NASA Clipper numpty

[Lundylad]

Help please.
I am trying to connect a NASA GPS repeater to a Standard Horizon CP300 and all I get is a no gps signal message on the repeater.

I am sending and recieving data from the plotter to the vhf and AIS so know that the plotter is ok.

The repeater has three wires, red +ve black -ve and blue nmea data in.

I am connecting the blue to the NMEA output of the plotter and the red and black to the 12v power source.

Any help would be most welcome.

 

[AngusMcDoon]

Sounds like it is connected correctly. There are various NMEA sentences that have GPS data in them. The Nasa repeater may not cope with them all. You'll need to look in the documentation of each device to see what they have implemented.

 

[Seajet]

I am certainly no electronics expert, but maybe a co-ax connection is more like it, I can't see a single blue wire sending all the info but stand to be corrected ?

 

[GrahamM376]

Have you phoned NASA for advice? I've found them very helpful in the past.

 

[RAI]

Have you checked the data-rate settings? Both units need to use the same speed.

 

[AngusMcDoon]

I am certainly no electronics expert, but maybe a co-ax connection is more like it, I can't see a single blue wire sending all the info but stand to be corrected ?

You are way off the mark as usual. The amount of data needed by a GPS receiver is trivially small compared to what can be sent down a single data line and ground. As you are not a marine electronics expert, why not just post some nice sunny pictures of your boat instead? It would be more useful to everyone.

 

[AngusMcDoon]

Have you checked the data-rate settings? Both units need to use the same speed.

I would expect on the Nasa end it is fixed at 4800 baud. It might be settable on the CP300.

 

[nigelmercier]

I am connecting the blue to the NMEA output of the plotter and the red and black to the 12v power source...

You also need a wire from the black lead to the Green (NMEA Ground) on the SH.

I am certainly no electronics expert...

So it seems

 

[AngusMcDoon]

You also need a wire from the black lead to the Green (NMEA Ground) on the SH.

Sounds like the SH outputs proper RS-422 differential levels to the NMEA 0183 specification, but the Nasa does not meet the specification and has a RS-232 input. Is this assumption right?

 

[winsbury]

AIS normally works at a much higher data rate, 38400 baud. From memory I don't think you can set the input and output data rates on the SH plotter to different speeds so if you are using the same port for position and AIS data it will be outputting position at 38400 which it would seem your VHF can cope with but the NASA repeater definitely needs a 4800baud single ended signal ( ie unbalanced .) There are ways round this problem using an external nmea mux but these are relatively expensive solutions.

 

[BruceDanforth]

It all depends on the diameter of the wire and the height of the ones and zeros. If the wire too wide the 1s will drift down sideways and there will be a lot of drag - in a thinner wire they will tend to go 'headfirst' with less resistance. It is less of a problem with the zeros because of the rounder shape.

I am certainly no electronics expert, but maybe a co-ax connection is more like it, I can't see a single blue wire sending all the info but stand to be corrected ?

 

[Lundylad]

Thanks for the replies.
The answer is that the connections are correct it only needs the single blue to be connected to the NMEA data out from the plotter at a Baud rate of 4800, which as mentioned by Winsbury for AIS the rate is higher.
So the boat came with a simple Garmin GPS I will reinstate that and use that for the repeater if multiplexing is to expensive.

 

[RAI]

The SH 300 has multiple NMEA outputs which each can have their individual baud rates set.

 

[Seajet]

You are way off the mark as usual. The amount of data needed by a GPS receiver is trivially small compared to what can be sent down a single data line and ground. As you are not a marine electronics expert, why not just post some nice sunny pictures of your boat instead? It would be more useful to everyone.

Angus,

since when did admitting I'm not an electronics geek and making a friendly suggestion become ' way off the mark ' ?

And why keep on about photo's of my boat, as I've said I can't get the new forum to work for that but if you're that desperate for a look at a proper boat PM me and I'll mail some !

Andy

 

[aslabend]

Help please.
I am trying to connect a NASA GPS repeater to a Standard Horizon CP300 and all I get is a no gps signal message on the repeater.

I am sending and recieving data from the plotter to the vhf and AIS so know that the plotter is ok.

The repeater has three wires, red +ve black -ve and blue nmea data in.

I am connecting the blue to the NMEA output of the plotter and the red and black to the 12v power source.

Any help would be most welcome.

I had problems with a nasa gps repeater , see thread 190207 you might find something useful in there.

 

[SteveSarabande]

the two wires you need are the same two that are going to your vhf. The one you are missing is the nmea common to the common terminal on the repeater