Carputer questions, cell band compatibility, Mobile platforms for cars, outdoor  - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: March 30, 2022, 12:40:08 pm
content: This is a bit long and rambling, I hope what I am getting at comes across..A couple of years ago wehad Hurricane Sandy where I live and the power and Internet in most homes went out for over a week. There also was almost no cell service where I live.. after the batteries died.When this happened, libraries saved so many peoples asses..The local free public libraries (which around here are really quite good, and function as sort of community centers..) had power and Internet service restored far earlier than the neighborhoods and became a lifesaver for people like us who had a need for net connectivity that went far beyond the usual.. In many cases peoples employers were depending on them being able to work online..Let me introduce this with a bit of whining abut the over optimistic lies told by the agents for various network providers..Thy just want tosign you up for more useless junk, and rarely tell the truth.. about what your getting when you make any change of any kind they almost always use that as an opportunity to screw you. This has made me an anti-cell phone person. Almost.My wife has a cell phone and we are both very frugal. She's been told by her cell carrier that soon it will no longer work and she has to get a newer one. We are in the US.Where and how can we find out what bands work where and will in the future?We want to make good hardware decisions.. This has been very hard.We want to ensure (somehow!) that any hardware purchases we make will work for their intended uses here, for a while..We need the provision, in a non-biased manner, of the technical issues in play that will effect the provision of both wireless and wired services.. And info about standards involved, and what hardware supports them.I prefer sometimes to use older, more reliable technology. My area has * lots * of cell phone cells, now (hundreds, lining every major road and highway and populating utility poles in even the quitest neighborhoods.. but I like to have as much choice as possible, and buy tech that's not limited to just one system or carrier.E-junk problem is out of control..Our house is littered with the detirus of old cell phone related purchases that no longer work or interoperate with anything. At all. And by and large the parts then become useless.. they cant be repurposed (maybe the displays can, like with old Nokia GSM phones, but thats it)Now we have to replace a bunch of stuff again because of this phasing out of the old cell phone system. Frankly I'm sick of all this and also sick of carriers promising us things will interoperate for a long time into the future and then raising rates or disabling functionality. This area is well served it seems by 3g and 4g, but the 3g is going away we're now told.. Some of the carrier execs have come out against 5g, they say they dont need it. They only recently finished rolling out 4G.I am probably a potential customer of mobile services, but even I am penny pinching these days and rankly, am not even the slightet bit interested in wtching videos or whatever on a cell phone. Hell, right now I dont even use a cell phone, an dI refuse to get another one as long as they remain what they are today. The system and functionality that I want I am perfectly willing to build myself in order to avoid the traps that are set up for the unwary who dont put the greatest care into buying cell phones, modems and related services.I still am bitter about the dismantling of my old TDMA flip phone which it seemed then, worked almost everywhere,even in the middle of the deserts of the Southwest,. Far away, like 50 miles from any town or major highway. It was truly amazing.. Alas, it no longer works anywhere.Up until a few years ago I had a GSm phone which I bought for its rugged reputation and advertised internal GPS. Alas, the GPS required a data plan to work, which cost a fair amount extra.. Thats a good example of false advertising. I researched the issue and there is no such thing as a GPS chip that does not support downloading its ephemeris itself. In other words, the internal GPS in my phone should have worked everywhere it had power, and the manufacturer and vendor was using the crap excuse that it only supported AGPS to extort people out of extra money for a data plan when in fact the GPS chip alwaysd downloaded the ephemeris and that data was always available in the pohone because the law requires it. (So that a telephone can always be tracked by its GPS data when making calls..) That is the real reasonOtherwise when its powered up its a few minutes before the GPS works unless its downloaded it within the previous few days and has it stored somewhere. (This is called warm start and takes a maximum of around 15 minutes. Ephemeris data is always available via the Internet from NASA. - as well as various chip and hardware manufacturers web sites. If you have access to the net.Whatever hardware I buy I want to know what I'm getting, better than I have in the past. The FCC site is useful, if you have an FCC id to look up..I like hiking and campingin the wilderness.. Meaning off the grid.. Where AGPS doesnt work..there not being any cell service..We both are very into GPS. And Internet especially, we need it.And need reliable cell phone data service when we are on the road.. especially during emergencies..RF performance and availability of a jack for an external antenna on RF hardware..is useful.When we had cell phones that worked far away from the city, it was very nice. (even though that phone didnt support hotspot mode)We could call and book motels and ask people for the info we needed.. Also we brought our phones with us and could use our phones and our home numbers wherever we were in the country (motels) where we got Internet service.. (we have a wifi router we used on the road, in our motel rooms when we had a net connection our phones had dial tone and our hoe numbers rang.. So it was transparent.Thats what a good carputer setup offers..I hope..Newer phones do allow tethering and mobile hotspot (on the cell carrier they are registered with only) when conditions allow it, its nice to be able to use a phone as a local hotspot. During hurricane-caused power outages which at one time (Sandy) lasted quite a long while, its been a lifesaver to be able to connect up to the net via a cell phone..I have been thinking about setting up a carputer that can give us the ability to use our own wifi when we go out for coffee.. (as long as we are close enough to our car) I am hoping that this would be cheaper than the usual price of data plans on plain old phones.. Mobile modems data plans might be cheaper (bandwidth/ciost wise than cell phones data plans) and with the right antenna might work as well or even better. even while on the road..I dont know.? Where can I find out what hardware to use in a reliable nonbiased manner..?Here in the US there is a web site, "Howard Forums" that has a lot of cell phone related info.Like DSLReports its been around for a long time and represents a well established, expert community.. Is that the best site for cell network info? Its so great when you can get straight answers to the kinds of questions that can trap you into bad technology choices..I know that commercial products are sold that bundle this functionality so non-experts can do it,but because I like DIY and like to optimize such things I'd rather rig up my own with a small PC, I think.. Then I can swap out the various parts.. I like the idea of having a small web server in our car that can be queried for info on where the car is say, when my wife is shopping..Also, as I said when we go out it would be really nice to be able to use our laptops wifi anywhere we were within range of our car.I am also wondering what the best very small low power consuming PC would be to base the carputer on. I have found thin client boxes to be super useful, although they draw a bit more power than Raspberry Pi and lack the PI's super useful hardware compatibility (GPIOs, etc) they support the far more flexible x86-64/amd64 architecture.. And most are substantially faster..Does anybody else here run a "carputer" ? Are there any carputer open software projects, (appliances)Ye, itlooks like there is this one which looks perfect for me as I have a pi 3 I can use..https://www.nomadicpi.com/and/orhttps://github.com/anthony-mills/raspberrypi-carputerI may still prefer to roll my own..Really, this subject deserves its own thread..

author: Dehv
author_rank: Contributor
timestamp: March 30, 2022, 09:37:01 pm
content: Your phones that are being retired are 3g gsm and previous cdma and 2g.Any LTE 4g smart phone from the last while (9years?) is probably all you will need for the next decade. If you can replace the battery a used phone would be fine.700mhz bands are the longest reaching currently, and 5g only has slightly farther reach. (There's talk of 600mhz band... on 5g, lower frequency = more distance).5g is mostly for urban areas, trading long distance for high speed.Or, rather than fooling around with batteries, hoping they are easy to replace; get a new cheap smartphone with "android go" (a lighter operating system that works better on low spec phones)You probably want an LTE (4g) repeater (single band 700mhz for 12/13, ) with small mag mount external roof antenna and interior strip rear view mirror type. That would be all you would likely need for 10 -20 mile reach. Pricing is under $100 for kits for vehicles on AliEx or ebay.Better would be a dual band 700/850 bands 2, 4, 5. 850mhz is the same frequency range that 3g used, by the way.A simpler solution, you could use a device like a Solis/skyroam LTE hotspot, which would detect the nearest tower and turn that into Wifi, or in combination with your booster and use that instead of a complex carputer. $50 a month unlimited data when you prepay 6 months. (20gb full speed and unlimited throttled)Or for voice use go with apps/VOIP and get a data only plan. Free phone number apps like Fongo in canada, been using my free number for 4 years now!

author: 50ShadesOfDirt
author_rank: Regular Contributor
timestamp: April 02, 2022, 04:57:55 pm
content: Agree that 4G is the sweet spot, if you are somewhat rural, as we are. We've four of the LG 4G phones for the family, and a netgear hotspot/booster, all on ATT, unlimited data plan. Hotspot works at home and on the road, and is our usual source of internet ... works most everywhere, as the booster helps with weak signal areas.For the carputer, we've nothing better to suggest than the surface tablet ... gives us a Windows PC in a small package, easily powered/mounted in a car. No need for a keyboard, unless you take it off and use it in your lap ... then its magnetic pop-on keyboard gets used. A simple USB GPS, and we've got full-blown mapping capability, on a large screen. Pop the pieces out, take into the hotel with you, and no fooling around with hotel wifi garbage. Works in some far-flung locations, if camping or such.I keep looking at, and passing on the many android tablets ... I'm always finding a personal limitation of some kind with them (os, apps, power, mounting, abandonware, something). Buy a windows program (or better, free open source), keep it for life, no nagging for the "pro" version. Everyone wants a subscription, but we've managed to avoid it in every case.Hope this helps ...PS: still have my moto flip ... haven't investigated how to resurrect it yet (or if it can), but it retains a spot on my tech shelf forever. All the others have been sent to places that supposedly recycle them in some fashion.

author: 50ShadesOfDirt
author_rank: Regular Contributor
timestamp: April 02, 2022, 07:17:32 pm
content: In addition, remember that the old smartphones still have one shot left at being useful, when their cellular capacity is shot (2g, 3g).If they have wifi, and decent battery life, or life as a plugged in device. Use them as a hand-held "computer". You'd need to determine if there is some useful purpose, but we've had plenty of recycling success with older smartphones as a computer of some kind.Suggested uses:- calculators: many free & good apps to turn these into scientific calculators- land/gps plotting devices: the land surveying apps turn these into use land/area mapping tools- apps that don't really need always-on cellular data: any useful (to you) database app, knowledge tool (pdf, other ebook reader), etc.We don't really dump these things until even this functionality is shot ... the thing won't turn on any longer and we can't pry the old battery out to replace it, or someone has dropped it enough to where the screen/display is shot.Hope this helps ...

author: El Rubio
author_rank: Regular Contributor
timestamp: April 05, 2022, 02:32:22 pm
content: I have worked in the cellular industry since the 80’s. When I started, everything was analog, most phones were just phones and mounted in cars. The only handheld was the Motorola 8000, aka “brick phone”. I have seen most technologic changes in the industry.Your experience during Sandy is not necessarily caused by dead batteries. Many, if not most cell sites have generator backup. Generators fail sometimes, or there may be no access to refuel after a major storm, but the real problems are the backhaul network. These are the links from the cell towers to the rest of the world. I experienced Katrina in New Orleans. The network was 2G and the backhaul consisted of T1’s connecting the cell site to a central switching office ( MTSO). The MTSO connected calls from cellsites to the landline telephone network. Internet was routed through a separate gateway, but still rode the T1’s with limited bandwidth. Katrina ( and Sandy to a lesser degree) destroyed the backhaul network. Within days after Katrina, we had dozens of sites ready to go back on air, but no backhaul. The main phone company switch in New Orleans had flooded and the wired network was devastated. We brought in unlicensed microwave radios and set about establishing links to cellsites. This was slow going at first. We were back on the air handling traffic before the phone company restored their main office. We managed to route everything through Baton Rouge (60 miles north). I tell you this because it isn’t as simple as “ the batteries died” during Sandy. Currently, most cell sites have generators and LTE/5G requires high speed fiber which is usually better protected from flooding and wind damage. It does require power and the many pedestals have battery backup. Many also have fixed generators.Libraries here offer free wifi and let you borrow a wireless hotspot. They don’t have any priority with network providers. Hospitals and Emergency Response like EOC, Police headquarters etc are prioritized for power and wireless restoration if possible.Older technologies like tdma would never have been able to deliver the data that LTE does. It could have been developed, but that research costs money and in some cases the wireless carriers paid for it. The manufacturers of hardware, like Ericsson and Nokia, settled on GSM. There was a couple of competing technologies in the US that were being squeezed. Cdma & ev-do were unable to compete with wideband cdma ( umts) performance-wise. Plus the one carrier here that used it was going to have to finance most of the research to improve it. LTE was a natural progression from UMTS (3G) and that from GSM (2G). Most areas are much better served by digital networks like 4-5G than they ever were with previous tech’s. I assume your wife’s phone is a 3G device. 3G has been active for at least 10-15 years. Features and major changes don’t happen overnight. The 3G sunset has been gradually setting up for years. As fewer people own 3g devices, those channels sit unused. At the same time, LTE is exploding with usage. The 3G network gets carved up and most becomes LTE, leaving one 3G channel working at a cellsite. Many new cellsites over the last few years didn’t get 3G installed at all.Someone suggested a repeater. That may help you in areas where service is weak. There are some designed for installation in a vehicle too. I would disagree with the suggestion to get one that does 700mhz or 850mhz. At&t & Vz own almost all of the 700MHz spectrum in the US. If you are one of their customers, no problem, but many of those cheaper Chinese single band repeaters are made for one or the other carrier. I would suggest a quad band repeater that covers all of 700, 850, 1900 ( PCS), & 1700/2100(Aws). I like one made by HiBoost.They have gain adjustments for each band and start around$300-$400. More expensive than the unbranded Chinese garbage, but they work. Other brands like WeBoost, Cel-Fi, and SureCall make quality boosters too. Anything with gain adjustments can be made to work without oscillating.

author: cdev
author_rank: Super Contributor
timestamp: April 05, 2022, 03:12:39 pm
content: Quote from: El Rubio on April 05, 2022, 02:32:22 pmHurricane Sandy was a real wake up call for many people who found themselves without needed Internet connectivity for a week or more.In 1989 which was before the Internet was in any way the presence it was a few years later I lived through the San Francisco Loma Prieta earthquake. Which knocked out power in the entire city. It was turned off a few minutes later (intentionally) and was not turned back on in the neighborhood that I lived in (Upper Market Street) for more than two weeks.People whose buildings had been red tagged (a great many people) were camping out in parks, one example, was Delores park.Its really striking hopw much modern society depends on networks of various kinds. When we build infrastructure it needs to be more resilient.A single solar storm could wipe out networks in the entire Northeast due to the presence of highly igneous rock underground deprives many areas of an effective ground in the event of a coronal mass ejection event. (often abbreviated in this literature as a "Carrington Class" CME. (after the 1859 Carrington Event)This will result in many high voltage transformers failing due to the DC pulse that unbalances them and saturates the magnetic core. These high voltage power transmission transformers then typically catastrophically fail.A single nuclear detonation at altitude would create similar effects, with a very powerful DC pulse being induced in any long wires for a very long distance. This happened due to nuclear testing in the 1950s, in the years immediately previous to the advent of solid state electronics. Still much electronic equipment failed and the ionosphere was also disrupted. Meaning GPOS and timing equipment would be forced out of operation or might fallover to depend on crystal or other kinds of high preision oscillators. Frankly, nobody knows what would happen, just that this could be extremely disruptive to society and that we are not fully ready for this, its likely.This is a huge weakness inherent to our current energy grid. If we used a different topology we might be able to avoid what may become an almost unavoidable disaster without this kind of chain reaction catastrophe being considered. In 1859 during the carrington event, all long wires, such as telegraphs (which were cutting edge for the time), were disrupted. Also the Aurora Borealis was visible in the entire US. Similarly with the Aurora Australis in Australia.Thank you for your explanation of the two hurricane caused outages!I hope we can make these networks resilient in such a way that the networks dont fail. People depend on them more and more. Wouldnt it be great if the next time this occurs we managed without major outages! That would really be a big accomplishment.

author: cdev
author_rank: Super Contributor
timestamp: April 05, 2022, 03:27:23 pm
content: Their frequent dependence on AGPS means that the GPS functionality (except for in the inaccesible control plane) and likely any attempt at telephopny of any kind, as it lacks the location info, simply doesnt work!Iattempted to find out if that was a fake made up limitation, and what I did find out is that nobody sells an GGPS-only GPS chip. All phones have a built in ability to work in the wilderness by working as they worked in the past, downloading the ephemeris data from satelltes when they have been powered off for an extended period and lack the ephemeris. This takes (typically) a little less than 15 minutes. However, it requires that they be in an area with data coverage to preseed the ephemeris top allow AGPS instant on, otherwise, the first few minutes after turn on might allow people to make cell calls without the location data being available and sent. Even if you dont purchase a data plan, the data is available to the network's non consumer ccessible control plane. For example, the e911 system.But if you dont have a data plan your GPS is rendered inoperative in order to get you to buy it. Even if you have a GPS right there in your phone. You cant use it. They give you all sorts of half assed excuses apart from the real ones.They gladly take your money for a GPS phone that will never work as a GPS in the wilderness, or if the network goes down. This is so nobody can make anything even remotely like an anonymous phone call, I am sure most people realize.They have to suppress whistleblowers, perhaps?Quote from: 50ShadesOfDirt on April 02, 2022, 07:17:32 pm

author: TomS_
author_rank: Frequent Contributor
timestamp: April 07, 2022, 10:45:19 pm
content: Most newer phones I've seen tend to support all bands, perhaps through some kind of SDR like technology. That or technology has just gotten better in general that they can make the silicon work on more frequencies than in the past.But seemingly gone are the days when you had 2-3 different models of phone supporting different frequency bands and it was a lottery if it even worked when you went outside of your home country. Maybe this still exists for the very low end of the market?I don't tend to buy the "latest greatest" phones, and I've had too many "less than ideal" experiences with the low end Android Go style phones - they really are slow and seem to rely on the fact that you'll install an SD card for storage, one such phone I have is constantly complaining that the internal storage has run out, and I haven't even installed any apps on it, and even uninstalled as much of the factory fluff as I could. :Shrug:So I tend to buy something like the Pixel 3a or now the 4a. It's a nice blend of higher end features but leaning a bit more towards lower end cost. And it isn't so big I can barely hold it.