Serg wrote: > Seems like nice module, I see that it has at least 3 variants A/B/C, could > not find a good document in English what is the difference.
It can be seen from Songbosi's huawei.jpg picture that the B version is Calypso-based, whereas the C version is LoCosto-based. Back in 2013 I made the decision to base my work on the Calypso chipset rather than LoCosto, and this decision is now enshrined in the FreeCalypso project name - and I am not switching. If Serg or anyone else feels like playing with LoCosto, you are on your own. > Also seems like it has dual band SAW filters installed in B version, so > additional components need to be installed in order to make it tri-band and > following the re-calibration process executed. Looking at Songbosi's huawei3.jpg picture (detailed view of the component side of the board), it can be seen that the board CANNOT be modified from dual-band to triband. One can remove DCS band support and add PCS band support in its place, but it is not possible to have DCS and PCS on the same board without redesigning the PCB. The antenna switch only has two Rx paths coming out of it, not 3, and as you can see in the photo, each goes through what looks like a series capacitor acting as a high-pass filter. The layout is done in such a way that the series capacitor for the high band Rx path can be populated in one way for DCS and in another way for PCS, but you still can't have both at the same time with this PCB design. To Songbosi: for my experimentation purposes I don't mind getting a dual-band modem module without PCS band support: even though I am located in USA-occupied California, I won't be operating the modem on live airwaves here, instead I do all GSM RF testing on my CMU200 instrument, and with that instrument I can operate in any band in my lab. I would indeed be interested in getting a few of these modules for experimentation and further reverse engineering, and Songbosi's asking price is very cheap, but I would really need a breakout board for the interface connector. M~ _______________________________________________ Community mailing list [email protected] https://www.freecalypso.org/mailman/listinfo/community
