Question

I’m currently using the GeoCordinateWatcher which abstracts away the information used to retrieve the position and speed it provides a status (disabled/ready/nodata/initializing) but that’s all.

I’ve seen a few apps such as RunKeeper that have a GPS signal strength indicator but I wasn’t sure whether that was accurate or whether it was calculated based on the HorizontalAccuracy property of the GeoCordinate

NOTE: I have read this link:
How to read GPS signal strength in Windows Mobile?

But this is dealing with WP6.5 and I don’t think helps on WP7.

Answer 1

Speaking from experience (as the developer of the RunKeeper Windows Phone app), you can’t access the GPS signal strength directly, but you can use the HorizontalAccuracy to display a relative strength indicator.

I use Rx Extensions to provide an observable position stream on the GeoCoordinateWatcher, then create an observable accuracy stream on top of that, so that I can subscribe to accuracy changes separate from position changes (rather than having to check and update on every position).

// Extension method.
        public static IObservable<GeoPositionChangedEventArgs&lt:GeoCoordinate>> GetPositionChangedEventStream(this GeoCoordinateWatcher watcher)
        {
            return Observable.Create<GeoPositionChangedEventArgs<GeoCoordinate>>(observable =>
            {
                EventHandler<GeoPositionChangedEventArgs<GeoCoordinate>> handler = (s, e) =>
                {
                    observable.OnNext(e);
                };
                watcher.PositionChanged += handler;
                return () => { watcher.PositionChanged -= handler; };
            });
        }

// Usage:
        var positionStream = this._watcher.GetPositionChangedEventStream();
        var accuracyStream = positionStream.Select(p => p.Position.Location.HorizontalAccuracy);
        ...
        accuracyStream.Subscribe((accuracy) =>
            {
                // Do something with the accuracy.
            });