Re: [Discuss-gnuradio] TX time control

[Yeo Jin Kuang Alvin (IA)]

Hi,

 

Thank you for giving me the manual, I have read them. From what I understand, the tx_sob and tx_eob only indicates when to start and stop, can it hold for a certain amount of time before the next tx_sob comes in?

 

To create stream tags in python, the code looks like this:

 

       def work(self, input_items, output_items):

           ....   add_item_tag(which_output, abs_offset,key, value, srcid)

    ....

 

I am not strong in python and I am wondering how can I relate the tx_sob, tx_eob, tx_time etc into the code to tell the usrp_sink. Do I have to use stream to PDU? Is the output connected to the command of the usrp_sink? Kind of lost and not sure how to start, appreciate if anyone could help me out.

 

Thank you in advanced!

 

 

From: Derek Kozel [mailto:address@hidden
Sent: Tuesday, 15 May 2018 7:48 PM
To: Yeo Jin Kuang Alvin (IA)
Cc: address@hidden; address@hidden
Subject: Re: [Discuss-gnuradio] TX time control

 

Hello Yeo,

Your application is becoming complicated enough that you will have to start writing Python code to support the timed transmissions.

The GNU Radio manual has details about adding tags to the start of each burst so that they are transmitted at a specific time. You can use just the start and end of burst tags if you do not care about the actual timing, but for a radar application you certainly will care about the timing of each chirp.
https://gnuradio.org/doc/doxygen/classgr_1_1uhd_1_1usrp__sink.html
https://gnuradio.org/doc/doxygen/page_uhd.html

Regards,

Derek

 

On Tue, May 15, 2018 at 7:58 AM, Yeo Jin Kuang Alvin (IA) <address@hidden> wrote:

Hi everyone,

Somehow, I managed to transmit by sending few pulse length and waiting for few pulse length using "Signal Generator Sync Pulse" and I have attached the .grc . If I am not wrong 1 pulse width of the signal source (sawtooth) is samp_rate/Freq = 6000, so in this example I am sending 1ms (6000 pulse length) and wait for 2ms (12000 pulse length).

The problem I faced now is the starting waveform that is sending is not fixed, it starts anywhere in the waveform. If I am making a chirp signal out, I want it to send at the start and stop 1ms later. How am I gonna solve this problem? Is it by inserting delays or is there a better solution to this?

Thank you in advanced!

-----Original Message-----

From: Discuss-gnuradio [mailto:discuss-gnuradio-bounces+yjinkuan=address@hidden] On Behalf Of Yeo Jin Kuang Alvin (IA)
Sent: Tuesday, 15 May 2018 1:10 PM
To: address@hidden
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] TX time control

Hi,

Alright! I was thinking of using square wave and a multiplier but the duty cycle is 50%, I don't know how to change it.

If I am sending a sine wave using signal source connected to the sink, how can I send in zero's after 2s for example? Is there any time control or variable I can use?

Thank you in advanced!

-----Original Message-----
From: address@hidden [mailto:address@hidden]
Sent: Tuesday, 15 May 2018 12:56 PM
To: Yeo Jin Kuang Alvin (IA)
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] TX time control

On Mon, May 14, 2018 at 08:13:13AM +0000, Yeo Jin Kuang Alvin (IA) wrote:
> I would like to transmit for an amount of samples/seconds, and stop transmitting for another few seconds and then transmit again. Example, transmit 2s, stop for 3s and then transmit for 2s and rinse and repeat.

You could try sending zero's into your sink block. That will effectively cause your radio to cease transmitting without actually turning it off.

BW


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