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630045.book Page ii Sunday, February 11, 2001 11:38 AM Copyright Notice Copyright © 2001 Magellan Corporation. All rights reserved. No part of this publication or the computer programs described in it may be reproduced, translated, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical photocopying, recording, or otherwise, without prior written permission of Magellan.
630045.book Page iii Sunday, February 11, 2001 11:38 AM SOFTWARE LICENSE AGREEMENT IMPORTANT: BY OPENING THE SEALED DISK PACKAGE CONTAINING THE SOFTWARE MEDIA, YOU ARE AGREEING TO BE BOUND BY THE TERMS AND CONDITIONS OF THE LICENSE AGREEMENT (“AGREEMENT”). THIS AGREEMENT CONSTITUTES THE COMPLETE AGREEMENT BETWEEN YOU (“LICENSEE”) AND MAGELLAN CORPORATION (“LICENSOR”). READ THE AGREEMENT CAREFULLY.
630045.book Page iv Sunday, February 11, 2001 11:38 AM DISCLAIMER OF WARRANTIES AND LIMITATION OF LIABILITY LICENSOR AND ITS THIRD-PARTY SUPPLIERS MAKE NO WARRANTIES OR REPRESENTATIONS, EXPRESS OR IMPLIED, REGARDING THE PROGRAM, MEDIA, DOCUMENTATION, RESULTS OR ACCURACY OF DATA AND HEREBY EXPRESSLY DISCLAIM ANY WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE AND NONFRINGEMENT.
630045.book Page v Sunday, February 11, 2001 11:38 AM Table of Contents Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The Global Positioning System (GPS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Surveying with GPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Post-process GPS Surveying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30045.book Page vi Sunday, February 11, 2001 11:38 AM Post-Processing Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Ashtech Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Chapter 3. Connecting System Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 GPS Receiver – GPS Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17 Handheld Computer – GPS Receiver . . . . . . . . . . . . . . . . . . . . . . .
630045.book Page vii Sunday, February 11, 2001 11:38 AM List of Figures Figure 2.1. Figure 2.2. Figure 2.3. Figure 2.4. Figure 2.5. Figure 2.6. Figure 3.1. Figure 3.2. Figure 3.3. Figure 3.4. Figure 3.5. Figure 4.1. Figure 4.2. Figure 4.3. Figure 4.4. Figure 4.5. Figure 4.6. Figure 4.7. Figure 4.8. Z-Xtreme GPS Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Geodetic IV Antenna without and with Groundplane . . . . . . . . . . . . . 9 Choke Ring Antenna . . . . . . . . . . .
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630045.book Page 1 Sunday, February 11, 2001 11:38 AM 1 Introduction Although difficult to believe, it has been nearly 20 years since precise positioning using the Global Positioning System (GPS) was demonstrated. In a relatively short time, this capability was put to commercial use with the introduction of the Macrometer V-1000 GPS receiver.
630045.book Page 2 Sunday, February 11, 2001 11:38 AM considerably so. RTK systems are somewhat more complex, requiring management of a communication link between GPS receivers. Finally, RTK GPS surveying is slightly less accurate than post-process. Even with the introduction of RTK GPS surveying in the mid 1990s, post-process GPS surveying has continued to be the most popular method of surveying with GPS. It remains the most accurate and reliable method to survey with GPS.
630045.book Page 3 Sunday, February 11, 2001 11:38 AM It’s important to remember that GPS observations result in vectors defining the relationship between the points observed. That is, a vector is the result of a GPS observation, not the coordinates of the surveyed points. To determine coordinates of surveyed points, a set of coordinates must first be supplied for one of the points.
630045.book Page 4 Sunday, February 11, 2001 11:38 AM Static data collection produces the most accurate and reliable results due to the amount of data collected during each observation. The disadvantage is in productivity. Long observations at each point reduce the number of points that can be collected in a day. Kinematic Data Collection With kinematic data collection, one of the GPS receivers in the system is designated as the base and remains stationary throughout the survey.
630045.book Page 5 Sunday, February 11, 2001 11:38 AM Applications Post-process GPS is well suited for most surveying tasks. Systems are being used today for control establishment, boundary surveys, and mapping applications such as topographic, planimetric, and as-built surveys. Post-process GPS is also very efficient for volumetric measurements such as stockpiles and gravel pits.
630045.book Page 6 Sunday, February 11, 2001 11:38 AM location, 7-10 GPS satellites may be visible and available for use, although the GPS system does not require this many satellites to function. Accurate and reliable positions can be determined with five satellites properly distributed throughout the sky. Therefore, an obstructed location can be surveyed if at least five satellites can be observed.
630045.book Page 7 Sunday, February 11, 2001 11:38 AM 2 System Components A GPS surveying system is made up of a number of components that, at first glance, may seem a bit overwhelming. On the contrary, setup of a GPS system is not a complicated task. The trick is understanding the purpose of each component in the system and how they relate to each other. With this understanding, connectivity of the hardware components, and when and how to use the software components, becomes logical and straight-forward.
630045.book Page 8 Sunday, February 11, 2001 11:38 AM Figure 2.1. Z-Xtreme GPS Receiver The Z-Xtreme supports an integral battery, removable PC card memory, and optional internal radio. It is capable of functioning as the base or rover in RTK and post-processed surveys. The integrated display and control panel supports the ability to perform some survey tasks without a handheld computer. Environmentally, the receiver meets MIL-STD-810E specifications for wind-driven rain and dust.
630045.book Page 9 Sunday, February 11, 2001 11:38 AM Geodetic IV The Geodetic IV antenna, Figure 2.2, is the standard antenna offered. System Components Figure 2.2. Geodetic IV Antenna without and with Groundplane The Geodetic IV is small, lightweight, and meets the needs of most users. It is available with an optional groundplane attachment, which is effective in reducing noise created by satellite signals reflecting off of nearby obstructions. The technical name for this noise is multipath.
630045.book Page 10 Sunday, February 11, 2001 11:38 AM Choke Ring Antenna The choke ring antenna, Figure 2.3, is the ultimate antenna for multipath rejection. Figure 2.3. Choke Ring Antenna For points located in harsh multipath environments, the choke ring antenna would be advisable. An example of a harsh multipath environment would be the top of a building which houses large metal compressors and air conditioning units. These structures will reflect satellite signals which the antenna may pick up.
630045.book Page 11 Sunday, February 11, 2001 11:38 AM Compaq Aero Pocket PC The Z-Xtreme Survey System offers, as an option, the Compaq Aero Pocket PC, Figure 2.4, a low-cost yet reliable handheld computer. Although not designed for use in harsh environments, the Aero comes with an environmental pouch that protects the computer, allowing it to be used in rain. The Aero Pocket PC operates under a Windows CE operating system. System Components Figure 2.4.
630045.book Page 12 Sunday, February 11, 2001 11:38 AM temperature. For most users, the available power from the internal battery will be sufficient. Figure 2.5 shows a typical internal battery. Figure 2.5. Typical Internal Power Source External Power For extended operation, an external power source is available as an option with the Z-Xtreme System. Internal to External Power Conversion Kit A kit can be purchased that allows the use of an internal battery as an external power source.
630045.book Page 13 Sunday, February 11, 2001 11:38 AM power source, the receiver should function un-interrupted for approximately 20 hours at room temperature.
630045.book Page 14 Sunday, February 11, 2001 11:38 AM Figure 2.6. Internal Power Source with External Conversion Kit Cable-to-User-Supplied Power Source In addition to the external power source, an optional cable is available to allow use of a vehicle battery for extended operation periods. Also available is a cable to power the GPS receiver from a cigarette lighter port. Software As with hardware, a GPS survey system includes a number of software components used both in the office and in the field.
630045.book Page 15 Sunday, February 11, 2001 11:38 AM The Z-Xtreme Survey System offers, as an option, the following field application software. Survey Control CE Survey Control CE was designed specifically for use with Ashtech post-process survey systems. The software guides you through the steps required to perform surveys using both static and kinematic data collection methods. Survey Control CE is a Windows CE-based software which runs on the Compaq Aero Pocket PC.
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630045.book Page 17 Sunday, February 11, 2001 11:38 AM 3 Connecting System Hardware At this point, you should have an understanding of the function of each hardware component of a GPS survey system and how the components relate to each other. In order for the different components to function as a system, they must communicate. This requires that the components be connected for both communication and power. Here we will examine the connectivity of the GPS system hardware components.
630045.book Page 18 Sunday, February 11, 2001 11:38 AM Figure 3.1. GPS Antenna Cable with TNC Connectors The GPS antenna cable connects to the Z-Xtreme via a TNC type connector found on the back panel of the receiver. The proper connector is labeled GPS. The other end of the cable connects to the GPS antenna via either a TNC type or N type connector depending on which antenna used, as shown in Figure 3.2. A TNC connector is found on the Geodetic IV antenna. An N type connector is found on the choke ring.
630045.book Page 19 Sunday, February 11, 2001 11:38 AM Handheld Computer – GPS Receiver The optional handheld computer must communicate with the Z-Xtreme GPS receiver to serve as an interface to the receiver. This is accomplished via an RS232 cable such as the one shown in Figure 3.3. The computer communication cable connects to the Z-Xtreme via one of the three serial ports on the back panel of the receiver. These three ports are grouped together and labeled SERIAL PORTS.
630045.book Page 20 Sunday, February 11, 2001 11:38 AM Figure 3.4. Aero Handheld Pouch GPS Receiver – Receiver Power System Supplying power to the GPS receiver can be accomplished in two ways. The ZXtreme receiver has a battery integrated into the receiver for power. This connection does not require a cable. The battery is simply inserted into the receiver. If the GPS system is to function unattended for a period of time not supported by the internal battery, an external battery can be used (Figure 3.5).
630045.book Page 21 Sunday, February 11, 2001 11:38 AM Figure 3.5. Z-Xtreme Connected to External Power The external power source can be connected at any time without concern of the internal battery. Connecting System Hardware 21 Connecting Hardware This concludes our review of the hardware component connectivity for the ZX SuperStation. We are now ready to examine the setup and execution procedures for performing a survey.
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630045.book Page 23 Sunday, February 11, 2001 11:38 AM 4 Survey Preparation & Execution The previous chapters laid the ground work for understanding the purpose of each component of the Z-Xtreme Surveying system and the relationship between components. This understanding of the functionality and connectivity of the system components will prove invaluable during survey preparation and execution. Let’s put this new found knowledge to good use.
630045.book Page 24 Sunday, February 11, 2001 11:38 AM Figure 4.1. Kit Bag In the kit bag you should find the Z-Xtreme GPS receiver, Geodetic IV antenna with tribrach adapter, antenna cable, HI measurement device, and internal battery. There is additional room in the kit bag for miscellaneous items such as a tribrach, and optional external power supply.
630045.book Page 25 Sunday, February 11, 2001 11:38 AM Figure 4.2. Inside View of Kit Bag Static Survey Prior to leaving the office to perform a GPS survey, check the following items: 2. Check to ensure that the batteries are charged. 3. Using the Mission Planning module of the post-processing software, check the satellite availability for the time period when data is to be collected. Ensure that satellite geometry is sufficient to support good GPS surveying.
630045.book Page 26 Sunday, February 11, 2001 11:38 AM 4. Ensure that each operator of a GPS receiver has blank GPS observation logs to utilize during data collection. Fill out one sheet for each observation of each point. Observation logs will be discussed in more detail later in this section. The post-processing software supports the ability to print blank observation logs for use during data collection. With the previous checklist completed, field data collection can begin.
630045.book Page 27 Sunday, February 11, 2001 11:38 AM Conventional Fixed-Height Figure 4.3. Conventional and Fixed-Height Tripods 3. Measure and record instrument height (HI) of GPS antenna Remember that measurements of satellite data are made at the center (horizontally and vertically) of the GPS antenna. Yet the location of the point to be surveyed is not at the center of the antenna but below it on the ground.
630045.book Page 28 Sunday, February 11, 2001 11:38 AM Figure 4.4. Measuring HI (Height of Instrument) of GPS Antenna Different GPS antennae will have different HI measurement points. For the Geodetic IV, the HI measurement point is the top of the ground plane. 4. Connect system components With the remaining system components residing in the field pack, connect all components as listed below. Some of these connections will already be made.
630045.book Page 29 Sunday, February 11, 2001 11:38 AM a new data file. Data will be recorded at an interval of 20 seconds, i.e once very 20 seconds, a data sample will be written to memory. This is the default factory setting for recording interval. If desired, the recording interval can be changed. For static survey method, recording intervals of 5 to 30 seconds are commonly used.
630045.book Page 30 Sunday, February 11, 2001 11:38 AM Determine if the GPS receiver is observing satellites and storing raw data. This can be accomplished by either using the field application software running on the handheld computer or the interface on the receiver. Your Z-Xtreme receiver is now collecting static data. No further interaction with the system is required for the duration of data collection at this location.
630045.book Page 31 Sunday, February 11, 2001 11:38 AM Figure 4.5. Z-Xtreme Survey System Performing a Static Survey Kinematic Survey The base system for a kinematic survey is set up in precisely the same manner as a system set up for a static survey, with one possible exception. During kinematic data collection, it is recommended that a more frequent recording interval be utilized. Common recording intervals for kinematic data collection are 1-5 seconds.
630045.book Page 32 Sunday, February 11, 2001 11:38 AM The rover system for a kinematic survey is set up in a slightly different manner due to the fact that kinematic data collection is dynamic in nature, i.e. the operator must be able to easily move around the project site with the rover system in order to position objects of interest. This requires that the rover system be set up in a manportable configuration, as described below. 1.
630045.book Page 33 Sunday, February 11, 2001 11:38 AM antenna, as shown in Figure 4.7. A special mounting bracket for the handheld is included in the rover system. Figure 4.7. Compaq Aero Handheld Mounted on Rover Pole 4. Connect system components • • • GPS antenna ↔ GPS receiver External GPS receiver power ↔ GPS receiver (optional if using internal battery) Handheld computer ↔ GPS receiver 5. Power-up rover system This is simply accomplished by pressing the power button on the GPS receiver.
630045.book Page 34 Sunday, February 11, 2001 11:38 AM As with performing a static survey, the only parameter that may require to be changed is the recording interval. The recording interval is set to 20 seconds by default. As stated earlier, an interval of 1-5 seconds is normally used for kinematic data collection. The recording interval can be set using the field application software running on the handheld computer.
630045.book Page 35 Sunday, February 11, 2001 11:38 AM Figure 4.8. Rover System Ready to Survey Now that the base and rover systems are configured, point location can begin. Using the rover system, you will move about the project area collecting data on points of interest in order to determine their position. This process involves two primary functions that you must execute repeatedly. These functions are Initialization and Point Observation.
630045.book Page 36 Sunday, February 11, 2001 11:38 AM the integer ambiguities. Once the integer ambiguities have been calculated, your current location can be determined very precisely. Solving for the integer ambiguities is the most time consuming part of GPS data collection. Once solved, the position of your currently location is instantly known. In addition, once you have calculated the integer ambiguities, they stay fixed as long as you maintain lock on at least five satellites.
630045.book Page 37 Sunday, February 11, 2001 11:38 AM You arrive on a new project site where you need to perform a kinematic survey. You set up the base station on an existing point with known coordinates or an arbitrary point where approximately coordinates will be assigned. You assign a point ID of 0001 to your base point. You drive a PK into the ground to mark your initialization point. You assign a point ID of 0100 to your initialization point.
630045.book Page 38 Sunday, February 11, 2001 11:38 AM on some arbitrary location. After two minutes, you are ready to begin locating topo points. You decide to start at the northeast corner of the landfill because it is wide open with no obstructions. It takes you approximately 1 minute to walk to the location of the first topo shot. By this time, you have already collected 3 minutes of data that will be used towards your initialization. You begin collecting topo points.
630045.book Page 39 Sunday, February 11, 2001 11:38 AM while walking. The ability to determine positions while observing a feature for a period of time and the ability to determine positions while moving around the project site results in two modes of positioning features of interest with the rover system. These two modes are termed Continuous Kinematic and Stop&Go Kinematic. Continuous Kinematic The Continuous Kinematic mode of data collection is best used when positioning linear features such as roads.
630045.book Page 40 Sunday, February 11, 2001 11:38 AM The Stop&Go Kinematic method is more precise than the Continuous Kinematic method since multiple data samples are used to compute one position for a point feature. With Stop&Go Kinematic, you can expect positions at the 0.01 – 0.03 meters (0.03 – 0.10 ft) level.
630045.book Page 41 Sunday, February 11, 2001 11:38 AM 5 Troubleshooting So, you followed all the steps to prepare the Z-Xtreme Survey System to perform a survey and the system is not working. Why? Well, the problem is usually due to one of two things: a component is malfunctioning, or the system is not set up properly. Improper setup can be caused by a memory lapse on the part of the operator or a system component.
630045.book Page 42 Sunday, February 11, 2001 11:38 AM GPS receiver does not track satellites A satellite tracking LED on the front panel of the Z-Xtreme receiver displays the number of healthy satellites supplying good data for data collection. This information is also available through the field application software running on the handheld computer. Refer to the receiver or application software documentation for details on how to access this information.
630045.book Page 43 Sunday, February 11, 2001 11:38 AM 2. Is the GPS antenna connected to the receiver? Look on the back panel of the receiver for a cable connecting the receiver to the antenna. Antenna Is Not Connected Connect the GPS antenna to the receiver. On the back panel of the Z-Xtreme, connect the antenna cable to the port labeled ‘GPS’. Ensure the connection is snug and not cross-threaded. At the antenna, connect the antenna cable to the antenna.
630045.book Page 44 Sunday, February 11, 2001 11:38 AM 1. Is the GPS receiver tracking satellites? The GPS receiver must first be tracking satellites before it can log data to memory. Check the data logging LED on the front panel of the Z-Xtreme receiver to determine if the receiver is tracking satellites. Receiver is not tracking satellites Refer to the above troubleshooting item on satellite tracking to try and determine the problem. Receiver is tracking satellites Go to step 2 below. 2.
630045.book Page 45 Sunday, February 11, 2001 11:38 AM This concludes the troubleshooting section. If the tips given here did not help you to resolve your problem with your Z-Xtreme Survey System, please call your local dealer or Ashtech customer support for assistance.
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630045.book Page 47 Sunday, February 11, 2001 11:38 AM Numerics 1227.60 MHz, 2 1575.
630045.book Page 48 Sunday, February 11, 2001 11:38 AM G GPS vectors, 3 grid systems, 2 N type connector, 18 H O observation times, 6, 26, 30 obstruction conditions, 3, 8 height of antenna, 8 HI, 24, 29, 32 HI tool, 27 horizontal angle, 3 horizontal position, 8 P I initial coordinates, 3 initialization, 4, 35 initialize, 6 L L1, 2 L2, 2 least-squares adjustment, 5 level pole and antenna, 32 linear features, 4 line-of-sight, 5 link previous points, 3 log sheet.
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