Hello OM community, I am pleased to announce that my company Falconia Partners LLC is now offering GSM RF tract recalibration services for Openmoko's Neo 1973 and Neo FreeRunner devices. Like all other commercial GSM phones and modems, these smartphones had their GSM RF parameters individually calibrated on the factory production line. This factory calibration normally persists for the lifetime of the device, but because the calibration values are stored in the Calypso modem's flash file system, it is possible that some Neo owners may have lost theirs as a result of careless playing with modem flashing tools. The latter scenario is quite likely to have happened in the bad old days before FreeCalypso when the modem was treated as some kind of "thou shalt not enter" forbidden zone, and the modem flashing tools and documentation were available only in a hush-hush, whisper-whisper manner. GSM RF calibration also needs to be redone if the RF hardware has been physically modified in any way, e.g., to convert a 900 MHz device to 850 MHz or vice-versa.
Because my company produces new Calypso GSM modems that are very similar to Openmoko's, we have the necessary facilities to perform our own RF calibration that is no worse than what OM's factory did. The RF test instrument that is used to perform the calibration is a Rohde&Schwarz CMU200, and this instrument itself needs to be kept in good calibration standing - the chain of traceability goes back to national standards labs like NIST. Our CMU200 instrument has just been calibrated by Rohde&Schwarz in Maryland; here is the official calibration certificate: https://www.freecalypso.org/members/falcon/calibration/CD_5000-309076293.pdf In addition to the measuring instrument, the process of calibrating the RF tract on a Calypso GSM device involves special software that talks both to the firmware running on the Calypso (which naturally needs to be TI-based) and to the CMU200 or other external RF test equipment. The original software that was used by OM's factory appears to have been lost, hence an entirely new replacement had to be developed from scratch here at Falconia Partners LLC, based on the available bits of documentation from TI and meticulous reverse engineering. Our new calibration software is freely published, so you can see exactly what we do when we calibrate a Calypso GSM device: https://bitbucket.org/falconian/fc-rfcal-tools If anyone has a GTA02 or GTA01 device that needs to be recalibrated or could benefit from such, you can send it to Falconia Partners LLC to be serviced. As long as the demand is low, there will be no charge for the recalibration service other than return shipping. If you are going to sending your device in for service, please take the battery out, i.e., send the device WITHOUT the battery. Postal services have become very uptight about lithium batteries recently, hence the return shipping will cost a lot more if I have to deal with the extra bureaucratic hurdles of shipping the device back to you with that Li-ion battery in it. The calibration service is completely non-invasive, i.e., your device won't need to be disassembled beyond taking the back cover off. Your Neo will have 3 cables plugged into it (USB for talking to U-Boot, another USB-serial cable in the headset jack for talking to the Calypso, and an RF test cable going to the CMU200 inserted into the RF test port under the back cover), the application processor will be booted into NOR U-Boot, the latter will be used to execute neo gsm on and neo gsm off commands via USB, and the headset jack serial port will be used to operate on the Calypso modem. Whatever software you are running on the phone's application processor will be left completely untouched. If there is interest, my company may also be able to offer a band conversion service, i.e., converting a 900 MHz FreeRunner to 850 MHz or vice-versa. To make such conversion, one SAW filter part in the GSM section of the motherboard needs to be changed (populate Epcos B7820 for 900 MHz or B7845 for 850 MHz), followed by recalibration. However, unlike pure recalibration, band conversion would require a bit of invasive surgery on the hardware, and this hw surgery would need to be performed at a professional board assembly and rework shop. If there is any serious interest, I can have a discussion with Technotronix (the shop where our new FreeCalypso modem boards are assembled) and see if they would be able to perform rework on Openmoko devices, and how much they would charge for the service. I won't be adding any margin of my own on top of whatever Technotronix folks will charge, but I would need to act as a middlewoman for logistics because devices would need to be recalibrated after the SAW filter change, and the calibration station with the CMU200 (a big, heavy and expensive instrument) resides in my own lab, not at Technotronix. Finally, if anyone has a FreeRunner that hasn't had the rework for bug #1024 and is interested in getting that rework done, I can talk to Technotronix about that rework as well - the hw surgery for bug #1024 rework and for the 900/850 band conversion involves the same shieldcan over the GSM section of the motherboard, so both can be performed in the same surgery. M~ _______________________________________________ Openmoko community mailing list firstname.lastname@example.org http://lists.openmoko.org/mailman/listinfo/community