TV Reception

[Grumpybear]

A cry for help.

When staying overnight on board in our marina, we sometimes try to watch TV using a yagi antenna on a pole attached to the pushpit. However, as the boat moves slightly on her warps, the reception varies drastically. Can anyone recommend an alternative aerial which could be attached, either permanently or temporarily, to the pushpit? We want to avoid the up-the-mast option.

 

[philip_stevens]

We've got a basic Omnimax wire type aerial mounted on a pole at the pushpit, with a 12v amplifier inside the boat.

This feeds a Freeview box and then onto a TV. The reception is generally very good - but depends on the aerial being able to get a good signal. The boat swinging on the mooring makes no difference to reception, other than when the mast may swing across the signal path.

The Freeview, when there is a half decent signal gives far better picture than without the Freeview - i.e. just an analogue signal.

 

[wooslehunter]

It really depends on what the signal level is in the area you are in. I'm no expert on what's actually available but it may be worth trying the caravan shops.

I do know about antennas though so here's the theory. All antennas including yagis are rather like magnifying glasses. The higher the magnification, the smaller the are they cover. If you have a weak signal level, you will need a high gain antenna which will have a very narrow beam width. hence if it moves slightly off you will lose the signal. However, if you are in an area where there is a good signal, you should be able to get away with a lower gain antenna. This will have a wider beam width and be less susceptable to mevement.

If you are receiving digital TV you'll need a higher signal level anyway.

So, try an antenna with less gain. It'll be smaller & have fewer elemets. You may get away with one of these on its own or add an antenna amplifier. If you are suffering from movement problems then putting the antenna up the mast may give a better signal but have far more movement.

 

[kengill]

I opted for the up the mast vroute and it's been absolutely brilliant. Status aerial on a glomex strut just below the tri/anchor. works perfectly when swinging to an anchor and you don't have to keep rigging and de-rigging. Gives superb FM reception as well for some reason.

 

[William_H]

Wooselhunter explained the yagi very well. You may find it convenient to remove some of the elements of the yagi. ie the ones at the front. This will reduce the gain and directivity a little which may be an easy fix for your problem. All of the boat/caravan antenna are designed for all round reception (omni directional) which reduces their sensitivity or gain so they usually include an amplifier to try to recover signal.
You could look for an amplifier from Maplins RS etc to try on your yagi and or try one of the omni directional antennas.
An antenna up higher will give more signal so directivity may not be so much of a problem with the yagi. good luck olewill

 

[Tomsk]

I saw a wonderful idea last year, and after suffering cronic reception for a couple of years gave this a try - life has been superb since. Place antenna in a flower hanging basket, tie a supporting length of rope (about 18") around back or forestay and hoist up on halyard. Can be removed in two mins. Works a treat! A downhauld can also be used to tension in a blow.

Happy viewing! /forums/images/graemlins/grin.gif

 

[Grumpybear]

Thanks everyone. An assortment of things to try when it stops snowing (outside, not on the screen)

 

[bob_tyler]

Now try to find a decent programme to watch!