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
>>
>>
>>
>> ___________________________________