Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

Learning and understanding I/Q from the radio

Mark_WS7M
Mark_WS7M Member ✭✭✭
edited November 2019 in SmartSDR API
Hello all,

I'm a programmer.  I've done a fair amount of signal analysis but never in the form of I/Q.  Most of the stuff I've done has been on raw signal data.

I've done a little reading on the I/Q stuff I've been able to find on the internet but I would like to understand it better.

In my software I've gained full access to the Dax Audio streams, Opus stream and got them nailed.  Now I'm playing with the I/Q output.  I'd like to figure out what I can get from it.

Any directives to what comes out of the Flex and ways to process/deal with it would be very much appreciated.

Of course this kind of question generally results in people asking what you want to do with it.  The answer to that is really open ended:

I'd like to play with writing a skimmer for CW, digital modes, etc

There has been a lot of talk about DXSPOTS but for a guy like me often the DXSPOT points to a station I can't even hear with my limited antennas.  I'd like to use I/Q data to create a map of what I can hear.

I'd like to play with a "signal searcher".  For this I have considered a mode that would scan the I/Q output, find what appear to be signals, tune to them and try to determine what they are or decode them.

Anyway you get the idea.  If I don't get a lot of pointers here I'll start to take the stream apart myself and see what I can figure out.  I've searched here and found one other good post on the I/Q stream.  Just looking for more.

Thanks - 73 - Mark WS7M

Answers

  • Andrew O'Brien
    Andrew O'Brien Member ✭✭✭
    edited September 2016
    I'd like to be able to take an I/Q stream and have any RSID over the stream's bandwidth detected and reported. 
    Andy K3UK
  • Mark_WS7M
    Mark_WS7M Member ✭✭✭
    edited September 2016
    Agreed.
  • Eric-KE5DTO
    Eric-KE5DTO Administrator, FlexRadio Employee admin
    edited February 2017
    Mark,

    Have you already read through the original SDR for the masses QEX articles?  If not, I would recommend starting there: http://www.flexradio.com/resources/articles/.
  • Ria
    Ria Member ✭✭✭
    edited November 2019
    I use CW skimmed by Alex, VE3NEA to skim up to 4 bands. I combine my telnet streams to one single one. Works pretty good. Read the articles as suggested but the reason SDRs used I/Q was for image rejection. Otherwise if you just have a single signal you'll get plus and minus the LO and it will be of no use:
  • Mark_WS7M
    Mark_WS7M Member ✭✭✭
    edited October 2016
    Ok didn't know these were there!  Nice... Thanks!
  • Mark_WS7M
    Mark_WS7M Member ✭✭✭
    edited October 2016
    Hi Ria, I understand the reason, I want to understand the data better and how to use it for reasons like you mention.

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.