I just looked at the spec sheet for the Gemalto PLS8 cellular modem, and the USB 2.0 connection is plenty fast for this modem. It is only a LTE CAT 3 modem with 100 MBit/s download and 50 MBit/s upload, so its USB 2.0 (480 MBit/s) is plenty fast.
Given that the max of G4 is 100 MBit/s downloads and the best average in places like Singapore, South Korea, Netherlands and Norway is around 50 MBit/s, the use of USB 2.0 isn’t important.
One annoying thing is that you have choose between the PLS8-US and PLS8-E, so people traveling between different parts of the world will have to buy two different modems. The late May update says that Purism is evaluating other modems, and I really hope that they find a modem that has worldwide coverage. Also the PLS8 only supports GPS and GLONASS, so the Europeans, Chinese, Japanese and Indians will be sad that their GNSS isn’t supported. More importantly A-GPS and LTO aren’t supported, so will be less accurate. I wonder if there are security implications to using A-GPS.
One thing that surprises me is the size of the modem chip. Look at the package sizes of the cellular modem and SoC in the Librem 5 compared to a high end Snapdragon that has both functions in it:
PLS8: 29×33 = 957 mm2
i.MX 8M Quad: 17x17 = 289 mm2
Snapdragon 845: 12.4x12.4 = 153.8 mm2
The modem will not be used for geolocalisation, the choosen chip supports more GNSS services:
The Teseo-LIV3F module is an easy to use Global Navigation Satellite System (GNSS) standalone module, embedding TeseoIII single die standalone positioning receiver IC working simultaneously on multiple constellations (GPS/Galileo/Glonass/BeiDou/QZSS).
Teseo-LIV3F provides also the Autonomous Assisted GNSS able to predict satellite data based on previous observation of satellite.
Within this link that confirms Quectel EM06-E certification is to be seen standardized modem card size (30x42mm) and its M.2 “B key” edge connector (if Librem 5 main-board will support this one as optional).
My bad. That will make make the European, Chinese and Japanese nationalists happy!
I should have clarified that I was talking about the USB 2.0 connection on the Gemalto modem, not the M.2 slot. There is no reason for Purism to limit the M.2 slot to USB 2.0, so future upgrades to modems with USB 3.0 and G5 will probably be possible. One difficulty is that you will also need a different antenna for 5G (especially if using mmWave), but I see that Qualcomm has figured out how to make tiny 5G antennas, so it will probably be possible to include both the 5G chip and antenna on the M.2 plugin card, but to get good 5G reception, you need to include 5G antennas on all four edges of the phone, because your hand can block reception if you only have antennas on one or two edges of the phone.
The more that I learn about 5G, the more that I think that it is a really bad idea. It will be very expensive and incredibly wasteful to setup millions of microstations with only a 250 meter range, and we have no idea what will be the health effects for humans living next to all those microstations. The way that 5G will be implemented in the US with mmWave sounds like a nightmare to me.
The one cool thing is that the large size of the PLS8 chip package means that Purism will have to use a standard-sized 3042 M.2 card in the Librem 5. Because the PLS8 is 2mm thick, plus another 1mm for its circuit board, this means that the Librem 5 will probably have a thick case (I’m guessing 12 mm or thicker), but it also means that we can buy a standard replacement cellular modem from any supplier as long as there are Linux drivers for it.
This is frankly awesome. I guarantee that every review is going to criticize the Librem 5 for being too thick, but I am going to love having a phone that isn’t designed for planned obsolescence.
Yes, the mmWave part of 5G is terrible, but that’s just part of it. Don’t throw out the entire spec just because of one of the frequency bands.
You only need a new antenna if you want to use the higher frequencies (along with their pathetic range, which will be a wonderful boon for those who track your location based on cell towers). They’re going to re-use the existing frequencies for 5G signals once 2-4G get retired in the future, and an antenna which works for one frequency now will work just as well for that frequency until the end of time (assuming that it’s not falling apart).
The newer signal encoding methods which it uses have a higher spectral efficiency than what we have now, translating directly into a higher data throughput (so: either faster data transfer, or more concurrent users at the same transfer rate). That part of the spec is good and actually useful.
@Caliga They likely won’t connect the Gemalto PLS8 GPS antennas which should render it neutered. Even if it does power up the GPS function it shouldn’t be able to pick up anything as without an antenna the signal gain will be below the noise threshold. Looking at the datasheet I don’t see any references for an on-board antenna so leaving it unconnected should be sufficient.
Yes, this is the idea. For some reason pretty much all current cellular modem modules have a GPS/GNSS function included, which we do not want to use for obvious reasons (starting with the modem having access to precise location data and the mystery code of the firmware being able to (mis-)use it). Luckily most modem have a separate antenna input for GPS/GNSS which we will deliberately leave unconnected.
Instead we implement a TESEO LIV3 dedicated GNSS chip which is pretty new and supports all current constellations and can track up to three constellations simultaneously. Which three can be determined by software at runtime. That should give pretty good results (with Galileo soon offering down to 20cm accuracy this will be pretty cool even
since there is still all the discussion about add-in cards; could we get any information on what is actually used?
Gemalto only ships the PLS8 as a LGA surface mount package, to be integrated directly on the PCB.
Add-in cards will have to be sourced from a third party vendor.
Which will it be, and if it’s indeed a card, what vendors are in the race?
Did you check out the NaviSoc chip (from Poland) ? It is quite small 9x9mm and most important is a dual frequency GPS. It works with all constellations but has Galileo core. I would very much like to have a dual frequency GPS because it could give up to 10 cm accuracy (or so they say). I mainly plan to use my Librem 5 for mobile applications (not desktop) and GPS is one of the most important. Another important hardware is of course the LTE modem. Hopefully we will get local LTE base stations (Nokia already has design such) connected to our fiber network. The operators do not have so good coverage especially on higher frequencies.
I suspect that we are seeing a build up to an announce. Notice that this months update was pretty big and it’s all about finalizing software so we are coming to the end of new features and it’s all bug fixes. So that means that the software platform is basically done and the usefulness of the DEV board is kind of complete. We should be hearing hardware news within the next month is my guess (guess being the operative word).