Re: [Discuss-gnuradio] Correlation Estimator Over the Air

[Washbourne, Logan]

Rich,

The test_corr_est block has the flow graph as follows: vector source-> constellation modulator -> stream mux(with null source) -> throttle -> channel model -> correlation estimator -> polyphase clock sync -> costas loop -> constellation and time gui sinks.

For my modified TX grc file I used the following flowgraph: vector source -> constellation modulator -> stream mux(with null source) -> constellation and time gui sinks as well as the UHD: USRP sink

For the RX grc: UHD: USRP Source -> correlation estimator -> polyphase clock sync -> costas loop-> constellation and time gui sinks.

The grc files can be found at: https://github.com/loganwashbourne/Logan.git

The files are called test_corr_est_TX and test_corr_est_RX.

Thanks for your time,

Logan Washbourne

Electrical Engineering Graduate Student

(Electromagnetics)

On Thu, Oct 1, 2015 at 3:44 AM, Richard Bell <address@hidden> wrote:

Hi Logan,

Can you give more detail on your synchronization choices for BPSK so we can tell you what more you may need to do?

Rich

Sent from my iPhone

> On Sep 30, 2015, at 7:14 PM, Washbourne, Logan <address@hidden> wrote:
>
> Hello,
>
> This is somewhat of an update to a previous post I made from last week. After talking to Julian and Martin, it was made clear to me that I needed to use a correlation system to insure my receiver would be synced up to my transmitter when trying to communicate over the air.
>
> I am trying to utilize the Correlation Estimator block to help me achieve those means. In order to ease myself into it, I am trying to turn the test_corr_est.grc example into an over the air program. I am getting communication between the transmitter and receiver(essentially I just split the grc program in two and took out the throttle block and the channel model and replaced them with UHD blocks). Now, I don't get any O's or L's or an abundance of U's, and I can clearly see data coming in on the RX side, but it seems to be a lot of noise, but noise generated by the TX side, because it goes away when I stop transmitting. The center frequency is 2.48GHz and the sample rate is 250k samples/sec.
>
> My testing method is plotting the constellation symbols right before they get sent out on the TX side and then plotting them right after the UHD block on the RX side. It is only bpsk and the symbols are covering all four quadrants.
>
> I haven't changed any settings on the polyphase clock sync or the modulation scheme.
>
> This is a little rambly but I appreciate your time,
>
> Logan Washbourne
> Electrical Engineering Graduate Student
> (Electromagnetics)
>

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