It can be difficult to tell if a receiver is carrier phase capable since it was usually a firmware option in most general purpose receiver boards and that option may not be labelled. Your best bet is a surveying receiver.
The main problem is a standard L1 frequency only receiver is not much better than a plain jane receiver when Selective Availability is turned off (and particularly is WAAS corrections are available). This is the standard operating mode of GPS today. Choke ring antennas, etc are fairly useless overkill in this application. To get any kind of real accuracy out of an L1 only receiver requires two receivers with one set up at a precisely known point. I have a three unit Ashtech Locus surveying system that is L1 only. The NGS is working on a version of their OPUS post-processing system for L1 only receivers. It remains to be seen what kind of accuracy one can get with a single L1 carrier phase receiver. For any serious accuracy you need an L1/L2 receiver that can track both carriers so you can do proper ionospheric corrections. These puppies will set you back around $10,000-$50,000 dollars. Your best bet is to probably find an Ashtech Z12 unit. These were state of the art around 15 years ago and are still hard to beat. With luck you can score one for around $1000... make sure it comes with a proper L1/L2 antenna. A replacement antenna will cost at least that much. To get an accurate fix on a single point with these units involves taking data for a long time interval (2-24 hours, 30 second intervals), dumping the data from the unit, converting it to RINEX format, uploading it to OPUS (it's freeeee), and getting back a Where-Da-Heck-Am-I report. If everything goes well you will get centimeter level accuracy (well 5-10 cm level is more likely). _________________________________________________________________ Windows Live™ SkyDrive™: Get 25 GB of free online storage. http://windowslive.com/online/skydrive?ocid=TXT_TAGLM_WL_SD_25GB_062009 _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
