/// <summary>
        /// Compute the position given the receivings
        /// </summary>
        internal static Position triangulate(List <Packet.Reception> receivings, DateTime receptiontime)
        {
            Position p           = new Position(Vector2D.Zero, receivings[0].ReceivingStation.location.room);
            Vector2D accumulator = new Vector2D(Vector2D.Zero);

            p.positionDate = receptiontime;
            String tag = "";

            if (receivings.Count() > 2)
            {
                double minrssi = 0;
                double avgrssi = 0;
                double vote    = 0;
                foreach (Packet.Reception pr in receivings)
                {
                    tag     += (Environment.NewLine + pr.RSSI + " " + pr.ReceivingStation.NameMAC);
                    minrssi  = pr.RSSI < minrssi ? pr.RSSI : minrssi;
                    avgrssi += pr.RSSI;
                    double weight = Math.Pow(Math.E, (pr.RSSI + 25) / 10);
                    accumulator = accumulator.Add(pr.ReceivingStation.location.MultiplyScalar(weight));
                    vote       += weight;
                }
                avgrssi    /= receivings.Count();
                accumulator = accumulator.DivideScalar(vote).Clip(Vector2D.Zero, p.room.size);
                tag        += Environment.NewLine + "avg: " + accumulator.X + " " + accumulator.Y;
                if (avgrssi < -105 || (avgrssi < -90 && minrssi < -70))
                {
                    p = new Position(0, 0, Room.externRoom);
                }
                else
                {
                    if (receivings.Count() == 3)
                    {
                        Vector2D tr = triangulate_circles(receivings);
                        if (tr != null)
                        {
                            //tag += Environment.NewLine + "tri: " + tr.X + " " + tr.Y;
                            accumulator = accumulator.MultiplyScalar(0.87).Add(tr.Clip(Vector2D.Zero, p.room.size).MultiplyScalar(0.13));
                        }
                    }
                    p._Import(accumulator);
                }
            }
            else
            {
                p.uncertainity = UNCERTAIN_POSITION + 1;
            }
            p.tag = tag;
            return(p);
        }