Lowest cost way of getting GPS feed into DSC VHF

Alfie168 said:
To use the DSC function I need a GPS aerial with NMEA output. The aerials seem to be more costly than the VHF!! Is there a more economical way of provided a GPS feed or am I stuck with my using it as a non DSC unit unless I spend about £100 notes?
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You can do it with a GPS mouse, but you need the right type - a serial one, and not a USB one. The GlobalSat BR355 does this and it is what I use on my boat to get NMEA GPS into my DSC VHF with AIS (acronym heaven :-). It's installed and working, so isn't armchair theory.

Here are the details...

http://www.diginetlink.com/GlobalSat_BR355_Mouse_GPS_Receiver_p/br355.htm

It comes with a PS2 connector on it, but cut that off and note the connections. You connect GND to NMEA- on the VHF, TX to NMEA+ on the VHF. You also need to supply it with 5 volts on the GND (-) and VCC (+) pins. By default mine came with its output speed set to 38400 baud and I used the software that comes with it to set it to 4800 baud that the VHF expects.

To get the 5V supply the easiest thing to do is get off Ebay a car socket to USB power converter and whip out the contents - 12V in and 5V out. Or you can get a 12V to 5V regulator from Maplin (QL31J) for 99p.
 
Searush said:
How about using a GPS mouse?

You can also get them with USB connectors if that would help. But, I don't have (or want) a DSC VHF, so I have never tried connecting one to a radio. They work fine on my PC as a chartplotter & for active OS maps tho'.
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A GPS mouse or mushroom is fine if it has Nmea output suitable for the radio however some sem to have hi speed outputs which a radio might not accept.

Something like the Standard Horizon mushroom antenna might be OK.

I wonder if it is confirmed the Etrex has no output as I used one similar to this where there was a mutlipin socket which accepted external power and gave data connections???
 
I think it has been confirmed that the eTrex does give an NMEA output.

Forgetting about the power can you not run a simple test and jury rig a connection from the eTrex terminals under the rubber plug to the radio?
 
A good 4-5 years ago now (Can't remember exactly) I bought a "Haicom" GPS mouse on eBay for not much money, cut the mini DIN plug off the end and connected it to my (then new!) XM DSC radio. It worked fine, and the readout on the radio always agreed with the "proper" hand-held GPS. I just used 4 AA alkaline batteries in a carrier to feed it with 6V, they lasted fine for the amount of sailing I did.
 
DaveS said:
Almost, but not quite. According to the Etrex manual the 4 connections are + Power, - Power, data in and data out, so to connect to the radio you will want to use the data out and - Power wires.
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Almost but not quite. :)

If you want to connect to the boat's 12V supply you will need to step down to 3V (I think) for input to the eTrex. Alternatively, buy the power/data cable that has the converter built into the cigar lighter plug.
 
Is this the cheapest solution?

I've just bought one of these http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180581292221 £10.18 at PayPal's exchange rate.

I's just a module, so will need housing in a case, and a 5V regulator to power it.

The plan is to mount it above the drop down electrical panel, so will be just below the fibreglass coach roof. Hopefully it will get a good enough signal there.

I'll let you know how it works when I get it, usually takes about 2 weeks from Hong Kong.

At this sort of price, it's a shame they don't just build one into every DSC radio.
 
pvb said:
Why is it described as "used"??
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Probably because it is an old design (Note: SIRF 2 not SIRF 3) that has been recovered from some obsolete equipment.

That said, with a bit of ingenuity it should do the job required.

My GPS 128 pre dates SIRF 2 but works well. It can be a bit slow to cold start, though, if it is not powered up in the same location that it was last powered down!
 
ProDave said:
Is this the cheapest solution?

I've just bought one of these http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180581292221 £10.18 at PayPal's exchange rate.

I's just a module, so will need housing in a case, and a 5V regulator to power it.
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Although it will be a couple of weeks before I actually get this (it's coming from Hong Kong) the seller has just emailed me all the documentation that goes with it.

It includes the description of the module, some software for a PC, and an NMEA reference manual.

However, I have some questions.

My VHF DSC is a Cobra MR F55 EU

The users manual is frankly as useful as a chocolate tea pot.

It has a 2 pin (jack plug) data cable, so okay it can only possibly be ground and RX data (i.e the DSC can only receive data from the GPS, it cannot talk to the gps)

So two questions:

What''s the baud rate? Yes the manual does not tell me. And what's the signal level? TTL or proper RS232 levels? again the manual does not tell me.

On the basis that the DSC can only receive data, then It must rely on the GPS module continually sending it's position data. So until I get this module and try it, I won't know if it does indeed do that. If the GPS module needs 2 way communication (i.e needs a data request command before it will send) then it won't work for what this thread is talking about.
 
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Playtime said:
Almost but not quite. :)

If you want to connect to the boat's 12V supply you will need to step down to 3V (I think) for input to the eTrex. Alternatively, buy the power/data cable that has the converter built into the cigar lighter plug.
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If you read the thread properly you will see that I was commenting on making connections to the radio after purchase of an appropriate power/data cable for the etrex.
 
DaveS said:
If you read the thread properly you will see that I was commenting on making connections to the radio after purchase of an appropriate power/data cable for the etrex.
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That's not exactly how the thread reads.

At #25 Lodesman was suggesting buying a data cable, not a power/data cable.

Your comment at #26 does not address the power issue, hence my (trying to be helpful) comment at #27 about the 12V supply. ;)
 
Playtime said:
That's not exactly how the thread reads.

At #25 Lodesman was suggesting buying a data cable, not a power/data cable.

Your comment at #26 does not address the power issue, hence my (trying to be helpful) comment at #27 about the 12V supply. ;)
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I agree that it is a waste of time using the data only cable as the bettery life of the Etrex is limited. The external power supply is required.
 
Playtime said:
That's not exactly how the thread reads.

At #25 Lodesman was suggesting buying a data cable, not a power/data cable.

Your comment at #26 does not address the power issue, hence my (trying to be helpful) comment at #27 about the 12V supply. ;)
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What I said was:
According to the Etrex manual the 4 connections are + Power, - Power, data in and data out, so to connect to the radio you will want to use the data out and - Power wires.

The Etrex manual only shows a combined power and data cable and it was the connections to this that I was referring to. Possibly I could have made this clearer. I assumed (wrongly I now see) that the previous post was also talking about this cable.
 
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