Re: CCSDS BER PLOT

[Jiya Johnson]

I have tried to do with a simple input 11011101 without noise and with noise noise also

On Sat, Aug 19, 2023, 7:52 AM U L <jareddpub@gmail.com> wrote:

Some ideas:

1. Remove the noise completely. Also use a fixed, repeating input vector rather than random bytes. Look at the actual error patterns between the input and output bits. Sometimes error patterns can clue you in.

2. Check symbol polarity (i.e. 0=>-1, 1=>1, or 0=>1, 1=>-1)

3. Try the more general (non-CCSDS) extended encoder with the same params as the decoder.

4. Esp if 3 works, compare the output of CCSDS with general extended encoder.

Good luck.

Jared.

On Fri, Aug 18, 2023 at 8:04 PM Jiya Johnson <jiyajohnson10@gmail.com> wrote:

Hi,

Based on the given modifications still I am getting a -0.300 range of BER constantly from 0 to 15 dB range of SNR values.No variations are happening.

How can I check the functionality of the block(encoder and decoder to check whether it's encoding and decoding properly)with a sample input.

On Sun, Aug 13, 2023, 8:11 PM U L <jareddpub@gmail.com> wrote:

One other thing I noticed is that the encode CCSDS, decode, CCSDS, and BER blocks all  operate on packed bytes. (See e.g. https://wiki.gnuradio.org/index.php?title=Encode_CCSDS_27). To do this you would change your random source to output from 0 to 256 byte values. Also, considering the output of the decoder block are packed bytes you should probably skip the byte->float and binary slicer after your decoder and just input it's output directly into the BER block. Finally, looking at the https://wiki.gnuradio.org/index.php?title=Decode_CCSDS_27 page it seems the delay out of the decoder is 4 bytes, so you could add a delay of 4 between your source and BER block to align the two streams.

Jared.

On Sat, Aug 12, 2023 at 9:58 PM U L <jareddpub@gmail.com> wrote:

One thing I think might be an issue is that you have no delay between your source reference and your BER block. Usually the FEC decoders (and possibly the encoder?) may output blocks of 0s before they output the samples that correspond to your inputs. I don't know much about those FEC blocks specifically, but maybe the docs have some info on their delays. You can just insert a delay block b/w your random source and the ber block to align the input and output bits.

Hope that helps,

Jared.

On Sat, Aug 12, 2023 at 4:28 AM Jiya Johnson <jiyajohnson10@gmail.com> wrote:

Dear community

   Need help for BER plot using the above flowgraph its always coming 10^-1.17 and whenever I tried to change the noise voltage the values are not changing.

Please find the attached GRC file for your reference.

Regards, JIYA JOHNSON