Raspberry Pi Tablet Gets Radio Surgical Enhancement

We always get excited when we buy a new tablet. But after a few months, it usually winds up at the bottom of a pile of papers on the credenza, a victim of not being as powerful as our desktop computers and not being as convenient as our phones. However, if you don’t mind a thick tablet, you can get the RasPad enclosure to fit around your own Raspberry Pi so it can be used as a tablet. Honestly, we weren’t that impressed until we saw [RTL-SDR] add an SDR dongle inside the case, making it a very portable Raspberry Pi SDR platform.

The box is a little interesting by itself, although be warned it costs over $200. For that price you get an LCD and driver board, a battery system, speakers, and an SD extension slot with some control buttons for volume and brightness. There’s a video of the whole setup (in German) below.

The whole affair weighs about 1 kg, a bit heavy for a tablet. It is also fairly thick although that’s good for making this kind of modification and also gives the touch screen a nice angle when it is flat on a table.

Most Raspberry Pi software isn’t setup for a touchscreen, but the post explains some of the issues they found when using a different Linux build instead of the default tablet software from the maker of the case.

We worried that the SDR inside the case would be subject to interference, but apparently, with an external antenna, it was negligible. You could see the interference when using an antenna attached directly to the box through the added RF connector, though. Your results could be worse if you used an SDR dongle without proper shielding, too.

We think we might prefer a more futuristic form factor. You can also get SDRs that directly work with the Raspberry Pi.

27 thoughts on “Raspberry Pi Tablet Gets Radio Surgical Enhancement

  1. Who do I have to kill (or what do I have to google) to get some short extension cables like that?! I can’t find any shorter than 10cm, and that double HDMI cable setup is awesome! Finding narrow and progressively taller cables like that! wow!

    yeah yeah, I’m sure they’re custom made and impossible to find. I may have to just chop some up after all.. been avoiding that.

  2. You know, back in those couple of months when netbooks were a thing, I bought one, and it quickly became my daily driver. And then they went out of style. Eventually somebody came up with tablets, and I thought, well, if it had a keyboard, I’d be okay with that. And then I saw that most people who bought tablets were also buying the folding cases that held a Bluetooth keyboard. So people were making their own netbooks, which the industry had stopped making because (they said) nobody wanted them. Okay, whatever.

    Wait. Did I have a point that has anything to do with this article? Oh, right: it’s the same thing with Raspberry Pies: you can make whatever you need out of them, even if it’s something that the industry doesn’t think anybody wants. Nice job.

    1. Very true, and with the compute modules and Zero you can even do lots of things in a very compact space if that matters to you – making something that could actually be a commercial product.

      I’m also with you on netbooks, I have no idea why tablets took off, netbooks are just tablets with a good additional input method and better battery life built in… I can understand phones taking off, capable of doing what you need in a pinch while being small enough to take anywhere – though that is become rarer these days as they tend towards far too big to fit in most pockets. Trying to find ‘small’ smartphones now is remarkably hard – and while I have the pocket space for the big ones most of the time having the small one like my really old ‘windows phone’ a HP something that will fit in any pocket at all, and is chunky enough built you can’t crack the screen by accident – even comes with a hard plastic cover over the screen and stylus – another thing I wish more phones did.

      1. i think the only thing i wasn’t too fond of on netbooks were how poorly Windows ran on so many of them. i know Android has its issues but the software seemed more lightweight for a portable device.

      2. The beauty of the compute module is that it is slightly bigger than a Pi Zero board (50% larger?) but has a quad-core CPU and a decent amount of memory built-in.

        This case would be a perfect candidate for a compute module, with a custom board that brings out selected i/o ports.

        1. The CM4 isn’t really bigger than a Zero at all – dimensionally different but in terms of size very comparable – just one is very square the other quite long and thin… Of course you can thin down a zero board easily at least in places, so it might well be the board for some jobs the CM4 just won’t fit as the CM4 is basically the size it is, nothing can be done to change that at all (at least I’d not bugger with it, the whole thing is far to dense a unit to find any real savings).

    2. The problem with netbooks was that they were built to a price-point, with the best specs possible at that price-point, which typically meant an Atom processor with maybe 2 gig of RAM and a slow eMMC storage chip all attached to a low-res display. Add to that early models ran a form of Linux, and Linux was “Not Ready for Prime Time” then.

      Towards the end of the netbook era, a few brave manufacturers stuffed nice processors that supported adequate ram & 2.5″ HDs and small, but standard resolution displays (I have one with an early i7 CPU from Asus I believe).

      Once MS made Windows free for netbook OEMs it was too late, the market had soured, and the requirements for the ‘free’ windows license were low ram (2 gig max), low-res display (800×600), and a screen 10.4″ or less diagonally (from memory).

      The real difference between netbooks ‘back in the day’ and tablets-turned-netbooks is that the OS is built for the tablet, the displays are higher-res, and the App Store is much, much better than the Linux apps available back in the day.

      1. Personally I don’t agree at all, other than the hardware in netbooks often not getting Linux support quickly or even properly at all, for the ones you could get it running it would be a great experience – as at least as far as I saw none of them were anything but Windon’t by default, and WIndoze of the day was really really awful on ‘low’ spec hardware, I’d argue modern WIndoze is no better too…

        App store wasn’t exactly good when it launched to my memory, far from reliable delivered apps… But Linux apps for the most part are in the repo even back then and just a package manger call away, and mostly they are good – infact if they are in the repo they probably at least work…

        As for screen resolution, well I ended up with an old netbook that has better DPI than anything that small needs, right on par with the better end today, and equally there are tablets out there in the cheap end with really crap screens, particularly early on in the tablet craze – that is entirely down to what hardware you bought…

      2. I think the demise of the netbook was that its original price point was too low, which made it attractive, but which made it impossible for sufficient performance to be provided. And once that price was set, the market wasn’t going to accept raising it.

        This SHOULD have been when Linux gained some traction, since Windows cost about 1/3 the price of the machine. I had mine triple-booted – Ubuntu 10, XP, and OS X Snow Leopard, but used it almost exclusively in Ubuntu.

        1. and that is exactly why Microsoft forced the netbook vendors to up the hardware specs and put Windows on them. It was no skin off Microsoft’s back that Linux based netbook prices were increased. Doesn’t anyone remember when all this happened the vendors were no longer selling the lower cost, now spec’ed Linux based netbootks? Another win for Bill Gates and Microsoft shareholders and another loss for consumers.

          1. And THAT is exactly why they died out. The extra performance was not worth the extra cost.

            This is what happens to niche products: the people who actually want the product as it is, get left behind when the industry realizes that by adding performance (or size, or features, or whatever), they can appeal to a larger market. But this drives the price up, or reduces its portability, or whatever it was the niche market wanted, making it no longer attractive to the people who wanted it in the first place. At this point, the broader market loses interest because they realize it isn’t what THEY wanted, either. “So it’s just a laptop with a smaller screen and smaller keys. Meh.”

            I don’t think tablets ever really HAD a niche. I think the people who bought tablets actually wanted netbooks, which is why (almost) everybody who bought one also bought a keyboard for it.

    3. In the pre-tablet world I wanted a good Netbook and didn’t understand why they supposedly flopped. I generally wait for a generation or two to come and go so I can buy used. Maybe that’s a common thing among people who would want a Netbook and so they really did flop.

      Or maybe the manufacturers just decided they didn’t want to push those. I do not believe that are market functions correctly. Buyers are supposed to choosing what manufacturers produce by buying more of it. I think they have mastered the art of manipulating what consumers will buy to the point that it’s the big manufacturers driving the trends, the consumers only think they are making a choice.

      But in this case I don’t think it turned out so bad.

      The advantage of a tablet is you can use the same device both ways, with and without the keyboard attached depending on what the situation calls for. The change I would make though is get rid of the bluetooth. If your keyboard is going to be in a clamshell case right along with your tablet there is no need for wireless. Why have a battery in your keyboard that needs to be maintained?

      And it has to have USB host. I think most tablets do now but for so long they didn’t, or they used the same port for charging and could only do one or the other at a time.

      Something like Microsoft Surface but with good Linux drivers. I think that’s the ideal portable device.

      1. “The change I would make though is get rid of the bluetooth.”

        A few years ago, I bought a Packard Bell (yes, I did) tablet at Menards for $88. It came with a detachable folding keyboard. (edit: by “folding” I mean that the keyboard was hinged to the tablet) The keyboard has 5 pogo pins that connected it to a long side of the tablet. It is quite useable (for a keyboard that was too small for my fat hooks to touch type on). Alas, and alack, it is now somewhere under the pile of papers on the credenza.
        (currently replaced by a Samsung Tab A -without a keyboard)

      2. I’d definitely agree you are correct the producers of tech really do steer the customers to a rather large extent – you can have all the free will in the world, but you can’t choose what doesn’t exist, and if they think they can sell you more extra accessories for yet more profit to make your tablet work properly of course they are going to take away your inbuilt keyboard, make you buy screen protectors and cases or replacement devices because didn’t…

    4. Netbooks where a hit for about 1+ years because they were cheap and ran Linux good enough. They stopped being a thing when Microsoft leveraged licensing contracts with netbook makers and forced them to install Windows which required more CPU power, more RAM and more battery capacity raising the price and Windows still wasn’t usable on them. If you don’t think Microsoft leverages its Windows license contracts look at all their OEMs they forced to sign a license for FAT filesytem because they sold Android/Linux tablets. Only Barnes & Nobel fought them and exposed the strong arm methods and this was because Microsoft had no Microsoft Windows licenses to be leveraged with. Microsoft was unable to raise the price of tablets (~$5) like they did netbooks(~$100+) so their FAT licensing could only provide them with shipping numbers and hundreds of millions in profits.

  3. “We always get excited when we buy a new tablet. But after a few months, it usually winds up at the bottom of a pile of papers on the credenza, a victim of not being as powerful as our desktop computers and not being as convenient as our phones.”

    So, you’ve hacked into the cameras of my tablets?

    1. I’ve been hacking on DIY computers since 1974 – great fun. But it does make me twinge when someone spends so much time and money to build a tablet around a Raspberry Pi. I love Raspberry Pi and have about a dozen running in my house, but they are performing custom tasks that are beyond off-the-shelf solutions.

      Microcenter sold the TW-700 tablet for $60 each (including charger) in 2015. It had Win 8.1 and apparently wasn’t “cool” enough. However, it also had the most amazing combination of features and quality ever available in any tablet. Go figure. I bought as many as I could carry, and have used them daily for hundreds of applications for the past 6 years. Not one failure.


      The RasPad looks like fun but before ordering all the parts, consider the OTS alternatives.

      1. There really are not off the shelf alternatives for some of the things a Pi just does, and getting good priced bits like that is not something to be relied upon.

        Not that I disagree with the principle, got lots of cheap and useful ‘obsolete’ tech around here. But if you want to build something, and even more if you want others to be able to replicate it the parts have to be source able or easily exchangeable, which despite the challenge it can sometimes be getting hold of a Pi or Pi accessory quickly they are… Also starting from a Pi you get to leverage the great community and its massive body of work – so may well not have to do half as much work for yourself.

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