Dedicated GPS receiver for VHF?

[elton]

Nor is the radio itself, without an external antenna!

The GPS requires an active antenna. A boat having a DSC radio installed is more than likely to already have a suitable VHF antenna fitted, but unlikely to have an external GPS antenna, unless they have a plotter which will as likely as not have an NMEA output which could easily be used to supply the VHF.

In any case, if they could profitably manufacture a practical DSC VHF with a built-in GPS I feel quite certain someone would do so. But they don't, so QED.

 

[Bilgediver]

One day (but not very soon) I might make a level converter and hook it up to the PC to see what's going on, but I have spent enough time on it and don't feel like spending more. Even if it's possible to configure it via the PC to send the correct data format, that would be no good for this application, because according to the instructions, it will revert to factory settings if unpowered for 20 minutes.
.

Back in the old days it was found that most PC s would cope with the low level TTL signals into the serial port and read them. Many Many discussions with non believers on a GPS Forum run by a Power boater in BC..Just try it using the windows terminal program.

 

[Playtime]

The GPS requires an active antenna. A boat having a DSC radio installed is more than likely to already have a suitable VHF antenna fitted, but unlikely to have an external GPS antenna, unless they have a plotter which will as likely as not have an NMEA output which could easily be used to supply the VHF.

In any case, if they could profitably manufacture a practical DSC VHF with a built-in GPS I feel quite certain someone would do so. But they don't, so QED.

Not all boats that want a DSC radio necessarily have a GPS fitted. How about RIBs, small cruisers or day sailers?

It would also remove what is clearly a compatibility/wiring problem for many owners of larger boats, as witnessed by several recent threads, including this one.

I'm surprised you dismiss the idea - such radios are already appearing - see later in this article.

 

[oldgit]

just out of interest have cheap GPS antenna in the cabin roof with the glassfibre of the flybridge between it and the satellite.It functions on both 7v and 12v and is working perfectly.Red and Braid are 12v and green is the signal +.
My previous Midland and my new Icom VHF use this arial.

 

[ProDave]

Back in the old days it was found that most PC s would cope with the low level TTL signals into the serial port and read them. Many Many discussions with non believers on a GPS Forum run by a Power boater in BC..Just try it using the windows terminal program.

Thanks for that suggestion.

So without doing any level converting, I have tried it.

It's certainly talking to my PC, I have captured a few lines of the data it's sending

$GPGSV,3,1,12,21,00,000,,10,00,000,,25,00,000,,09,00,000,*74
$GPGSV,3,2,12,07,00,000,,03,00,000,,11,00,000,,15,00,000,*7B
$GPGSV,3,3,12,02,00,000,,30,00,000,,01,00,000,,26,00,000,*7E
$GPRMC,000103.995,V,,,,,,,020504,,*2B
$GPGGA,000104.995,,,,,0,00,,,M,,,,0000*35
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,12,21,00,000,,10,00,000,,25,00,000,,09,00,000,*74

BTW that's still with the inverter in circuit.

It's not getting a position fix (hardly surprising as it's indoors)

So that leaves the question, is it "working" but not getting a position fix, or is the data the wrong format for the DSC?

I think my next step will be to find a long bit of cable so I can take the receiver outside, and still have it connected to the PC indoors. Definitely a job for tomorrow.

 

[elton]

I'm surprised you dismiss the idea - such radios are already appearing - see later in this article.

Contrary to the article subtitle, the Standard Horizon GX2100 does not have an inbuilt GPS receiver. The article doesn't mention any other fixed DSC sets with GPS. unless I missed something.

I'm aware there are handheld DSC radios available with built-in GPS, but the GPS functionality is as unlikely to work below decks as any other handheld GPS.

 

[concentrik]

Update / help?

This is the GPS puck I used:

http://bit.ly/i4iinZ

From Cashcow (next day delivery and helpful with the tech data BTW).

Others posted about the supply requirements - it is +5V - I built a little regulator which I also used as a 'junction box' for the various connections (I use the speaker output from the VHF to feed a cockpit speaker)

Now, it does seem to work..... the GPS icon no longer flashes. On power up, the icon is steady, no flashing, then after a minute or so the icon begins to animate some 'rays', like a representation of a signal 'beaming down'.

Like this:

http://www.mediafire.com/?css94s1wreodj4b

At least I think it's working - that's where the 'help?' bit comes in. The manual for the radio (Uniden Oceanus) is woefully reticent about this aspect of operation.

I can't see a way to display position on the radio LCD. There is a facility to ask another station for it's position (lat/long) and receive it, but how is this displayed? Would this be sent out on the GPS OUT connection?

So to summarise, I think it's working, but I don't know how to confirm it! Any ideas anyone? Someone with the same VHF?

Anyway, if it is working, I'm very happy with it - I hope I never need to use it.

 

[ProDave]

This is the GPS puck I used:

http://bit.ly/i4iinZ

...

Others posted about the supply requirements - it is +5V - I built a little regulator which I also used as a 'junction box' for the various connections (I use the speaker output from the VHF to feed a cockpit speaker)

Now, it does seem to work..... the GPS icon no longer flashes. On power up, the icon is steady, no flashing, then after a minute or so the icon begins to animate some 'rays', like a representation of a signal 'beaming down'.
...

I can't see a way to display position on the radio LCD. There is a facility to ask another station for it's position (lat/long) and receive it, but how is this displayed? Would this be sent out on the GPS OUT connection?

So to summarise, I think it's working, but I don't know how to confirm it! Any ideas anyone? Someone with the same VHF?

Anyway, if it is working, I'm very happy with it - I hope I never need to use it.

Sounds like you have had more success than my attempt.

I'm surprised there's no display on the radio. I thought all DSC radios had a lat / long display, mine does, and it says 99.999 etc with no position input. If yours doesn't, then there's no point in requesting someone's position is there.

Regarding my project, it's in the "failed projects" pile. I think my conclusion was I have a faulty unit that simply doesn't receive a signal, so gets no fix.

I did try it on a long lead with the receiver outside connected to the PC inside, but that didn't work. RS232 was never renowned for working over a long cable, so it was no surprise really when a simple TTL level unit wouldn't drive a long cable.

I also tried the receiver powered up, but not connected to any device, up on the roof of our summerhouse with a really good clear view of the sky, but still it didn't lock on (according to the flashing light that should have turned to a steady light once it got a position fix) even after several hours.

It would have been good to diagnose it with the PC, but I wasn't prepared to lug the desktop PC outside. I mourn the day manufacturers dropped RS232 ports from laptops.

 

[ostell]

I can't see a way to display position on the radio LCD.

Is there a facility on the radio setup menu to select what is displayed on the screen? There is on mine, though lat & long is on by default.

 

[concentrik]

Finally...

Replying to my own thread to round it off, I can report that the GPS puck referred to earlier worked fine. It was set to 4800 baud on receipt and satisfied the Oceanus DSC VHF that there was NMEA data being sent.

The Oceanus does not display its OWN lat/long. There's no way to see the information being given to it. You need to get another DSC VHF to send a position request to your MMSI to verify that the Oceanus is indeed receiving valid data. In my case, it is.

The control program for the Garmin puck, which enables you to do all kinds of complex stuff via an RS232 port, works too. I tried it on an elderly laptop which had the required connector. I stopped all the NMEA sentences except the one the radio needs.

So what I got for my 25 quid was a standalone, dedicated, low power GPS input to the DSC, ready for when my freezing trembling hand lifts the little red cover and presses the button....