GPS receivers: Difference between revisions

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== GPS ==
http://gpsinformation.net/ Reviews and information
[http://www.fs.fed.us/database/gps/mtdc/gps2000/gps_comparison.htm US Forest Service paper comparing GPS receivers] summer 2000
[http://home1.gte.net/clseng/DGPS_index.htm Build your own DGPS beacon receiver] It might be a bit more cost effective to get a WAAS based receiver these days,
but here you can learn what goes into a beacon receiver.
=== Transferring data into a GPS ===
Any platform
Garnix
http://www.gpsbabel.org/
==== Windows ====
ArcMap extension for Garmin [http://www.mxgeo.com/index.htm mxgeo] (does not work on my computer) ($50 shareware)
==== Linux ====
[http://gpsd.berlios.de/ gpsd] data collector
http://www.ncc.up.pt/gpsman/wGPSMan.html
http://sourceforge.net/projects/gpstrans
=== Data formats and protocols ===
==== RINEX = Receiver Independent Exchange Format ====
[http://www.navcen.uscg.gov/pubs/gps/rinex/default.htm RINEX 1] [http://gps.wva.net/html.common/rinex.html#rinex:_the_receiver_independent_exchange_format_version_2.10 RINEX 2]
Using RINEX to do differential postprocessing on your GIS data.
# Collect raw data [http://artico.lma.fi.upm.es/numerico/miembros/antonio/async/ using Garmin equipment]
# [http://www.helenav.nl/rinex.htm Conversion of Raw Observation Data and Navigation Message Data to RINEX] See [http://www.unavco.org/facility/software/teqc/teqc.html TEQC software] and [http://www.nottingham.ac.uk/iessg/gringo/ GRINGO software]
# Download [http://www.ngs.noaa.gov/CORS/Data.html CORS data]
# Postprocess; using [http://www.nottingham.ac.uk/iessg/gringo/READMEP4.HTM P4] (companion to Gringo)
[ftp://ftp.hgmp.mrc.ac.uk/pub/ajb/jeeps/ JEEPS] is a library that you are supposed
to be able to use to build Garmin and post-processing applications. I don't think
this means DGPS post-processing though...
[http://www.prairie.mb.ca/ Prairie] has an intersting collection of information on using Garmin and [http://www.prairie.mb.ca/usp_rhino.htm Rhino] products for DGPS. Rhino is a product of
[http://www.uspositioning.com US Positioning].
"Proven Success With Rhino" (and therefore probably with RINEX conversion software?)
eTrex, eTrex Summit,
eTrex Vista, eTrex Legend,
GPS 12, GPS II +, GPS III, GPS III +,
GPS V,
GPS 16, GPS 16A,
GPS 17N,
GPS MAP 76, GPS MAP 76S,
GPS MAP 176, GPS MAP 176C
==== NMEA ====
NMEA = National Maritime Electronics Association
[http://www.nmea.org/ NMEA] [http://www.nmea.org/pub/0183/index.html 0183 standard] is the ASCII format for (among many other things) GPS spatial data. You have to pay $250 to get a copy of the 0183 standard, these people don't know about the Internet and open standards yet. (The NMEA 2000 standard is $3800, ha ha ha.) If you are designing a new device and you have the bucks, you have to pony up. If all you want to do is grab data from your handheld and process it, the manufacturer manuals from both Garmin and
Trimble are good. (Probably others too, these are just the ones I have read.)
==== RTCM ====
RTCM = Radio and Telephony Communications Maritime or something like that.
[http://www.rtcm.org RTCM] is another standards body in the business of selling
information that really probably should be distributed for free. The publication set
on differential GPS is $100. NTRIP which is the standard for distribution of the data
over IP networks (via HTTP) is $50.
==== TSIP and TAIP ====
These are the proprietary Trimble protocols. TSIP is binary and TAIP is ASCII.
I have not tried TAIP yet. The [[Lassen SQ]] really wants to be in TSIP mode though you can switch it to NMEA 0183/RTCM. (I should say, Trimble's software wants it to be in TSIP mode.)
The protocol is documented in the back of the Lassen manuals. It is supported by third party software such as ESRI [[ArcPad]].
=== Selected GPS Hardware ===


My interest is in learning how to do as much as possible for the least cost.
My interest is in learning how to do as much as possible for the least cost.

Revision as of 18:35, 30 April 2006


My interest is in learning how to do as much as possible for the least cost. I have a Garmin eMap and a Garmin GPS 25-LVC module, and Trimble Ace II and Trimble Lassen SQ modules. I recently got a Magnavox GPS reference station.

For hobbyists probably the best place to turn is [Spark Fun Electronics], they have a bunch of other modules that I don't list here yet.

Garmin

Garmin OEM information

Model Accuracy Channels Price Comments
eMap 15m/2m 12 $200 or so Handheld, accepts RTCM for DGPS. Apparently a bad choice for Rinex software
GPS 10 15m/3m WAAS 12 $250 bluetooth module
GPS 15 15m 12 bare module
GPS 16 LVS, 16 HVS, 16A
3.3-6V / 6-40V / 8-40 V		 15m / <3m WAAS / 3-5 USCG RTCM 12 channel 2 serial ports, deck mount
GPS 17 $200 basically the same as a GPS 16 but in a white, pole mount case
GPS 18 15m / 3m WAAS 12 $130 CMOS serial or RS232 or USB hockey puck
GPS 25-LVC (3.6-6V), -LVS(3.6-6V RS232), -HVS(6-40V RS232) 15m / 5m DGPS ? bare module; capable of raw data output (pseudorange and phase)

[1]

GPS 35 / 36 15m / 5m DGPS ? 35 = mouse style, 36 = pole mount

The GPS 17 is designed for marine applications but is often pressed into service in backpack style data collectors.

Trimble

GPS modules

Model Accuracy Channels Connectors Price (est) Comments
Pathfinder Pocket 10m/2m DGPS 8 2 RS232 via one DB9, SMB 3.3v, power $500 includes an external antenna.
M-Loc 10m (no DGPS) 12 3.3v 35mW(68mW)

25 x 25 x 6.9 mm

 $45 FirstGPS software runs on host processor
Lassen SQ 6-9m,no DGPS 8 8 pin header, H-FL-R-SMT 3.3v/100mW
26x26x6 mm, 5.7g 		$45 (use IQ instead!) Use w/RF transition cable
Lassen IQ 5-8m,no DGPS 12 8 pin header, H-FL-R-SMT 3.3v/85mW
26x26x6 mm, 5.7g 		$50 Updated more accurate version of SQ. Purchase from SparkFun
Ace II 25m/2m DGPS 8 8 pin (2 CMOS TTL serial) SMB 5v/25mA 5v / 95mA / .47W
82.6 x 46.5 x 11.5 mm
cheap Discontinued but I got one from eBay for $10
Ace III 25m/2m DGPS 8 8 pin (2 CMOS TTL serial) SMB 5v/25mA 5v / 95mA / .47W
82.6 x 46.5 x 11.5 mm
$80
Lassen SK-8 25m/2m DGPS 8 8 pin (2 CMOS TTL serial) SMB 5v/25mA $ Discontinued; use SKII
Lassen SKII 25m/2m DGPS 8 8 pin (2 CMOS TTL serial) SMB 5v/25mA 5V / 95mA(120mA)/ .47W(.60W) $80
Lassen LP 25m/2m DGPS 8 2 serial and power via 8 pin header, MCX/3.3v 12mA 3.3V / 55mA(67mA)/ .182W(.221W)

66.167 x 31.75 x 12

$55 Low power; can be programmed to power up/down on schedule
Style Gain Connector Price
Micropatch 26dB 5m cable with MCX $17
Hardmount micropatch 26dB TNC $
Bullet 35dB 22m cable with SMB adapter $

DIY USB Lassen SQ

ToppTec -- purveyors of Trimble OEM modules

Delorme

http://www.delorme.com/

Consumer grade; Earthmates are WAAS enabled but the older Tripmates are cheap on eBay if you just need a NMEA GPS source.

Model Accuracy Channels Price Comments
Tripmate 15m? 12 $20-30 on eBay rs232 (discontinued)
Earthmate WAAS 12 $100 USB
Blue logger WAAS 12 $150 bluetooth enabled

Other links

Leica
Thales and Magellan
U-blox sells mostly Sony modules.

GPS simulators

People make boxes that simulate NMEA-capable devices to allow testing when the actual data stream is not available and to enable regression testing.

There is an Open Source GPS Simulator

GPS mission planning software

A GPS mission consists of three phases. planning, execution, and post-processing. Mission planning software packages run on a desktop system at your office and assist with planning and post-processing phases.

The two commercial programs that I know of are tightly integrated with the field software so they are not all that useful unless you buy in to the whole enchilada -- data collector, proprietary data collector software, and "office" software.

The two programs are Trimble GPS Pathfinder Office for use with Trimble data collectors and TDS SoloOffice which works with TDS SoloField.

Planning for a GPS mission should include checking for suitable conditions. This includes knowing that the satellites will be positioned propitiously when you will be in the field.

I use Trimble's free planning program for this. You can download it from [insert Trimbles download site]. The bad part is that it is available only for Windows systems but it's handy enough that I use it anyway.

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