Connecting a GPS device to my VHF

[Bill Roosa]

And that is why I said crack the case and get 5 volts from the VHF and then port the puck output to the VHF directly if you want a “ruggedized system”.
And Universal Serial Buss (USB) is really just a serial buss without all the control lines. The control lines where needed when comms lines where noisy analog circuits. You really only needed the TX and RX and a ground to communicate. Add a power wire and, let me see is that not what an USB is????
I do agree that using a computer to supply GPS info to the VHF is kinda dumb if you are considering a "life and death" situation. Course I would not stake my life on a VHF either (with or without GPS interface). I'm thinking that the OP is trying to rely on technology to the extent that he can "be safe". Never going to happen. The sea is a cruel mistress and will extract her pound of flesh no matter what you do.
Perhaps a better solution is to practice using the radio to relay your position using your mouth and ears, keep track of your position on a paper map (the horror) and maintaining a watch and keeping a weather eye out. I’m pretty sure that Columbus and Magellan got through without even the map so ...........
Technology will never “make you safe”. You may “feel” safe but it is up to the captain and crew to make a safe boat.

FDR
If they can’t even figure out the USB to nmea thing what makes you think they are going to be able to compile gpsd. Gpsd 3.5 is experimental and has lots of dependency issues BTW

 

[kenn]

USB to Serial

... Universal Serial Buss (USB) is really just a serial buss without all the control lines. The control lines where needed when comms lines where noisy analog circuits. You really only needed the TX and RX and a ground to communicate. Add a power wire and, let me see is that not what an USB is????

Um, no, it isn't. Honest.

From Wikipedia:

USB supports the following signaling rates.

• A low-speed rate of 1.5 Mbit/s is defined by USB 1.0. It is very similar to full-bandwidth operation except each bit takes 8 times as long to transmit. It is intended primarily to save cost in low-bandwidth human interface devices (HID) such as keyboards, mice, and joysticks.
• The full-speed rate of 12 Mbit/s is the basic USB data rate defined by USB 1.0. All USB hubs support full-bandwidth.
• A high-speed (USB 2.0) rate of 480 Mbit/s was introduced in 2001. All hi-speed devices are capable of falling back to full-bandwidth operation if necessary; i.e., they are backward compatible with USB 1.1. Connectors are identical for USB 2.0 and USB 1.x.
• A SuperSpeed (USB 3.0) rate of 5.0 Gbit/s. The written USB 3.0 specification was released by Intel and partners in August 2008. The first USB 3 controller chips were sampled by NEC May 2009[64] and products using the 3.0 specification arrived beginning in January 2010.[65] USB 3.0 connectors are generally backwards compatible, but include new wiring and full duplex operation.

Notice - no 4800 or 9600 bit/s (such as required for NMEA).

Also, USB is not a port, it's a bus, that carries data from and to several devices, though because of normal physically topology - USB hubs, etc - it still may appear to us as single lines.

To interface USB to serial devices, you need an active adaptor. This one is typical (but pricy; I bought two similar USB-serial adaptors directly from China for about $10 shipped). Note that this isn't just a cable, there's an IC or two molded into the big end, powered by the USB.

Here's some sample converter circuits. In both cases the magic IC is an FT232.

Not looking for a fight, I'm only interested in correcting misinformation.

 

[knothead]

Very interesting and thanks to all who have replied to my question. "fdr", is your $180 Garmin powered from the 12V house batteries or the USB 5V source or AA batteries? Was it simply "plug and play" into your ICOM? As TimR pointed out much earlier in the thread, the Garmin GPS Hx17HVS fob/puck antenna can be made to work ( at least with my VHS) with a little bit of DIY connection for about $130. As an extra feature it has two separate Rx/Tx connections so it can be split between a laptop and the radio. An internet search from Bombay to Taiwan revealed no more cost-effective solution but I am intrigued by the simplicity of your approach. Standard Horizon now offers the GX1700 with a GPS built in for about $230 which answers a previous post about this being the most sensible solution. I'd be interested to hear how this unit performs.