Poor gps signal

[miles from the sea]

I was sailing out from the Orwell this week using the Navionics app and noticed that the gps was frequently dropping, out sometimes for a few minutes. I thought this was a fault with my new ipad but found it was happening on my iphone also. Strangely the signal was not always dropping from both devices at the same time suggesting they had locked onto different satellites. Typically the loss of gps would coincide with weed sending the echo sounder bonkers which was not great when short tacking up a river. I also noticed that the radio took a long time to establish a gps position. The safe trx app worked fine on Tuesday but seemed only record the start and finish on Wednesday and Thursday which is concerning. It may have just been due to the atmospheric conditions but has anyone else experienced these problems? I would suggest checking the robustness of your gps system before getting into a position of really needing it.

 

[Gargleblaster]

What was the cloud cover like. I find thick cloud can greatly affect a GPS signal.

 

[xyachtdave]

Anyone know what the quality of the GPS is in a phone or ipad compared to say a Garmin handheld GPS?

 

[shanemax]

It was probably a Russian attack submarine, directly under your boat, hiding in the noise from your wake and using GPS counter measures.

 

[AntarcticPilot]

I think there's high solar activity, which will interfere with GPS.

 

[Gargleblaster]

Anyone know what the quality of the GPS is in a phone or ipad compared to say a Garmin handheld GPS?

That is an interesting question. I use two hand held Garmin GPS as my main means of navigating. My Garmin 73 which is linked to my VHF and resides in my cabin picks up the satellites in seconds. My Garmin 60 which I keep in the cockpit takes up to 15 minutes to find all teh satellites. That 15 minutes is usually when I haven't turned it on for some weeks.

Oh and my mobile phone inside the house, car or boat seems to find itself in seconds as well and I only use the GPS for a limited number of apps such as tide times or maps. But then I think Goog;le might leave it turned on without me using an app that I have authorised to know my position.

 

[The Q]

The American military do interfere with GPS, if they have a vessel in the vicinity.
Iirc last year they had a carrier in the Clyde moored for some time and in the area around it they stuffed GPS.

I wouldn't be surprised if their air force do something similar, especially if air force trump goes flying by.

 

[bluerm166]

Yes I had a garmin 73 which picked up very rapidly including from most spots inside the cabin.
I think most phones have good gps reception because a) you need to navigate at speed when driving and b) they are definitely keen to get your location for advertising purposes.

 

[MikeBz]

Mobile phones also use the mobile signal and WiFi to improve positional accuracy when GPS signal is poor.

 

[AntarcticPilot]

Mobile phones also use the mobile signal and WiFi to improve positional accuracy when GPS signal is poor.

More than that, they use something called A-GPS to acquire ephemeris data over the internet rather than by downlink from the GPS satellites. This speeds up signal acquisition substantially. Also, the rough position provided by the phone network is good enough to shorten the initial position finding. They can only do this where there is a phone or wifi connection.