Standard Horizon GPS Antenna NMEA independant output

[ghorne]

I have purchased a Standard Horizon CP300 (external GPS). I also have Raymarine XPS-10 autopilot computer which receives Seatalk and NMEA GPS sentences, I have a Raymarine ST60+ Graphic display at the chart table which is a repeater and receives both Seatalk and NMEA GPS sentences (to display speed, depth, wind and LAT-LONG for log updates). The ST60+ Graphic also outputs some other data from the Seatalk bus such as water temp, hull speed, wind etc that could be used by the chart plotter. I also have a GX1500E VHF which receives GPS sentences and can also send DSC-DSE sentences to the chart plotter for example.

The yacht is being setup for long distance (low power consumption) cruising. (No air conditioners or generators on this baby). The chart plotter consumes 8.5 watts whereas a single GPS antenna normally consumes only 1 - 1.5 watts. For long distances (ocean sailing) I would like to power the GPS independent of the chart plotter and when powered provide the ST60+ Graphic, Autopilot and VHF with GPS sentences from the GPS independent of the chart plotter being powered.

Is there a problem with this plan to power the Standard Horizon GPS externally and siphon the NMEA GPS signals off to other devices? The manual does not talk of the antenna used any other way and only talks of this being used for the chart plotter.

If this does not work and I don't use the Standard Horizon GPS antenna, could the GPS sentences for the chart plotter be input from an other manufacturers GPS antenna using NMEA?

If I use another GPS antenna, could a signal multiplexed from both the AIS and GPS onto a single wire at 38.4K speed be input for the chart plotter for GPS and AIS data? I have this plan because on long distance sailing trips I could afford to run the Raymarine ST60+ instruments, a Standard Horizon GPS antenna with NMEA out into an EasyAIS which multiplexes both the GPS NMEA output (with optic to electric) and AIS specific sentences out at 38.K which can be read and actively watched by a VESPER AIS Watchmate with very low power consumed and an active AIS watch maintained.

Any ideas would be helpful. I am IT guy (strong background in comms and networking) with little NMEA electronics experience (so I am an NMEA virgin).

Thanks
Graham

[jhebert]

As you probably already know from a careful reading of the CP300 manual, the GPS Smart Antenna talks to the chart plotter on its NMEA PORT 3 input. I don't see why you couldn't run the GPS Smart Antenna from a separate power source, buffer its NMEA-0183 output, and connect it to the CP300 and other devices. It seems reasonable that this should work.

The glitch might be that the GPS Smart Antenna and the chart plotter of the CP300 communicate in some fashion other than NMEA-0183 during the start up process or at some other time. If that is occurring, it might prevent your idea from working. Although the documentation only mentions the chart plotter as receiving data from the Smart Antenna, it seems like the chart plotter can send data to the Smart Antenna. There is at least one hidden menu where you can enter some settings which seem to affect the GPS receiver, such as the pre-selection of a PRN code to use for WAAS correction source. That seems to imply there has to be some bi-directional communication.

The technical support people at Standard Horizon seem quite knowledgeable and willing to help. You should consider contacting them via email to get their opinion.

You might also find this article interesting:

http://continuouswave.com/whaler/reference/CP300.html

[Standard Horizon]

ghorne,

One solution is to adjust the backlight on the CP300 to lower power consumption.

680mA backlight full brightness (8.5W at 12.5V)

320mA backlight lowest position (4W at 12.5V).


Instructions below to connect the GPS antenna to an independent power source:

1. Cut the antenna cable and plug in antenna connector into the CP300

2. Strip insulation back on the cable with the connector which is attached to the CP300.

3. Connect the Green wire to the Green wire of the GPS antenna cable. (the green wire is the +NMEA Signal wire so it can be connected up to 3 other devices)

4. Connect the black wire from the cable with the connector to the black wire on the GPS antenna cable and connect to battery ground. (Both signal common and battery ground)

4. Connect the red wire on the GPS antenna cable to 2A fuse and to 12VDC.


If you have any questions please contact tech support 800-767-2450.

[ghorne]

So let me see if I understand this correctly.

The Standard Horizon Smart GPS antenna can be powered independently of the chart plotter as a standalone GPS antenna and provide GPS NMEA sentences to other NMEA 0183 compliant devices. In my case the GPS NMEA 0183 (GGA, RMC, GSA, GSV) sentences from the Standard Horizon Smart GPS antenna would be sent (wired to) to the following devices:
Standard Horizon CP300e Chart Plotter as NMEA IN (on say PORT 2)
Raymarine ST60+ Graphic Display as NMEA IN
EasyAIS Type B AIS WatchMate system as NMEA IN
Standard Horizon GX1500E as NMEA IN

If the EasyAIS Type B AIS Receiver is wired so that it receives GPS NMEA sentences, (the WatchMate has just one NMEA IN and needs both GPS and AIS data hence multiplexed by EasyAIS) it then multiplexes the GPS NMEA 0183 (GGA, RMC, GSA, GSV and VDM) sentences received from the GPS and AIS receiver together. When the EasyAIS then transmits its NMEA sentences as NMEA OUT, it does so @ 38.4Kb (special AIS speed). This unit will then provide this (GPS+AIS) NMEA data from NMEA OUT to the following 2 devices:
Vesper AIS WatchMate system as NMEA IN
Standard Horizon CP300e Chart Plotter as NMEA IN (on say PORT 3 IN @ 38.4Kb) for AIS

As I understand it the CP300e Chart Plotter would accept the NMEA (GGA, RMC, GSA, GSV) sentences sent directly by the Smart GPS antenna @4.8Kb (on say PORT 2). That is great, but what will it do with the sentences transmitted (multiplexed in with AIS VDM sentence) at 38.4Kb by the EasyAIS WatchMate system?

The CP300 is able to receive the AIS NMEA (VDM) sentences, but what of the second set of GPS NMEA sentences also transferred at this speed? Are they discarded by the CP300? Would receiving the same sentences on different ports have any effect on the CP300?

The Standard Horizon GX1500E NMEA (DSC, DSE ) sentences would be sent from the GX1500 as NMEA OUT and received by the CP300 chartplotter as NMEA IN (on say PORT 3)

Thanks for your help

Regards
Graham

[Standard Horizon]

Ghorne,

Connect the GPS Smart antenna to the EasyAIS, then connected easy AIS to CP300 port that is set to 38.4Kb

[thataway]

Graham,
You might want to think what is essential for your sailing? I have made a number of ocean crossings, under sail. I understand the limits of power managment in a long distance sailing boat. The reality is that the less power you use the better. Running the boat on a wind vane is the first time honored way of sailing and uses the least power. Since you say no generator--how are your generating 12 volt power? Auto pilots use considerably more power than the nav instruments do. Secondarily running auto pilot via compass uses far less power, than running via chart plotters. I have only run on compass courses, which have some advantages over the averaging of the GPS "course". You don't have to run the GPS/chart plotter all of the time--in fact it is counter productive to do that. Nothing out there but open ocean until you are closing the coast. If your are doing long distance sailing you need to know conventional route navigation (and probably have some back up along the way).

AIS--Sounds like a good idea to run this with the alert all of the time. According to the S H manual AIS can be set to NMEA input 4 and then the baud rate set properly. We saw few vessels on transoceanic voyages, but it would be a great precaution. (Assuming that the ships have the AIS on)

Do you have a class B Transceiver or just a receiver? (which I hope is not just class B)

[ghorne]

Could not agree more. I did not mention it but for ocean crossings I use a Hydrovane. The autopilot is for Med cruising (fluky winds and short distances). I also didn't mention that I carry 130watts of solar panels which in the Med pumps a lot of power. Even though this is the case I manage power usage carefully. When I think of someone using an autopilot to cross oceans (Atlantic) with a following breeze I cringe.

Thanks for your input.

Regards
Graham