[TG] [TG11] Ais 700 "saw "targets only 0.3 nm range

[Tom - Raymarine - Moderator]

Hello Antonia and marlahe,

VSWR readings of 1.6 and 1.5, measured at the AIS, are good values. They don't tell you for sure that the antenna is actually radiating the power effectively as radio, but they do tell you that the AIS's output power will effectively be transferred into the antenna.

How are your AIS's transmit ranges? If you check with other boats, how far away can they see you? If your transmit range is good but your receive range is poor then interference is a likely cause.
Before you think about removing anything from the boat though, try powering the AIS off a separate battery (e.g. a smaller 12V motorcycle battery) with the boat's main battery isolators off: if the AIS works well then and gets good receive range, interference is the cause. If the performance hasn't improved then interference is either caused by something powered straight off the battery or the problem isn't interference.

As another alternative, you could have a technical Service Dealer check with an RF analysis tool (here in Australia we recommend our dealers use a type of low-cost portable spectrum analyser called RTL-SDR for this sort of testing) to identify noise levels and sources.

Regards,
Tom