param> <param> <key>grid_pos</key> <value></value> </param> <param> <key>id</key> <value>wxgui_fftsink2_0_0</value> </param> <param> <key>notebook</key> <value>nb, 1</value> </param> <param> <key>peak_hold</key> <value>False</value> </param> <param> <key>ref_level</key> <value>0</value> </param> <param> <key>ref_scale</key> <value>2.0</value> </param> <param> <key>fft_rate</key> <value>15</value> </param> <param> <key>samp_rate</key> <value>baseband_rate</value> </param> <param> <key>title</key> <value>FM Demod</value> </param> <param> <key>type</key> <value>float</value> </param> <param> <key>win_size</key> <value></value> </param> <param> <key>win</key> <value>None</value> </param> <param> <key>y_divs</key> <value>10</value> </param> <param> <key>y_per_div</key> <value>10</value> </param> </block> <block> <key>wxgui_scopesink2</key> <param> <key>ac_couple</key> <value>False</value> </param> <param> <key>alias</key> <value></value> </param> <param> <key>comment</key> <value></value> </param> <param> <key>affinity</key> <value></value> </param> <param> <key>_enabled</key> <value>True</value> </param> <param> <key>_coordinate</key> <value>(1056, 500)</value> </param> <param> <key>_rotation</key> <value>0</value> </param> <param> <key>grid_pos</key> <value></value> </param> <param> <key>id</key> <value>wxgui_scopesink2_1</value> </param> <param> <key>notebook</key> <value>nb,7</value> </param> <param> <key>num_inputs</key> <value>1</value> </param> <param> <key>samp_rate</key> <value>2375</value> </param> <param> <key>t_scale</key> <value>0</value> </param> <param> <key>title</key> <value>Scope Plot</value> </param> <param> <key>trig_mode</key> <value>wxgui.TRIG_MODE_AUTO</value> </param> <param> <key>type</key> <value>complex</value> </param> <param> <key>v_offset</key> <value>0</value> </param> <param> <key>v_scale</key> <value>0.4</value> </param> <param> <key>win_size</key> <value></value> </param> <param> <key>xy_mode</key> <value>True</value> </param> <param> <key>y_axis_label</key> <value>Counts</value> </param> </block> <connection> <source_block_id>analog_wfm_rcv_0</source_block_id> <sink_block_id>freq_xlating_fir_filter_xxx_1</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>analog_wfm_rcv_0</source_block_id> <sink_block_id>wxgui_fftsink2_0_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>blocks_complex_to_real_0</source_block_id> <sink_block_id>digital_binary_slicer_fb_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>blocks_keep_one_in_n_0</source_block_id> <sink_block_id>digital_diff_decoder_bb_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>digital_binary_slicer_fb_0</source_block_id> <sink_block_id>blocks_keep_one_in_n_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>digital_diff_decoder_bb_0</source_block_id> <sink_block_id>gr_rds_decoder_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>digital_mpsk_receiver_cc_0</source_block_id> <sink_block_id>blocks_complex_to_real_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>digital_mpsk_receiver_cc_0</source_block_id> <sink_block_id>wxgui_scopesink2_1</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>freq_xlating_fir_filter_xxx_0</source_block_id> <sink_block_id>analog_wfm_rcv_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>freq_xlating_fir_filter_xxx_0</source_block_id> <sink_block_id>wxgui_fftsink2_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>freq_xlating_fir_filter_xxx_1</source_block_id> <sink_block_id>root_raised_cosine_filter_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>gr_rds_decoder_0</source_block_id> <sink_block_id>gr_rds_parser_0</sink_block_id> <source_key>out</source_key> <sink_key>in</sink_key> </connection> <connection> <source_block_id>gr_rds_parser_0</source_block_id> <sink_block_id>gr_rds_panel_0</sink_block_id> <source_key>out</source_key> <sink_key>in</sink_key> </connection> <connection> <source_block_id>root_raised_cosine_filter_0</source_block_id> <sink_block_id>digital_mpsk_receiver_cc_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> <connection> <source_block_id>rtlsdr_source_0</source_block_id> <sink_block_id>freq_xlating_fir_filter_xxx_0</sink_block_id> <source_key>0</source_key> <sink_key>0</sink_key> </connection> </flow_graph>