FlightAware Discussions

Antenna Location on Stats Page

How important are accurate details of antenna position on statistics page?

Whilst Google Maps is a great tool I’m not sure how accurate their Lon/Lat positions are, plus I’m guessing the height above sea level is again relying on internet data.

I’m doubting the aircraft positioning is dependent on PiAware owners accuracy of data input so am wondering; what is the importance (or not) of the antenna position data?

Geoff

Multilateration needs an accurate position (ideally <10 meters, but it’ll tolerate worse). The height component is less critical.

ADS-B positioning does need to know receiver location in some cases, but only at a very coarse level - anything within 50 miles is fine.

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Thank you for very prompt reply.

I did enquire once about a portable PiAware system where I forgot to disable mlat. It was suggested that mlat would be ignored during synchronisation if positions were wrong.

So <10 meters ideal, I’ll check mine again for accuracy.

Geoff

Don’t forget you can use a GPS/GNSS dongle for portable setups. It just needs to work with GPSD.

Are the FlightAware tuners compatible with GPS/GNSS ?

Not something I’ve looked in to. Only couple of times took the Pi out for a ride in the car :wink:

Geoff

Don’t you have a smartphone?
Look for “GPS Test” apps, they’l give you accurate position of the phone (like 4 meters horizontally in my case) - just be close enough to the Pi antenna.

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I believe building a GPS soft receiver with a rtlsdr dongle has been done (with a lot of work), but that’s not what you want to do; just go get a cheap dedicated USB GPS receiver.

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Thanks, I’ll give that a look.

My phone signal erratic where I live, usually I just enlarge Google map, plonk the pointer where my home appears to be and take that reading. Sometimes though following someone on a live location they suddenly appear to be in a field (hope not) then back on the road again.

Geoff

You don’t need a phone signal to use the GPS - the internal gps will be accurate to within a couple of meters once it has settled. The reason you see people in locations like fields next to the road is because phones can determine their location by looking at the wifi network and cell towers they can see. This isn’t as accurate as gps, but requires less power than activating the gps chip and is sufficient to maintain a general location for things like weather updates that don’t requite the precision of a proper fix.

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The mysteries of mobile phones. What I have noticed is that if I want to send someone a specific location on whatsapp, eg wallmart, sainsbury, Regents Park it doesn’t seem to list specific places unless I have wifi enabled. Then it does.

I did know they used wifi, hence getting a location indoors, wasn’t sure how the mobile actually got its location, whether GPS, wifi or a mixture.

Geoff

That’s because it requires some reference to be able to tell you what is nearby. The GPS will provide a latitude/longitude fix, which is very accurate but by itself not particularly useful. The utility comes when you reference that position against something else like a map or a database of points of interest. In most cases this will not be stored on the phone, but have to be retrieved by the internet, either via mobile data or wifi. Some apps will cache this information (eg google maps can save data for use when offline), and others will need an active connection to work.

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