Hi Martin,
Thank you, it works well. But I want to change the frequency automatically, so
I change the frequency to array like:
pmt.cons(pmt.string_to_symbol("freq"),pmt.to_pmt(numpy.array([2.4e9,2.45e9],dtype=numpy.float32)))
and I also import numpy in GNU Radio, but it comes up with error :
thread[thread-per-block[10]: <block gr uhd usrp source (1)>]: pmt_to_double:
wrong_type : #[2.4e+09 2.44999987e+09]
Thanks,
Yan
-----Original Message-----
From: discuss-gnuradio-bounces+eexyh22=nottingham.ac...@gnu.org
[mailto:discuss-gnuradio-bounces+eexyh22=nottingham.ac...@gnu.org] On Behalf Of
Martin Braun
Sent: 15 March 2016 00:43
To: discuss-gnuradio@gnu.org
Subject: Re: [Discuss-gnuradio] Change frequency in USRP source automatically
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_co
>> mmands
>>
>>
>>
>> Many thanks ,
>>
>>
>>
>> Yan
>>
>>
>>
>>
>>
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