We really need more videos of this genre. This sort of detailed videos are so rare. Everyone wants to hack wireless but no one goes to details like you do
Agreed. When I started playing with this, the hardware was $1,800 but the newer instant SDR kit from Ettus is only $675 now. I'm guessing the price will continue to drop.
Yes, the Instant SDR kit from Ettus is a great way to get started. That will work great for OpenBTS. I didn't need to change antennas - I'm just using the same Vert900 antennas shown at the beginning for all the demos in this video.
Hi Anders, nice video! I have a question if I want to do the same I need to buy USRP N210, WBX Board, cable MCX, power supply, ethernet cable and two antenas or there is something else. Thanks for your support!
The RFX900 will work - I have several implementations that use those. You will get slightly better signal at higher power with the RFX900. You can assume that whatever is written for the USRP N210 will work on the USRP N200 as far as OpenBTS is concerned. Best of luck with your project!
@athosuk Correct. The deal is you buy a N210 (essentially the FPGA) and you get a radio transmit / receive board and antennas that work within the bands you need. (for GSM, usually 850Mhz, 900Mhz, 1.8Ghz or 1.9Ghz) The radio board I got for my N210 was the WBX which gives you 50Mhz - 2.2Ghz at 100mw. I also have the RFX900 in my two E100s which only cover 800Mhz - 1Ghz but transmit at 200mw. Obviously you will also need a computer to run OpenBTS!
It wasn't easy - I had lots of help from the core OpenBTS team. These days, however, it is much better supported. I believe it compiles out of the box now.
@010675dario That's correct. The only reason you should need an external clock is if you wanted to coordinate a number of devices or use the device you have in conjunction with a public network.
The N210 is an Ethernet connected device while the B100 from the Instant SDR Kit is a USB device so the big difference is the bandwidth you have between the radio and the computer. The FPGA is also bigger in the N210 as well but that won't matter for OpenBTS. Either can be used for OpenBTS so if you are just starting / testing, I'd suggest the Instant SDR Kit.
@whyteks Yes, on the Nexus One it does. In fact I have a T-Mobile SIM in one of the phones. I can pick my test network, camp to it and then shut down the network and then just pick T-Mobile and it camps there without a restart. After you have done this once, the phone sees my test network as a preferred network and I don't even have to select it. On other phones, things may not be so simple - camping is up to the phone, not the BTS.
You can get a Rubidium frequency standard for less than the cost of the USRP, I would highly recommend using one for holdover when the GPS fails if you're operating a GSM station for real. You can get one that goes on the PPS line between your GPS and your clock consumer, so the setup is practically identical to using GPS but with holdover.
I've been working with the Osmocombb project. The hardware was cheaper, I don't have the cash to get a usrp just yet. Always love working with this stuff. I watched a few of your videos and like the layout. high quality/well done.
Thanks for the reply. I shall check it out. How do i ensure that no transmission happens even (just to be safe). I do own a receiver and listen using a licensed device though.
@gabrielflautista OpenBTS works fine with the USRP / USRP2 radios - that is supported in the main codebase. Support for the UHD interface is less common and AFAIK only supported in Thomas Tsau's openbts-uhd git repo.
@whyteks Yes, get the GPS kit if you can. I don't have skew enough in my clock to require cold boot but who's to say you won't too? GPS is the best way to be sure. I wouldn't think the Nexus One would connect to a test network (yes, I'm running a test network in a test country) but I wouldn't have expected it to reconnect automatically when a "real" network was also available. Seems handsets tend to ignore the test flags and happily camp away! Almost can't count how many foreign IMSIs camp!
@010675dario You would have to use more USRPs to get more concurrent calls. Of course as soon as you have more than one USRP, clock differentials become a problem so you'll probably also want to use an external clock. Fortunately, Ettus hardware supports reference clock inputs as well as MIMO operation.
Thanks. The airbands are just AM transmissions from 118-136.975 MHz. (steps of 25 kHz) The examples included in GNURadio include AM transmit / receive logic so it should just be a matter of tuning to get it going. (don't just transmit on these frequencies though - lives are obviously at stake!) There are some interesting ADS-B examples on Github as well. (receive only - also for good reason!) I don't know if I'll have time to make a video about them though - I'm working on an LTE example first!
@Dusty696969 Yes, you can listen but no you can't understand it - GSM transmissions are encrypted. However, if you run your own BTS and handsets decide to camp to that, you obviously have access to calls that way. It is legal to buy these in the US, but it generally isn't legal to run them on public frequencies. As with any transmitter in licensed frequencies, you need to check with the FCC and make sure you comply with regulations. The URL where you can get these is in the description.
thanks for the super fast reply. By the way, did you use a SIM max card for your setup or a regular SIM. My TMobile device can't seem to pickup the openBTS network.
@swedishvolvo No, you don't make calls to the public phone network through another phone. A VoIP provider presumably gives you phone numbers which you assign to handsets and then they make calls through the OpenBTS setup which connects to Asterisk on the host computer which connects to your VoIP provider. I hadn't assumed "other phones" in your original post meant the public telephone network only.
Wow. That's pretty amazing. I think I might need to get one of these. Could this decode something like analog video, for example fastscan ATV or security cameras? Or would that simply be too large in terms of bandwidth?
You need Asterisk to manage phone calls. You can swap in Cisco Call Manager or FreeSWITCH or essentially any other SIP server that you control. OpenBTS basically converts GSM to SIP and back although the SIP stack is fairly bare-bones.
I keep answering this question over and over - please read the comments before posting. 1 block with this radio but you can go up to 35km with the proper radio add-on.
@gabrielflautista I'm not using a USRP2 here - the N210 is a UHD device. I compiled OpenBTS on a Mac and drive the N210 via Ethernet. I wouldn't suggest trying to use a Mac unless you really know what you are doing. Using a Linux machine would be better to start with.
@digilk Make sure you have a direct connection from your n210 to your computer - use a cross cable if your computer's ethernet port doesn't auto-cross - and put any static address (192.168.1.10 for example) on your linux machine so the interface is marked up.
In this case I'm using 900 MHz but all 4 GSM bands work. There is a second open source GSM BTS project that also works on the same hardware called OsmoBTS. In my opinion it works a bit better than OpenBTS but both are in active production environments around the world.
@anders94 Yes camping is up to the phone, and most if not all phones have an easy network selection process. but as you explain so well, if the USRP clock is well off, after a cold boot and camping to openBTS, the phone may not be able to find it's home network without a reset. It's interesting your Nexus see's your BTS as preferred, as that's NOT actually something that I would want. I think I will get the GPS Kit anyway.
I don't know exactly but I'm fairly sure there isn't room on the FPGA to run multiple instances together. That said, most of the GSM "stuff" is done in software on the host - the radio is just moving frames back and forth off the air. Lately I've been using OsmoBTS on this hardware - most of my experiments relate to that these days.
@smawis Yes you can make calls to the standard telephone network. All you need is some VoIP connection to it. Think of OpenBTS as a GSM to SIP gateway so if you pair it with Asterisk that is already on the PSTN, you can just use GSM handsets instead of VoIP phones and make calls / receive calls. I have OpenBTS also going with FreeSWITCH which functions similarly. I don't have docs but there are resources in the net that are reasonably good. Best of luck on your research.
@gauravpride1985 Using gnu radio, you build flowchart-like programs visually that get compiled and sent to the FPGA on the radio. The most common non-visual way to do the same thing is based in python, so I suppose this is the direct answer to your first question. The development daughterboards I use here are defined here: ettus.com/downloads/ettus_daughterboards.pdf
You should plug the Ethernet directly into your laptop. You have to use a crossed Ethernet cable or have an Ethernet port that auto-crosses. (like the ones built into the MacBook Pro) Through a switch will work but you don't want stray traffic contending for bandwidth between your computer and the USRP.
This setup didn't have it but yes, there is support for it. Its called GPRS though it is fairly under-developed at this point. (think EDGE support) Alternatively, the commercial version of OpenBTS by Range Networks supports up to 3G I believe.
Nice video Anders, you show it all working, as you say - if you set it up right. Are you using the UHD version of OpenBTS there without gnuradio? You mention some of the issues with the handsets internal clocks, but did you have any of these notorious clocking problems that happen with the USRP1 with it's default clock, or would you say the N210 + WBX board is a working solution out of the box?
Thanks for posting this....fantastic! I read that a license is not needed in this band because the transmit power is below a certain threshold. Is it true that this is kosher fcc-wise?
I don't think it supports the USRP Hardware Driver (UHD) Interface.. but any thoughts on using a LimeSDR with OpenBTS? What is the purpose of the FIR filter before the WBFM Receive PLL? When would you use the Low-Pass filter Block instead? I've seen examples where the input signal is multiplied by a cosine wave (-1.75Mhz) in order to the zero IF and spike... is that what the FIR filter is for? Also any idea why the STEREO "WBFM Receiver PLL" block has been deprecated in favor of the (MONO?) "WBFM Receiver"? To implement a STEREO receiver using the new block seems to require quite a few more blocks.. I assume for proper 19khz pilot decoding, RDS, etc?
Without question you can get a suitable setup under $3000. The embedded Ettus E100 is $1,300 and the USB connected Ettus B100 is $650. Either of those would replace the $1,700 N210. They come at the cost of less bandwidth (USB) and less CPU power (E100) but they are great for testing. Also watch Fairwaves (fairwaves.ru) for some very interesting alternatives out soon. Those should retain the bandwidth for less cost than the Ettus devices.
If they are associated with your OpenBTS instance, yes. If they are associated with a public BTS such as AT&T, technically you could hear them but they are encrypted, so no.
There is a strong chance your USB Ethernet adapter doesn't auto-cross the transmit and receive lines. If the Windows route doesn't work, get a crossed Ethernet cable.
Yes, that can be made to work. The default USRP clock is 64Mhz so to use a 52Mhz clock, there are two things you have to do - a hardware fix (simple soldering) and possibly some source file changes and a recompile. For more info on that, have a look at: gnuradio. org/redmine/projects/gnuradio/wiki/OpenBTSClockModifications
@anders94 Thanks Anders! I have read that there were issues using the USRP1 and one daughterboard - the RFX900 or 1800. The issues were to do with TX/RX channel isolation. so the recommended configuration with that box now is two daughterboards, one TX and one for RX. Do you know if the WBX would suffer the same problem?
Hi Anders, Thanks for this very informative video. It answered a lot of "getting started" questions I had. I really want to do this project, as I have a lot of experience with Asterisk and I also have a large collection of cell phones that I'd really like to put to use. I have my eye on Ettus' Instant SDR kit, but I'm concerned about the clock issue you mentioned in the video. Will it work with the internal stock clock? All I'll be doing is making calls and sending texts... no handoffs. Thanks!
@whyteks I'm using Thomas Tsou's OpenBTS-UHD repo on github so no GNURadio for the BTS stuff: github.com/ttsou/openbts-uhd.git Of course the FM radio and frequency sweep demos are GNURadio. (gnuradio-companion for that) I'd say the clock that comes with the N210 and the E100 I also have here work perfectly right out of the box. An N210 + WBX + antenna should be all the gear you need with a Linux box (or Mac in my case) to have a great working setup.
Yes, you can do cognitive radio and energy sensing with the N210 - it would be a good device for that. I don't know anything about how it would work with Windows 7 though - I'd suggest you run Linux to work with the N210 personally because that is the most popular platform. I don't think I follow your other questions... Once you get a working system though, I might be able to help more. Best of luck with it.
Very nice. I would be interested to see regular segments as time goes by regarding USRP. I would like to see some examples of satellite applications using USRP. Thank you.
oh ok. I actually build that last night, but I didn't know I had to rebuild gnuradio to have it show up. I'll rebuild gnuradio and see if it shows up. Thanks.
That depends on the transmitter you are using. If I were to run this one outside, it would probably cover several city blocks. I have a more powerful transmitter that would do a little more and you could purchase a significantly more powerful transmitter that would give you the range of a normal BTS. (up to 40Km) However, this requires licensing in most places in the world. You would also have to shield the radio so you don't get lots of crosstalk.
If I was reasonably confident this was a solid alternative to the FLEX radios, it would be an ideal hobby device - incredible ham radio features and lots of other hobby projects to boot - but I don't know how fully-featured it would be for ham radio out of the box.
The number of phones you can connect is practically unlimited, but the number of phones that can be in a call at any one time is 7. That means if they are calling each other, you can have 3 calls at the same time. (6 phones in 3 calls and 1 phone without another it can call) But if you have a SIP provider and the phones all call people on the regular phone network, you can do 7 concurrent calls.
The phones see your test network? Are you sure they are unlocked? I've had issues where the SIM was configured not to accept unknown / test networks. Same SIM or different on all the phones?
I just adapted some of the standard examples out there. Here's a working example: oz9aec .net/index.php/gnu-radio/grc-examples#fmrx Best of luck with your masters thesis.
So do you plug in the ethernet directly from the USRP to your laptop? no router? I thought that was strange... OS X is telling me that "USB Ethernet is Not Connected", like this thing isn't providing any power to it. If I plug it into my router it indicates a signal. Any idea?
Although they can see the network, bad timing may not allow them to connect. Try a timing source like GPS... I'm sorry I don't have any other suggestions.
@greatJeaorb It depends. You need to check with the FCC to make sure you are compliant in your area. The power is low (and can be turned down even more with a software setting) so it is usually OK but you have to make sure. In the end, you are responsible for making sure you aren't breaking the law!
i really appreciate your presentation. Thank for this great job. I want to have an idea about the best module i can choose for test with a good price, and the description of the other modules and the difference between them, i am studying telecomunication, and i want to test it...if you have a link for me i am waiting, thanks a lot.
Actually, it's -$100 for just the card off the $850 price. The sma connectors, DIP to Cable assembly and periodic PCB antennas only cost $100, but just the card still costs $750. Still much less then the $1500 for a N200 or $1700 for the N210. So what do you think?
If you don't intend to handoff, the clock won't be an issue for you. In very rare circumstances, the internal clock you get won't be good enough. Very rare though.
BTW, I would not assume this project is illegal unless you are interfering with normal cellular operation - femtocells are widely available both independently and sold directly by virtually every major carrier. This device doesn't run more power than those appliances - and probably less.
Hey Anders. Loving your videos! I have been working with the USRP over FM channels for some time (both transmit and receive) and I tried snooping around live GSM channels to get some data dump. I could go any further for decryption etc. because of software issues . I want to do my Btech project on this and I wanted to know is their anyway we can compare the USRP BTS and the GSM module functionality on the same FPGA , but using a GSM module? any other interesting GSM experiments you could share?
Hello Anders! Have you any idea on how many concurrent calls can handle the N210 with Asterisk with openbts configuref with one ARFCN? Best regard, Dario
We really need more videos of this genre. This sort of detailed videos are so rare. Everyone wants to hack wireless but no one goes to details like you do
Can you use the USRP mini for this as well?
So happy to see someone who is working with the openbst project
Agreed. When I started playing with this, the hardware was $1,800 but the newer instant SDR kit from Ettus is only $675 now. I'm guessing the price will continue to drop.
Yes, the Instant SDR kit from Ettus is a great way to get started. That will work great for OpenBTS.
I didn't need to change antennas - I'm just using the same Vert900 antennas shown at the beginning for all the demos in this video.
Thanks for the feedback. I did another video called "Software Radio / Data Tunneling" as well.
Its actually a very active project. With falling prices on the hardware required, I'm sure we will see much more.
I want to make one but I don't have the materials
Both but in this case, Ethernet. The older USRP devices are USB based. The N210 supports "UHD" which is Ethernet based.
Hi Anders, nice video! I have a question if I want to do the same I need to buy USRP N210, WBX Board, cable MCX, power supply, ethernet cable and two antenas or there is something else. Thanks for your support!
The RFX900 will work - I have several implementations that use those. You will get slightly better signal at higher power with the RFX900.
You can assume that whatever is written for the USRP N210 will work on the USRP N200 as far as OpenBTS is concerned.
Best of luck with your project!
@athosuk Correct. The deal is you buy a N210 (essentially the FPGA) and you get a radio transmit / receive board and antennas that work within the bands you need. (for GSM, usually 850Mhz, 900Mhz, 1.8Ghz or 1.9Ghz) The radio board I got for my N210 was the WBX which gives you 50Mhz - 2.2Ghz at 100mw. I also have the RFX900 in my two E100s which only cover 800Mhz - 1Ghz but transmit at 200mw.
Obviously you will also need a computer to run OpenBTS!
It wasn't easy - I had lots of help from the core OpenBTS team. These days, however, it is much better supported. I believe it compiles out of the box now.
No it doesn't
@010675dario That's correct. The only reason you should need an external clock is if you wanted to coordinate a number of devices or use the device you have in conjunction with a public network.
The N210 is an Ethernet connected device while the B100 from the Instant SDR Kit is a USB device so the big difference is the bandwidth you have between the radio and the computer. The FPGA is also bigger in the N210 as well but that won't matter for OpenBTS.
Either can be used for OpenBTS so if you are just starting / testing, I'd suggest the Instant SDR Kit.
@whyteks Yes, on the Nexus One it does. In fact I have a T-Mobile SIM in one of the phones. I can pick my test network, camp to it and then shut down the network and then just pick T-Mobile and it camps there without a restart. After you have done this once, the phone sees my test network as a preferred network and I don't even have to select it.
On other phones, things may not be so simple - camping is up to the phone, not the BTS.
Thanks for your quick response. I will take that into consideration. Much appreciated!
You can get a Rubidium frequency standard for less than the cost of the USRP, I would highly recommend using one for holdover when the GPS fails if you're operating a GSM station for real. You can get one that goes on the PPS line between your GPS and your clock consumer, so the setup is practically identical to using GPS but with holdover.
I've been working with the Osmocombb project. The hardware was cheaper, I don't have the cash to get a usrp just yet. Always love working with this stuff. I watched a few of your videos and like the layout. high quality/well done.
In short, yes. You may come across SIMs that let you connect to a test network though. LMK when you get a working system.
Thanks for the reply. I shall check it out. How do i ensure that no transmission happens even (just to be safe). I do own a receiver and listen using a licensed device though.
@whyteks I'm sure separate boards would be better but the WBX is sufficiently isolated. I haven't had a problem yet.
@gabrielflautista OpenBTS works fine with the USRP / USRP2 radios - that is supported in the main codebase. Support for the UHD interface is less common and AFAIK only supported in Thomas Tsau's openbts-uhd git repo.
Yes, the Instant SDR Kit from Ettus will work just fine.
@whyteks Yes, get the GPS kit if you can. I don't have skew enough in my clock to require cold boot but who's to say you won't too? GPS is the best way to be sure.
I wouldn't think the Nexus One would connect to a test network (yes, I'm running a test network in a test country) but I wouldn't have expected it to reconnect automatically when a "real" network was also available. Seems handsets tend to ignore the test flags and happily camp away! Almost can't count how many foreign IMSIs camp!
@mrafiq26 Yes, the USRP2 will work as well.
@010675dario Up to 7 because that's how many calls you can get in the spectrum the radio tunes to. Its a limit of the GSM spec.
@010675dario You would have to use more USRPs to get more concurrent calls. Of course as soon as you have more than one USRP, clock differentials become a problem so you'll probably also want to use an external clock. Fortunately, Ettus hardware supports reference clock inputs as well as MIMO operation.
Thanks. The airbands are just AM transmissions from 118-136.975 MHz. (steps of 25 kHz) The examples included in GNURadio include AM transmit / receive logic so it should just be a matter of tuning to get it going. (don't just transmit on these frequencies though - lives are obviously at stake!) There are some interesting ADS-B examples on Github as well. (receive only - also for good reason!) I don't know if I'll have time to make a video about them though - I'm working on an LTE example first!
@Dusty696969 Yes, you can listen but no you can't understand it - GSM transmissions are encrypted. However, if you run your own BTS and handsets decide to camp to that, you obviously have access to calls that way. It is legal to buy these in the US, but it generally isn't legal to run them on public frequencies. As with any transmitter in licensed frequencies, you need to check with the FCC and make sure you comply with regulations. The URL where you can get these is in the description.
thanks for the super fast reply. By the way, did you use a SIM max card for your setup or a regular SIM. My TMobile device can't seem to pickup the openBTS network.
@swedishvolvo No, you don't make calls to the public phone network through another phone. A VoIP provider presumably gives you phone numbers which you assign to handsets and then they make calls through the OpenBTS setup which connects to Asterisk on the host computer which connects to your VoIP provider.
I hadn't assumed "other phones" in your original post meant the public telephone network only.
@athosuk Nope, just the radio, the antennas and the WBX boards that run in the cellular frequencies.
Does your database exist in the right place? Is it read / writable by the user you are running OpenBTS as?
This was pre OpenBTS 2.8 - version 2.6 I think - I don't remember exactly. If you have the N210, I'd suggest the latest / greatest version of P2.8.
Yes. The examples near the end are grc.
Wow. That's pretty amazing. I think I might need to get one of these. Could this decode something like analog video, for example fastscan ATV or security cameras? Or would that simply be too large in terms of bandwidth?
One could have a lot of fun with this! I want one!
You need Asterisk to manage phone calls. You can swap in Cisco Call Manager or FreeSWITCH or essentially any other SIP server that you control. OpenBTS basically converts GSM to SIP and back although the SIP stack is fairly bare-bones.
Oh yeah. You're right. Thanks!
I have a Ettus N210 and SBX daughterboard. And I want use them to make an wifi acces ponit
I keep answering this question over and over - please read the comments before posting. 1 block with this radio but you can go up to 35km with the proper radio add-on.
@gabrielflautista I'm not using a USRP2 here - the N210 is a UHD device. I compiled OpenBTS on a Mac and drive the N210 via Ethernet. I wouldn't suggest trying to use a Mac unless you really know what you are doing. Using a Linux machine would be better to start with.
@swedishvolvo Right, unless I connected Asterisk to other phones or a VoIP provider.
@digilk Make sure you have a direct connection from your n210 to your computer - use a cross cable if your computer's ethernet port doesn't auto-cross - and put any static address (192.168.1.10 for example) on your linux machine so the interface is marked up.
In this case I'm using 900 MHz but all 4 GSM bands work.
There is a second open source GSM BTS project that also works on the same hardware called OsmoBTS. In my opinion it works a bit better than OpenBTS but both are in active production environments around the world.
@anders94 Yes camping is up to the phone, and most if not all phones have an easy network selection process. but as you explain so well, if the USRP clock is well off, after a cold boot and camping to openBTS, the phone may not be able to find it's home network without a reset. It's interesting your Nexus see's your BTS as preferred, as that's NOT actually something that I would want. I think I will get the GPS Kit anyway.
@whyteks Yup, that's it. In fact to get it to work reliably, I typically put the transceiver in the next room because it is so strong.
I don't know exactly but I'm fairly sure there isn't room on the FPGA to run multiple instances together. That said, most of the GSM "stuff" is done in software on the host - the radio is just moving frames back and forth off the air.
Lately I've been using OsmoBTS on this hardware - most of my experiments relate to that these days.
@smawis Yes you can make calls to the standard telephone network. All you need is some VoIP connection to it. Think of OpenBTS as a GSM to SIP gateway so if you pair it with Asterisk that is already on the PSTN, you can just use GSM handsets instead of VoIP phones and make calls / receive calls. I have OpenBTS also going with FreeSWITCH which functions similarly.
I don't have docs but there are resources in the net that are reasonably good.
Best of luck on your research.
Most expensive access point ever - sounds like a lot of fun though!
@gauravpride1985 Using gnu radio, you build flowchart-like programs visually that get compiled and sent to the FPGA on the radio. The most common non-visual way to do the same thing is based in python, so I suppose this is the direct answer to your first question. The development daughterboards I use here are defined here: ettus.com/downloads/ettus_daughterboards.pdf
do this installation require a particular version of ubuntu???
You should plug the Ethernet directly into your laptop. You have to use a crossed Ethernet cable or have an Ethernet port that auto-crosses. (like the ones built into the MacBook Pro) Through a switch will work but you don't want stray traffic contending for bandwidth between your computer and the USRP.
@syirrus depends on the radio board you use. I get about 2 blocks with mine but in theory you can go 35km.
This setup didn't have it but yes, there is support for it. Its called GPRS though it is fairly under-developed at this point. (think EDGE support) Alternatively, the commercial version of OpenBTS by Range Networks supports up to 3G I believe.
Nice video Anders, you show it all working, as you say - if you set it up right.
Are you using the UHD version of OpenBTS there without gnuradio?
You mention some of the issues with the handsets internal clocks, but did you have any of these notorious clocking problems that happen with the USRP1 with it's default clock, or would you say the N210 + WBX board is a working solution out of the box?
Thanks for posting this....fantastic! I read that a license is not needed in this band because the transmit power is below a certain threshold. Is it true that this is kosher fcc-wise?
I don't think it supports the USRP Hardware Driver (UHD) Interface.. but any thoughts on using a LimeSDR with OpenBTS?
What is the purpose of the FIR filter before the WBFM Receive PLL? When would you use the Low-Pass filter Block instead? I've seen examples where the input signal is multiplied by a cosine wave (-1.75Mhz) in order to the zero IF and spike... is that what the FIR filter is for?
Also any idea why the STEREO "WBFM Receiver PLL" block has been deprecated in favor of the (MONO?) "WBFM Receiver"? To implement a STEREO receiver using the new block seems to require quite a few more blocks.. I assume for proper 19khz pilot decoding, RDS, etc?
Without question you can get a suitable setup under $3000. The embedded Ettus E100 is $1,300 and the USB connected Ettus B100 is $650. Either of those would replace the $1,700 N210. They come at the cost of less bandwidth (USB) and less CPU power (E100) but they are great for testing.
Also watch Fairwaves (fairwaves.ru) for some very interesting alternatives out soon. Those should retain the bandwidth for less cost than the Ettus devices.
If they are associated with your OpenBTS instance, yes. If they are associated with a public BTS such as AT&T, technically you could hear them but they are encrypted, so no.
I was wondering if I need some blank SIM cards and a SIM programmer. Thanks again!
Just make sure there is no TX block.
I fly helicopters so I have the same hardware / radio license.
Hello I like your videos I’d like to see more but I have a question for you do you know where I can possibly find the software for USRP
There is a strong chance your USB Ethernet adapter doesn't auto-cross the transmit and receive lines. If the Windows route doesn't work, get a crossed Ethernet cable.
Yes, that can be made to work. The default USRP clock is 64Mhz so to use a 52Mhz clock, there are two things you have to do - a hardware fix (simple soldering) and possibly some source file changes and a recompile. For more info on that, have a look at: gnuradio. org/redmine/projects/gnuradio/wiki/OpenBTSClockModifications
This is basically like a FlipperZero on steroids, and it's been around for the last decade.....
How is this the first time I'm hearing of this?!?!?!
Would you say the B210 or the N210 you're using in the video is better for this?
@anders94 Thanks Anders! I have read that there were issues using the USRP1 and one daughterboard - the RFX900 or 1800. The issues were to do with TX/RX channel isolation. so the recommended configuration with that box now is two daughterboards, one TX and one for RX. Do you know if the WBX would suffer the same problem?
Hi Anders,
Thanks for this very informative video. It answered a lot of "getting started" questions I had. I really want to do this project, as I have a lot of experience with Asterisk and I also have a large collection of cell phones that I'd really like to put to use. I have my eye on Ettus' Instant SDR kit, but I'm concerned about the clock issue you mentioned in the video. Will it work with the internal stock clock? All I'll be doing is making calls and sending texts... no handoffs. Thanks!
@whyteks I'm using Thomas Tsou's OpenBTS-UHD repo on github so no GNURadio for the BTS stuff:
github.com/ttsou/openbts-uhd.git
Of course the FM radio and frequency sweep demos are GNURadio. (gnuradio-companion for that)
I'd say the clock that comes with the N210 and the E100 I also have here work perfectly right out of the box. An N210 + WBX + antenna should be all the gear you need with a Linux box (or Mac in my case) to have a great working setup.
@anders94 Wow - is this just with the WBX board and those VERT900 antennas in your lab? You must be getting a fairly decent signal out of it then.
Interesting - I'll take a look.
Hi great vid. I have a USRP1 and I'm having clock issues. Can you recommend a place for me to order a 52mhz clock? Thanks.
Yes, you can do cognitive radio and energy sensing with the N210 - it would be a good device for that. I don't know anything about how it would work with Windows 7 though - I'd suggest you run Linux to work with the N210 personally because that is the most popular platform.
I don't think I follow your other questions... Once you get a working system though, I might be able to help more. Best of luck with it.
Very nice. I would be interested to see regular segments as time goes by regarding USRP. I would like to see some examples of satellite applications using USRP.
Thank you.
oh ok. I actually build that last night, but I didn't know I had to rebuild gnuradio to have it show up. I'll rebuild gnuradio and see if it shows up. Thanks.
Can I use the USRP mini for this as well?
Yes, I think so but I haven't tried it.
That depends on the transmitter you are using. If I were to run this one outside, it would probably cover several city blocks. I have a more powerful transmitter that would do a little more and you could purchase a significantly more powerful transmitter that would give you the range of a normal BTS. (up to 40Km) However, this requires licensing in most places in the world. You would also have to shield the radio so you don't get lots of crosstalk.
Thanks for the reply, very cool project! Its just a shame the radios are so expensive!
If I was reasonably confident this was a solid alternative to the FLEX radios, it would be an ideal hobby device - incredible ham radio features and lots of other hobby projects to boot - but I don't know how fully-featured it would be for ham radio out of the box.
The number of phones you can connect is practically unlimited, but the number of phones that can be in a call at any one time is 7. That means if they are calling each other, you can have 3 calls at the same time. (6 phones in 3 calls and 1 phone without another it can call) But if you have a SIP provider and the phones all call people on the regular phone network, you can do 7 concurrent calls.
Hi. I was wondering what of the 2400 and 900 Antenas is best? And why? Thanks in advance!!
The phones see your test network? Are you sure they are unlocked? I've had issues where the SIM was configured not to accept unknown / test networks. Same SIM or different on all the phones?
I just adapted some of the standard examples out there. Here's a working example:
oz9aec .net/index.php/gnu-radio/grc-examples#fmrx
Best of luck with your masters thesis.
You will get the IMSI (SIM number) but not the phone's "default operator network". You don't get the phone's number either.
I wonder what kind of software would you use for searching through HF, VHF and UHF bands?
So since these two phones are corrected to your base station they would not be able to make calls to other phones outside of your network right?
So do you plug in the ethernet directly from the USRP to your laptop? no router? I thought that was strange... OS X is telling me that "USB Ethernet is Not Connected", like this thing isn't providing any power to it. If I plug it into my router it indicates a signal. Any idea?
Anders, Can I set up the GSM base station shown here with the less expensive "USRP Instant SDR Kit" (i.e. B100 instead of N210)?
Thanks Chief. While parking i just realized that the remote i use for the gate runs 433 mHz. So may be that can be another project i can work upon.
Although they can see the network, bad timing may not allow them to connect. Try a timing source like GPS... I'm sorry I don't have any other suggestions.
@greatJeaorb It depends. You need to check with the FCC to make sure you are compliant in your area. The power is low (and can be turned down even more with a software setting) so it is usually OK but you have to make sure. In the end, you are responsible for making sure you aren't breaking the law!
i really appreciate your presentation. Thank for this great job.
I want to have an idea about the best module i can choose for test with a good price, and the description of the other modules and the difference between them, i am studying telecomunication, and i want to test it...if you have a link for me i am waiting, thanks a lot.
Now that GSM/2G is dead in the states, is this useless now?
This is your own network, it doesn’t rely on other networks. Plus 2G is still alive with T-Mobile.
Great Job! please can you tell me what version of software you used....I have a usrp ettus n210. Thanks
Actually, it's -$100 for just the card off the $850 price. The sma connectors, DIP to Cable assembly and periodic PCB antennas only cost $100, but just the card still costs $750. Still much less then the $1500 for a N200 or $1700 for the N210. So what do you think?
If you don't intend to handoff, the clock won't be an issue for you. In very rare circumstances, the internal clock you get won't be good enough. Very rare though.
So if i understand well, with this N210 USRP there is no need to disable the internal clock and use an external 52 MHz clock like the USRP1???
Which programming language is used to program this device and what is specification of the development board.
hello Anders, did you have to buy any extras to get a rig like this?
BTW, I would not assume this project is illegal unless you are interfering with normal cellular operation - femtocells are widely available both independently and sold directly by virtually every major carrier. This device doesn't run more power than those appliances - and probably less.
Hey Anders.
Loving your videos! I have been working with the USRP over FM channels for some time (both transmit and receive) and I tried snooping around live GSM channels to get some data dump. I could go any further for decryption etc. because of software issues . I want to do my Btech project on this and I wanted to know is their anyway we can compare the USRP BTS and the GSM module functionality on the same FPGA , but using a GSM module? any other interesting GSM experiments you could share?
Hello Anders!
Have you any idea on how many concurrent calls can handle the N210 with Asterisk with openbts configuref with one ARFCN?
Best regard,
Dario