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Re: [Discuss-gnuradio] OFMD Known Symbols


From: Chris_Spain
Subject: Re: [Discuss-gnuradio] OFMD Known Symbols
Date: Sat, 19 Jun 2010 11:34:18 -0700 (PDT)

Thank you very much Tom

Tom Rondeau wrote:
> 
> On Sat, Jun 19, 2010 at 2:11 PM, Chris_Spain <address@hidden>
> wrote:
>>
>> Thanks Tom, but in DVB-H, the continual and scattered pilot are used for
>> the
>> sync, If I change, in TX and RX, the position and value of knows symbols,
>> Will I lost the sync?
> 
> Sure, because DVB-H is a continuous stream, so you don't need to
> resync for bursts and the pilots are just used to track it.
> 
> In this case, you would want to get rid of the idea of the known
> symbols altogether. Then, you'll need to add the pilot handling code
> into the receiver. This will probably call for a pretty thorough
> redesign of the ofdm receiver that's in GNU Radio. It will probably
> also require you to write a new ofdm sink C++ block to handle the
> specifics of the standard.
> 
> Tom
> 
> 
>> Tom Rondeau wrote:
>>>
>>> On Sat, Jun 19, 2010 at 1:20 PM, Chris_Spain <address@hidden>
>>> wrote:
>>>>
>>>> Hello I'm trying to modify the OFDM module implemented in GNU Radio,
>>>> and
>>>> I
>>>> have a question. In DVB-H I need to set the continual pilot carrier and
>>>> the
>>>> scattered pilot carrier. Both are known by TX and RX, then, Are the
>>>> known
>>>> symbols, implemented in OFDM module, pilots carrier?
>>>>
>>>> Thanks!
>>>
>>> No, the known symbols are preambles used for initial sync of a burst.
>>> There is kind of a placeholder in the code for pilots (in the ofdm
>>> mapper), but we haven't implemented anything here to handle them in
>>> the receiver. I believe others have done this on their own.
>>>
>>> Tom
> 
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