Hi,
I have created another version, BPSK_test_02_4, which transmits a packet containing a pair of random bytes every second. I log the generated pairs (01_byte_tx_log.csv) and the received pairs (06_byte_rx_log.csv) and add CRC. This allows me to match pairs and accurately identify the delay and buffering of my packets in the receiver block (matched_bytes.csv). I assume that I lost many pairs due to imperfections in my project, but the delay and data buffering are noticeable and interesting.
Main github link: https://github.com/yabool2001/BPSK_test_02_4/
Best regards,
Yabool2001
niedz., 18 maj 2025 o 13:35 Maciej Zemło <mzemlo.pl@gmail.com> napisał(a):
Hi,Important and interesting update.During the testing of the BPSK_test_02_3 project, I initially believed that no valid demodulation was occurring when transmitting a packet every second. However, after accidentally leaving the transmission running for a longer duration, I observed that after approximately 95 seconds, a first burst of aggregated packets appeared. Interestingly, when repeating this experiment several times, the first occurrence of the packet burst consistently appeared after the same duration of 95 seconds. This behavior suggests a systematic delay or data accumulation occurring at a specific time interval, leading to a sudden release of aggregated data packets.Statistics Based on log files:
In the transmitter block, 470 packets containing a 1-byte payload were sent every second (01_complex_tx_bpsk_mod_log.csv - too big to view on github). In the receiver block, 306 packets were received as follows (06_byte_rx_log.csv):
- at 95.16 seconds, 23 packets were received. Then a short pause.
- at 95.66 seconds, 3 packets were received. Then a long pause.
- at 188.78 seconds, 7 packets were received. Then a short pause.
- at 189.27 seconds, 11 packets were received. Then a long pause.
- at 282.39 seconds, 32 packets were received. Then a short pause.
- at 282.89 seconds, 56 packets were received. Then a long pause.
- at 376.00 seconds, 6 packets were received. Then a short pause.
- at 376.01 seconds, 29 packets were received. Then a short pause.
- at 376.50 seconds, 54 packets were received. Then a long pause.
- at 469.62 seconds, 36 packets were received. Then a short pause.
- at 470.12 seconds, 49 packets were received. End of test.sob., 17 maj 2025 o 14:32 Maciej Zemło <mzemlo.pl@gmail.com> napisał(a):Hi Marcus and Adrian,
Apologies for the incorrect link to the private image. You are correct, the diagram in the README.md is the proper one. Thanks a lot for your advice.
For now, I've tried the simplest solution — adding a "Simple Squelch" block to feed the "Polyphase Clock Sync" only when a signal is present. The updated schematic is now available in the README.md of the project on GitHub:
https://github.com/yabool2001/BPSK_test_02_3Unfortunately, it didn't help. In this configuration, the project only works with a continuous source, such as "Constant Source". If there is a better implementation for signal detection that could assist in burst transmission, I'd be grateful for your recommendation.
Now, I will also try Adrian's suggestion to implement the "Correlation Estimator" block.
Thanks again for your support!
Best regards,
Yabool2001pon., 12 maj 2025 o 14:51 Marcus Müller <mmueller@gnuradio.org> napisał(a):Hi Maciej,
sadly, you attached a link to a picture on
https://private-user-images.githubusercontent.com… , which is github-account-specific and
can't be used by anyone but you. But the raw URL in your Readme works,
https://github.com/user-attachments/assets/3f9eee70-811e-41be-9d43-877b2dcbb078
so I'm assuming that's the one.
What I think is wrong here is that the Polyphase Clock Sync drifts off during the pauses
between frames: it doesn't know whether it's looking at noise only or signal, and so tries
to "wildly" guess what it should do during the "noise only" periods, just to then be off
from the correct timing enough to not be able to catch up with it during the first few
symbols of each frame.
In a practical system, you'd need to first detect presence before you feed it through the
clock synchronizer.
Best regards,
Marcus
On 5/12/25 10:47 AM, Maciej Zemło wrote:
> Hi everyone,
>
> I've developed a brief demonstration project in GRC that transmits a single byte via Pluto
> using BPSK modulation. The project works well when using a "Constant Source" block that
> continuously sends the byte, but it completely fails to function with the "Message Strobe"
> block, which sends a byte every 0.5 seconds.
>
> The project is available on GitHub for further reference: https://github.com/yabool2001/
> BPSK_test_02_3 <https://github.com/yabool2001/BPSK_test_02_3>
>
> I've attached a screenshot illustrating the structure of the project, available here
> <https://private-user-
> images.githubusercontent.com/38382353/442661233-3f9eee70-811e-41be-9d43-877b2dcbb078.png?
> jwt=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJnaXRodWIuY29tIiwiYXVkIjoicmF3LmdpdGh1YnVzZXJjb250ZW50LmNvbSIsImtleSI6ImtleTUiLCJleHAiOjE3NDcwMzkyNTIsIm5iZiI6MTc0NzAzODk1MiwicGF0aCI6Ii8zODM4MjM1My80NDI2NjEyMzMtM2Y5ZWVlNzAtODExZS00MWJlLTlkNDMtODc3YjJkY2JiMDc4LnBuZz9YLUFtei1BbGdvcml0aG09QVdTNC1ITUFDLVNIQTI1NiZYLUFtei1DcmVkZW50aWFsPUFLSUFWQ09EWUxTQTUzUFFLNFpBJTJGMjAyNTA1MTIlMkZ1cy1lYXN0LTElMkZzMyUyRmF3czRfcmVxdWVzdCZYLUFtei1EYXRlPTIwMjUwNTEyVDA4MzU1MlomWC1BbXotRXhwaXJlcz0zMDAmWC1BbXotU2lnbmF0dXJlPTg2MmQ3MjAxM2U2NDg3MmI3MzZkZGQyNGFlMzdlODdkZjlmYjRlMjc1ZDgzYzgwYmE4OGQ1ZDE5OTM2MWFjNjkmWC1BbXotU2lnbmVkSGVhZGVycz1ob3N0In0.whxllXKHs55LV7wgcRfq7BPy3oQjAiGJWUoKc-J8en8>.
>
> Could someone point me in the right direction regarding what might be going wrong here?
>
> Thanks in advance for your assistance!
>
> Best regards,
> Yabool2001
>
No comments:
Post a Comment