Hi, I'm using the examples rx_ofdm.grc and tx_ofdm.grc together to transmit and receive packets over the air. Both work over a simulated channel, but when I actually transmit and receive over the air, I get the error:
*"Detected a packet larger than max frame size (100 symbols)"* I saw the previous thread on this called "OFDM transmitter receiver" which goes as follows, but I don't really know what to make of this... I tried to run *sysctl kernel.shmmax *in terminal, but I got the message "No such file or directory". I'm also not sure what kernel.shmmax is. These are my parameters: fft length= 64 cyclic prefix = 16 packet length = 96 no. of occupied carriers = 53 no. of pilot carriers = 4 I'm very new to gnuradio, and any insights into this would be appreciated!! Thanks, Jenny PS sorry if this is redundant. I didn't get my email through the list so I'm assuming it didn't go through the first time. ------------------------------------------ *From*: Martin Braun *Subject*: Re: [Discuss-gnuradio] OFDM transmitter receiver *Date*: Tue, 26 Aug 2014 11:10:53 +0200 *User-agent*: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 ------------------------------ Try and not kill the context in a mailing list thread; these are also archived and are used by others for referral. Max frame size depends on max_output_buffer(). 80 symbols at a 64-sized FFT would be ~40kB... that doesn't seem unreasonable. Not sure if there's a problem here. I suggest you have a look at the buffer sizes to track down this problem. M On 08/25/2014 03:31 PM, Martin Braun wrote: >* What's your kernel.shmmax value? (run sysctl kernel.shmmax)* > >* M* > >* On 08/25/2014 12:47 PM, sreena p h wrote:* >*> Hi* >*> I used the ofdm transmitter receiver blocks to create a simple system as* >*> shown in the attachment. I used the system parameters as those used in* >*> the example transmitter and receiver grcs. Now I get error that* >*> 'Detected a packet larger than max frame size (80 symbols)'. I would* >*> like to know how the max frame size is set and should I add more* >*> information to the grc. * >*>* >*> My transmitter- receiver parameters* >*>* >*> fft length= 64* >*> cyclic prefix = 16* >*> packet length = 96* >*> no. of occupied carriers = 48* >*> no. of pilot carriers = 4* >*>* >*>* >*>* >*> ___________________________________*
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