On Thu, Apr 14, 2016 at 7:44 AM, Yan Huang <eexy...@nottingham.ac.uk> wrote:
> Hi all, > > > > I’m using Message Strobe to control UHD: USRP Source to receive signal > with specified frequency(2.4GHz), but I find flow graph start running > before Message Strobe set the frequency as 2.4 GHz. > > > > Message Strobe -> UHD: USRP Source ->File Sink > > > > So I want to use stream tag to know the time of first item with 2.4GHz. I > think I can change File Sink to File Meta Sink to receive the ‘rx_time’ > stored in ‘tag_sense1.hdr’ file(attached), and I use the existing program > called ‘gr_read_file_metadata’ to read out the header information, but it > comes out an error: > > > > File "tag_sense1.hdr", line 1 > > SyntaxError: Non-ASCII character '\xb5' in file tag_sense1.hdr on line 2, > but no encoding declared; see http://www.python.org/peps/pep-0263.html > for details > > > > I have checked the link, but I don’t understand what’s the encoding > information of the python source file. Do need to add # -*- coding: > <encoding name> -*- to the source file? > > > > I problems are: > > > > 1. How can I read the’ .hdr’ file? > > 2. Am I right to use file meta sink to get the start receiving time? > > 3. Do I need to add stream tag and then read it out using other > blocks in this scenario? > > > > Any advice will be appreciated. Many thanks in advance. > > > > Best Regards, > > > > Yan > Yan, Have you fully read over the description of the metadata files and how to use them in the manual? http://gnuradio.org/doc/doxygen/page_metadata.html Specifically, since you have a .hdr file, you've set this into Detached mode. You'll need to use the -D flag to indicate that to gr_read_file_metadata. Tom
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