Dreamcatcher v3.02: Feedback Thread


#483

Jim,
I bought a pair of Chinese 2.4 GHz SX1280 boards before the DC3 came out. I was considering changing the crystal on it to cut the frequency in half. I had bought several Watkins-Johnson doubly balanced mixers to up/down convert the LoRa board into one of those ham bands.

The Outernet board made this whole thing much more obvious. It has a mixer just like moRFeus on it. It takes the output of the LNB (in the L-Band) and up-converts it to 2.4 GHz. For me, the 23 cm band is very attractive. There’s not a whole lot of modifications to get it to listen on that band since it’s right there in the L-Band. In all fairness, Outernet could come out with a 1240-1300 MHz transceiver for a ham version of LoRaWan. It could potentially out-perform AX-25 packet on VHF at 1200 and 96000 baud.

I would love to try it on a nearly dead band.

–Konrad, WA4OSH


#484

I never heard of LoRaWan. Could you give us a brief explanation of what it is? I plan on doing some research later today. I am always looking for alternative methods of communications.


#485

Nice work everybody - - we all have frame lock :heart_eyes:

2018-04-18 08_27_37-Outernet Status Dashboard


#486

I’ve been working on the English Wikipedia article on LoRa. LoRa uses a spread-spectrum technology. It’s another one, not FH or DSS. It’s called Chirp Spread Spectrum (CSS).

LoRa has ISO layers like many Internet Protocols. It has a PHY layer and upper layers.

The LoRa standard is proprietary and describes the PHY layer. It’s implemented by the LoRa chip used in Outernet. A few hackers seem to have reverse engineered it.

The upper layers are described by LoRaWAN. These layers are specified in an open standard. However,
Outernet replaces the upper layer protocols with its own receive-only protocol.

LoRa, IMHO, has several very good features:

  1. It has Process Gain. This in short enables LoRa to hear below the noise level. This is why Outernet works when we have SNRs below zero.
  2. It has a really high PAPR, meaning it does not require highly linear amplifiers and thus amplifiers are relatively easy to build for it.
  3. It has the ability to cover very large distances due to 1) and 2)
  4. It’s immune to Doppler. This is not an issue with GeoStationary satellites. But, there’s plenty of things that might involve LEO satellites.

LoRaWAN is being implemented world-wide. It’s shortcoming is that it’s being deployed in very crowded unlicensed ISM bands. Wouldn’t it be nice if it could be deployed in a ham band where the near line of sight properties can be fully utilized?

–Konrad, WA4OSH


#487

Coast-to-coast in the lower 48!

Do we need some more people to test the coverage on the southern border of the US? i know of a couple people that live down south that might be interested.

–Konrad, WA4OSH


#488

I’m heading out to Santa Barbara, CA, this weekend and will test my portable there. Ken

(PS - - Not quite very far South, but a different venue)


#489

It’s still another data point. I will look for you.

–Konrad, WA4OSH


#490

26cm flat antenna is a waste of time. harder to find the satellite, worse performance. :unamused:


#491

Welp that idea now goes out the window…


#492

Can we get pushes of the GOES-16 images, separate from the predictive weather app in the firmware? Just the raw decoded high-res JPEGS that show current USA weather? They are full-disk and sent often, down to even even lightning plots.

This would be very helpful to many. Maybe some others who are more articulate on this topic can jump in here and explain the amazing high resolution data that this new NOAA satellite is sending down down right now. Lots of amateurs are decoding the data, and it should be all ‘free’ for use.

Regards
-Liam


#493

47 AM

Rock Solid.


#494

For those of us worried about lightning. I recommend something to protect the dreamcatcher. My choice is PolyPhaser because I have used for other projects and many of the facilities require them.

I don’t have the right part number yet since I need to ensure they DC-pass signal and they pass the 1.2GHZ frequency.

My amazon search has for about $20 – note: you have run a ground wire.


#495

click the “°C” symbol to switch units. Same with KM/h.


#496

@Syed, @clavo
Thank you. This works once and awhile now, however, now the app is now reloading itself every couple of minutes, which really isn’t helpful. It seems to have been upset from where it was yesterday. With only the data from the night before at 1800 hrs, it isn’t very helpful. Interesting, but not current enough. I would be interested in the GOES-16 images, as Liam refers to, also.


#497

I’d be happy to dig for more info on a stable GOES-16 image source if it will 100% be added, otherwise it’s not worth my time.

Lots of people decode these and post them on twitter too. Being that it’s a geostationary satellite… It’s not like the old NOAA satellites that need to be tracked. The images are VERY high res. I’m sure someone out there in our crew knows more about this than me though.

This guy has a good sample of some of the new HRIT stuff:

https://twitter.com/uhf_satcom?lang=en

Ideally, Outernet can add a dish at their HQ / NOC and decode this stuff themselves. The software is out there.

-liam


#498

So far - - no joy. I’ll try again. Looking 119 deg mag, elevation 37 deg, skew ccw 38 deg. Even with my 8"x4"x2" horn. Ken


#499

What ya looking for at 119? one of the GOES?

I’m not sure what, of the new ones, are all active now. GOES-16 is at 72.2W

https://usa-satcom.com/xrit-decoder-for-goes-satellite/

and

tell a bit.

-liam


#500

@kenbarbi ken, it looks like a good -80.2 signal and the angle, elevation and skew all match. Odd that it would be difficult, as on the map it looks really strong.


#501

I’m in Southern California (Orange County) and I posted my results a while back. I can’t get get better than about -15 SNR with the bare LNA. With my 36" oval dish, I get a SNR of +6. I know using a dish is kind of cheating to get a really good signal but my goal is to be able to put this on a moving boat so along with the dish I may need to build a gimbal for it.

I don’t show up on the status map because I’m checking the stability of the system when it is not connected to the Internet for a while. I have noticed an issue where after about 7-12 days the Dreamcatcher gets very sluggish when using the installed apps and I get a bunch of error messages. A reboot fixes it all. It has happened twice. When I have time, I would like to repeat it again as well as document it in a more organized manner. As an example, when using the log viewer, I get lots of Javascript errors, and the weather app pauses for about 20 seconds any time you do anything in it.


#502

Oh, missed your ‘i’m on the road…testing’ post… @kenbarbi