OpenBSC April 2009

openbsc@lists.osmocom.org

13 participants
54 discussions

AW: BS-11 runs, but no Network on my Mobile
by Andreas.Eversberg 06 Apr '09

06 Apr '09

you can set the clock of BS-11 to internal oscillator. then you need to set the E1 card into clock slave. (not pcm slave) modprobe hfcmulti port=0x200 debug=0x40000 # see hfcmulti.h or http://www.linux-call-router.de/download/driver/hfc_multi-dsp-2.0.pdf and watch the system messages. you can see that the card will get the clock from the E1 interface and uses it for internal processing. if you like to get the clock from a different card that is connected to telephone network, you can connect the clocks, and the driver will automatically switch to received clock. i will see, if i can provide instructions on how to connect both clocks. also a small application must keep layer 1 and layer 2 of the isdn line up all the time. -----Ursprüngliche Nachricht----- Von: openbsc-bounces(a)lists.gnumonks.org [mailto:openbsc-bounces@lists.gnumonks.org] Im Auftrag von Dieter Spaar Gesendet: Samstag, 4. April 2009 20:00 An: openbsc(a)lists.gnumonks.org Betreff: Re: BS-11 runs, but no Network on my Mobile Hello, I did a few more tests to check the BS-11 clock accuracy. I took a phone which is registered to an official network and tried if I can see the BS-11 test network doing a manual network search. As long as the BS-11 oscillator is not locked to the E1 clock, I can reliable find the test network. After the BS-11 oscillator has locked to the E1-clock, the test network is only found every now and then. Here with my BS-11 it takes about 5 minutes till the oscillator is locked, the attribute is NM_ATT_BS11_CCLK_ACCURACY, "0" means "high accuracy" (locked), "1" means "medium accuracy" (free running), "2" most certainly "low accuracy" (not yet warmed up, I have not verified this value). Most certainly the BS-11 oscillator is better than the oscillator of the E1-card, however I don't know if the calibration is still OK on all BS-11 units. I have not yet found an easy way to measure the BS-11 clock (without opening the case), the RF signal is always modulated and I don't have the equippment to measure the frequency of the modulated and pulsed RF signal in an accurate way. So this measurement has to wait. What you can try is to disconnect the E1 line for about 30 seconds, this should be enough so that the Abis Link goes down. If you reconnect, I assume it takes a similar time to lock the oscillator like it did here. So you have a few minutes to start OpenBSC and check if you can find the test network. If this works for most units, a possible workaround is to use the RX clock for TX on the HFC-E1 card instead of its own oscillator (this way the BS-11 oscillator determines the E1 clock). I tried that here already (on Windows), and it seems to work. However I don't know if mISDN can be configured this way or if it requires a small patch. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: bs11 now runs
by Dieter Spaar 06 Apr '09

06 Apr '09

Hello Andreas, On Mon, 6 Apr 2009 10:55:14 +0200, "Andreas.Eversberg" <Andreas.Eversberg(a)versatel.de> wrote: > > finally it works. i had allot of trouble, because the BTSM was suddenly > locked. no restart, no object recreation worked. i fixed this by doing a > software download. You have LMT, right ? If this happens again, it would be interesting to know if there is some error message available. LMT has a menu command (sorry, I don't have the exact name available right now) which allows to read the errors (I think OpenBSC also receives those errors when it starts up). Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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bs11 now runs
by Andreas.Eversberg 06 Apr '09

06 Apr '09

finally it works. i had allot of trouble, because the BTSM was suddenly locked. no restart, no object recreation worked. i fixed this by doing a software download. also i updated the mISDN driver, so i don't need the patch anymore. now it works with the latest GIT commit. i connected the clock from external isdn line card to the e1 card. but i think it will also work without line clock. after call setup from my mobile, i get disconnected, because the number is not know. this is ok, but i get continuous messages about a time slot (traffic channel) that cannot be .... (next time i write down the exact message). EH09: anyone at easterhegg in hamburg this year? (www.easterhegg.de) i will bring test server and BS-11.

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Re: BS-11 runs, but no Network on my Mobile
by Dieter Spaar 04 Apr '09

04 Apr '09

Hello, I did a few more tests to check the BS-11 clock accuracy. I took a phone which is registered to an official network and tried if I can see the BS-11 test network doing a manual network search. As long as the BS-11 oscillator is not locked to the E1 clock, I can reliable find the test network. After the BS-11 oscillator has locked to the E1-clock, the test network is only found every now and then. Here with my BS-11 it takes about 5 minutes till the oscillator is locked, the attribute is NM_ATT_BS11_CCLK_ACCURACY, "0" means "high accuracy" (locked), "1" means "medium accuracy" (free running), "2" most certainly "low accuracy" (not yet warmed up, I have not verified this value). Most certainly the BS-11 oscillator is better than the oscillator of the E1-card, however I don't know if the calibration is still OK on all BS-11 units. I have not yet found an easy way to measure the BS-11 clock (without opening the case), the RF signal is always modulated and I don't have the equippment to measure the frequency of the modulated and pulsed RF signal in an accurate way. So this measurement has to wait. What you can try is to disconnect the E1 line for about 30 seconds, this should be enough so that the Abis Link goes down. If you reconnect, I assume it takes a similar time to lock the oscillator like it did here. So you have a few minutes to start OpenBSC and check if you can find the test network. If this works for most units, a possible workaround is to use the RX clock for TX on the HFC-E1 card instead of its own oscillator (this way the BS-11 oscillator determines the E1 clock). I tried that here already (on Windows), and it seems to work. However I don't know if mISDN can be configured this way or if it requires a small patch. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: WG: BS-11 runs, but no Network on my Mobile
by Dieter Spaar 03 Apr '09

03 Apr '09

Hello Andreas, On Fri, 3 Apr 2009 12:27:05 +0200, "Andreas.Eversberg" <Andreas.Eversberg(a)versatel.de> wrote: > > so, if this works, i will try to use an hfc-pci single port card (cheap) > and provide a document on how to link the E1 card to the single port > card. only two clocks are required, a frame clock and a bit clock. with > the right settings, both clocks are compatible. Great idea ! I am definitely interested in the results. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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WG: BS-11 runs, but no Network on my Mobile
by Andreas.Eversberg 03 Apr '09

03 Apr '09

i forgot in send it to the list -----Ursprüngliche Nachricht----- Von: Andreas.Eversberg Gesendet: Freitag, 3. April 2009 12:27 An: 'Dieter Spaar' Betreff: AW: BS-11 runs, but no Network on my Mobile this is an issue i understand. here is my idea on testing it: i derrive clock from my t-com isdn line. the line clock is provided by a gps receiver and transferred via telekom's access hardware to my isdn line. because i talk to it PTP, it keeps up layer1. (the line provides coninuous clock signal.) i will connect a 4 port isdn card to it, to get the clock. this card is interlinked to the E1 card, so the clock is provided to that card. by default, the hfc-e1 card will use crystal clock if card is in NT-mode and clock master. in slave configuration, the clock is provided from pcm interface. i will use an oscilloscope to verify the signal with the received clock on the 4 port isdn card and on the e1 card. line ---> card 1 ----> e1-card | +-> card 2 on my line are two card: both are 4-port isdn cards. the second card provides one clock signal to the oscilloscope, the e1 card provide the second clock signal. so i can proove if the card 1 actually synchronize to the line clock. so, if this works, i will try to use an hfc-pci single port card (cheap) and provide a document on how to link the E1 card to the single port card. only two clocks are required, a frame clock and a bit clock. with the right settings, both clocks are compatible.

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Re: BS-11 runs, but no Network on my Mobile
by Dieter Spaar 03 Apr '09

03 Apr '09

Hello Marcel, On Thu, 02 Apr 2009 22:33:01 +0200, "Marcel Klein" <marcel(a)koeln.ccc.de> wrote: > > Okay, second try didn't work anymore... so the problem still exists. I > even tried 250mW. I received an important hint that the problem is most certainly related to a clock issue. Some background: The BS-11 synchronizes its internal clock to the clock of the E1 line. Its does not have a high stability clock which is needed for GSM. The official networks use a very stable and exact clock, the requirement for a BTS according to GSM 05.10 is +/-0.05 ppm. (There was a variant of the BS-11 sold which had a versatile interface card which can also work with standard ISDN, this variant had an oven controlled oscillator which can run standalone with the required stability. But we don't have any of this BS-11 variant). The phone itself synchronizes its clock from the network it receives. If the phone searches for networks, the carrier search range is limited to a certain window, it will only find a network if the carrier falls inside this window. Now the problem: If the phone is synchronized to an official network and searches for other networks, it will only find them if they are within the search range. No problem for an official network, they use exact timing. However if the BS-11 network is not within the range, its network is not found. When the phone is powered on and not yet synchronized, the search range window is larger, however the phone starts looking at the ARFCNs first which it received the last time when it was registered to a network. So it normally would find an official network first and miss the BS-11 if its is clock is off too far. To confirm this, I run a test with an HP 8922 GSM tester. It can simulate a network and also has a tuneable reference. If I start with a phone registered to an official network, I can only see the HP 8922 network if the refenrence is with about +/- 1 ppm. The same is true the other way round, if I start beeing registered to the HP 8922 network, I can only see the official networks if the reference is within the above range. I used an older Nokia phone for my tests, the range may depend on the phone. If the BS-11 is locked to the E1 clock, its reference is controlled by the oscillator of the E1 card. ISDN timing requirements are not very strict, +/- 50 ppm is good enough. I don't have the datasheet for the oscillator on the HFC-E1 card, probably the clock can be in the range of +/- 20 ppm. Two ideas to solve this: Start at a place were no other network than the BS-11 network can be received (OK, could be difficult ;-). Or write the information of the BS-11 network to the SIM card so that the phone starts receiving the BS-11 ARFCN when powerted on. Basically this information is the cell allocation information in SYSTEM INFORMATION 2 and have to be written to EF_BCCH on the SIM card (if you want to change the location update information on the SIM card so that the phone is already registered in advance, EF_LOCI has to be modified). One other thing: I did not notice those problems with the BS-11 yet. This ccould have two reasons: Differences in the oscillator drift or because I usually turn off the HFC-E1 card if I don't use OpenBSC. mISND on Linux is constantly running and the E1 clock is on all the time, here in my configuration (Windows) I turn off the HFC-E1 chip after running OpenBSC. According to some documentation it can take up to 30 minutes until the BS-11 synchronizes to the E1 clock. So maybe the BS-11 oscillator is better than the oscillator of the E1 card and so the problem only occurs if the BS-11 is locked to the E1 card ? Just a guess, but I will try to see if I find an easy way to measure the BS-11 clock. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: AW: AW: AW: BS-11 runs, but no Network on my Mobile
by Dieter Spaar 01 Apr '09

01 Apr '09

Hello Andreas, On Wed, 1 Apr 2009 13:44:52 +0200, "Andreas.Eversberg" <Andreas.Eversberg(a)versatel.de> wrote: > > does BS-11 need to react on telephone messages in order to show the > network to the phone? or does the phone just receive the BS-11 > signalling information in order to display the available network? i > don't know if the receiver works. To just "see" the network, the phone does not have to send anything and the BS-11 does not need to receive anything. This is necessary only when the phone registers to the network (Location Update). However the Abis link has to be up so that the cell information is sent, if the Abis link is down, the transmitter is most certainly still sending (I measured this here, but it was not yet confirmed by others so it might be wrong) but a phone won't see the network (probably no system information is sent in this case). > also i can create BBSIG1 and PA1, but it will not be used by bsc_hack. > what do i need to change in order to use the second transponder? maybe > this one works. I am not sure if OpenBSC already supports the second TRX. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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BS-11 runs, but no Network on my Mobile
by Andreas.Eversberg 01 Apr '09

01 Apr '09

hi, i finally completed the BS-11 setup: - original kernel 2.6.27.4 the mISDN-patch was for - bs11 with software load as described in the wiki - all BS-11 objects created as described - PA test passed - LMT shows no alarms (except cabinet-alarm) - after start of bsc_hack, all 8 channels on the first tansmitter are provisioned. - FM receiver clearly receives transmitter on channel 123, where no other base station is transmitting but i do not get any other network on my mobile. my mobile just finds: e-plus, t-mobile, o2, vodafone any ideas? thanx in advance andreas

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Re: AW: AW: BS-11 runs, but no Network on my Mobile
by Dieter Spaar 01 Apr '09

01 Apr '09

Hello Andreas, On Wed, 1 Apr 2009 12:36:15 +0200, "Andreas.Eversberg" <Andreas.Eversberg(a)versatel.de> wrote: > the load is correct. i get an error pop-up while starting bsc_hack. this > is because the LMT seems not to be 100% compatible with the load. with > an older load i don't get this error pop-up, but it also doesn't work. > also no alarms show on the LMT after syncing database. i will get the > exact error message this weekend. The error message that LMT is not compatible to the firmware version should be no problem, it just complains about unknown attributes. Its strange, because you already know that the transmitter is working, so I wonder why you don't receive something on the phone. Have you tried a different phone, just to be sure ? Maybe also using a different ARFCN might help. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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OpenBSC April 2009