Receive a GPS Signal onboard a Train? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 04, 2017, 12:09:24 pm
content: HiThe problem is very simple. I need to receive the GPS Signal and draw my own Map.The Main Railway Track Operator refuse to give me the GPS Information of his Tracks.That mean I have to collect it my own. The problem on the new Cars who have Windows who have a Metal Coating on. My ordinary USB GPS Receiver dont work.My old Receiver is an U-Blox who work with the Software perfect. I like there Software who work Stable up to 12h and more.How about that:http://www.navilock.de/produkte/1299_u-blox-NEO-M8U/62756/merkmale.html?setLanguage=enIs there a chance that the work better?I think the Austrian Railway dont give me any Datasheet from the Windows Manufacture to see what kind of Metal the use.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 04, 2017, 12:33:58 pm
content: Active Antenna?or try and extract the detail from OpenStreetMap?

author: cdev
author_rank: Super Contributor
timestamp: October 04, 2017, 12:36:58 pm
content: Skytraq sellvery sensitiveand accurate receivers. In some ways, even more so than ublox.Multi-constellation, multi frequency systems are coming to all GPSs soon which will work on a much wider range of frequencies and be inherently accurate to only centimeters without needing RTK. Even inside buildings or possibly even inside of some train tunnels. This is so people can be located in emergencies.Did you receiveanysignal at all through the coating?

author: voltsandjolts
author_rank: Unknown
timestamp: October 04, 2017, 12:45:31 pm
content: Buy a GPS logger with magnetic or sucker mount - stick it on the outside of the train car before you get on!Edit: This was just a joke, hence the exclamation mark. This would actually be a dumb thing to do.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 04, 2017, 12:56:03 pm
content: QuoteWith my "old" GPS Receiver no i dont think so.I will make a Test the next time when I board the Train it will be next week.QuoteDo the have a Software who I can "Control" there Receiver and Record the GPS Track?QuoteGood idea but the most "Pc/ Laptop" Style GPS Receiver dont have an Antenna Port. The next problem how to power the Antenna? The "old" Trains have no Powersocket.QuoteThe Data get often from Images not from a Real GPS Position. I would like use the information in the future for my Big Data project.For example if the Train dont Stop at the Station A1, A2, A3 and Stop on A4 it have to be a Fast Train.The same think for Statistic Data. If the Train is at Time X on Point the need at least Time Y to get to Station A5...But something like this need Time to find a solution for.QuoteSo for what kind of Freq are you talking about? Sat Based Nav. like GPS, Glonas, Baidu or Cell Phone, Wifi Based?QuoteThe Chassy is Aluminium.QuoteCan you recommend some withQuotewho stick on by 230kmh?

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 04, 2017, 01:59:38 pm
content: Quote from: Lord of nothing on October 04, 2017, 12:56:03 pmThat's an idea. Stick yourself to the outside of the trainI think active antennas are <20mA @ 5V. Not a huge deal.Depending on your software but is likely that you could use pretty much any module that has a SMA or equivalent powered connector to an external antenna. i,e, the software probably can be configured for $GPGGA.In any case your accuracy might be limited by line of sight to the sky.Which receiver do you currently have?

author: cdev
author_rank: Super Contributor
timestamp: October 04, 2017, 03:18:10 pm
content: Please don't attempt to stick your antenna on the outside of the train car-For one thing, magnets don't work with aluminum. Also, its likely against the rules.Doing so is likely, if not certain to get you into trouble as well as potentially dangerous to you if something were to happen to your GPS.Just don't do it. get a better antenna and accept that you need to improve the signal that comes through that window, or give up on recording the train route, and settle for the maps you get from books/online. (which I am sure are better than the ones you are likely to be able to record.)I have almost never run into a situation with a modern GPS where it could not get a signal if I was near a window. Even a tinted window.Metallic window films may attenuate signals but they never have completely blocked them for me.Make sure the antenna is facing up and outward.Skytraq's control center is similar to U-center on ublox, its used for configuring the GPS's adjustable parameters for different applications. All GPSs have settings - the technical name for them is "Kalman filter", which tell the GPS what kind of movement is most likely to be signal and not noise.For train travel, certain conditions would apply - Train travel is likely to involve low speed horizontal movement with very little of the vertical component. You want to make sure the GPS Kalman filter is set to the right setting. Pedestrian or car settings are likely to work best. Avoid the settings for a stationary GPS, model airplanes and rocketry. Most importantly, use a good active antenna with a ground plane. The ground plane can be small but it should be at least twice the size of the antenna itself. If you have a 25 mm ceramic patch, use at least a 50 cm square ground plane for best results. If you are using one of those magnetic active antennas, attach it to some steel object thats flat and put that in the top of your backpack facing upward. Make absolutely sure the antenna is facing upward. It can't work properly if it is oriented incorrectly.I hope this is helpful.Again: Don't do anything if it requires you attempt to stick anything anywhere outside of your own luggage.Don't attempt to put your data logger or antenna anywhere other than inside your own luggage unless you have the train operators explicit permission.Your own luggage is your business but their cars and your behavior while on their cars is their responsibility and they are trying to protect you and everybody else..That said, it also seems to me that the information you seek is almost certainly available in maps, etc.Even if you feel it isn't, and you're right, that's likely for some reason.Unless there is some very large reason to not do so, put common sense above your natural desire to "know" everything and default to accepting their decision making process.Seriously..Also, its likely you just need a better GPS and /or GPS antenna to get the signals inside of the car through the tinted window, safely.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 04, 2017, 04:17:09 pm
content: QuoteI am not a German.Quotehttp://www.navilock.de/produkt/60095/pdf.html?sprache=en(I think there is no other with the "red" Mark.)QuoteI am not Stupid.QuoteRight.QuoteThe Maps dont have a GPS Position in.QuoteI believe your never got on an ICE T! The are horrible. Very Bad Cellphone Signal. Outside 100% -> all Doors Close -> ~20% Signal (in the Railway Station).Quotefor you 200km/h is low speed? Depend on the Track there is vertical moment.In Italy to Train goes up to 300km/h:How about an Pannel Antenna?QuoteYou never saw me onboard a Train.When I put of my VHF Antenna the look like that ->QuoteI dont need a Map I need the GPS Position of the Track.

author: cdev
author_rank: Super Contributor
timestamp: October 04, 2017, 05:22:38 pm
content: I'm sorry, when I said "low speed" I was thinking of trains that went much slower.Also, some people use GPS in model rocketry, high altitude ballooning, etc. What I said still applies to the Kalman filter, train movement is unlikely to contain much of a vertical component compared to its horizontal component unless you are on a funicular train. This is to allow the GPS to reject "cycle slips" which might otherwise show up as sudden jumps in the track file you record.Also, I've heard stories of people (on much older, slower trains, whose windows opened) who stuck heads, arms, etc. out of said open windows and were decapitated or seriously injured.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 04, 2017, 05:33:11 pm
content: Apparently I am missing something here?I can right-click on any spot on Google maps and it will tell me the Latitude and Longitude to six decimal places.That would seem more than adequate for the kind of application proposed. For example...

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 05, 2017, 02:16:54 pm
content: Quotesure but a small Antenna for example VHF/ UHF who is "mounted" on the Window isnt a Problem (during Summer).QuoteYes but I need a 3D Trail. Just the Data I receive are "open source".

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 05, 2017, 03:09:22 pm
content: Quote from: Lord of nothing on October 05, 2017, 02:16:54 pmWhy? Are you targeting offensive weapons? How much does altitude vary? A few meters? What are the consequences of a few m up or down?QuoteIf I understood what that meant, I would probably ask "so what"?Perhaps you have not explained the actual project sufficiently for us to understand what seem to be bizarre and unwarranted requirements? You seem to be painting yourself into an impossible corner for no apparent reason.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 05, 2017, 03:25:11 pm
content: Quote...QuoteHere in our Country we have something who Call Mountain who the Train goes up and down.QuoteFirst I will draw my own Map because there are noofficialopen source Data.Later with the Data I will try to make an Big Data thing and collect the GPS Data of many People who want to contribute to see where the Train have to break and calculate the Time who is need to reach an Station.With the hole stats I can make predictions.If i find people near an Railway Track I can track trains by there Wifi Hotspot (who is cheaper than Optical Tracking).

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 05, 2017, 04:18:44 pm
content: Thank you for that explanation. However it does not clarify the need for altitude data? Do you anticipate data from people tunneling UNDER the tracks? Or from people flying OVER the tracks? I would think that reports from any position within 10m(?) of a straight-line approximation of the rail path would be "valid".The operators of rail companies here in this country are considering use of semi-automated drones to patrol and inspect every mile of rail and the right-of-way to either side of the rail line. They received extra encouragement after a recent derailment spilled 100s of gallons of petroleum product along a major river.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 05, 2017, 04:42:14 pm
content: QuoteThe most Trains goes the Mountain up and down.So I will show it in 3D where the Train goes.Quote10mI know modern GNS Systems have an accuracy of ~1m.QuoteUntil the goes to low and fly into the powerline...Here we have some special inspection Cars who get hand on a (Passanger) Train and the measure the Track and Powerline.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 05, 2017, 05:03:46 pm
content: Quote from: Lord of nothing on October 05, 2017, 04:42:14 pmBut altitude isn't that important, is it? Are you anticipating the tracks moving up or down? Surely if there were ANY vertical movement it would indicate a far more serious problem (earthquake, volcano, etc.). Surely the only people who care about altitude for ground-level transportation are the people who design and build the roads (or rails or canals, etc.) The people who travel on those ways don't care about altitude, do they? Do they have any choice about altitude? The only people who care about altitude are aircraft pilots (and the air traffic control network).QuotePerhaps we still don't know what the purpose of your project is? I thought you wanted some method of rail commuters reporting (and alerting others) to rail transport information. Train location, arrival (or delay), incidents that affect schedules, etc. The precise location of the rail line doesn't appear to be of any particular importance here? You aren't expecting users to go out and survey the precise location of the tracks, are you? That seems pretty unlikely.QuoteBut by the time that special inspection car has got to the location, the train has already passed through. The purpose of the drones is to inspect the rails BEFORE any train traffic is assigned to go through that route.

author: cdev
author_rank: Super Contributor
timestamp: October 05, 2017, 05:20:18 pm
content: Cartographic inaccuracy in the vertical plane is an important, under-recognized, issue along coastlines.https://mobile.wunderground.com/hurricane/elevation.aspAlso, many newer cell phone GPSs are now RTK-capable and accurate to only a few centimeters or even better.Of course, trains now have GPS trackers.. but many of them may not be RTK-aware and so only accurate to a few meters. Upgrades for train GPS trackers may be a low priority but they should be raised on the priority list because system managers need to know immediately if the track position shifts even a few millimeters downward.they could offer immediate warning of any shifts in track position due to earth movements or heat expansion.Of course, when cars allow the passage of RF statistical methods make it possible for transit systems to use aggregated data to generate precise, ongoing (almost realtime) measurements of any track movements (or gross elevation map inaccuracies) if any of the newly RTK-enabled riders phones receive signals at all. but they would then have to estimate the height of those riders phones..(in pockets a few inches above seat level) which introduces enough error to make the data much less useful.They really should be able to be notified of any shifts that occur with millimeter accuracy. that requires a sensor with a known height and position above the track. it would actually be even better if two GPS receivers, one for each side of the track could be used.

author: cdev
author_rank: Super Contributor
timestamp: October 05, 2017, 05:45:09 pm
content: "Moving base" RTK-GPS - is a technique which people have been using since around 2011 to determine the precise relation in space bwtween two points of known distance from one another.. I have fooled around with this in my backyard..https://www.google.com/search?hl=en&as_q="Moving+base"+RTKShort baseline RTK could give the exact location and position relative to one another of two GPSs on a drone's wingtips- combined with video - photogrammetry's "visual structure from motion" technology, or on track sensors which extended out behind the last car of a train to automatically survey tracks for minute movements such as would likely occur shortly before catastrophic track failures.Quote from: Richard Crowley on October 05, 2017, 05:03:46 pm

author: AG6QR
author_rank: Frequent Contributor
timestamp: October 11, 2017, 02:38:11 am
content: Here's a photo of my GPS unit on board a high speed train, just east of Padova, Italia, headed toward Venezia. Our speed was 132mph, or about 212 km/hr. The other number shown are the heading of 071 degrees, vertical speed of 0 feet/second, and elevation of 24.9 ft.I took this photo almost ten years ago, October 25, 2007. The GPS is a Garmin GPS V, purchased in approximately 2002. It is using the stock factory antenna, a quadrafilar helix. As you can probably see, it is next to the window.That GPS unit is antique by today's standards. Virtually any modern GPS units gets better reception. Other than placing the unit near the window, nothing special was done to make this work. I was seated on the north side of the train. The south side should have had a slightly better statistical chance of getting more satellites, but being on the "wrong" side didn't matter.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 11, 2017, 12:52:10 pm
content: sry for the short replay.The problem old trains dont use(ed) window with metal on.Newer Trains +/- 2000 have mostly window with metal who block everything.The newest should use Window "lte freq" optimized windows.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 12, 2017, 05:18:56 am
content: So now I am onboard the Train and there is quite no GPS Signal.I record the GPS Signal from the Train ride if someone want analyse the Signal I can upload it to my Hoster when I am back home. (Depend on the Delay I get the connection or not...)

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 12, 2017, 06:52:20 am
content: So with hours without an GPS Signal now I switch the USB Port an what happed?The bastard now received at least 2 Signals from GPS Sat.

author: Rerouter
author_rank: Super Contributor
timestamp: October 12, 2017, 07:02:52 am
content: Most of the doors have a buffer rubber where they meet, i would have just picked the quiet door and poked through a pigtail antenna as they close if the carradge was really such a faraday cage.Equally the same follows for the bending junctions, those areas have a rubber skirt and generally are not foil or metal wrapped, so sitting adjacent to one should improve any signals.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 12, 2017, 07:19:48 am
content: omg... I dont want get banned from Public Transport.The Train are pressure sealed and the door is very solid.There is no way to pock anything troth.So 30min bevor arriving my first transfer station I got an 2D Signal.5 GPS Signals at the moment.Does anyone here have experience with the Ublox Chiptset and maybe know why the have some strange behaviour?A Standalone GPS Device hat hat the benefit to get a fix and track the Sat bevor someone board the Train.Will a helix Antenna bring any benefit or does the Ceramic do a better Job?THX!

author: Rerouter
author_rank: Super Contributor
timestamp: October 12, 2017, 07:33:06 am
content: did you have a full 3D fix at the station before boarding the train, most recievers can maintain a 3D fix, but stuggle to fix one in poor recption conditions, once 3d fix is made you can maintain 10m positioning off even 3 satellites, but in reality a modern gps / glonass / bidao reciever should have about 16 signals outside of city centers. allowing for very good positioning accuracy.If you have an android phone, you can compare with something like the app "gps status" to see how well your reciever is working in comparisonEqually its ideal to have a receiever on for atleast 10 minutes before you put it in poor conditions, by then it should have enough of the alminac to manage.Ceramic patch antennas are what i am mostly used to using.

author: cdev
author_rank: Super Contributor
timestamp: October 13, 2017, 12:47:48 pm
content: @Rerouter's advice is perhaps the most important thing.Simply remember to get a decent fix outdoors under clear sky earlier..which takes a minimum of around 13 - 15 minutes.That 13 minutes is what it takes to pick up the ephemeris under ideal conditions. Cell phone GPSs which use AGPS download the ephemeris from the network, but often don't work without it.Tha ephemeris data is what allows the GPS to pick he very weak signals out of he noise. It knows in advance where they are going to be in the sky, and when, and where itself is, roughly.You should be in a better position to pick it up with that data already in your GPS's memory.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 13, 2017, 01:18:49 pm
content: QuoteNo I had something to carry but the first Train ride was just ~30min before who I use it.QuoteThe can Receive just GPS and maybe if sometimes the European work the should come an Update for.QuoteWhere can I download the Software?QuoteI cant board the Train with an Laptop in my Hand.QuoteIt is an USB GPS Mouse. The Software show me Sat.does anyone want the Recorded Data and analyse it?

author: Rerouter
author_rank: Super Contributor
timestamp: October 14, 2017, 04:39:02 am
content: Quote from: Lord of nothing on October 13, 2017, 01:18:49 pmOk, you can get the program off the app store. Looms like a play button.You can board a train with a folded laptop in hand. Go in to the power settings and turn off the sleep when lid is closed option. This way it remains running.This will also fix the losing power issue. While at the same time most laptops also have an always on phone charging port.Sure post the logs. Havent yet played with bare metal gps logs.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 14, 2017, 02:45:24 pm
content: QuoteWhere is the Store located? Do you have an Adress? I never saw it before.QuoteThe risk that some steal is very hight.QuoteIts from my Ublox Software thing.I will upload it to my Webspace and post the URL.

author: Rerouter
author_rank: Super Contributor
timestamp: October 14, 2017, 08:52:26 pm
content: Go to this address on your phone, if its an android phone it will give you the option to install it.https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2If its an iphone it looks like it costs $3https://itunes.apple.com/us/app/gps-status-toolbox/id1198499960?mt=8As for the laptop, fine have it folded in your bag as your about to board with the gps mouse sticking out the zipper.The threat of theft is fairly low where i live so i dont normally think about that angle.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 14, 2017, 09:03:27 pm
content: Here are all files I record: publictransportforum.at/images/extern/GPS_Log_Wien_Graz_Feldkirch_Wien.rarQuoteIt is there want to login wo something I never saw before.QuoteThe HDD get damage when I move my backpack.QuoteIts very dangerous to have something bigger in the Hand like a laptop or a tablet the could grabbed very easy and the can run away with.

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 18, 2017, 11:16:10 am
content: Does anyone here look into the GPS Recording?

author: 4CX35000
author_rank: Regular Contributor
timestamp: October 29, 2017, 09:07:12 am
content: Quote from: Lord of nothing on October 18, 2017, 11:16:10 amA few year back at work we had to record GPS position various data surveys and that used a Garmin GPS60 with the USB interface and external antenna. From what I recall the output would be recorded to file in CSV format with other data from a GSM receiver. CSV was used as it is the most widely compatible format and efficient for storing data we required at the time.The Garmin GPS60 can record the data into its internal memory. The storage contained the normal altitude, longitude, and latitude data in various intervals from 1 second upwards. The downside from what I recall was the internal memory was only 1MB, so the data interval needed to be 3 seconds or greater to allow the Garmin to be used for a full working day. I don't recall how the data was downloaded, but it was possible to save it as a text file or CSV and open it in Excel, whilst the output format location (Northing/Eastings or Degree's decimal) was dependant upon the setting within the software/firmware

author: Rerouter
author_rank: Super Contributor
timestamp: October 29, 2017, 09:18:31 am
content: The recording is just a serial dump of nema strings, Its a bit more than i am willing to decode myself, It opens fine in notepad ++,

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 29, 2017, 09:21:18 am
content: I used GPSBabel as converter to Google KML File. I had to Select "NEMA...." as original Format.Ublox Software Write some Debug Information into the File.Are anyone interested in the other Recordings?Does anyone here have experience with GPS Data Analyse?

author: 4CX35000
author_rank: Regular Contributor
timestamp: October 29, 2017, 10:13:58 am
content: Quote from: Lord of nothing on October 29, 2017, 09:21:18 amI recall it was possible to download the data from the GPS60 into various different formats and also possible to import the data into Google Earth and show the individual points on Google Earth and export the file as a KML file. In Google Earth the data was shown on the map as a selection of continuous dots were the GPS data was recorded on the route and these could be manipulated as you require. I don't recall there being any need to convert the file into any other format, but it was 10 or more years ago when I worked on this and I have forgotten much of the inner detail.At work we only ever used Google Earth and I think a program called MapSource to check the route against the map. The important data for work purposes was data required the GPS data alongside GSM signal strength and GSM quality data for propagation prediction purposes, so a HP iPaq was used to interface with a Ericsson GSM transceiver and the GPS60 to produce the data file we needed.You can buy external antenna which can be mounted internally on a car window, so it might be worth looking at one of these antenna and mount the antenna using suction cups to the train window.Whatever method you decide to use, the file result will be a file with individual timing/locations points were the GPS unit has recorded Time, Date, Latitude, Longitude and Altitude.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 29, 2017, 10:37:02 am
content: Quote from: Lord of nothing on October 14, 2017, 09:03:27 pmThat's a pretty sad statement of affairs. Is it really that bad?

author: Lord of nothing
author_rank: Super Contributor
timestamp: October 29, 2017, 11:25:32 am
content: QuoteNot that bad as in Italy, Spain. It depent on the Date and Time and the Railway Station. Onboard the 1Class is quite safe.Thanks you Mrs. Merkel.QuoteI on the most Trains I tried to get a good Signal just the Railjet failed totally.After some Minutes without a Signal the Receiver or the Software drive insane and I get no signal anymore.

author: NivagSwerdna
author_rank: Super Contributor
timestamp: October 31, 2017, 04:01:46 pm
content: Quote from: Lord of nothing on October 29, 2017, 11:25:32 amI'm increasingly glad we have a moat.

author: cdev
author_rank: Super Contributor
timestamp: October 31, 2017, 11:41:48 pm
content: GPSBabel is the way to go for GPS log file conversion on all sorts of computers.http://www.gpsbabel.org/GPSBabel is FOSS and doesnt connect up to anything external.Many GPS data loggers log in the GPX data format. Thats likely the best all around format for that kind of thing.GPSBabel can turn your track logs into KML files that can be imported into Google Earth.

author: cdev
author_rank: Super Contributor
timestamp: October 31, 2017, 11:45:49 pm
content: I have a bunch of USB GPS's they all will store the so called ephemeris data for a while after they have been used, basically what I mean is use it a bit before you travel, like that same day.Don't completely "cold start" it, because almost any GPS will have issues if you cold start it in a basement..or a metal box..Behind mirrored glass in a metal train car is probably similar.

author: Lord of nothing
author_rank: Super Contributor
timestamp: November 01, 2017, 10:16:37 am
content: But why does it drive insane after some short Signal Loss?

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 27, 2021, 04:34:07 pm
content: dont worry normally there is an Public Announcement before you reach the Station.You can also use for Austria fahrplan.oebb.at .

author: radiolistener
author_rank: Super Contributor
timestamp: July 28, 2021, 02:20:45 am
content: Quote from: Lord of nothing on October 04, 2017, 12:09:24 pmJust install GPS antenna outside a car or a train and it will works