Portable Raspberry Pi SDR Spectrum Analyser made from scraps!

hi man dr armstrong and welcome to the back office tear down lab this is the beginning of a two part episode first i'm going to show you this this is something i made entirely out of scraps that's things i could find on the shelves in the back office and in and about my garage and you can see it's a peli type box from wonderful safety equipment case and it was just a standard waterproof type case it weighs quite a bit now and you'll see why and you could tell probably because there's these number plate screw caps on the outside this was really jacked the back story is i was asked by my brother-in-law to trace a frequency that was jamming there's a signal that was jamming his alarm systems and i i didn't have anything that could do it but i knew from software refined radio experience that i could knock something together so literally knock this together in about 30 minutes and i'll show you the components inside it i'm going to tilt it slightly so you get a better view excuse the reflections on the top here you have a touch screen it's a tft touchscreen and it is about seven i i say they'd probably call it a seven and a half inch it's probably about really more like seven inches viewable side to side diagonally and it's an hdmi screen and i've got a very flat ribbon type cable that you can buy an hdmi hdi ribbon cable it's going from there to there and then inside there you've got raspberry pi that has been hot glued there's a lot of hot glue in this it's been hot glued down but it's in a case that i 3d printed so that way i can still take it out by just undoing the four screws and removing it because of course the sd card is in there and you can see the power to the raspberry pi is provided via this usb which we're going to leave aside for now inside the case as well is a battery bank so this is one that i had on the shelf for years doing nothing and it's all three bars almost fully charged a lens cloth because i don't like dirty screens especially been touching with your fingers it's nice to buff them up and an antenna the antenna is removable you can see it was on a magnet to this metal piece of angle line that i had already prepared for something else and just bolted it to the side a bit of gate or something i just made a hole and just put put the bolt on the end and then that on the end and then beyond that you can see a software-defined radio tv dongle so it's actually a television dongle that's a standard tv rf connector there and there's a usb here and that goes to the screen for its touch screen so what i'm going to do is power it on and we can see what it does and i think to do that i'm going to tilt this that away as i apply the power power is happening it's loading up the full raspberry pi operating system you can see that takes time to boot it's a little bit painful but it does get there eventually and you can see here something called freak show freak show which is an adafruit piece of software that i managed to coerce to work on this it wasn't necessarily designed to work on this particular screen raspberry pi combination but i got it working and that's cool and it has a touch screen interface which is really cool it's written i think in python or qt something like that but you can modify it if you want to so one of the tests i had is a traditional garage or gate opener and you can see nothing going on that's because of course we're not in the right frequency range so all we have to do by the way let me just show you this it's pretty cool you've got the frequency waveform there on the top you can hit switch mode at any time and you'll get the waterfall effect so if you've used software defined radio you get the waterfall in fact excuse the shine on the screen i'm just going to open the antenna a little bit more because we might get a little bit more interesting stuff to see and you can hit config anytime and that will allow you to select the frequencies that you're looking for so for us i think i i'm guessing i think these are megahertz so we push four eight zero except and then we can go back and then hopefully as i'm pushing the button we might see some effect in fact i'm gonna go to this mode because you could often see a little spike on this um you see the line's quite high up there there are some adjustments we can get it down here it's at at the moment it's automatically brought out there for some reason it's not always perfect um i don't think i'm at the right frequency maybe it's four three three let's have a look for clear that four three three except hit back and i'm gonna push it again oh there you go you can see it right away so if i put it into the waterfall mode so you can see when i push it i'm going to push it now and then i'm going to let go then i'll push it now let go now i'll let go and now yep you get the idea you can see the signal right there technically it should work for fm but i'm in the back office we've got this particularly bad amount of interference here it doesn't always it's not always clear but let's see let's do 95.8 capital uh we're not in london though we're not going to get to them but ah there you go you are seeing it you can see all the different radio stations here on fm and if we do switch mode again it might not be so easy to see but there that auto i'm not really happy on that i have to play with this automatic gain control um gain 10 db i'm not always convinced you see oh that's actually quite good i'm not always convinced by the gain controls that are existing these tv dongles i've had really good results from external ones and that's it that's all this box does pretty much the whole raspberry pi that you could access it over ssh to tinker with it you could probably load games so i tend to just leave it like that once we've done a little bit of analysis and figured out what we're looking at through just tinkering with the software it's crude software so you do have to manually mess with some of the numbers till you can really pinpoint what you're looking at but it's absolutely fine for this purpose all i do is i pop out the usb power and you can collapse the antenna which i like to stick in here boom and that's it put it away back on the shelf and i think that's a really neat solution that works for most things and if you really want to you can lock it if you're curious this is a pressure release valve don't think it has any application in what we're really doing but maybe you could use that for something that'd be quite cool powerport wouldn't it so there hopefully that's been interesting to you please stay tuned though to the next video and i'll give you a little sneak peek of what we'll be doing in the next video so i've got the bits here and what we'll be trying to do is upgrade this because there are some things that i think it would benefit from so apart from a software uh update so it would be really cool to have a touch screen sdr radio receiver running please comment down below if there's a touch screen sdr radio receiver software that you think i should try a linux based one so that way you can just we can put a speaker on here and actually just listen to it use as a communications receiver that's neat something else that tv stick is using that rf stick which limits it in the sdr world because most sdr things use these other connectors called sma i believe these type that you've seen on things which are like a little mini coax not too much different from your f connector just a smaller version and uh unfortunately that's really annoying because it doesn't do that i do have these antennas you see these are like a tv antenna another tv antenna with that rf it's it's just i don't want to use that i'd rather use a different system so what i'm going to do is remove from this spelling here this connector and i'm going to be soldering onto that and then that way i get to use this very kindly provided to me by gpio labs and lna which is a low noise amplifier in fact it says it's an ula lna ultra low noise amplifier and that allows me to apply usb power to here to switch in and off this additional gain which is really cool remember i was telling you about the lnas built into these things i don't trust them if you have this you can just externally flick a switch and just instantly apply it and take it off if you want that's no problem and then of course we have some smaller usb leads maybe it's possible to reduce the length like this touch screen is really long and that's probably a better cable more useful in a different application so hopefully that's been of interest to you stay tuned for a future video on this probably the next video might be this it might be here it might be there it might be in the links as ever thank you for watching you

Channel: backofficeshow

Views: 4,956

Keywords: playlist, @backofficeshow, Dr Andrew Armstrong, The Backoffice, playlistteardown, elektor labs, software defined radio, software defined radio transceiver, raspberry pi, raspberry pi sdr radio, raspberry pi sdr, how to

Id: pUMzct78tQg

Length: 9min 10sec (550 seconds)

Published: Sat Dec 05 2020