Re: [Discuss-gnuradio] Change frequency in USRP source automatically

[Martin Braun]

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: address@hidden address@hidden on behalf of Martin Braun address@hidden
> Sent: 14 March 2016 17:18
> To: address@hidden
> 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
>>
>>
>>
>>
>>
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> Please do not use, copy or disclose the information contained in this
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> University of Nottingham.
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> This message has been checked for viruses but the contents of an
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