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GPS Position Information

The positions of our base station antennas were established utilizing static GPS post-processing techniques, supplied by NGS. The positional antenna data transmitted is referenced by the ARP (Antenna Reference Plane), along with the NGS antenna file information.

Subsidence and/or Building Movement

The base station antennas were constructed using 1 ½ inch stainless steel pipe, bolted directly into solid concrete poured block walls at various sites. Care was taken to mount the antennas (per NGS standards) at or near the corner of the buildings, to insure the minimum of movement possible.

Equipment

The Las Vegas Valley Water District has currently established six (6) permanent base stations throughout the valley, using Leica GRX 1200 Pro GPS receivers and Leica AT504 Choke ring antennas. The software for this system is Leica Spider version 2.2 build 2479. The Spider Network solution provides for both existing RTK radio broadcast corrections, as well as RTK corrections, via TCP/IP internet protocol.

File Naming Convention

The file types available from the District’s ftp site are available at a 5-second epoch rate, stored as 24-hour files in a zipped Rinex (Receiver Information Network Exchange) data format. The standard for this file type is as follows: [Note – 24-hour files are configured at GMT, if the format (xxxxyyy0.zip), where xxxx = site name, yyy = julian day & 0 = 24-hour file] 

File Availability and Roll-Over

The District stores files for all LVVWD base station sites. It is available at a 5-second epoch rate, stored as 24-hour files in a zipped Rinex (Receiver Information Network Exchange) data format, beginning and ending at 0:00 and 24:00 GMT (Greenwich Mean Time) respectively. The 24-hour roll-over is at GMT and is compatible with PDT (Pacific Daylight Savings Time) or PSD (Pacific Standard Time by subtracting 7 or 8 hours respectively. This equates to local roll-over at 4 p.m. PST and 5 p.m. PDT.

Real-Time Kinematic (RTK) data Link

The current District radio transmission frequencies, pursuant to FCC license, file number 0002091395, expire 06-16-2015 and are as follows:

The District currently provides an RTK data-link at the frequencies listed above. The code formats are CMR (CMR standard, not CMR-Plus). The measurement record is for over-the-air analog using Trimble Trimmark 3 radios, modulated to Trimble Trimtalk 450S radio encryption. The current protocol, settings are, 8-bit coding, odd parity and one stop bit (8-odd-1), running at a 9600 bit-per-second baud rate.

The District also provides an RTK data-link via the internet at IP address 205.159.85.60. For GPS users’ using NTRIP or TCP/IP connections, the District provides the following real-time products:

Note: To obtain access via the internet using NTRIP, prospective users must contact the District Surveyor at (702) 870-2011 to establish an account with a unique user name and password.