Dreamcatcher Chat Application


#82

Could you explain a bit to us not as familiar with LoRa as you are.
I do understand it is generally Spread Spectrum, like cell phone technology. In fact it’s called Chirp Spread Spectrum and a whole lot more. Looks like the smaller the Spread Factor, the greater data bit per second. And the higher the bandwidth, more data gets through. What are the negative side effects, like Big Pharma tells you? :upside_down_face:


#83

Could something like Openfire Instant Messenger Server
https://www.igniterealtime.org/projects/openfire/
Be setup to accept the data from the DreamcatcherChat


#84

There are many different types of spread spectrum technology. The two old school technologies were Frequency Hopping (FH) and Direct Spread (DS). As you can tell from the name, FH changes frequencies in order to avoid jamming. DS takes the message and “chips” it. In layman’s terms, the same bit gets sent over and over again, by a spreading factor … say 256 or 2**8 times. At the receiving end, the chips can be voted on. The majority wins. If you sent the message twice, it’s like having 3 dB of gain. If you sent the message four times, it’s like having 6 dB of gain. 256 times is 8 doublings, or 24 dB gain. This is called “process gain”. incidentally, the spreading factor is that power E.g. SF8

Outernet uses a technology called Chirp Spread Spectrum (CSS). LoRa is an implementation of CSS. Like DS, it also has process gain because it too sends the bit over and over again, but in a different manner. I can find some articles and YouTubes for you if you are interested in the details … it’s interesting.

TANSTAAFL!!! … (There ain’t no such thing as a free lunch) … It’s a trade-off between process gain and bandwidth. If you want a small antenna and still recover the signal, you can use bits of your message for process gain instead of data speed/bandwidth.

–Konrad, WA4OSH


#85

Konrad explains it all absolutely correctly. We can either provide a higher speed download, but require a larger antenna, or provide a lower speed service with a small antenna. You can see that we are trying to find the happy medium, even still.

In an ideal world (which I have yet to find) we would have an entire high-throughput transponder at our disposal, which would allow us to deliver a 100kbps to an omnidirectional circularly polarized antenna. At 11 GHz, that is smaller than a dime.


#86

I’ve taken some time to edit these Wikipedia articles to reflect the technology better:
Chirp Spread Spectrum
LoRa
Process gain

Outernet uses only LoRa PHY The upper layers are proprietary, and perhaps patent pending?

Here are my notes on LoRa :

Technical details on the PHY layer. These articles will explain how LoRa works:

  1. Matt Knight, “Decoding LoRa: Realizing a Modern LPWAN with SDR”, Bastille Networks, Sep 09, 2016

  2. Matt Knight, "lecture: Decoding the LoRa PHY Dissecting a Modern Wireless Network for the Internet of Things, Chaos Communication Congress 12/29/2016

  3. LoRa Physical Layer & RF Interface

kgrr talk 08:50, 26 March 2018 (UTC) <— yup, that’s me on Wikipedia

–Konrad, WA4OSH


#87

Great lecturer Matt Knight. Fast talker, but clear voice He has a passion for his field. I need to watch and listen again. Thanks Konrad.


#88

Here’s a nice primer video on LoRa:

LoRa crash course by Thomas Telkamp

–Konrad, WA4OSH


#89

Konrad, have you seen this LoRa device? it could be an i-gate too, I don’t know if it could be a phone patch, I suppose it depends on whether the optional available 3G or 4G module has audio or not. The device does have two USB and two ethernet interfaces, and WiFi.


#90

I have not used one, but I have seen the marketing blurbs.

–K


#91

I’ve been enjoying Scuttlebutt recently

https://www.scuttlebutt.nz/

There is code for Linux (does this compile on Dreamcatcher? Anyone fancy trying?)
https://ahdinosaur.github.io/patchwork-downloader/

Or Alpha for Android

It seems that it would be interesting to broadcast the Android app.

If we could find space to broadcast the feed then it would be a really interesting online/offline social network.


#92

How is this to an advantage…being one way?

-liam


#93

So I live in a village in Sudan.

My mum lives in Europe.

My friend Jamal goes to the city once a week and has a internet connection there.

There is a Outernet device in the village school.

I have a smartphone, as do a few friends.

We chat to each other on SSB, our chats are synced whenever we happen to be near the school.

Jamal gets all the updates, so once a week they are synced with the internet. My mum can see what’s going on in the village.

She can reply to messages I send, her replies are sent over Outernet to the school, so I often get a reply the day after Jamal has gone to the city.


#94

The chat application allows two DreamCatcher 3.xx boards to communicate with each other without a satellite connection.

There is no Outernet Satellite coverage in Sudan. Only the US lower 48 states, parts of Canada and Mexico currently have coverage. Stay tuned for announcements regarding coverage for your country.

–Konrad, WA4OSH


#95

Dear sir


#96

Dear sir
Mname is ibrahim living in Saudi Arabia i heared that there is a device for free internet
How can i buy it and is it work in saudi arabia.?
Please advice with thanks
Ibrahim


#97

Outernet only broadcasts data; it’s not a two-way Internet service. Second, Outernet is only available in the lower 48 states of the US, parts of Canada and Mexico.

Stay tuned, service may be added for other parts of the world.

–Konrad


#99

This may be of interest for using the LORA on the dreamcatcher.
Here is an interesting proposal by a company asking to use the unlicensed frequencies to do point-to-multipoint data communications. and asking for higher 45dbm power levels.


Current regs only allow omni-directional system configurations at relatively low power (kind of what is used in 802.11 wifi systems).

If this is granted, then maybe everyone will be allowed to use steerable antenna phasing and the higher power levels…

There are good and bad things of this type of fcc authorization. (like increased unwanted noise in the already crowded unlicensed bands)


#100

I’m having a few issues understanding the LoRa chat application installation,

Do I install the git onto a debian/stretch SD card that replaces the skylark sd card? Also, when interfacing with the terminal if the above is true, will that be done over uart?


#101

No, you download the entire package, which is really ARMbian with the chat application already running on it. ARMbian is essentially Debian Linux re-compiled to run on an ARM chip like the AllWinner that’s on the DreamCatcher 3.0X board.

The interfacing is done over USB.

–Konrad, WA4OSH


#102

I don’t think it’s a LoRa related thing at all. It looks like they want to make changes to what we know as WiFi.

–Konrad, WA4OSH