NEW TO OTHERNET - Information Request (Technical Project)

Mark_Phillips · 2020-10-19T18:19:38.426Z

Hostility? What? Not at all. Advice from someone that’s been there.

As a past teacher of Master level Computer Science students I can tell you that this sort of idea comes up all the time. I’m simply pointing out the flaws in your idea. You can be assured that the scholarship committee at the college will be well versed in the current state of SDR and your other proposed technologies. What sets you apart from the herd is the ability to overcome the committee’s arguments rather than overcome the technical issues.

As for the APRS-IS server, you can only send messages to that if you are A) a licensed ham radio operator (I did tell you to get a license) and B) if you have a transmit ability (you gotta put the message in there somehow).

Are we assuming that “techminds” is an expert in these matters simply because he has a poorly researched “look what I can do” youtube channel? He at least has a ham radio license that allows him to use the APRS-IS system (which he neglects to mention in his video)

A total system failure would be pretty difficult to recover from on a boat. However, a backup system such as you are describing would also not help much if you could not alert others to your issues. So how about you add a 30 meter band QRP HF transceiver to the mix so that you can put that message into the APRS-IS system? Many sailors have a ham radio license for no other reason than backup.

maxboysdad · 2020-10-22T16:21:41.825Z

@S_H
Of course this would be possible. Pretty costly, but assuming you own the boat, the end justifies the means. Just a few questions, hoping to help you understand. Please don’t take this as insulting, YOU asked the questions. Mark has already given you some excellent guidance, but please consider these things: How large a Pelican™ case are you planning for? You have not stated your battery technology to be used, nor how the Raspberry Pi™ is to be implemented. What are the keyboard and mouse for? Will this be used with a laptop, or will the Raspberry Pi™ be used with a monitor (not included in your list).

S_H · 2020-10-22T17:09:59.786Z

There are a lot of questions, I will answer them one by one.

Maybe the emergency part of the system I have spoken about is a little too complex for what I am hoping to create. I think the scope of the project should be limited to receive only, as this allows me to use familiar hardware, as I don’t know much about transmitting signals, so here is the new scope with all the details.

The scope is now just a redundant weather and general information index for Skylark software, if in need of up to date weather or general world news, you can use this “computer” to access this.

Another thing that I was thinking about recently is a gyroscopic auto aligner for the antenna, I have used something similar while working at university, we used a raspberry pi nano and a gyroscope that had a compass to firstly align with north, then cross reference the pitch of the antenna via a stepper motor to correctly focus on a satellite.

I think this could work if you had a database already in memory with relative satellite positions and earth (Longitude/Latitude) data. Again, I think this would also need a GPS for it to work correctly, so this is something to consider.
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

The size of the pelican style case would be as follows – Reference (iM2200 STORM CASE)

Int. Length (mm)	381
Int. Width (mm)	267
Int. Depth (mm)	152
Int. Lid Depth (mm)	51
Ext. Length (mm)	411
Ext. Width (mm)	322
Ext. Depth (mm)	168

The battery is going to comprise of a 10Ah Battery made from 18650 cells running at 12v it will be connected to a BMS > Inverter (Solar Charging) > 5V step down to USB output.

1 = USB Power output (Predefined) – Raspberry Pi Computer

1 = USB Power output (Predefined) – Dreamcatcher v3.05

1 = 12v Power output ^ Inverter (Predefined) – laptop Screen Touch screen (Waterproof)

The Raspberry Pi computer will be used to interface with the Dreamcatcher device though a WI-FI module connected to the Raspberry Pi, the PI will then display the information of the skylark system to the monitor via HDMI.

Connected to the raspberry pi will be a USB keyboard mouse combo (similar to the old ThinkPad (nipple mouse) this will be covered in a rubber waterproof layer >

This will be used to interface with the Raspberry Pi computer. Running an OS (Android or Linux).

maxboysdad · 2020-10-22T17:31:27.965Z

How much of this will be exposed to the weather when using it? I have spent a good deal of time at sea, and I know you will want to consider this. So far, it looks like you could operate for about two hours on battery as configured.

Syed · 2020-10-22T17:45:34.686Z

You should take a look at the work that @Martin has done.

S_H · 2020-10-22T17:49:03.102Z

I think the battery could be made bigger, but then the weight pay off could mean its tiresome to maneuver.
the ports of external charging and input for the solar panels will be covered by a rubber seal “plug” in my head i think this would be the best option, especially if it is a heavy duty plug with decent O-Rings.

but to answer your question, the parts that will be in direct contact would be the Monitor and the Keyboard, but bare in mind the monitor will be sealed with some kind of adhesive, and the keyboard covered in a rubber membrane.

One problem i can think of is if you damage the rubber membrane.

S_H · 2020-10-22T17:51:05.614Z

That is exactly what i was thinking! just without the extender.

i think you could make it pretty compact.

Syed · 2020-10-22T18:07:07.349Z

If you are starting this from scratch, you may not need the Arduino, as there are a few pins exposed on the Dreamcatcher which should allow you to control external hardware.

S_H · 2020-10-22T18:09:51.430Z

Does the Dreamcatcher allow for reprogramming?> I saw that the I/0 pins.

Is there a Schematic anywhere that outlines the IO ?

Syed · 2020-10-22T18:27:46.786Z

Dreamcatcher 3.05 SoC-GPIO Schematic.pdf (1.5 MB)

S_H · 2020-10-22T18:31:22.950Z

Thank you, does the software allow you to add extra code?

Syed · 2020-10-22T18:49:34.586Z

You have root access to Skylark, which is based on Buildroot, so you can do whatever you want. But it’s highly stripped down. Sorry, we don’t provide any support on custom development projects.

S_H · 2020-11-04T22:52:25.199Z

Schematix1328×729 46.6 KB

So this is what I have been thinking so far.

Can anyone spot any obvious problems with this?

Thanks for all your help!

maxboysdad · 2020-11-05T16:12:42.391Z

It looks good, but I question what do you need the “Digital Signal Video Decoder” for, as the RasPi has HDMI output? Just asking because it looks like you are pretty well covered otherwise. Jerry

S_H · 2020-11-05T16:47:04.285Z

The Video Decoder is just the driver board for the HD monitor, I have decided not to go with a normal panel design, so the monitor comes in 2 parts.

The screen itself, and the driver board that handles the signal processing and has access to 12v rail voltage.

Thanks, I was toying with designs today to make sure it would actually fit, although very basic. this is what i was hoping the internals to look like.

Schematic 4.PNG2337×826 404 KB

Schematic 3963×1068 64.8 KB

Schematic 21692×948 285 KB

Schematic 1.PNG2355×920 710 KB

maxboysdad · 2020-11-05T17:21:24.506Z

That looks like a pretty good layout. How will your LNB be mounted when operating?

S_H · 2020-11-05T17:41:59.974Z

I was hoping to make something that would auto track to the nearest satellite.

The thought was to have a X,Y axis servo holding the LNB, Have the system run on a Arduino Nano.
My hope was to get a GPS receiver and a compass module to send Longitude/ Latitude data to the Nano, and by using the magnetic compass, use that information to move the servos pointing the LNB in the correct position.

Another way I was thinking of is using a startup script from the host Raspberry Pi, that would run the servos through the max range, while doing this, the signal strength from the satellites would be used to almost auto focus on the specific point in the sky.

They both have various bad points to them. Its just how far do i want to be pushing it.

I want to make something that is efficient but also not complex, the least amount of complexity the better, less things to fail.

What do you think to the idea?

maxboysdad · 2020-11-05T17:48:14.760Z

I like the ideas you are putting forth. A bit advanced for me to take on, but it can work. I would send you to read @Martin Martin’s threads here:

Outernet for sailors (weather forecast grib files) Feature Requests

Unfortunately not yet. The part with the battery is still missing because the lowest layer just won’t fit into the hole. I need to make a new one with the CNC first. But there are no LEDs in my setup plus the transparent ball would not light up in the dark like a white one. I don’t have a lot of time at the moment to work on it, but I’ll make a video when its ready.

A lot of good ideas and he shows how he is building his unit into a geodesic designed weatherproof enclosure…

Martin · 2020-11-05T23:47:50.379Z

@maxboysdad Thanks for mentioning me here, also @Syed, but sorry I seemed to have missed your post. @S_H I like your project and your ideas! I also have a GPS included in my setup but I’m not using it in the code yet. I guess the best way would be a combination of both methods you mentioned. I am planning to use the GPS and compass/gyro to roughly point to the position of the satellite and do the fine-tuning by checking the signal strength. Also if you won’t use a GPS, since the satellites are geostationary it would be much faster only checking the sky towards the equator. Another issue I recently learned about is that the reception with the bare LNB seems to be not reliable enough in most areas to get a good reception. You should think of adding a kind of horn to your setup. Also have in mind, that on a boat, especially on a steel boat, the compass readings can be quite a bit off. My boat is made of steel and judging by my magnetic compass this seems to be quite an issue. I’d like to make a test with a magnetic sensor and my arduino to make a kind of deviation table. But anyway, cool project and I wish you best luck with your scholarship!

Mark_Phillips · 2020-11-06T19:30:07.698Z

You’ll need to make sure that the “inverter” has a built in solar charge controller otherwise you’ll get nothing from your solar array. Whilst solar panels claim to output (say) 5amps they only do that when they are in full sunlight and there is no significant load connected to them. The charge controller makes sure that the panel does not see a significant pull from the load.

Try to calculate your load including battery charging draw. This will dictate how large of a charge controller and panel arrangement you’ll need. A PWM charge controller is simple to design but a MPPT controller will yield more power for longer. Bear in mind that you are only getting full solar output for about 5 hours a day. You can increase this by aligning the panels optimally with the sun until it sets.