VHF and AIS unit physical separation

[alexhibbert]

Hi,

Does anyone know if there's a rule of thumb for how close together a fixed VHF and AIS transponder can be mounted, without causing each other issues? I presume you should keep both a distance from any compasses.

To clarify, the units themselves and not the antennas.


Any other mounting tips welcomed too.
Thanks.

 

[Jamie Dundee]

I’ve got a Simrad RS40B where the vhf and AIS are built into the same unit. I’ve also got an Emtrak transponder sitting 3’ from the vhf, no problems.

 

[geem]

I’ve got a Simrad RS40B where the vhf and AIS are built into the same unit. I’ve also got an Emtrak transponder sitting 3’ from the vhf, no problems.

AIS unit and vhf about 150mm apart. Separate antenna on mizzen spreaders. Range on transmit over 13nm

 

[Bilgediver]

AIS unit and vhf about 150mm apart. Separate antenna on mizzen spreaders. Range on transmit over 13nm

Although you might not hear a problem on the radio from the low powered transmissions of the AIS it is possible that the higher powered transmissions of the radio have an effect on the reception of the AIS if the antennas are too close together , causing some data to be lost and some updates not received and displayed.. DO the reception leds on the AIS come on when the radio is transmitting. Mind you it is possible that they only come on when data is being decoded and the interference may be seen as noise and not detected but still affecting reception.

 

[Boathook]

Raymarine AIS a few inches below an Icom VHF. Nothing in the manuals I seem to remember about separation distance of the units.

 

[Refueler]

The base units themselves are fine next to each other.

But the antenna's need to be at least 2m (6ft) apart in all directions ...... the further the better.

 

[geem]

Although you might not hear a problem on the radio from the low powered transmissions of the AIS it is possible that the higher powered transmissions of the radio have an effect on the reception of the AIS causing some data to be lost and some updates not received and displayed.. DO the reception leds on the AIS come on when the radio is transmitting. Mind you it is possible that they only come on when data is being decoded and the interference may be seen as noise and not detected but still affecting reception.

Possible but I don't sail in the Solent so the radio is rarely used. It's only listening

 

[Refueler]

Possible but I don't sail in the Solent so the radio is rarely used. It's only listening

Good point ...

Lets be honest - how much actual time spent on the VHF ? Even if a prolific user - it will still not change what AIS gives ...

Also the antenna cable is a shielded cable - designed specifically to 'contain' RF ...... its internationally as well as CE / UL / BS specification to maintain RF integrity ....
The radio itself is subject to strict specifications similarly. Its only really when users fail to install connectors properly that any chance of problem could appear.

 

[PaulRainbow]

Although you might not hear a problem on the radio from the low powered transmissions of the AIS it is possible that the higher powered transmissions of the radio have an effect on the reception of the AIS causing some data to be lost and some updates not received and displayed.. DO the reception leds on the AIS come on when the radio is transmitting. Mind you it is possible that they only come on when data is being decoded and the interference may be seen as noise and not detected but still affecting reception.

This is all incorrect. There is nothing wrong with installing an AIS close to the fixed VHF, it's the antennas that must be kept apart.

 

[Bilgediver]

This is all incorrect. There is nothing wrong with installing an AIS close to the fixed VHF, it's the antennas that must be kept apart.

Thanks Paul... Some words were left out as brain ahead of fingers. Now corrected. I was only discussing transmissions from antennas.

 

[Refueler]

There is always 'leakage' of RF ..... so inevitably one will have a slight effect on other - but based on CE and other specifications - such leakage etc. is to be contained within the unit ...

 

[alexhibbert]

Thank you team!