The best Antenna for Receiving the GNSS Systems? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 10, 2018, 01:56:26 pm
content: HiI need the Map my own Railway Map. The former Federal Railway refuse to give me the Permission to use there Data.So I need to Map the Track my own with a hight accuracy. I try to use my Cellphone for Tracking and the results are worse.up 150m off Railway Track!!!I got 2 different Cheap Ublox Receiver with an internal Antenna I will try in Local Railway Cars but I guess the dont perform that better. The Main problem when the Train leef the Tunnel with 230kmh (sure on long distance trains) the Receiver crash and output no data. I have to unplug it.So can someone recommend an Active Antenna who give the best results are possible?Thanks!

author: E Kafeman
author_rank: Regular Contributor
timestamp: September 11, 2018, 07:55:36 am
content: 100 mm average accuracy is possible with dgnss but require both good antenna and good receivers.Best antenna, ie allowing for most precise measurements, is something with integrated receiver and with an antenna radiation elevation optimized for your location and with a pure circular polarization within whole that elevation angle.Car mounted solutionHand held gnss with RTK correction.Antenna most be located such that false reflections are avoided. Big buildings are common to create false reflections. As long as number of received satellites are many enough can false signals be detected and excluded by software. Antenna reflections do also change direction of polarization rotation, why antenna should be selected such that wrong polarization is suppressed.Dead counting using electronic compass and multi-axis accelerometer while no gnss signal is available such as driving in a tunnel will cause drifting of real position more and more with time but it is normally not a big problemMy car navigation system have no problem with navigation even after been parked over night in multi floor underground garage. Location error next day is typical 10 meter, ie I can easily see that I am driving in correct direction while still underground.For increased long time stability while doing dead counting is it common to add an electro-mechanical gyro in ships and airplanes.A modern cell phone with multi system GPS/Glonass/Galileo and smart software should be able to deliver good accuracy within few meter during travel up to 500 km/h but height can show a rather big error, depending on environment.Your Ublox units can maybe be programmed to be RTK compatible.Replace each PCB-mounted antenna with something likethis.

author: hagster
author_rank: Frequent Contributor
timestamp: September 11, 2018, 08:31:47 am
content: I presume you are trying to do this as a passenger on a normal train.If so, it's never going to work well. You need clear line of sight to all satellites used for the position solution. To get this you would at minimum need the antenna to be on the roof of the train, otherwise the signals you receive will always have bounced off various internal and external structures to get through the train windows.Any reason you can't use Google Earth and just plot the track from the imagery?

author: coppercone2
author_rank: Super Contributor
timestamp: September 11, 2018, 04:09:11 pm
content: the glonass system makes me think of seaweed ass.