Yan, simply convert "freq" and your frequency to a PMT before passing into cons().
Cheers, Martin On 03/14/2016 03:44 PM, Yan Huang wrote: > Hi Martin, > > Thank you for your kind reply. But I'm still comfused that I already have to > input in pmt::cons(“freq”,2.4e9), cause in the manual it said: > > pmt::cons(KEY, VALUE): This format is useful for commands that take a single > value. Think of KEY and VALUE as the argument name and value, respectively. > For the case of the QT GUI Frequency Sink, KEY would be "freq" and VALUE > would be the new center frequency in Hz. > > Could you please give me an exmaple about it? > > Thank you a lot, > > Yan > ________________________________________ > From: discuss-gnuradio-bounces+eexyh22=nottingham.ac...@gnu.org > [discuss-gnuradio-bounces+eexyh22=nottingham.ac...@gnu.org] on behalf of > Martin Braun [martin.br...@ettus.com] > Sent: 14 March 2016 17:18 > To: discuss-gnuradio@gnu.org > Subject: Re: [Discuss-gnuradio] Change frequency in USRP source automatically > > Yan, > > check the PMT manuals. cons() takes 2 PMTs as input. > > > Cheers, > Martin > > On 03/14/2016 09:09 AM, Yan Huang wrote: >> Hi all, >> >> >> >> I want to change the frequency in “USRP source” automatically, for >> example 2.37GHz-2.43GHz with each time stepping 2MHz. >> >> >> >> 1. As you know, the USRP source has an input message port, so I want to >> connect it to a “Message strobe” to control the frequency change. But >> after I see [1][2], I write PMT type commands in “Message PMT” in >> “Message Strobe” as: >> >> pmt::cons(“freq”,2.4e9) >> >> it comes up error “invalid syntax(<string>,line 1)”, so I don’t know how >> to further stepping the frequency. >> >> 2. If I use the “Message Strobe” to define frequency, what can I put in >> the “frequency” in “USRP source” block? Put it as 0? >> >> >> >> [1] https://gnuradio.org/doc/doxygen/page_uhd.html#uhd_command_syntax >> >> [2] >> https://gnuradio.org/doc/doxygen/page_msg_passing.html#msg_passing_commands >> >> >> >> Many thanks , >> >> >> >> Yan >> >> >> >> >> >> This message and any attachment are intended solely for the addressee >> and may contain confidential information. If you have received this >> message in error, please send it back to me, and immediately delete it. >> >> Please do not use, copy or disclose the information contained in this >> message or in any attachment. Any views or opinions expressed by the >> author of this email do not necessarily reflect the views of the >> University of Nottingham. >> >> This message has been checked for viruses but the contents of an >> attachment may still contain software viruses which could damage your >> computer system, you are advised to perform your own checks. Email >> communications with the University of Nottingham may be monitored as >> permitted by UK legislation. >> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > This message and any attachment are intended solely for the addressee > and may contain confidential information. If you have received this > message in error, please send it back to me, and immediately delete it. > > Please do not use, copy or disclose the information contained in this > message or in any attachment. Any views or opinions expressed by the > author of this email do not necessarily reflect the views of the > University of Nottingham. > > This message has been checked for viruses but the contents of an > attachment may still contain software viruses which could damage your > computer system, you are advised to perform your own checks. Email > communications with the University of Nottingham may be monitored as > permitted by UK legislation. > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
