Re: [Discuss-gnuradio] OFDM cyclic prefixer

[Ron Economos]

If you're sending packets, then Length Tag Key should be
set to the packet length you're using. If you're sending
a stream (like DVB-T), then this field is not used (and
left blank).

The OFDM cyclic prefixer is used after the (reverse)
FFT block. The FFT Length in the OFDM Cyclic Prefixer
block should match the FFT Size in the FFT block.

Ron

On 5/13/2014 6:06 PM, Yuri P.M wrote:

Hello,

My name is Yuri.

​ I very new to GNU Radio, and I'm using GRC 3.7.1.​

I am doing a research, and I need to modulate specific signal in OFDM. I would like to insert cyclic prefix (or guard interval in my project, the same thing with a different name).

I looked at the examples

​under gr-digital

​/examples/ofdm, and I've also read some papers about OFDM technics.

My doubt is: what is the parameter "Length Tag Key"? I've seen it working in the examples located in the folder above, I've tried to do the same in my project, but it states a message that this parameter is missing.

By chance, does this cyclic prefixer block only works with other blocks of the same category? I mean, do I need to use OFDM carrier allocator before it, or something like that?

Thank you for your attention,

Yuri.