Weak AIS Signal?

[a64pilot]

I’d agree that most splitters do attenuate the signal, and if it’s just a splitter, it has to.
However the Vesper splitter is different, it’s not just a splitter Read the advert, plus that has been backed up by observations here
https://www2.vespermarine.com/antenn...splitter-sp160

[CaptTom]

Originally Posted by a64pilot

I’d agree that most splitters do attenuate the signal, and if it’s just a splitter, it has to.
However the Vesper splitter is different, it’s not just a splitter Read the advert, plus that has been backed up by observations here
https://www2.vespermarine.com/antenn...splitter-sp160

Interesting. I use a dedicated AIS antenna for my XB-8000. I wonder if there would be any benefit to a device like this which adds a "low noise amplifier."

[a64pilot]

Originally Posted by CaptTom

Interesting. I use a dedicated AIS antenna for my XB-8000. I wonder if there would be any benefit to a device like this which adds a "low noise amplifier."

Maybe, but would it be worth it?
My bet is that any difference would be insignificant, maybe a real radio nut would appreciate it, but most of us that just use the the things and aren’t tweaking every last dB possible for the enjoyment of just doing so would be wasting our time and money.
My mentor as a test pilot had a saying I liked, “Perfection is the enemy of good enough”. Sometimes good enough, is all that is needed.

Or said another way, if there was a big difference of having the amplifier, wouldn’t there be one in the Vesper to begin with? Maybe the amp is more about preventing excess loss?

[ka4wja]

Oh goodness....there is way too much to cover here, to give detailed answers to everyone, and I don't know where to start!


FYI, most VHF installs (VHF-FM Voice and VHF-AIS) see seriously improved coverage when old cable / connectors (and masthead antenna) are replaced....'cuz old cable can be lossy and old connectors are notorious for causing major issues / losses!
Many sailors that do this with "low-loss" cable, rave at the results, thinking it's due to the "low-loss cable", when most of the time it is due to NEW cable and connectors!


BTW, please read these threads linked/referenced below!!
For lots of details!
(and ask questions there, and/or in a new thread)

And read these brief answers here:

1- Old coaxial cable and old connectors are fraught with issues and should be replaced!

2- Corroded connections are always a problem!! Replace them and the cable, as moisture has wicked into the cable and increased its loss, as well as made properly securing the connector darn near impossible!!
(in an emergency you can try cleaning them, but you should just replace them and the cable!)

3- Old VHF antennas (> 5 to 6 years) are suspect and should be looked at...
Really old VHF antennas (> 10 years old) should be replaced!!


4- Most sailboat VHF installation designs assume approx. 3db of coax loss...and while less is better, please do not be lead down the path of thinking that reducing your loss by 1db or so will make any significant difference. It won't!
{This means use RG-213, or RG-8x (mini-8), coax...or if you're a fanatic like me, and are using a low-loss AIS splitter (like the SP-160) and cannot fit RG-213 in your mast conduit (as I cannot), you can use LMR-240uf, to compensate for the loss in the splitter...but no need to go crazy here, do NOT spend the money and frustration using larger cables, like LMR-400uf!!}
Bottom line, use RG-213 or RG-8x (from a name-brand company, like, Belden, Commscope, Times, Davis, etc...), with properly installed connectors, and you'll be fine!!


5- Properly installed connectors!!
That means buy pre-made cable assemblies or have a professional install the connectors for you! (do not let just some "marina maintenance guy" do this, as it takes someone that knows what they are doing!!)
And, while professional crimp connections are fine (professionally or properly installed of course), please do NOT use those "marine store crimp-on connectors!! Ever!


6- If your AIS system is working fine for you, do not think that "adding a splitter with a pre-amp" will be better...it probably won't (unless you have a problem with your system now)
The "pre-amp" in the splitter is there to compensate for the loss of the splitter, and while it can "theoretically" improve the receiver noise figure, it actually won't as AIS transponder's receivers are already as good as they are going to be...trust me, been doing this for ~ 40 years, and continue to keep up with current state-of-the-art!


7- Separate antenna for AIS is fine!!


8- Antenna separation is VERY important...
I recommend vertical separation....and usually 3' - 6' is good...
But, if you think you can mount them next to each other (not recommended), you will need to keep them separate by at least 6'...
{yes, you may get away with some closer spacing, but at your own peril!!}


9- If you need the range (most do NOT) for offshore voyaging in heavy weather (most are NOT doing this), then using your masthead VHF antenna with the Vesper SP-160 "Splitter" (splitter/relay/pre-amp), is an excellent choice....as this gets your AIS signal out from the wave troughs in heavy seas (and if heeled over, even more so)...
But, FYI, as stated above, a separate antenna is fine and good for most.


10- There is nothing wrong with a good antenna and one that provides a good match (low VSWR) across the whole VHF marine band (including the AIS frequencies), but be aware that it usually isn't critical !!
With most sailboat VHF antenna installations, you do NOT need a "specially tuned AIS antenna"!!

Yes, if you're buying a new one, and/or your present VHF antenna is like 10+ years old, it should be replaced anyway, so....it is recommended to get one that works well across the entire VHF marine band, including the AIS freqs near the top end of the band....but if you have a "newer" VHF antenna, it is usually not necessary to have one specially tuned for AIS!

{note this is due to two factors:
1- most VHF installs have enough cable loss to mask slight VSWR issues and not recognize any issue...
2- most sailboat VHF antennas are broadbanded enough to cover the entire band with VSWR's of ~ or < 2:1, which should not cause any AIS transponders to reduce power..}

In the US, Caribbean, and in some of the rest of the world the most ubiquitous sailboat VHF antenna is the Shakespeare 3' SS whip on the masthead...(in EU and Aus/NZ, I know there are other brands that are popular)
5215 Classic AIS Squatty Body® Antenna | Shakespeare Marine Antennas

And, please forgive my bluntness here:
In our world of VHF marine comms, any 3' to 4' long vhf antenna, as long as it is from a known-good manufacturer (well-made), and securely installed, will perform the same no matter what "design", no matter what "color", etc....
Buy a Shakespeare 5215, or an equivalent from another well-known manufacturer, use good quality cable and connectors, and you'll be fine!!
There is NO need to obsess over this....all 3' to 4' long marine VHF antennas are all "1/2-wave antennas" and are not "loaded", etc...
Buy a new one, use good cable and connectors (properly installed), and you're good-to-go!!




With all the recent talk of AIS issues, I suspect many sailors might not be grasping the details of antennas, coax losses, "splitters" (relay/splitter/pre-amp), radiowave propagation, etc., so I thought it might be good to address the specifics again??

While there are a lot of details in these thread that can of great help to some, others may find it to be overwhelming...
Sorry about that...
Just read what you can.
But, please do have a look!! You will learn a LOT!

http://www.cruisersforum.com/forums/...ld-130803.html

http://www.cruisersforum.com/forums/...ge-149499.html




I hope all the above helps!


Fair winds.

John

[theway]

Originally Posted by transmitterdan

I thought those units gave an actual number for VSWR. I must have been thinking of a different brand. Just saying "OK" is less helpful in this situation.

Sorry, the image shows
“Less than 3:1”

[theway]

Originally Posted by DavefromNZ

I had exactly the same problem. I knew the signal from my yacht was very poor as I tried to satellite track her plus it was average around the coast. The problem was simply that I was using a splitter through my VHF aerial. If you want to fix it then get a proper AIS tuned aerial and fit it on your top spreader. It must not be at the level of your VHF aerial as that can cause interference. It does not have interference even though close to a stay.

I am now tracked 100% by SAT AIS and I see big ships 80nm away. Aerial set at about 60ft. The signal is very strong.

I know it is a hassle to fit a new aerial but a splitter is poor.

Wouldn’t this not be the fix, because I already tried going straight into the XB8000 from antenna? Unless it’s the properly tuned aerial that’s the solution.

Thanks for the info.

[ka4wja]

Going to try this again.

VSWR on most Marine VHF systems (AIS or Voice) will not be an issue....there is usually enough coaxial cable loss to reduce / "mask" the real VSWR at the antenna to an acceptable level once measured down below.

You do NOT need to worry about a "properly tuned aerial"....please read the material provided.

{FYI, I have seen VHF systems show an acceptable VSWR on the meter in the cabin, with NO antenna connected at the masthead at all! And, while when the antenna was attached, the VSWR measured in the cabin, was darn close to perfect....but the system does not work well at all...'cuz there is effectively no antenna at all!! Please understand that a "good swr" tells you next to nothing when you have substantial coaxial cable losses between the meter and the antenna!}

Please read the previous info/recommendations posted, the answers are there!! a
And read those other threads. Please!
(and, replace your cable, connectors and antenna....I know, I know, you don't replace stuff just to see if it will work... But, your own words say things aren't working, so you cannot say "if it ain't broke, don't fix it"...'cuz it is broke!)

I wish you all the best....I've done all I can...fair winds.

John

[terah]

@ka4wja Any guidance on connectors if a professional installer is not available?

[ka4wja]

Terah,
As I have no idea what cable you have, nor what issues you're having, I can only give you generic answers, based on my experience over the past 40 some years...and, these are based on US suppliers...

Originally Posted by terah

@ka4wja Any guidance on connectors if a professional installer is not available?

I do not have any personal knowledge/experience with UK suppliers/vendors...


I think there may be some here that might have some UK sources, etc...
And, hopefully Bill (btrayfors) will chime in too!!


1) First off, although for many years I clung to my traditions of using only Amphenol 83-1SP connectors (solder-type, silver-plated PL-259's)....but, over the years I've been convinced that high-quality crimp (and/or crimp + solder) connectors are best in most applications, including on-board boats (especially in environs where soldering can be difficult)
Modern crimp connectors also makes proper installation of connectors easier for laypersons....but more expensive!


2) Secondly, if you are unwilling to spend the $$$ (or GBP) necessary for the proper tools, then just buy pre-made cable assemblies / jumpers, using good-quality cable and connectors, from know-good / reputable suppliers...
(or hire a professional!)


3) Here are some links to my two favorite supplies (in the US, but they should be able to accommodate shipping to UK, etc.)

DX Engineering
https://www.dxengineering.com/

Texas Towers
Texas Towers, Home Page


4) The exact connectors and tools needed, depend on the cable you have....but since you didn't mention what cable you have, I cannot give you any specific recommendations...
So, in general:

DX Engineering Cables
https://www.dxengineering.com/search...2%2B4294952392

https://www.dxengineering.com/search...rder=Ascending

https://www.dxengineering.com/search...2%2B4294951385


DX Engineering Connectors
https://www.dxengineering.com/search...rder=Ascending

https://www.dxengineering.com/search...rder=Ascending


DX Engineering Tools
https://www.dxengineering.com/parts/dxe-ut-crmp2

https://www.dxengineering.com/parts/dxe-ut-crmp2-8x

https://www.dxengineering.com/parts/dxe-ut-405c-p1

https://www.dxengineering.com/parts/dxe-ut-240c-p1



Texas Towers Cable
Texas Towers, Coaxial Cable Page

Texas Towers, Coax Jumpers Page


Texas Towers Connectors
Texas Towers, Coax Connectors Page

Texas Towers, Coax Connectors Page


Texas Towers Tools
Texas Towers, Coax Tools Page



Hope this helps some.

Fair winds.

John

[JPA Cate]

The way,

I think if you follow John's advice about replacing the coax and the antenna, your situation will improve substantially.

The reason to use pre-made connectors is because it is fiddly to do your own, and easy to not do it right.

Ann

[Dsanduril]

Here in Oz the easiest place to find PL-259s is JayCar Electronics, if you're heading north from Coffs there are about a dozen branches, some even near the water, in the greater Brisbane area. They have both cheap (bare copper) and moderate quality (tinned copper) coax cable.

You can also try Whitworths, they have both connectors and cables but as a marine shop they are a little dear.

If you have access to a vehicle then RF Solutions in Albany Creek (NW Brisbane, not close to the water) is probably the best overall shop.

[theway]

Originally Posted by Dsanduril

Here in Oz the easiest place to find PL-259s is JayCar Electronics, if you're heading north from Coffs there are about a dozen branches, some even near the water, in the greater Brisbane area. They have both cheap (bare copper) and moderate quality (tinned copper) coax cable.

You can also try Whitworths, they have both connectors and cables but as a marine shop they are a little dear.

If you have access to a vehicle then RF Solutions in Albany Creek (NW Brisbane, not close to the water) is probably the best overall shop.

Thank you much for the info. I’m going to be stopping into BoatWorks soon and getting this and many other things tested and figured out. I’ll have a look then too.

[terah]

Originally Posted by ka4wja

Terah,
As I have no idea what cable you have, nor what issues you're having, I can only give you generic answers, based on my experience over the past 40 some years...and, these are based on US suppliers...
I do not have any personal knowledge/experience with UK suppliers/vendors...

Thanks John,

I'd asked generically to try and avoid thread hijack, but should have given a bit more detail.

In my case I have 12 year old RG58 and antenna so planning to replace with RG-213 or RG-8x as you've recommended previously, and replace the antenna with the Vesper VHF/AIS antenna. This will then be connected to a Vesper SP160.

Will look through the links you've posted.

[ka4wja]

terah,
Sounds good!

Sorry, sometimes I just get going on a roll and don't stop.
I probably should've just asked you what you needed...

FYI, for your application (assuming a ~ 65' masthead VHF antenna), I'd use RG-213....and either:

a) buy a pre-made length (or two, if you need a mast-base splice/connection), if you can fit the cable and connector in the mast conduit (doubtful)....or

b) buy some RG-213 and connectors (and crimp tool) from DX Engineering, and do-it-yourself...or

c) hire a pro to do it...

All depends on costs and time and availability of professional personnel..

Fair winds.

John

[terah]

That's great John. a) out due to lack of space and c) due to lack of availability, so cable, connectors and crimp tool ordered!