4 ms·
Ask HN: Sim card control frequency?
Does the sim card control the frequency transmitted? And does the transmitter in the phone allow for a large range of frequencies, like from below 900Mhz up to and past wifi (2.4Ghz)??
- byoung2 9y agoIt would seem not, since phones (at least in the US) are required to be able to connect to the tower in the absence of a SIM card for 911 calls.
- ParameterOne 9y agoAre 911 calls analog?
- jepler 9y agoI am not a specialist in GSM networking, but I went looking at the relevant standards documents to see whether I could answer your question. It appears that the handset can request information from the SIM about frequency bands. For example, see section 10.3.38 of 3gpp specification #11.11 "Specification of the Subscriber Identity Module - Mobile Equipment (SIM - ME) interface", which discusses EF_CPBCCH: "CPBCCH storage may reduce the extent of a Mobile Station's search of CPBCCH carriers when selecting a cell" https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=419 https://portal.3gpp.org/desktopmodules/Specifications/Specif... [click 'versions' and then the link '8.14.0' to get a zip of a doc file that renders like hell in libreoffice 5 on debian stretch] However, after that I lose myself in random standards document and can't give a clearer or more authoritative answer.
- sbierwagen 9y agoThe SIM card doesn't contain the radio, the phone itself contains the radio. Phones can only transmit on a fairly narrow set of frequencies, you can't tune one to an arbitrary frequency in the gigahertz range. If you want to transmit on an arbitrary frequency you'll need to buy a software defined radio, like the HackRF http://www.kr4.us/HackRF-One.html?gclid=CJGdyMDLqtQCFYGUfgodhdkE_A http://www.kr4.us/HackRF-One.html?gclid=CJGdyMDLqtQCFYGUfgod...