one feedback, and one question.

[xy_se]

This is sunny again!
Thanks for all your help and I am now able to build a OOK tranceiver. I am now moving toward to cascade the 5610 upconverter and 5600 downconverter to 5640.

I just have one feedback for your Burst OOK demodulator IP. I modified it and used it for my tranceiver, basically it worked but two things has to be noticed(may be changed):
1. The symbol rate in the VI shall be doubled. For example, According to your original design, 3.125M correponds to decimation 32, which took the symbol rate to be 3.125M and only one sample per symbol. Unfortunately, this is not correct according to Nyquist sampling theory and inconsistent with the demodulation subVI. I changed it to 3.125M correponding to decimation 16, so the actual sample rate is 6.25MHz to be consistent with the demodulation subVI and Nyquist theory.
2. In the demodulation subVI , there is a bug in the find threshold VI. Once the threshold to arbitrate 0 and 1 is found, the output valid signal shall not be toggled.

My questions :
1. For cascading the 5640 to 5610 upconverter, I used the upconverter only mode VI , it worked, I just wondered if there is a way to turn on the RF carrier wave all the time even when no signal is generated by NI 5640 because in my application I need this feature.

2. About the NI-tuner for cascading   the 5600 downconverter: I looked at the two available examples in the ni Tuner directory, should I just use the getting started VI and then connect the output of 5600 to the AI port of 5640? I also find that in another example,  it uses NI scope. But I guess it doesn't apply to my case because there is no digitizer now(it is 5640 instead).

So any suggestions?




帖子被xy_se在05-29-2008 01:28 PM时编辑过了

[sree_405]

Hi Sunny,
This is Sreenivasulu.i need OOK modulation VI using modulation tool kit or any other.
If u did that one,or if U have please upload your ook VIs.

Thanking you
Sreenivasulu.O

[Vinay_Kumar]

Hi Sunny!

1. ADC by default operate at 100MHz and DAC at 200MHz.
On the transmitter side, symbol rate= 3.125M (which is per symbol) is converted to 2 samples per symbol. See OOK_Configure IF RIO for Transmission.vi
On the receiver side, symbol rate = 6.25M (is for 2 samples per symbols) which corresponds to decimation of 16 (100M/16) and is the sampling rate, which meets the nyquist criterion. May be the control should have been named as sampling rate.

2. Once the threshold is found, the output valid signal is not toggled. The selection of one of the 2 samples happens when the max eye is performed.

You can ask questions relating to the RF and Communications IP from the page where you downloaded them. This way you will be in direct contact with the developer and will get the  answers without much delay.

--Vinay

[Vinay_Kumar]

Hi Sree,
OOK is basically ASK with only two levels of amplitude ON/ OFF. So change the symbol map input of ASK modulator to 1+0j and 0+0j for bit 1 and 0 respectively.

--Vinay

[sree_405]

Hi Vinay,

For OOK how i have to specify 0 amplitude for bit '0'.in ask constellation to be 2 means M value is 2, i am correct.How i have to map symbols  to 1+0j and 0+0j for bit 1 and 0 respectively.
i done it in matlab.but here i am getting problem.
If possible plz send related VI in Labview 8.2

please help me to come out from this problem.


Thanking you Vinay

Sreenivasulu.O

[Vinay_Kumar]

Hi Sree,

Use MT Modulate ASK.vi to modulate your bit pattern. This VI requires symbol map and pulse shaping filter coefficients.
Use MT Generate ASK system parameters (M).vi to get the symbol map.
Use MT Generate Filter Coefficients.vi to get the pulse shaping filter coefficients.
Send the bit stream to MT Modulate ASK.vi. You need not worry about how to map the bits on to the symbols, this VI will take care of it.

Modulation toolkit ships with examples, provided you have installed RFSG and RFSA drivers (which can be obtained from NI website).
These examples will give you a clear understanding of how to use the MT VIs.
You can find these examples from the example finder under the following category.
Toolkits and Modules-> Modulation -> NI-RFSG

Hope this helps!
--Vinay
 

[Airian]

hi Vinay

I am new to NI 5640 and trying to implement the QAM transceiver example of Modulation toolkit on NI 5640 but I am not able to set the parameters like IQ rate at TX and RX

and what should be the relation between ADC nad DAC sampling rate with samples per symbol at receiver, for this reason i am not getting the RX constellation right plz help me on this I am sending you my VI,

Or send me OOK transceiver example you have made on the NI 5640 that would be really kind of you.

Best regards

Airian

[sree_405]

Hi Vinay,
Thanks for your reply.i used ASK correctly,from ASK how i have to generate OOK.
here i am attacing one image wat i got for ASK output.
tell me what are the chnages in ASK to get OOK.

[sree_405]

Hi Vinay,
Thanks for your reply.i used ASK correctly,from ASK how i have to generate OOK.
here i am attacing one image wat i got for ASK output.
tell me what are the chnages in ASK to get OOK.

[Vinay_Kumar]

Hi Airian,

To set your Tx IQ rate:
1. Get the complex output waveform from MT after QAM modulation.
2. Get the dt component of this waveform. Set 1/dt as the IQ rate using ni5640R Configuration Generation.VI. But 5640R does not support all IQ rate. Hence find using the ni5640R Get Actual IQ Rate.vi to get the closest supported/ coerced IQ rate.
3. Using the new IQ rate, use MTs IQ resample to resample the modulated waveform to the new IQ rate.
4. Now write this waveform into the 5640R using ni5640R Write Waveform.vi.

On the Rx side,
1. Set the IQ rate to the newly obtained IQ rate.
2. Resample the acquired waveform to the original IQ rate.
3, Now perform the demodulation.

If you notice, in the examples of MT with RFSG, the write waveform VI actually performs resample internally and then writes the waveforms into RFSG's memory. But 5640R does not resample.

The OOK transceiver that we have developed is an example to show how the FPGA of the 5640R can be programmed using LabVIEW FPGA.
You can find the FPGA based IP that the team has developed at ni.com/ipnet.

Cheers!
--Vinay