Most installations are somewhat fixed in location, however when the installation is on a Yacht, that can be a problem for providing maintenance and service.
This particular installation went very well whilst the yacht was being fitted in Southampton, however after being sailed to the Mediterranean and lived on for a while, some problems were discovered with the system.
The Yacht has four music zones using the Linn DS digital streaming players. supported by a WiFi router, managed switch and ripping NAS drive. Internet connection is provided by a separate GSM/WiFi router. This works well when playing music from the Hard Disk, however The system is enabled for Airplay, and problems occur when playing songs from a connected iPhone via Airplay. The dreaded jittering occurs, and then connectivity is problematic causing zones to disappear from the list, and control to be intermittent driving everyone involved crazy.
To investigate this we flew out to where the yacht is moored for the winter in Turkey, and spent a day checking the system. The WiFi router was replaced by one recommended by Linn, and the WiFi signal strength around the Yacht measured using a WiSpy dongle connected to a Laptop. Moored on the crowded quayside, there were dozens of WiFi signals from neighbouring Yachts, local bars and restaurants, but these didn’t seem to be crowding the bandwidth as they did not have much traffic. We looked for interference from other equipment on the yacht (e.g. inverters, navigation aids, radio, radar telephones etc., but could not find anything obvious. The main culprit simply seemed to be signal strength.
It seems that Airplay likes to have a really strong signal to work reliably, and that Glass fibre is very good at soaking up WiFi signals. There is a drop off in the WiFi signal at the foredeck and aft swim platform, that is sufficient to upset Airplay from these areas, and this is further exacerbated when there is no connection to the Internet, as it seems the Apple IOS devices get upset by a lack of internet connection causing Airplay to sometimes be intermittent.
We determined that the drop in WiFi signal by about 10dB between the main saloon and the foredeck was enough for Airplay to become jittery, and came up with two simple ways to improve the signal:
- Raise the WiFi router / antennas up
- add directional antennas to the router pointing fore and aft
We could also change the WiFi router for a managed SME style WiFi system, however this would mean significant work and cost to install the cables, WiFi Access points and network management processor required.
We predict an 18dB increase in signal strength as a result of the two simple moves, which should be enough to get sufficient strength and hence bandwidth for Airplay to become reliable again. The router has three antennas arranged as 1 transmit, and two receive antennas for signal diversity. By replacing the receive antennas with directional ones, we should get a far better path from the portable device to the WiFi router. The next problem is how to find directional WiFi antennas in a sleepy seaside resort town out of season within a few hours. This proved too hard, so we determined to supply the necessary parts to the Skipper for him to install in a coupe of months ready for the next season.