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  Lowrance 500 series GPS and NMEA Devices

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Author Topic:   Lowrance 500 series GPS and NMEA Devices
Menemsha69 posted 06-05-2010 02:12 PM ET (US)   Profile for Menemsha69   Send Email to Menemsha69  
After installing the connector and T-adapter from my 527c Lowrance Depth Finder, GPS, and chart plotter combination and figuring out how to display information from the different NMEA devices, I still have questions about what some of these devices are and what they do. I read Jimh's excellent article:
http://continuouswave.com/whaler/reference/L500.html
I understood most of it, although I must admit I got "lost in the stars" during some of the satellite tracking information!
My first question is about the LCG-3000 unit. Is there any advantage to using this unit for the GPS receiver as opposed to the built in receiver in the Lowrance 527c?-k
jimh posted 06-05-2010 04:08 PM ET (US)     Profile for jimh  Send Email to jimh     
If you have two GPS receivers connected to a NMEA-2000 network, you are in the same situation as a man who owns two watches, that is, you are not quite sure of the time, and, as a result, of where you are.

Actually, I do not know precisely what happens if you have an LCG-3000 connected to a network with an LMS-527c that also has a GPS receiver. I would defer to Lowrance and inquire if there was some mechanism in the LMS-527c that shut off its receiver in favor of the other one. Perhaps a very thorough reading of the literature from Lowrance might reveal the outcome.

Menemsha69 posted 06-05-2010 08:37 PM ET (US)     Profile for Menemsha69  Send Email to Menemsha69     
When I read page 203 of my Lowrance manual the information states:
Press ↓ to Set Active and press ENT. The LGC module is now the active
antenna for your unit. The Internal GPS antenna was automatically
disabled when the LGC module was set to active.

There is nowhere in the manual that I can find any sort of advantages or disadvantages to using the LCG-3000 unit instead of the internal receiver. Is it more sensitive? More accurate? I am guessing that it would locate the position quicker (as Jimh implies in his reference article) as it starts up with the motor. I am also guessing that due to it's location on my Menemsha it might not lose it's signal as opposed to the internal unit that is sometimes shooting through a windshield. Just guesses at this point. Any thoughts? -k

SJUAE posted 06-06-2010 04:28 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
Menemsha69

Both internal and external units appear to be 12-parallel channel GPS+WAAS receiver.

On the newer external recievers they appears to have a faster update rate over the internal ones, but this is not specified for yours.

So apart from slight chance that the external receiver has a better chance of a fix due to it's location over the internal, in certain circumstances. I'd say little or no difference, although it's nice to have the back-up of the internal one.

Regards
Steve

Menemsha69 posted 06-06-2010 04:46 PM ET (US)     Profile for Menemsha69  Send Email to Menemsha69     
That is interesting, and I can test it out this week. I find that while fishing with the electric trolling motor I am moving too slowly (1/2 mph) for the "heading up" arrow to compensate, often times the screen reads me pointing in one direction while I know I have come about 45 seconds to 1 minute ago in a long arc. I might be able to notice this difference.-k
jmorgan40 posted 06-06-2010 08:22 PM ET (US)     Profile for jmorgan40  Send Email to jmorgan40     
Kevin--If you have the latest software update, the Lowrance unit will always take the most accurate location when more than one receiver is linked to the NMEA network.
jimh posted 06-07-2010 08:10 AM ET (US)     Profile for jimh  Send Email to jimh     
A GPS receiver is typically unable to measure heading directly, but it has to deduce the heading by comparing the current position with previous position. If you are moving slowly the error in position may produce a significant error in the deduced heading.
SJUAE posted 06-07-2010 03:46 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
jmorgan40

I'm not sure if the internal reciever is classed as a NMEA2000 device, it may be bridged output to NMEA2000.

As a point of intrest how would it know which is the most accurate location of the two, assuming both are working and are the same specification :)

Regards
Steve

jmorgan40 posted 06-07-2010 04:04 PM ET (US)     Profile for jmorgan40  Send Email to jmorgan40     
Below is the statement of changes in the latest update for my LCX-26C HD. I assumed it was also in Kevins update for the 527 but I now nticed it is not listed.

V2.1.0
"Added Automatic GPS Selection - With this new feature, the user can have multiple GPS modules on their vessel and the head unit will automatically select the GPS module with the best position error, giving the user the best lock at all times and providing means as a fail safe for long voyages "

SJUAE posted 06-07-2010 05:08 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
Thanks, that seems more resonable

Regards
Steve

Menemsha69 posted 06-12-2010 04:03 PM ET (US)     Profile for Menemsha69  Send Email to Menemsha69     
I had a little time to tinker and I was able to switch from the Lowrance 527c internal GPS receiver to the LCG-3000 GPS receiver while fishing this morning. I didn't notice any difference in performance, however in order to use the LCG-3000 receiver I must keep my key switch in the "ON" position at all times (which also activates my I-Command gauges).
The Lowrance unit doesn't recognize any of the NMEA devices without power going to them, which to me is a needless waste of battery power as I spend a lot of time using my electric trolling motor with its own isolated deep-cell battery, and my depth finder (powered by the house batteries) to locate schools of fish.-k
SJUAE posted 06-12-2010 09:53 PM ET (US)     Profile for SJUAE  Send Email to SJUAE     
Menemsha69

Why would you want engine info etc if it's not on :)

Run a seperate switched power supply to the LCG-3000 or just keep it as back up and use the internal receiver.

Regards
Steve

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