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SmartWorx Viva – Using Leica Viva Antennas in NGS OPUS Service

Firmware Version 4.01

FEB12

To properly submit GPS static data in RINEX format to the NGS OPUS service, you need to make

sure you understand the requirements for entering antenna heights. NGS receives antennas

from all manufacturers and perform antenna calibrations on them to define the actual phase

centers in each antenna. From these antenna definitions listing in the OPUS submittal site you

can select the manufacture model of the antenna used while observing the static data. For

more information about the antenna calibrations performed by NGS you can visit the NGS

website at:

http://www.ngs.noaa.gov/ANTCAL/main.jsp

For Leica Viva antennas the height is always referenced to the Antenna Reference Point (ARP).

The ARP is the physical point on the antenna housing the meets the mounting point of the

accessory being used with the antenna. For example, the ARP for an antenna being used with

a 2 meter pole would be the point of contact that the bottom of the antenna makes with the

top of the pole. For all Leica GNSS antennas the ARP is the bottom surface of the mounting nut

on the antenna housing. The ARP locations for the Leica Viva GNSS antennas are shown as

follows:

GS15 GNSS Antenna ARP

AS10 GNSS Antenna ARP

GS08 and GS12 GNSS Antenna ARP

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Using a Fixed-Height Pole for Static Observations

If you are using a 2 meter fixed-height pole with bipod to observe static data on a point, the antenna

height to be entered into OPUS would be 2.000 meters. The height of the fixed-height pole is entered

as 2.000 meters then OPUS will add the needed offsets to the phase centers from the NGS antenna

model when computing the coordinates for the observed point.

Diagram 1

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Using a Tripod with Leica Accessories for Static Observations

If you are using a Leica tribrach and antenna carrier during your static survey, you will be measuring the

height to the ARP by using the Leica GZS4 height hook (Art. No. 667244) that inserts into the antenna

carrier. You will read the measured distance to the survey point from the white line on the height hook

to the top of the survey point by reading the measured distance on the tape at the white line on the

lower end of the Leica GZS4 height hook. This is the distance shown as Item E in the diagram. The

distance shown as Item D in the diagram is a known distance from the design of the high precision Leica

accessories used in this method. The distance from the white line of the Leica GZS4 height hook to the

ARP is know because the machined distance from this point to the point where the centerline of the

shaft of the height hook inserts into the carrier. Next the machined distance from the centerline of the

height hook shaft to the top of the Leica antenna carrier is also known. These two distances are equal to

Item D shown in the diagram. This provides the user a way to measure the Vertical Height reading to

the ARP instead of having to try and measure a sloped distance to some imprecise point on the shell of a

manufacturer’s antenna.

Diagram 2

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The offset is automatically recorded in Leica’s software by defining the type of setup used (Pole vs.

Tripod). However, OPUS only accepts the total vertical reading to the ARP in meters. If you are

exporting RINEX data directly from Leica Geo Office (LGO), you can find the vertical reading by viewing

the GPS Processing page in your LGO project, selecting the observation that you will sending to OPUS

and then selecting Properties… from the menu.

The Interval Properties window from the selected observations will show you the Total Vertical Height

that will be inputted into your OPUS file upload.

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If you are not using LGO but are exporting RINEX data directly from you Viva GNSS receiver you will need

to know the value you entered from the measurement from the height hook (Item E from diagram 2)

and the offset value for the Leica antenna carrier you are using. Images and examples for the three

available Leica antenna carries will be explained as follows:

A. If you are using the Leica GRT144 (Art. No. 667313) in combination with the GAD31 (Art. No.

667217) 5/8 inch thread adapter or if you are using the stand-alone GRT146 (Art. No. 667216)

the distance offset from the height hook measurement to the ARP (Item D from diagram 2) is

always 0.360 meters.

Vertical Height to ARP = Leica GZS4 Height Hook Measurement + 0.360 meters

Leica GRT144 Antenna Carrier and

GAD31 Adapter

Leica GRT146 Antenna Carrier

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B. If you are using the new GRT247 (Art. No. 770715) short, 5/8 inch thread carrier the distance

offset from the height hook measurement to the ARP (Item D from diagram 2) is always 0.255

meters.

Vertical Height to ARP = Leica GZS4 Height Hook Measurement + 0.255 meters

Leica GRT247 Antenna Carrier

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OPUS Leica Antenna Listings

The Legacy Leica antenna listings for System300, System500, System1200 and others are all listed in the

antenna definitions on the NGS OPUS webpage. The new Leica Viva antenna listings are shown below:

Listing to use for Leica Viva GS15 Antenna (LEIGS15)

Listing to use for Leica Viva AS10 Antenna (LEIAS10)

If you have Technical Support questions, please contact us at G360…..

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