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Hi,
I have a couple of questions regarding WARPLAB continuous transmission:
1. When TxMode is set to 1, is there any delay between two frames or is the transmission absolutely continuous.
2. If we set the Txlength to less than 2^14, say 2^12, will the continuous transmission use ignore the rest of the buffer and repeat frames of length 2^12 samples.
Thanks
Vijay
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1. There is no delay between frames, the data is repeated back-to-back
2. No, the continuous transmission runs through the whole 2^14 length buffer and ignores the TxLength.
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In this case，how the receiver handles the different frames?
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The WARPLab Rx will start whenever it's triggered from your MATLAB script, and capture whatever is being transmitted at that time. The continuously-transmitted frames won't be aligned with the Rx captures.
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I am confuzed about the continuous transmission scheme. How it works in the real transmission and what is the difference from the single transmission mode.
In single transmission , you can specify the length of packets transmitted, and specify how many bytes the rx should receive.
In continuous transmission, it seems that you have no way to control these two parameters.
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Continuous transmission mode transmits every I/Q pair from the Tx buffer in order, just like non-continuous mode. However, in continuous mode, when the last I/Q value in the buffer is transmitted, the address counter wraps and starts transmitting the full Tx buffer again. This repeats until the Tx stop command is sent. You still have full control of the transmitted waveform from MATLAB; if you want a short waveform (less than 2^14 samples) transmitted continuously, you need to fill the Tx buffer with repeated samples (i.e. cyclicly extend your waveform to fill the Tx buffer).
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Hi,
I am trying the continuous tx mode option in WARPlab to transmit by buffer repeatedly. i am using waplab_siso_example_TxRx.m. i set the TxMode = 1. But the response is similar like single transmission(TxMode=0). I am using single WARP 2x2 mimo board and i didnt changed rest part of program. Kindly advise me the procedure to implement continuous txn in WARPlab siso.
Regards,
Sabari
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In continuous Tx mode, the transmission stops when you send the RADIO2_TXDIS command, which waplab_siso_example_TxRx.m script does after the Tx/Rx cycle.
Look at the warplab_siso_example_ContinuousTx.m script for a better example of using continuous transmit mode.
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Is there any delay between the last sample of the buffer and the first sample when the wrap around is done or is the D/A converter is fed continuously. Can we check this without using oscilloscope. Using Matlab we can capture only one frame at the receiver. Can you please tell me if we can somehow capture two continuous frames at the receiver.
Thanks
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I believe the wrap around occurs without a delay; it's implemented as a counter which wraps from its maximum value back to 0 in a single cycle.
You would need to modify the WARPLab Sysgen design to change how long a waveform it captures. The reference design captures 2^14 samples per antenna. I believe Sysgen will allow buffers up to 2^16 (maybe? I might have this wrong). If you do this, you would probably need to remove support for some antennas (otherwise you'll run out of on-chip memory).
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I was checking the sysgen model but could not find where the TX and Rx buffer lengths are defined. I don't even want to increase the memory size of the buffers. I just want, in continuous transmission mode, Rx to be able to capture two frames. So, instead of increasing the Rx buffer length, I would like to reduce the buffer length of Tx. Can you please tell me where in sysgen should I change the parameter.
On a different question, I would like to see the received signal on an oscilloscope. But unfortunately, we do not have oscilloscopes which can work at 2.4 GHz. We have a baseband oscilloscope which can work in a bandwidth of 100MHz. Is there any way I can capture the baseband signal from the board. I checked the Maxim ic datasheet and pin no 45 - 46 are designated as RxBBI-, RxBBI+. I could not find if there are any connecting points provided on the board to extract these signals. Can I connect the two connectors of my oscilloscope to these two pins (although the pins are very small and I don't have such connectors) to see the RxI signal. Your help is very much appreciated.
Thanks
Last edited by chan (2010-Nov-18 05:36:05)
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Can you please update me with information on tapping the baseband signal from the radio board. I cannot find the schematics of the radio board to know if there are any port points provided to capture the Tx or Rx baseband signal. We are in urgent need of this information. your help is highly appreciated.
Thanks
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The schematics are in the repository.
The radio board does not have connectors for the baseband I/Q. These signals are routed directly between the MAX2829 and ADC/DACs via very short traces. We use an Analog Board when we need to access baseband analog I/O.
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