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Does BladeRF support full duplex mode? I want to create a FM transmitter and receiver on a BladeRF a device. So can I receive and transmit from the same BladeRF device. Can someone post a sample flowgraph for full duplex application.

Thanks

Full duplex is supported, and there's also an internal loopback (so you don't have to externally connect TX to RX).

http://www.w6rz.net/loopback.grc



Ron

I used your example but the output was not as I had expected. I'm attaching a video on the google link showing the output.
https://docs.google.com/file/d/0B5ZnEve ... 0xa0U/edit
I don't get what is wrong with it so if anyone can help me out with it.
Thanks

Should look something like this.



Make sure your bladeRF library and gr-osmocom are up to date. Loopback was added around 2/16/14.

Ron

Seeing your plot I am confused why there is a peak at 429MHz. Could the problem in my case be because of high CPU usage? As I have the latest grosmosdr blocks.

Thanks

The spike in the middle is just the DC offset. You can mostly tune that out by adjusting the levels of the I and Q signals (so that they're centered on 0 in the scope plot).

http://www.w6rz.net/loopbackdc.grc





I've also reduced the sampling rate in case you're having performance issues.

Ron

Hi Ron,

I have the following errors in osmocom Source block of yours loopbackdc.grc file. I'm using GNU Radio Companion 3.7.3.

Param - Ch0: Gain Mode(gain_mode0):
Expression "0" is invalid for type bool.

Param - Ch1: Gain Mode(gain_mode1):
Expression "0" is invalid for type bool.

Param - Ch2: Gain Mode(gain_mode2):
Expression "0" is invalid for type bool.

Param - Ch3: Gain Mode(gain_mode3):
Expression "0" is invalid for type bool.

Param - Ch4: Gain Mode(gain_mode4):
Expression "0" is invalid for type bool.

I noticed that you use GNU Radio Companion 3.7.4. Could this be the reason for the errors?

Thanks.

BR,
Blagoja

This same exact thing happened to me the other day, with flow graphs that had been behaving perfectly fine before. I'm not sure if it was the result of a GNU Radio upgrade or what.

At any rate the workaround for me was the following:

• Open the block properties
• In the pulldown for the number of channels, select the count of complaining channels (5 in your case)
• Scroll down through all the properties, and everywhere you see a "ChX Gain mode" (I think they'll be red to denote an errror) set to 0, click on the drop down and change it back to "Manual"
• After you've done this for all of the complaining channels, set the chanel count (from the second step) back to 1
• Click apply

Update: Ignore this...Olaf's suggestion is far better

Delete osmocom source from Ron's flowgraph and drag a new one from Gnuradio menu...that solved the error in my case

I believe it's due to this fairly recent commit to gr-osmosdr.

http://cgit.osmocom.org/gr-osmosdr/comm ... 7d4202ab24

I had built the graphs with a version of gr-osmosdr before that commit.

Ron

Is there a way to extract s-parameters?

Right now I can't think of a way to get the reflected power from the port.

I believe we could extract only the forward parameter, but not the rest of them.

I will keep thinking about it, though. Maybe with some external hardware, something can be figured out.

Brian

Can someone produce a working example of measuring the amplitude and phase of a connected coax between Tx and Rx ports?

If it's possible, we could then attach a wideband directional coupler and calibrate to measure simple parameters like a connected antenna's reflection characteristics.