r/Lora

Haltec V3 Just opened

Tried using a web flasher to install meshtastic software.

With every cable, both on windows 10 and on Linux Mint, I've got the same error:

Couldn't open the serial port.

I have no clue how to fix it. I found one similar entry and it seems like they had to reboot or use another cable (they didn't answer at the end). And "similar" isn't that similar, because they were stuck at connecting, while I don't get to that step at all.

Upd: It seems like it can't open it, because it's already open. No clue how to fix it, because there're no solutions online which I haven't tried yet (I killed a modem manager, I searched for any software that can do something about it, looked through settings of my device in case there was some problem.) It still doesn't work.

Upd 2: I tried fucking everything I have no clue what I'm supposed to do I already relapsed and had a mental breakdown Why in the fuck I am the only person to encounter that issue

Upd 3: Still have no clue what went wrong 15 minutes on another PC and I was able to get it on

Hi everyone,

I'm currently working on my high school graduation project (Maturaarbeit in Switzerland) and I'm stuck on a frustrating DSP/SDR issue. I'm hoping some of the experts here might be able to point me in the right direction.

The Project: I am building a custom, license-free wireless protocol to bridge the gap between Wi-Fi (high bandwidth) and LoRa (high range). It operates in the 2.4 GHz ISM band using a 10 MHz bandwidth and a low Spreading Factor of 5 (SF5). To increase the data rate beyond standard LoRa, I expanded the modulation:

• CSS (Chirp Spread Spectrum) as the base.
• Slope-Shift Keying (SSK): Using both up- and down-chirps (+1 bit/symbol).
• QPSK: Embedding phase offsets into each chirp (+2 bits/symbol).
• LDPC: Forward error correction (IEEE 802.11n based).

The Setup & Code:

• Hardware: 2x ADALM-Pluto (modded to AD9361 for 56MHz BW), TCXO 0.5 ppm.
• Software: Built entirely from scratch in Python (NumPy, libiio). I purposely didn't use GNU Radio because I wanted to code the math and DSP pipelines myself to understand them fully.
• GitHub Repository: You can find the complete source code and simulations here:https://github.com/Valix-s/CSS_Hybrid_Modulation/tree/main

The Problem: My baseband simulation (including an AWGN channel and the full LDPC pipeline) works flawlessly, even at negative SNRs. However, when transmitting over the air, the packet synchronization fails completely. The receiver is unable to reliably detect the preamble (packet start). If the start index is off by just a few samples, the symbol boundaries shift, and the dechirped payload turns into garbage.

What I've tried so far:

1. Time-Domain Cross-Correlation (scipy.signal.correlate): Failed completely over the air. The slight Carrier Frequency Offset (CFO) caused phase rotation, leading to destructive interference when correlating over the 16-symbol preamble. Wi-Fi bursts in the 2.4 GHz band also caused massive false positives.
2. Frequency-Domain Sync (Dechirp + FFT): I switched to a sliding window approach using pure NumPy. I multiply the incoming signal with a local down-chirp and run an np.abs(np.fft.fft()) to find the peak, avoiding phase rotation issues. It works perfectly in simulation, but still fails on the actual hardware.

My Suspicions:

• Python Processing Latency: My pure Python DSP loop might be too slow. While processing a chunk, the PlutoSDR hardware buffer might overflow/overwrite, effectively "cutting" the preamble in half.
• OS Timing Jitter: I tried implementing a rudimentary TDMA slot system to separate TX and RX windows and give Python time to compute, but Windows OS timing jitter makes my slots highly inaccurate.
• 2.4 GHz Interference: The AGC might be getting crushed by high-energy Wi-Fi bursts, suppressing my preamble peaks.

Next Steps: I ordered u-blox NEO-6M GPS modules to extract the hardware PPS (Pulse Per Second) signal via an ESP32 to enforce strict, hardware-level TDMA slots and eliminate the Python/OS timing jitter.

My Questions for the Community:

1. Has anyone implemented a custom CSS/LoRa sync algorithm in pure Python? How did you handle continuous buffer reading vs. heavy processing time?
2. Are there any known tricks for robust preamble detection in heavy ISM-band noise environments using PlutoSDRs?
3. Am I overlooking a fundamental hardware limitation when doing 10 MHz wide CSS via libiio in Python?

I recently tested a simple 1/4-wave (868 MHz) antenna made from 0.8 mm silver wire.

In open terrain with clear line of sight ( about 2 meters from ground level ), I was able to maintain a stable link at just over 20 km.

I'm curious about everyone else's results.

I'd love to compare setups and see what's realistically possible.

I have a ESP32-WROOM-32 module with a DX-LR30 (SX1262) LoRa module and Ublox Neo-6M GPS module.

I started with DIY v1 Meshtastic code then I tried Hydra code but the node was unstable and I could not connect neighter by Bluetooth nor via web. The nod was rebooting every 5 minutes and when started it was showing Critical fault #3.

After reading some documentations and some posts I decided to compile my own code so I started to do it. Now I have the code compiled and uploaded and except LoRa (I still have Critical fault #3), the rest is working great.

Can someone help me to understand how can I bypass the error?

Folowing the link is variant.h that I added in the downloaded meshtastic project and I also the log from my node.

Which Model is better for Training Character + Concept LORA?

I want to train a character with specific height, skin texture and anatomy. I tried Zimage Turbo. ZIT captured face flawlesly, but when it comes to skin texture, Height and anatomy it failed.

Any idea what I did wrong. Please suggest which model should I use.

Is it possible or not something we can even dream of ?