From: Robin K. <ml...@ro...> - 2011-07-30 13:46:41
|
Hi all! OK, so I'm pretty new to this whole GSM networking / OpenBTS thing, and just starting to get into it really. I'd really like to build up my own OpenBTS network as a kind of hobby project as a first step just to get into the matter, and then decide where to go next once I've gotten a hands-on experience of what's possible with the hardware and software. So, first thing I did was I had a look at the "OpenBTS for dummies" guide (had to search for it on Google, as the link on the Wiki appears to be broken). So far, it looked quite OK to me, and I guess I'll be able to wrap my brain around most of the things that need to be done. However, I'm a bit helpless concerning the clock which needs to be soldered onto the board in order to create a functioning GSM network. Personally, I'm an experienced computer user, I know about all hardware inside my PC and how to replace any of them. However, when it comes to things like soldering and all kinds of stuff like that, I am a total noob, and don't really feel like experimenting with these things on a $700 USRP. Very unfortunately, I also can't think of anyone within my social network who would have sufficient skills, so I'm not really sure how to proceed with this. Is there any place where I could buy a USRP that already comes with a more advanced onboard clock? I've had a look at the USRP development kit, but this seems to be a complete hardware / software solution, and I don't wanna spoil myself the fun of at least setting up the software side of things myself. So, is there any way for me of getting around this issue? Thanks a lot for any suggestions! Robin |
From: Sylvain M. <24...@gm...> - 2011-07-30 14:30:01
|
> Thanks a lot for any suggestions! Well you can take their development kit and just "don't look" at the software ... The other option is taking unsupported hw (that you can make work with available patches). I think a N200 + an ettus GPS DO kit + WBX would do. Of course that's 1500$ + 450$ + 750$ = 2700$ of hardware, but it's off the shelf and no need to modify it. That's the two options I see. Either you have the cash to get all ready hardware, or you need to skill to adapt the hardware youself. Cheers, Sylvain |
From: Kurtis H. <khe...@cs...> - 2011-07-30 18:16:54
|
The clock changes are only needed if you want the network to run at any scale. For small-scale desktop testing, the 64mhz clock is fine, so you shouldn't have to solder anything. On Sat, Jul 30, 2011 at 6:46 AM, Robin Kipp <ml...@ro...> wrote: > Hi all! > OK, so I'm pretty new to this whole GSM networking / OpenBTS thing, and just starting to get into it really. I'd really like to build up my own OpenBTS network as a kind of hobby project as a first step just to get into the matter, and then decide where to go next once I've gotten a hands-on experience of what's possible with the hardware and software. > So, first thing I did was I had a look at the "OpenBTS for dummies" guide (had to search for it on Google, as the link on the Wiki appears to be broken). So far, it looked quite OK to me, and I guess I'll be able to wrap my brain around most of the things that need to be done. However, I'm a bit helpless concerning the clock which needs to be soldered onto the board in order to create a functioning GSM network. Personally, I'm an experienced computer user, I know about all hardware inside my PC and how to replace any of them. However, when it comes to things like soldering and all kinds of stuff like that, I am a total noob, and don't really feel like experimenting with these things on a $700 USRP. Very unfortunately, I also can't think of anyone within my social network who would have sufficient skills, so I'm not really sure how to proceed with this. Is there any place where I could buy a USRP that already comes with a more advanced onboard clock? I've had a look at the USRP development kit, but this seems to be a complete hardware / software solution, and I don't wanna spoil myself the fun of at least setting up the software side of things myself. So, is there any way for me of getting around this issue? > Thanks a lot for any suggestions! > Robin > ------------------------------------------------------------------------------ > Got Input? Slashdot Needs You. > Take our quick survey online. Come on, we don't ask for help often. > Plus, you'll get a chance to win $100 to spend on ThinkGeek. > http://p.sf.net/sfu/slashdot-survey > _______________________________________________ > Openbts-discuss mailing list > Ope...@li... > https://lists.sourceforge.net/lists/listinfo/openbts-discuss > |
From: Sylvain M. <24...@gm...> - 2011-07-30 18:44:11
|
> The clock changes are only needed if you want the network to run at > any scale. For small-scale desktop testing, the 64mhz clock is fine, > so you shouldn't have to solder anything. No it's not ... YMMV ... you may be lucky that your crystal is fine. Mine was actually fairly ok as well, but I've seen several USRP where it just plain doesn't work ... You can tempt it, but if it doesn't work, don't come here and complain you can't see your network. |
From: Kurtis H. <khe...@cs...> - 2011-07-30 18:47:11
|
Oh, are there just some bad clocks on USRPs? I had always assumed it was the alignment issues, not inconsistent clocks. On Sat, Jul 30, 2011 at 11:44 AM, Sylvain Munaut <24...@gm...> wrote: >> The clock changes are only needed if you want the network to run at >> any scale. For small-scale desktop testing, the 64mhz clock is fine, >> so you shouldn't have to solder anything. > > No it's not ... YMMV ... you may be lucky that your crystal is fine. > Mine was actually fairly ok as well, but I've seen several USRP where > it just plain doesn't work ... > > You can tempt it, but if it doesn't work, don't come here and complain > you can't see your network. > |
From: David A. B. <dbu...@jc...> - 2011-07-30 19:30:54
|
The stock 64 MHz crystal has low phase noise, but a lot of variation from one unit to another and a lot of variation with temperature. "A lot" means several kHz. This is a problem, even in single-BTS systems. Sometimes you get lucky. Usually you don't. The hardware in our Range commercial units has software-trimmable, temperature-compensated clocks. On Jul 30, 2011, at 11:46 AM, Kurtis Heimerl wrote: > Oh, are there just some bad clocks on USRPs? I had always assumed it > was the alignment issues, not inconsistent clocks. > > On Sat, Jul 30, 2011 at 11:44 AM, Sylvain Munaut <24...@gm...> wrote: >>> The clock changes are only needed if you want the network to run at >>> any scale. For small-scale desktop testing, the 64mhz clock is fine, >>> so you shouldn't have to solder anything. >> >> No it's not ... YMMV ... you may be lucky that your crystal is fine. >> Mine was actually fairly ok as well, but I've seen several USRP where >> it just plain doesn't work ... >> >> You can tempt it, but if it doesn't work, don't come here and complain >> you can't see your network. > |
From: Matt E. <ma...@et...> - 2011-07-30 20:05:14
|
There are no bad clocks on USRPs. They all meet their specs, which is +/- 20 ppm. It's just that 20 ppm is not good enough for GSM. Some will be close enough to use and some won't be. Matt On 07/30/2011 11:46 AM, Kurtis Heimerl wrote: > Oh, are there just some bad clocks on USRPs? I had always assumed it > was the alignment issues, not inconsistent clocks. > > On Sat, Jul 30, 2011 at 11:44 AM, Sylvain Munaut <24...@gm...> wrote: >>> The clock changes are only needed if you want the network to run at >>> any scale. For small-scale desktop testing, the 64mhz clock is fine, >>> so you shouldn't have to solder anything. >> >> No it's not ... YMMV ... you may be lucky that your crystal is fine. >> Mine was actually fairly ok as well, but I've seen several USRP where >> it just plain doesn't work ... >> >> You can tempt it, but if it doesn't work, don't come here and complain >> you can't see your network. >> > > ------------------------------------------------------------------------------ > Got Input? Slashdot Needs You. > Take our quick survey online. Come on, we don't ask for help often. > Plus, you'll get a chance to win $100 to spend on ThinkGeek. > http://p.sf.net/sfu/slashdot-survey > _______________________________________________ > Openbts-discuss mailing list > Ope...@li... > https://lists.sourceforge.net/lists/listinfo/openbts-discuss |
From: Kurtis H. <khe...@cs...> - 2011-07-30 20:20:43
|
Got it, thanks for the clarification folks. On Sat, Jul 30, 2011 at 12:13 PM, Matt Ettus <ma...@et...> wrote: > > There are no bad clocks on USRPs. They all meet their specs, which is > +/- 20 ppm. It's just that 20 ppm is not good enough for GSM. Some > will be close enough to use and some won't be. > > Matt > > > On 07/30/2011 11:46 AM, Kurtis Heimerl wrote: >> Oh, are there just some bad clocks on USRPs? I had always assumed it >> was the alignment issues, not inconsistent clocks. >> >> On Sat, Jul 30, 2011 at 11:44 AM, Sylvain Munaut <24...@gm...> wrote: >>>> The clock changes are only needed if you want the network to run at >>>> any scale. For small-scale desktop testing, the 64mhz clock is fine, >>>> so you shouldn't have to solder anything. >>> >>> No it's not ... YMMV ... you may be lucky that your crystal is fine. >>> Mine was actually fairly ok as well, but I've seen several USRP where >>> it just plain doesn't work ... >>> >>> You can tempt it, but if it doesn't work, don't come here and complain >>> you can't see your network. >>> >> >> ------------------------------------------------------------------------------ >> Got Input? Slashdot Needs You. >> Take our quick survey online. Come on, we don't ask for help often. >> Plus, you'll get a chance to win $100 to spend on ThinkGeek. >> http://p.sf.net/sfu/slashdot-survey >> _______________________________________________ >> Openbts-discuss mailing list >> Ope...@li... >> https://lists.sourceforge.net/lists/listinfo/openbts-discuss > > |
From: Alexander C. <ale...@gm...> - 2011-07-30 21:11:00
|
On Sat, Jul 30, 2011 at 10:29, Sylvain Munaut <24...@gm...> wrote: >> Thanks a lot for any suggestions! > > Well you can take their development kit and just "don't look" at the > software ... > > The other option is taking unsupported hw (that you can make work with > available patches). > > I think a N200 + an ettus GPS DO kit + WBX would do. > Of course that's 1500$ + 450$ + 750$ = 2700$ of hardware, but it's off > the shelf and no need to modify it. > > That's the two options I see. > Either you have the cash to get all ready hardware, or you need to > skill to adapt the hardware youself. I think the third option is to contact Olifantasia - I think they supply ready to use packages for OpenBTS. But I'm not really sure about their current status, so it's better to contact them directly. The 4th option is to go look outside of your current social network ;) Go to some HW/mobile repair shop, ask on your local forums, etc - I'm sure quite some people will offer you some help just to look how it works. -- Regards, Alexander Chemeris. |
From: Robin K. <ml...@ro...> - 2011-07-30 22:05:02
|
Hello listers, thanks so much for all the info! The whole discussion about clocks that came up here has also been helpful to me in order to get a better understanding of why it is actually required, so thanks a lot for that as well! I think the best solution for me would be the package from http://www.olifantasia.com/drupal2/en/node/12 This includes a modified USRP 1 with the Clock Tamer and includes all required components, so sounds like a suitable option for me. It's a bit more expensive than just purchasing the single components, but with my limited electronics skills, I'd say it's better to be safe than sorry :-) Thanks again! Robin |