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| From: | Nick Foster |
| Subject: | Re: [Discuss-gnuradio] Underflow and Overflow |
| Date: | Wed, 23 May 2018 08:12:42 +0100 |
Hi all,
Btw in this flowgraph, I’ve noticed there is nothing transmitting out when I change the file source from repeat to no repeat. Originally, I thought the waveform stored in file sink is immediately transmitted out from file source and continue the process till I stop the flowgraph.
When I on the repeat, signal starts transmitting out. Why is this so?
Thank you in advanced!
From: Kevin McQuiggin [mailto:address@hidden]
Sent: Wednesday, 23 May 2018 11:35 AM
To: Yeo Jin Kuang Alvin (IA)
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] Underflow and Overflow_______________________________________________
Hi Alvin:
On May 22, 2018, at 6:38 PM, Yeo Jin Kuang Alvin (IA) <address@hidden> wrote:
I want to do a transceiver, so instead of receiving a signal elsewhere out of the board. I self-generate out a chirp signal internally in USRP B210 and do a loopback to the receive port and then re-transmit out using another transmit port.
You will have to be very careful with this. Looping back the USRP output port back to the input port can blow the front end of the USRP receiver. Make sure that you use an external attenuator, not just a loopback cable. I would start with 30 dB.
Please tell the group more about your “transceiver": this is a broad statement, what are you trying to achieve? There are several different types of transceivers and the implementation will depend upon the application you have in mind.
Kevin
Thank you in advanced!
From: Kevin McQuiggin [mailto:address@hidden]
Sent: Wednesday, 23 May 2018 9:03 AM
To: Yeo Jin Kuang Alvin (IA)
Cc: address@hidden
Subject: Re: [Discuss-gnuradio] Underflow and Overflow
Hi Alvin:
Well, for one thing, you are trying to write USRP output samples to a file at 30 MB per second. That is likely to generate overflows.
Your flowgraph indicates to me that you haven’t fully internalized how gnuradio works and how it interacts with whatever front-end hardware you are using.
Don’t take this comment as overly critical, we all (myself included) started with only basic understanding, and had to build our skills from there.
I suggest going to the gnuradio web site and following, as a start, the set of tutorials that have already been recommended by others on the list. They will help you as you start to climb the learning curve!
Kevin
Sent from my iPhone
On May 22, 2018, at 17:48, Yeo Jin Kuang Alvin (IA) <address@hidden> wrote:Does anyone know this?
From: Discuss-gnuradio [mailto:address@hidden] On Behalf Of Yeo Jin Kuang Alvin (IA)
Sent: Tuesday, 22 May 2018 5:42 PM
To: address@hidden
Subject: [Discuss-gnuradio] Underflow and Overflow
Hi all,
May I know what causes my flowgraph to have so many U’s and O’s, is there any block that causes this? I am trying to hit a higher sampling rate possibly 20 MHz or higher. I have searched online and some suggest switching to a different OS and I did switch from windows to Ubuntu, only a slight difference. Some say is the computer’s processing speed not fast enough, thus, changing a better one will help. Others did mentioned that the flowgraph connection might cause this problem.
I am getting “OOOUOO” when transmit a sine wave sampling at 20 MHz and receive to a file sink.
I am using USRP B210, running on a Intel Core i7-4700MQ CPU @ 2.40 GHz x 8, 64 bit computer.
Any help would be appreciated!
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