[Discuss-gnuradio] packet encoder, qam, program jammed up

[Paul Miller]

I'm trying to take an input file, encode it as qam and dump it to a wav file.
You know, one of those simple things students do for no reason.

Well, when I try it without a packet_mod_b, the output I get from
my decoder is all 0s, I'm not sure what I expected to happen
without synchronizers, but it doesn't work.  Heh.  But that's
just background.

When I put a packet_mod_b in there, the program freezes and never
only outputs the first 100k of the output wave (buffers
presumably).  I think it's maybe 40k short.  I end up hitting ^C
after a while...

Why is it freezing up on me?


[The code below is generated by GRC.]
>> def __init__(self):
>>     gr.top_block.__init__(self, "Encoder")
>> 
>>     ##################################################
>>     # Variables
>>     ##################################################
>>     self.samp_rate = samp_rate = 256000
>> 
>>     ##################################################
>>     # Blocks
>>     ##################################################
>>     self.gr_wavfile_sink_0 = gr.wavfile_sink("data.wav", 2, samp_rate, 8)
>>     self.gr_sig_source_x_0 = gr.sig_source_c(samp_rate, gr.GR_COS_WAVE, 
>> 8000, 1, 0)
>>     self.gr_multiply_xx_0 = gr.multiply_vcc(1)
>>     self.gr_file_source_0 = gr.file_source(gr.sizeof_char*1, "data.jpg", 
>> False)
>>     self.gr_complex_to_float_0 = gr.complex_to_float(1)
>>     self.digital_qam_mod_1 = digital.qam.qam_mod(
>>       constellation_points=64,
>>       mod_code="gray",
>>       differential=True,
>>       samples_per_symbol=2,
>>       excess_bw=0.35,
>>       verbose=False,
>>       log=False,
>>       )
>>     self.blks2_packet_encoder_0 = 
>> grc_blks2.packet_mod_b(grc_blks2.packet_encoder(
>>             samples_per_symbol=2,
>>             bits_per_symbol=6,
>>             access_code="011001010111011001101111",
>>             pad_for_usrp=False,
>>         ),
>>         payload_length=457,
>>     )
>>     self.band_pass_filter_0 = gr.fir_filter_ccf(1, firdes.band_pass(
>>         1, samp_rate, 5000, 12000, 500, firdes.WIN_HAMMING, 6.76))
>> 
>>     ##################################################
>>     # Connections
>>     ##################################################
>>     self.connect((self.gr_complex_to_float_0, 1), (self.gr_wavfile_sink_0, 
>> 1))
>>     self.connect((self.gr_complex_to_float_0, 0), (self.gr_wavfile_sink_0, 
>> 0))
>>     self.connect((self.gr_multiply_xx_0, 0), (self.band_pass_filter_0, 0))
>>     self.connect((self.band_pass_filter_0, 0), (self.gr_complex_to_float_0, 
>> 0))
>>     self.connect((self.gr_sig_source_x_0, 0), (self.gr_multiply_xx_0, 1))
>>     self.connect((self.digital_qam_mod_1, 0), (self.gr_multiply_xx_0, 0))
>>     self.connect((self.gr_file_source_0, 0), (self.blks2_packet_encoder_0, 
>> 0))
>>     self.connect((self.blks2_packet_encoder_0, 0), (self.digital_qam_mod_1, 
>> 0))



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