Re: Deliverable GPS data logger
- From: Richard Owlett <rowlett@xxxxxxxxxxxxx>
- Date: Fri, 03 Jun 2005 08:29:34 -0500
Jack Erbes wrote:
Richard Owlett wrote:
<snip>
I've gone to site. Is this a gpslogger or serial data logger?
It could be called a GPS NMEA 0183 serial data logger.
Read the description, http://www.prairie.mb.ca/gpsdatalogger.htm, it "records NMEA position data from a GPS". You connect a NMEA 0183 output from a GPS to it and it stores (logs) the data.
Major case of "seeing what I really wanted to see, not reality" ;}
Don't see any USB dump capability.
It does not have one. In fact, there may not be such a thing anywhere.
NMEA 0183 serial and USB serial communications are two different kinds of serial communications. But they can talk to each other through intermediate hardware (a converter or multiplexer for example).
If you cannot find a logger with a USB port, you will have to either use RS-232 or a RS-232 to USB converter.
yes *BUT*
I want USB for its capability of transmitting 1.5 MBytes per second.
[ If I get to do everything I really want to do I'll be accumulating ~5 MBytes of NMEA sentences before downloading to PC ]
Also, my PC has available USB port.
There is always some sort of learning curve on newly encountered technology. Things I think I have learned are that:
1 - NMEA 0183 communications are serial communications by definition. Any device that says it will output NMEA 0183 data is, in effect, saying that it has a serial communications port.
OK
2 - NMEA 0183 serial communications are defined as being RS-422. But a great many (especially common consumer level) GPS devices output their NMEA 0183 data using RS-232 instead. The hardware manufacturers made them that way to save money and make the devices work with the more commonly found RS-232 serial ports (on PCs for example).
They do refer to it as RS-232 ;)
They would also get arguments from early RS-232 purists. I was around in early days of RS-232C.
See good article at http://en.wikipedia.org/wiki/RS-232
[ particularly http://en.wikipedia.org/wiki/RS-232#Voltage_levels ]
3 - It is fair to assume that a consumer level GPS device describing itself as having a "NMEA output" is saying that it has a RS-232 serial output. Unfortunately, studying the specs may or may not verify the specifics.
YES!
4 - USB is a different kind of serial communications than RS-232 or RS-422. USB, RS-232, and RS-422 can can only communicate directly with like ports.
Yes.
5 - You can buy (they are widely available and can be pretty cheap) RS-232 serial to USB converters. These have a DB-9P serial plug on one end and a USB plug on the other. In between the plugs are some electronics (powered by the USB bus) to do the conversion.
Yes, but as I mentioned above, speed is primary motivation for wanting USB.
6 - Ports (USB or serial) don't do "dumps" in the sense that they will store data and initiate a transfer. Think of the NMEA 0183 data stream out of the GPS as being continuous, the data needs to be used (or stored for later use) as it is generated. The data logger is a means of storing the data for later use.
Have sent inquiry to sales dept.
Based on last night's first impression I had even transferred appropriate amount from savings to checking. It's about to return :{
Why? I think one of the data loggers at the site above, a GPS receiver to feed it data, and a serial to USB converter (for when you do the downloads) will do all the things you say you want to do.
But I want a single package. Delorme's Blue Logger GPS Receiver provides close approximation. But they can't deliver until ????? It also uses Bluetooth not USB.
I'm not an expert. What I am saying are things I learned here and other places and present for discussion. If nothing else, anything that is not right will be quickly corrected by the experts here and I'll be smarter than I was before.
And often pointed in directions I would have not thought of exploring.
Jack
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