modulation tool kit synchronization

[nolsqn]

hey

 i am having a problem in understanding the mod_syn_symbol.vi of the modultaion toolkit which is used is almost every example....actually the real problem is that i have to use the vi as a sub vi but i am not able to understand what actully is going in the vi ..if somone can help me

thnx

[Stephen_S.]

Hi nolsqn,

I am sorry that I do not have that toolkit installed at the moment so I do not know what the specific VI is doing. In general, information can be found using the Context Help (Ctrl+h and mouse over the VI) and the Detailed Help that comes up in the Context Help Window. More information about some VIs, usually including examples, can be found under File>>VI Properties>>Category>>Documentation. Also, you can often double click on a subVI to open it and see the programming that is occurring inside the VI (sometimes double clicking multiple subVIs within subVIs) and follow the logic that way.

If you have already looked at these resources and are still confused, or if these ideas are not helpful, let me know and I will see if I can get more information for you.

Regards,
Stephen S.

[nolsqn]

hi Stephen_s

it willl be more helpful if u can find some more info

thnx

[Chris_D]

Hey nolsqn,

I went through all of the VI's in the Modulation Toolkit, yet was unable to find this VI. What version of the toolkit are you using? We may have different versions. Also, what examples were you looking at that use this VI? Why do you need to use it in your VI? I would be happy to look into the function of the VI if you can provide some more information.

[nolsqn]

hey chris_d

i am using labview 8.5  with modulation kit 3.2 ..its the vi named  mod symbl synch.vi ...its in the modulation toolkit all of the examples .

[Chris_D]

Hey nolsqn,

I was able to install the older version of Modulation Toolkit 3.2 on a test machine and locate the mod_Symbol Sync.vi. This VI is a lower level driver VI and it looks like what it does is search the signal for a user-defined sync word pattern. This VI is used in some of the higher level VI's such as Demodulate ASK or Demodulate QAM and you should not have to modify these VI's in order to use the Modulation Toolkit.

To use the Modulation Toolkit you should only need to use the high level VI's located in the LabVIEW block diagram palette. You can access these by right-clicking on your block diagram and going to Addons » Modulation.

Additionally, there are many examples that make it easy to get started with the Modulation Toolkit in the NI Example Finder in LabVIEW at Help » Find Examples » Toolkits & Modules » Modulation.

I hope this helps and let me know if you have additional questions.

[nolsqn]

hey chris_ actuall what i needed to do was to understand that how in the examples the labview is acheiving the synchronization ..so that i could implement it on my ofdm (TX/RX) simultaion.......any help..if u say i can send u vi

Message Edited by nolsqn on 08-12-2008 01:21 AM

[Chris_D]

nolsqn,

None of the Modulation Toolkit examples utilize the symbol synchronization even though the VI is located in the examples. The demodulation VI's will only synchronize the symbols if you provide the synchronization parameters, otherwise, it will just skip over the sync process. If no synchronization parameters are provided then there will be a ±90° phase ambiguity.

There are 4 synchronization parameter inputs: Expected Sync Location, Sync Sequence, Sync Location Uncertainty, & Sync Indent.

Expected Sync Location - This where you input the approximate location of the sync sequence. Providing a -1 will search the entire signal array for the sync sequence.

Sync Sequence - The actual sequence that you are searching for in your signal array.

Sync Location Uncertainty - The amount of leeway outside of the expected sync location that you want to search for the sync sequence.

Sync Indent - Sometimes the sync sequence may fall in the middle of the message. This input identifies how many symbols come before the the sync sequence.

Additionally, you can use the Generate Synchronization Parameters VI to generate the parameters for you when you modulate the signal.

I hope this helps and let me know if you have additional questions.

[nolsqn]

chris D

it really helped now i will try to implement it ..i will let u know as soon as i get any problems ...thnx a lot