INFO: Detected an invalid packet at item INFO: Parser returned #f

Hi all:
Thank you in advance.I have searched the question"INFO:
Detected an invalid packet at item INFO: Parser returned #f".
The answer may be “RF settings are distorting your signal” or others.I
want to ask a question.Which block in gnuradio give us this hint.Where
is the source code of the block?And have someone can help me to explain
this problem more details?Why will have this error/warning?
Thank you.
Best regards,
zs

Hi,

On 01/29/2015 01:03 PM, zs wrote:

Detected an invalid packet at item INFO: Parser returned #f".
The answer may be “RF settings are distorting your signal” or others.I
want to ask a question.Which block in gnuradio give us this hint.Where
is the source code of the block?And have someone can help me to explain
this problem more details?Why will have this error/warning?

~/src/gnuradio >> ack-grep -C 3 “an invalid packet”
gr-digital/lib/packet_headerparser_b_impl.cc
80- );
81-
82- if (!d_header_formatter->header_parser(in, tags)) {
83: GR_LOG_INFO(d_logger, boost::format(“Detected an invalid packet at
item %1%”) % nitems_read(0));
84- message_port_pub(msg_port_id, pmt::PMT_F);
85- } else {
86- pmt::pmt_t dict(pmt::make_dict());

I guess your packet header is corrupt.

Best,
Bastian

Hi Bastian:
Thank you so much for your kindly reply.Can you tell
me,for general,in which circumstance,the packet header maybe corrupt?
Thank you so much.
Best regards,
zs

Hi,

On 01/29/2015 03:13 PM, zs wrote:

Can you tell me,for general,in which circumstance,the packet header maybe
corrupt?

This is very hard to tell since I don’t know what you are doing. I guess
you use a header_formatter in your flow graph and (for whatever reason)
its header_parse method returns false.

For example with the default header it looks like this happens if the
CRC is not correct

Hi Bastian:
Thank you so much.I use the ofdm example,and I think
maybe the crc is wrong as you said,thank you.
Can you give me some advices to avoid these
warning?Thank you so much.

Best regards,
zs

Hi Bastian:
Thank you so much.I use the ofdm example,and I think
maybe the crc is wrong as you said,thank you.
Best regards,
zs

On 30 Jan 2015, at 14:00, zs [email protected] wrote:

Hi Bastian:
Thank you so much.I use the ofdm example,and I think maybe the
crc is wrong as you said,thank you.
Can you give me some advices to avoid these warning?Thank you
so much.

The fact that your CRC is not correct just means that something does
not work. This can have a lot of reasons. For example you could try
different gain settings. Also assert that the samples that you stream to
your USRP are in the interval [-1, 1].

If that doesn’t solve your problem you can debug your flow graph with
graphical sinks and check if the signal looks as expected.

This is very hard to tell since I don’t know what you are doing. I guess

this problem more details?Why will have this error/warning?
85- } else {


Dipl.-Inform. Bastian B.
Distributed Embedded Systems Group
University of Paderborn, Germany