Vesper WatchMate 650 connection to ACR iPro EPIRB

[Marathon1150]

I recently installed an XB8000 AIS AND connected it to my old WatchMate 650 to inter alia distribute the GPS signal to two radios (ICOM 504 and 802) In addition to an ACR iPro EPIRB. Everything is connected using an NMEA 0183 protocol at 4800 BAUD. The radios are receiving the signal just fine. The EPIRB is not. ACR has helpfully provided advice regarding wiring etc and everything looks good but the EPIRB provides a "NO NMEA GPS DATA" message after a self-check.

I connected a Garmin GPS 72 to the EPIRB and the GPS message went through to the EPIRB. ACR advises that the iPro requires the NMEA sentence GPGGA. Vesper has not been able to tell me what sentence the 650 transmits. I have determined that the XB8000 does send this sentence but at 38400 BAUD. It can be slowed down but that seems like a bad idea from an AIS perspective.

Any suggestions regarding how the 650 can feed the EPIRB or alternatives would be much appreciated.

Fair Winds

[Paul L]

Your m802 also wants the GGA sentence, so that should not be the problem. Are you sure you are hooking data-out and the gnd to the ACR cable?

I have an ACR iPro also but decided not to hook up the external GPS nmea signal. Adds complication in mounting and I don't see any real advantage. It might reduce the time-to-first-fix by a few minutes, but that's all.

[Marathon1150]

Thanks. I have checked the wiring several times and all is as ACR says it should be. I used the same connections on the Garmin and it worked. The LED on the ACR behaves differently when the Garmin is connected compared to the 650. When the latter is connected the EPIRB LED blinks for awhile and then stays on continuously. But no GPS data is captured by the EPIRB. When the Garmin is connected, the LED does a short-long blink sequence continuously and the GPS data is captured by the EPIRB. Vesper has not been able to determine what sentence is being transmitted by the 650 and I am equally perplexed that the radios are happy with whatever the sentence is.

As you suggest, it is probably not worth worrying about given that the EPIRB has an internal GPS.

[barnakiel]

Originally Posted by Marathon1150

a) Everything is connected using an NMEA 0183

b) Vesper has not been able to tell me what sentence the 650 transmits.

a) if the connect is a 3 wire system (232) then you can only split the signal 2 max 3 times, I have seen the singal lost on the 3rd split.

b) you can simply connect 650 to a PC and read the sentence then you know what sentence it is.

What do you mean when you say 38400 slowed down? It takes a chipset to read 38400 at one end and spit out 4800 or any other on the other end. I am not sure I have seen one but they likely exist. Maybe a brookhouse serial multiplex can do this. Should I check this?

I will re-read your post but maybe yo could post a draft or a more detailed text on what connects to what and which interfaces are in use (232? 422? usb?).

Cheers,
b.

[barnakiel]

I have looked up both manuals and I believe there are two alternatives:

Option A)

1) feed 8000 data into 650 at 38400 on port 1 of 650,
2) set port 2 of 650 to 4800, use the output to feed other equipment with gps data.

The above, in theory, should forward the GGA sentence (present on 8000) thru 650 onwards. Check with any PC and hyperterminal or OpenCPN / NavMon, etc.

MIND the number of splits on RS232 cables is LIMITED (see my earlier post). 650 uses 232 cabling. (rx/tx/gnd common - 3 wires) After you split it once or twice there is not enough energy in the signal for further listeners.

Option B) Use another gps source for the EPIRB.

NOTE: you can actually test Option A by switching off the two radios and then using the 650 output on the EPIRB only. If the sentence is there at all, signal loss will be no culprit and the EPIRB should lock on it. If it does not, the sentence is likely NOT being forwarded.

Maybe others have a better solution. I stay tuned in.

Cheers,
b.

[Marathon1150]

Option A is what I am using. The 2 radios and the EPIRB are wired using NMEA 0183 protocol as follows:

650 port 2 data out to NMEA input (+ve)
650 port 2 ground to NMEA input (-ve)


The 650 is receiving GPS data from the XP8000 at 38,400 via Port 1 and displaying AIS data including GPS information normally. It is sending data to the three devices (2 radios and the EPIRB) at 4800. The radios are happy but the EPIRB is not. Interestingly, several dock neighbours suggested before I started this that the 802 would use all of the signal but it doesn't. Turning the radios off is an interesting idea so I tried it. The EPIRB is not happy.

Here is what Vesper said when I first asked them about feeding multiple devices:

"The XB-8000 can easily drive multiple devices simultaneously on its NMEA 0183 port, but if you are planning to use your WatchMate 650 along with it you will need to use 38400 baud to communicate between the XB-8000 and the 650. But your radios and EPRIB will want 4800 baud. So that excludes using the XB-8000 for both.

However, you can use your 650 to do that for you. Wire those other devices (multiple ones are fine - wire them in parallel) to the 650's other unused output port. Then tell the 650 to output GPS data onto that port. That's all."

Option B. Use another GPS to feed the EPIRB. I now know that a Garmin 72 can feed the EPIRB but I don't want to have one more device when it is unnecessary.

New Option C. Get rid of the 650 and follow Vesper's advice to use the XB8000 to provide GPS info to the other devices. I can replace the 650 with my iPhone, iPad via wireless or a laptop via USB. This probably makes the most sense as it eliminates one piece of equipment which is nice to have but not essential. I have used the Vesper app on the IOS devices and it works as well as the 650 or better as I can have them in the cockpit not just at the nav table. Similarly, I have connected the XB8000 via wifi to iNavX and that also works well.

Many thanks for the advice. I'll update this thread when I have rewired everything as per Option C.

Fair Winds

[barnakiel]

Yep. If you use any tablet to substitute the 650 then the 8000 port is free to work at any speed. If the port is 422 (4 wire style) then it can feed up to 10 (I think) listeners. And the sentence you want is there as 8000 manual says so clearly.

Indeed Vespers App is very slick. You can even enable/disable the Tx remotely.

Let us know when done! I will have a similar exercise this fall.

barnakiel