1722C Loosing GPS Lock

[Anonymous]

I have a 1722 C that is experinceing an interesting problem. Basic story is if I have not used the boat in a while, the 1722 comes on normally and stays locked for 30-45 min no matter what speed I am running. After that time speeds above about 10 mph and the unit looses its GPS lock. If you slow down to trolling speeds it once again finds the signals and locks in. I have watched this thing lock in, loose it, lock in, just by speeding up and slowing down over and over again above and below 10 mph..

So in summary I loose the lock running out, I have it trolling around all day and I loose it again on the way back. Any suggestions?

 

[Johnny Electron]

It sounds like your GPS has weak reception and loses fix when you start moving at faster speeds. My guess is the GPS receiver is having problems. Have you checked the signal strength of the received satellites? Have you ensured that the GPS antenna is outside the beam of any radar and away from any other RF transmitting sources? (Like VHF, WI-FI or Cell boosters)

 

[Anonymous]

I have not looked at the signal strength, I can do that now as the boat is in the driveway but will unable to do this at any speed for a while. This unit has been on the boat for many years with the same configuration. I did loose one antenna years back but otherwise has worked fine for a long time. I also have a 1650DF and its head unit is positioned in the exact configuration relative to the dome, just on the other side of the hard top, its never failed.

The head should be above the radar beam. It is positioned within a few feet of the VHF antenna while the 1650 head unit is further away.

 

[Johnny Electron]

The VHF whip needs to be at least 3 feet away from the GPS antenna.

 

[Anonymous]

The head unit is 12 inches from the whip. I can tell you the problem is happening weather I have the radio on or not, but maybe the damage is done?

The sat signals show 9 sat signals from satellites 01-32. At the bottom of the histogram 138 flashes on and off every 1 second, coinciding with a W flashing within the circular diagram. I dont think I have seen that before.

 

[Johnny Electron]

“138” is the WAAS satellite for the East coast.

12 inches is way too close to the VHF. The VHF will damage the front end amplifier of the GPS where getting a fix gets harder and harder (Even when you are not currently broadcasting). Like you said, the damage is done. Sounds like you need a new antenna. If you don't want to keep replacing it, every so often, I would recommend relocating it or the VHF. If you would rather, you can wire the GPS data from your GP1650DF into the NavNet display and let it used the same GPS data it has.

 

[Anonymous]

ok, by it blinking, it means its not happy. I did watch it for a while and it will stop blinking for very short periods but then starts again.

The plan is to replace both of these units with a TZ touch. It takes the same antenna, correct? I am waiting on word from furuno about their sounder chirp technology. Would it be safe to purchase the TZ and when chirp comes out I can just install that or will it be integral to the TZ? thanks

 

[Johnny Electron]

The GP320B and your GP1650DF are NMEA 0183 items. The TZtouch system is NMEA 2000. You would not directly connect either of these units directly to the TZtouch without a proper NMEA 0183 to NMEA 2000 interface. If you are planning on upgrading the boat to TZtouch; I would recommend using the GPS data from your GP1650DF over to the NavNet to provide position for it, until you upgrade. This way instead by buying a new GP320B, you can invest the money into the NMEA 2000 GP330B for your TZtouch system.

I am sorry; I do not have anything to offer about CHIRP at this time. Furuno USA normally releases products during the Fort Lauderdale or Miami boat shows and I would hope to see some information then. For the cost of a CHIRP transducer alone, I personally haven't seen that they offer a vast improvement over our existing systems. Granted, other companies have seen advantages because their normal sounders were a bit lacking. I have seen some impressive depths shown with CHIRP but who wants to sit in one place for two and a half hours to get a bottom number, where fish with headlights live. You can chase fish or the newest buzz word. Furuno doesn't normally chase the newest buzz word unless it adds value to the customer. When and if Furuno releases a CHIRP unit, you can bet it will be nice. That is my two cents anyway... Sorry, I honestly don't have any inside track when it comes to product development. I normally find out about new products, the same time you do.

 

[Anonymous]

Hi, I was just looking at a new antenna, I looked this morning and like you said its a GP320B, I assume this is as well even tho it does not say so:

http://www.boemarine.com/Furuno_BBW-GPS ... _-BBW-GPS/

I understand what you are saying about product releases, my fear of course is to buy the best and find out 4 months later its outdated by a new release. I would think Furuno sees someting in the chirp system since they are in development with it.

I am already moving depth from m 1650DF to my 1722C, how would I move the GPS signal? The only thing about doing this is now I dont have redundant systems but its worht considering, thanks

 

[Johnny Electron]

Yes, the GP320B is sold by Furuno USA under the "BBWGPS" (Black Box WAAS GPS) part number. The link you provided is correct.

No doubt that CHIRP has potential. But CHIRP has a cost and in the past it was just way too expensive. CHIRP is not really new, has been around a long time. Now that the costs have come down a bit, it is worth considering but there is still a cost versus benefit. If cost is not a factor, we have a great system called the WASSP that will blow your socks off. The system is available today.

Sorry... back to the real subject.
You are correct about redundancy. GPS is something you do not want to be without. To wire NMEA GPS data from the GP1650DF, use the 6 pin NMEA cable [WHITE (+) and BLACK (-)] to the data port 1 of the 7" NavNet [YELLOW(+) and Green(-)]. If you wanted to use the cable from the broken GPS, you could cut the cable (disconnect first) and then use it as your input cable for the 7". The input colors for that cable would be WHITE (+) and BLUE (-).

 

[Anonymous]

I ordered a new one, I will let you konw if something other than resolution occurs. I will move the antenna further away from the whip. In the mean time I am going to continue to search for clues on what Furuno is doing with new technology and what my best options are for upgrading. thanks for the help.