 Thanks for coming to my talk. I know it's the last one of the day, so I keep them everyone from dinner and beer, so you know. So I work for Versaulca Group. I'm a software engineer there. So this claimer, this isn't my day job, so it's kind of a hobby. So if I get anything wrong during the talk, just let me know. Like I said here, I do have a hand license in the US. There's my call sign. I actually haven't used it yet. I've only had for like six months. So basically my talk will go over about receiving signals with SDR, transmitting costs a lot more and has more legalities. And there's tons of interesting things to receive. So SDR basically is moving traditional radio equipment into ASICs and FPGAs. Something that would be huge can fit down to something this size. Basically it can fit the backpack. And also as I do high-end stuff with something it only cost you maybe $5 or even a couple hundred dollars. It's like GSM base station at access point. And the infamous $5 RTSDR, which you can do pretty much everything, a hobby related to that. So when you want to get started with hardware selection, utility matters, frequency range that you can listen to with your SDR card. The bandwidth matters depending on what you're going to sample. I mean if you're looking at air traffic, it doesn't really take much or FM radio, obviously. The sample rate matters. It's aliasing. Also the ADC fit rate doesn't matter if you can do high bandwidth sampling if your ADC doesn't give you an accurate representation. Cost matters. So like I said the $5 RTSDR you get pretty much in the electronics market. It's like five bucks. You get them on eBay about the same price. A little higher up is the Air Spy. It's $150 but obviously has better frequency range and sample rate and better ADC. Also most of these are pretty portable although some of these are pretty large so you can't put them in a backpack and some they're quite expensive. Some of them were up to about $500 even more. Like I said larger devices are usually more expensive. So some other equipment once you get a SDR card is the TENAs. So it's wide assortment. So many TENAs are pretty fun hobby as well. You can basically make them out of a coffee can or a pop can and solder on a connector. Professional TENAs obviously usually have a better gain but have to cost more and that's fun to tinker around with. Most of them have connectors. Usually SMA or BNC but there's usually more exceptions for compact hardware like Bluetooth. You'll want to get an assortment of cables and connectors on like eBay or Alibaba. So there's some optional equipment you can get. Most these SDR cards only do high frequencies like 1800 megahertz to 600 megahertz. If you want to listen like in a hand band you're going to need like a up converter. So basically turn converts the frequency to something your SDR card can read. Then you're going to need to make an antenna which this is just basically a TV for a CTV. You just solder on the SMA cable. It works decent for you know ham radio that's nearby 2 meter band. So yeah this is a 5 inverter so this I think this was about $70 or something. US obviously. So there's typically different antennas that you'll want to get. Obviously some have better gain than others. Bonapoles usually if great if you would have like a line of sight that's above you. Like if you're on a flat plane dipoles usually better if you can mount it high up which you lose some of the gain in one section of the plane. Patch is good for satellites and since you know the dish antennas here if you need a license this is a good substitute. Obviously doesn't doesn't make up for a dish antenna but it's you know nice and compact. In a long periodic one it's like this is a PCB one. It's a good wide band antenna. It's omnidirectional. Not omnidirectional let's yeah it's omnidirectional. Actually it's just directional you have to point it at what signal you're trying to receive. Yeah legal review I'm not a lawyer so it's up to you to make sure you're doing is legal. Just because you can receive a signal doesn't mean it's legal. I mean there's things that you can't pick up like pager traffic which is illegal but it's not encrypted. Also for actually transmitting anything that's not on nice unbanned industrial scientific medical which it varies widely between ITU regions. I don't know what's in here but in US it's 915 megahertz roughly in Europe it's 415th member correctly and that region. Like I said some equipment can be restricted. Like I said even some transmissions can have legal and illegal components to listen to. When we like satellite traffic you can't listen to paging data or voice calls which you could actually look at the satellite location data that's being paged down. Line of sight matters obviously in Singapore there's not really any high elevations so obviously the higher train block of obstacles buildings and being outdoors will improve signals. Of course that can be tricky here since you probably can't mount an antenna outside. So monopole will work better and like here for certain signals because it's here low low line area and valleys. If you can hoist the antenna up on a dipole that might work better for certain signals and since you know you can't do dish this doesn't really matter because as long as you have a line of sight to satellite or whatever signal you're trying to receive isn't attractive. So there's some gains and mixing SDR so there's a few things there's a low noise amplifier so basically you can get signals that are coming into your radio. You can also amplifier I think this was like 50 bucks online says powered actually over powered over the actual connector port and that gives you a signal. Important thing to note is when you amplify a signal you're just not amplifying the signal you have to find the noise to. So if you over amplify it you can lose some of your signal and just just have clips like clip signal. There's just local oscillator mix there's a mixer so basically the local oscillator mixes with the RF that's coming off coming in and you get intermediate frequency which is what you can do actually use processing software like a new radio on. So you need to match the signals to the antenna so now radio waves are linear or polarized like typically satellite and extracurricular ones are circular polarized. It helps to get through clouds and other obstructions. Linear polarization is usually vertical but with the exception of television which is horizontal this just because at the time it seemed like so we're using vertical for radio but just use horizontal for television and it's kind of legacy. And also the magnetic loop tenors with this is basically just a coil current gets inducted otherwise you guys have a long wire antenna which would be like hundred meters or more for ham radio. So you want to reduce noise I mean radio waves are what committed signals and linear polarization has that right angle so it's reflective. Most radio circuits listen to the e-field I mean most antennas are e-field antennas except for magnetic loop antennas. Ideally you want to keep your antennas and your equipment away from your electronics I mean keep your SDR card and antenna away from electronics to reduce noise. So bias T thus this basically allows you to power an RF device like an active antenna or the load noise amplifier using RF output so basically puts five volts off this. Again make sure you don't have antenna that's connected to it that's grounded. So it does take less cables I mean otherwise you have to have another another power cable going to your amplifier but it does require shielding on the amplifier and it's more compact in deployment as possible. So here's just a basic depth diagrams how that actually can work. So the power DC and RF goes into the device DC goes out the inductor filters out any AC coming from RF and the RF allows the capacitor allows the RF frequency to go through the device. So yeah this is the actually the load noise amplifier that I'm using is LNA for all. It's some guy and I think Romania that makes these people on the forums like it. So I recommend that and ideally you want to have the amplifier close to 10 as possible. So outdoors will clearly increase signals but they help having a load noise amplifier can help in all applications but again keep in mind over amplification can be worse than none so just don't assume that you can crank it up and it'll improve things. So here's some common interesting signals now once you've gotten all your equipment. So the typical one that everyone really gets into is the automatic dependent surveillance broadcast which is just basically you can see where playing positions are and you can use that for the $5 RTSDR I mean as people do mostly. Basically the AIS is basically the same thing only with ships. Obviously that's a little harder because you want to be higher than the ships so you can go see out farther because otherwise you're just seeing over the curvature of the earth so it's not that exciting. Also most of those are today are actually broadcasted satellite because piracy they don't want to you know only when they come into ports they actually start broadcasting. GPS that's a high end you need a special module for that and high-end SDR it's a little but you can make you can you basically make unlocked GPS unit which you technically can't buy but you could. Ham radio so there's certain like said there's certain signals you can't listen to even if you you know can't pick them up like air traffic control. I think I was reading this at League of Olives listening to Singapore. I think technically you're not supposed to listen to ham radio bands if you don't have ham radio license but it was obviously they highly improve that but just no no law. You can also see there's a nice wiki of different signals you can read up on. They have the waterfall chart and from the radio. Also they have the frequency that you listen to it and if it's common or uncommon. Some of the interesting ones are the actual number stations all over the world it's you know spy issues. So a little brief thing on open source utilities obviously most are going to radio based because as you know a full suite of you know filters and other things and a lot of you do a lot of stuff it's not it's not easy software to learn I mean it's very complex. So actually use just for libraries directly which could be something which is dump 1090 which is an actual looking at air traffic. So yeah there's like well there's like 500 different forks I think of that repo on github and yeah some some of them have interesting features that would be nice if you have on this card if you have but you know trying to you know get merge all those changes be monumental. Although a lot of them do use GR Osman SDR plug-in which has support for a lot of SDR cards. Now obviously the the original purpose was for their device but AirSpot, AirSpot, Edis and other cards work with it. Yeah so most have an own version of RTL FM which is just basically you can set a frequency you want to listen to the bandwidth and it just does a sick pipe of audio so that's you know basically the way to listen to FM but you can also pass it through another program to processing. Like I said the AirSpot I have here has his own version and pretty much most cards have some the utility in some form. So here's an example of the waterfall of one of the radio radio front-ends GR GQRX so this is basically just listening to FM radio you can see you can see the different stations and yeah so there's there's some other application just besides you know having a hobby and listening interesting signals and you can you can detect you know possible things that are broadcasting they should be broadcasting you can also use to detect overpowering signals that shouldn't be you know overpowering like Wi-Fi or similar and there's there's actually a if you don't want to actually want to buy a card there's a web SDR.org that has tons of cards all over the world that you can listen to like FM radio and other bands that doesn't cost you anything if you get started there. So in conclusion SDR is a fun hobby it's cheaper than it used to be and it's a fun or a fun experience and like I said yeah I did run through it quickly so anyone have any questions yeah yeah that's kind of more expensive right yeah you could modify it yeah I'm not really sure if there's any applications I did it right now that is true yeah yeah any more questions all right thanks