baseband-devel May 2010

baseband-devel@lists.osmocom.org

16 participants
15 discussions

update on layer 3 work
by Andreas.Eversberg 13 May '10

13 May '10

hi, i like to give a short update: currently i am testing the processes of selecting a cell and the network. the processes depend on the coverage, the sim card (network, inserted or not) and the mode (manual or automatic network selection). i hope i will finish this week. to configure mode and sim card and other parameters in the future, i use the VTY, you already know from the OpenBSC project. there you can get informations about the subscriber, the mobile station and the received cells (system informations). i will move all hacked parameters (test sim) to VTY config file. manual network selection mode requires reaction of the user, so it will also be added to the VTY. later the VTY can also command the "call" part to dial, answer and hangup a call. my idea: later these VTY command structure may be used for the phone's menu (up - down - enter - escape), if compiled appropiate. also: if layer 3 is running on the phone, the serial port could directly connect to the VTY, so the phone gets a console interface for debugging and faster configuration. currently the process (with sim card) ends while trying to do a location update. if the given channel is not supported, the program exits. to prevent this, just keep radio TX feature disable. the cell will be re-selected again and again (hopefully if the process works correct). sometimes, especially at the first run, the radio process stops. (no results for measurements, no sync to selected frequency.) also there is something i am wondering: calibration especially for the burst signal phase is measured and then stored on the eeprom by the manufacturer. do we use it? or do we need to do our own calibration? regards, andreas

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public project with MTK baseband firmware project
by Harald Welte 10 May '10

10 May '10

Hi all! In case you're interested, there seems to be a public project on code.google.com that contains the build environment and baseband firmware sdk from mediatek: svn checkout http://mobile-phone-mtk-project.googlecode.com/svn mtk-project Please note that I don't know about the legality of this. However, it is distributed on a public server/service without any kind of authentication... Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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Request for help with VCTCXO measurements
by Harald Welte 09 May '10

09 May '10

Hi all! Right now, one of our many issues in L1 is the frequency stability (or lack thereof). What we do right now is very primitive and is mostly based on guesswork, rather than measurements and good algorithms. In order to change this, we need some measurements to be done. As I am currently again travelling a lot, and my time for OsmocomBB is more limited now, I hope that somebody else will be able to take the measurements as described below. There is a big number of people in this project who now have a Racal 6103 (or similar) measurement device. Also, for those in Berlin, the CCC Berlin has one in its basement lab. What needs to be done: 1) Determine the relation between AFCDAC output and actual carrier frequency. All that is needed is some manual control over the AFCDAC value (e.g. based on keypad events) while the AFC is disabled. Then we continuously transmit bursts (content is unimportant) to the Racal 6103 and note the measured frequency error by the 6103 for every AFC value that we input. Those measurements should then be repeated for each supported band of the phone, preferrably each with a low-frequency channel, a medium frequency and a high-frequency channel. This means something like 10 different AFC values for 3 different channels of each of the 2 bands that the c123/c155 support. Basd on those measurements (preferrably do that series with 2-3 phones) we can construct a function that will tell us which AFCDAC value we should program if we want a given carrier frequency increase/decrease. 2) Determine the temperature related frequency drift and corresponding temperature ADC reading Especially when we transmit, the temperature in the RF section of the phone is assumed to change quite a bit. This means we need to measure the temperature in the oscillator (using the RITA-internal temperature sensor connected to one of the ADC channels of IOTA) and compare that with the frequency drift. In order to measure this, we first need a temperature-ADC driver. Once that exists, we can lock onto a BCCH, then make sure the AFC is disabled and the AFCDAC output value will be stable. Next, one can use e.g. a hairdryer or ice spray to change the temperature. While doing that, we can measure the difference in carrier frequency with the Racal 6103. The absolute temperature in centigrade/kelvin is not actually interesting to us all. All we want to know is: What is the 6103-measured frequency error at a given temperature-ADC-reading. Once again, the measurements should be done for high (1800) and low (900) band independently, just to be sure. Based on their relation we can also model a function, table or other approximation and include that in our AFC code. I think I'll be able to write the code even while I'm on the road - if somebody is able to do the measurements and post them to the mailing list. Thanks in advance, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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Osmoloader stored in Flash?
by Rust, Marco 03 May '10

03 May '10

Hello, I checkout the prom/loader AND prom/loader-crc part and merged it (perhaps I use git wrong way) When I run the loader with "osmcon -m c123xor" the loader starts but says "Failed to initialize flash". I tried to "romload" it with "-m romload" there only beacons but no valid response from phone. Sending beacon... Sending beacon... got 1 bytes from modem, data looks like: ff got 1 bytes from modem, data looks like: 00 got 1 bytes from modem, data looks like: ff Sending beacon... Sending beacon... Sending beacon... Sending beacon... 1. Why the flash initialization fails? 2. Is it (currently) possible to run programs (ex. L1test from flash)? I (think I)read all this rom/ram/bootloader stuff. ------------------------- Marco Rust FOKUS - Fraunhofer Institute for Open Communication Systems Kaiserin-Augusta-Allee 31, 10589 Berlin marco.rust(a)fokus.fraunhofer.de

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I see cells
by Andreas.Eversberg 03 May '10

03 May '10

hi, tests with layer 3 pointed out a problem. when i select a cell, i get updates of system informations, paging requests and immediate assignments. after about half an hour, i get some corrupt frames. i don't know yet what is wrong. 1. is the communication between the layer 1 and layer 2 (over serial link) secure? 2. i must be sure that a message between layers always are: - never get lost (except unit-data or data when connection is aborted) - never are corrupt - received in the order they are sent 3. does layer 1 drop (bcch) frames, if they have biterrors? (as it should do) andreas

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baseband-devel May 2010