Open-ondd: decode files from a UDP stream

Syed · 2021-03-31T17:29:42.296Z

The old free-outernet file decoder has been updated to support the current broadcast, but you’ll need to grab it from this fork.

GitHub

GitHub - Othernet-Project/open-ondd: Free Software Outernet receiver

Free Software Outernet receiver. Contribute to Othernet-Project/open-ondd development by creating an account on GitHub.

Dreamcatcher 4 is being updated to provide a UDP stream over wifi, but that doesn’t help anyone (now) who wants to experiment downloading files on a Pi–or downloading files with Armbian instead of Skylark on Dreamcatcher 3. The LoRa packets still need to be grabbed from the SX1281 and inserted into a UDP stream, but that should be relatively straight forward by using Dreamcatcher Chat as a starting point.

Syed · 2021-03-31T17:30:13.167Z

@caveman99 @Tysonpower

Syed · 2021-03-31T17:31:53.826Z

Being that it’s all Python, applications for Windows/Mac/Android could also be developed.

destevez · 2021-04-02T08:36:37.509Z

This is amazing! Thanks to Othernet for maintaining and updating my old software.

I’m now interested in seeing a DIY receiver set up from scratch with open-ondd. To demodulate the LoRa frames, an SX126x plus microcontroller will be needed. Another alternative is to try to use an SDR and gr-lora. Perhaps I’ll give a try to this and post here about my results.

caveman99 · 2021-04-02T08:41:18.426Z

i am fiddling with this already, partly for the files but more for an efficient voice/news satellite radio project. Just a pointer so you don’t go the wrong route. You need an SX128x not an SX126x so you can use the 1st IF of the satellite LNB directly. Theres a scematic of the new DC4 board in the github repository at https://github.com/Othernet-Project/Dreamcatcher/tree/master/hardware/schematic . i think you can take the part west of the SPI to start with the decoded LORA frames. Or wait for the DC4, it will have an UDP raw output for the decoded Lora Frames.

destevez · 2021-04-02T08:56:03.040Z

In Europe we have the Astra-3B signal at 11681 MHz, so this ends up at 1931 MHz or 1081 MHz with the regular 9750 and 10600 MHz LNB LOs. I don’t think these lie into the frequency coverage of the SX128x (nor the SX126x), so I plan to use some form of frequency conversion. But your comment now makes me wonder whether the UHF and 2.4 GHz LoRa protocols are interoperable or if there are any differences besides frequency range that prevent an SX126x and SX128x from talking to each other.

caveman99 · 2021-04-02T09:17:34.891Z

Europe is not on Astra 23.5E any more but moved to Eutelsat 8 WB on 12623 V which means 2873 MHz on 9750 MHz and 2023 MHz on 10600 MHz. There still needs to be some frequency shifter, but not as heavy as with the below-1GHz Semtech types. The Lora Modulation itself should be interchangeable between the SX12 chips.

@Tysonpower has a prototype RX with SX1280 up and running but needs an external frequency shifter.

caveman99 · 2021-04-02T09:19:19.055Z

@Syed after looking at it again are you planning to update the schematic? the Semtech IC outline is missing… plus i think therer’s been some updates in the HF path before the SX1281.

destevez · 2021-04-02T09:36:29.591Z

Thanks! Good to know it’s now in Eutelsat 8 WB before I start chasing ghosts in Astra 3B.

Tysonpower · 2021-04-02T10:51:24.415Z

Infos: EU Beam on Eutelsat 8WB: 12.6231V GHz

Syed · 2021-04-02T12:26:41.757Z

Yes, I’ll post the most recent version of the board today. I don’t have it yet, so no idea of it actually works.

***Please note that the the SX128x and all sub-GHz LoRa chips are incompatible. It’s not the frequency difference that sets them apart. The new LR1110, for example, can tune all the way from 100 MHz to 2700 MHz (with small drop outs along the way). The key difference between SX128x and all other variants is the supported channel bandwidths, which are not the same as the other radios.

SX128x: 200, 400, 800, 1600 (kHz)
SX127x, SX126x, LR1110: 64, 125, 250, 500 (kHz)

I would guess that there is a secret register setting in all of the Semtech LoRa devices which allows any channel bandwidth to be selected, but that type of information is hidden from users and most customers.