Users Manual

FCC ID: JUP-6999600

Users Manual

Download: PDF

FCCID_1223378

Draft
SNM910 Site-Net Modem Getting Started
Guide

Tr im ble SPS M odu la r GPS
Re ce ive r s H e lp
This Help describes how to use the following products:
• Trimble SPS GPS receivers
This family of receivers comprise the SPSx52 Modular GPS receiver,
the SPSx51 Modular GPS receivers, the SPSx61 Modular Heading GPS
receivers, and the SPS882 Smart GPS antenna.
• SNM910 site-net modem
Where necessary, this Help contains references to specific receivers in the
product family. When information is specific to a particular model, then the
specific model name is used.
Even if you have used other Global Positioning System (GPS) products before,
Trimble recommends that you spend some time reading this manual to learn
about the special features of this product. If you are not familiar with GPS,
visit the Trimble website (www.trimble.com) for an interactive look at Trimble
and GPS.

1

Introduction

Re la t e d in for m a t ion
Sources of related information include the following:
• Release notes – The release notes describe new features of the
product, information not included in the manuals, and any changes to
the manuals. They can be downloaded from the Trimble website
(www.trimble.com/support.shtml) .
• Trimble training courses – Consider a training course to help you
use your GPS system to its fullest potential. For more information, go to
the Trimble website at www.trimble.com/training.html.

Technical support
If you have a problem and cannot find the information you need in the product
documentation, contact your local dealer. Alternatively, go to the Support area
of the Trimble website (www.trimble.com/support.shtml). Select the product
you need information on. Product updates, documentation, and any support
issues are available for download.
If you need to contact Trimble technical support, complete the online inquiry
form at www.trimble.com/support_form.asp.

Your comments
Your feedback about the supporting documentation helps us to improve it with
each revision. Email your comments to ReaderFeedback@trimble.com.

7

Getting Started Guides
SNM910 Site-Net Modem
Safety Information

Before you use your Trimble product, make sure that you have read and
understood all safety requirements.

Use and care

This product is designed to withstand the rough treatment and tough
environment that typically occurs in construction applications. However, the
receiver is a high-precision electronic instrument and should be treated with
reasonable care.

Ca u t ion – Ope r a t in g or st or in g t h e r e ce ive r ou t side t h e sp e cif ie d t e m pe r a t u r e
r a n ge ca n d a m a g e it .

Regulations and safety

Some SPS receiver models with Base capability contain an internal radio-
modem for transmission or can transmit through an external data
communications radio. Regulations regarding the use of the 410-470 MHz
radio-modems vary greatly from country to country. In some countries, the
unit can be used without obtaining an end-user license. Other countries require
end-user licensing. For licensing information, consult your local Trimble dealer.
All SPS receiver models are capable of transmitting data via Bluetooth.
Bluetooth, and 900 MHz1 , (and 2.4 GHz radio-modems - Ja pa n on ly) operate
in license-free bands.
The SNM910 contains an internal Quad-Band GSM 850/900/1800/1900MHz
radio Modem.
Before operating a Trimble GPS receiver or GSM modem, determine if
authorization or a license to operate the unit is required in your country. It is
the responsibility of the end user to obtain an operator's permit or license for
the receiver for the location or country of use.
For FCC regulations, see Legal Notices.

Type approval

Type approval, or acceptance, covers technical parameters of the equipment
related to emissions that can cause interference. Type approval is granted to
the manufacturer of the transmission equipment, independent from the
operation or licensing of the units. Some countries have unique technical
requirements for operation in particular radio-modem frequency bands. To
comply with those requirements, Trimble may have modified your equipment
to be granted Type approval.
9

SNM910 Site-Net Modem Getting Started Guide

Unauthorized modification of the units voids the Type approval, the warranty,
and the operational license of the equipment.

Exposure to radio frequency radiation

For 450 MHz radio

Safet y. Exposure to RF energy is an important safety consideration. The FCC
has adopted a safety standard for human exposure to radio frequency
electromagnetic energy emitted by FCC regulated equipment as a result of its
actions in General Docket 79-144 on March 13, 1986.
Proper use of this radio modem results in exposure below government limits.
The following precautions are recommended:
• DO NOT operate the transmitter when someone is within 20
cm (7.8 inches) of the antenna.
• DO NOT operate the transmitter unless all RF connectors are
secure and any open connectors are properly terminated.
• DO NOT operate the equipment near electrical blasting caps
or in an explosive atmosphere.
• All equipment must be properly grounded according to
Trimble installation instructions for safe operation.
• All equipment should be serviced only by a qualified
technician.

For license-free 900 MHz radio1

Ca u t ion – For you r ow n sa fe t y, a n d in t e r m s of t h e RF e x p osu r e
r e qu ir e m e n t s of t h e FCC, a lw a ys ob se r ve t h e p r e ca u t ion s list e d h e r e .

• DO NOT operate the transmitter when someone is within 20
cm (7.8 inches) of the antenna.
• Do not co-locate the antenna with any other transmitting
device.

For 2.4 GHz radio2

Safet y. Exposure to RF energy is an important safety consideration. The FCC
has adopted a safety standard for human exposure to radio frequency
electromagnetic energy emitted by FCC regulated equipment as a result of its
actions in General Docket 79-144 on March 13, 1986.
Proper use of this radio modem results in exposure below government limits.
The following precautions are recommended:
• DO NOT operate the transmitter when someone is within 20
cm (7.8 inches) of the antenna.
The maximum gain of the antenna must not exceed 8 dBi.

10

Getting Started Guides

For Bluetooth radio

The radiated output power of the internal Bluetooth wireless radio is far below
the FCC radio frequency exposure limits. Nevertheless, the wireless radio shall
be used in such a manner that the Trimble receiver is 20 cm or further from
the human body. The internal wireless radio operates within guidelines found
in radio frequency safety standards and recommendations, which reflect the
consensus of the scientific community. Trimble therefore believes that the
internal wireless radio is safe for use by consumers. The level of energy
emitted is far less than the electromagnetic energy emitted by wireless devices
such as mobile phones. However, the use of wireless radios may be restricted
in some situations or environments, such as on aircraft. If you are unsure of
restrictions, you are encouraged to ask for authorization before turning on the
wireless radio.

For GSM/GPRS radio

Safet y. Exposure to RF energy is an important safety consideration. The FCC
has adopted a safety standard for human exposure to radio frequency
electromagnetic energy emitted by FCC regulated equipment as a result of its
actions in General Docket 79-144 on March 13, 1986.
Proper use of this radio modem results in exposure below government limits.
The following precautions are recommended:
• DO NOT operate the transmitter when someone is within 28
cm (11 inches) of the antenna.
• All equipment should be serviced only by a qualified
technician.

Installing antennas

Ca u t ion – For you r ow n sa f e t y, a n d in t e r m s of t h e RF e x posu r e
r e qu ir e m e n t s of t h e FCC, a lw a ys ob se r ve t h e se p r e ca u t ion s:
– Alw a y s m a in t a in a m in im u m se pa r a t ion dist a n ce of 2 0 cm ( 7 .8
in ch e s) be t w e e n you r se lf a n d t h e r a d ia t in g a n t e n n a .
– D o n ot co- loca t e t h e a n t e n n a w it h a n y ot h e r t r a n sm it t in g de v ice .

Ca u t ion – Th e GPS a n t e n n a a n d it s ca b lin g sh ou ld be in st a lle d in
a ccor da n ce w it h a ll n a t ion a l a n d loca l e le ct r ica l code s, r e gu la t ion s,
a n d pr a ct ice s.

Th e a n t e n n a a n d ca b lin g sh ou ld be in st a lle d w h e r e t h e y w ill n ot
be com e e n e r giz e d a s a r e su lt of fa llin g n e a r by pow e r lin e s, n or be
m ou n t e d w h e r e t h e y a r e su b j e ct e d t o ove r volt a ge t r a n sie n t s,
pa r t icu la r ly lig h t n in g. Su ch in st a lla t ion s r e qu ir e a d dit ion a l pr ot e ct ive
m e a n s t h a t a r e de t a ile d in n a t ion a l a n d loca l e le ct r ica l code s.

Trimble SPS internal radios have been designed to operate with the antennas
listed below. Antennas not included in this list are strictly prohibited for use
with this device. The required antenna impedance is 50 ohms.

11

SNM910 Site-Net Modem Getting Started Guide

The antennas that can be used (country dependent) with the 4 5 0 M H z r a dio
are 0 dBi and 5 dBi whip antennas. The antennas that can be used (country
dependent) with the 9 0 0 M H z radio are 0 dBi, 3 dBi, and 5 dBi whip antennas.
The antennas that can be used (country dependant) with the2 .4 GH z r a dio
are 2 dBi and 8 dBi whip antennas.
To reduce potential radio interference to other users, the antenna type and its
gain should be so chosen so that the equivalent isotropically radiated power
(e.i.r.p.) is not more than that permitted for successful communication.

Battery safety

SPS receiver internal lithium-ion battery

W ARN I N G – D o not da m a ge t he r e cha r ge a ble Lit hium - ion ba t t e r y. A
da m a ge d ba t t e r y ca n ca use a n e x plosion or fir e , a nd ca n r e sult in pe r sona l
inj ur y a nd/ or pr ope r t y da m a ge .
To pr e ve nt inj u r y or da m a ge :
– D o not use or ch a r ge t he ba t t e r y if it a ppe a r s t o be da m a ge d. Sign s of
da m a ge inclu de , but a r e not lim it e d t o, discolor a t ion, w a r ping, a nd le a k ing
ba t t e r y fluid.
– D o not e x pose t he ba t t e r y t o fir e , high t e m pe r a t ur e , or dir e ct sunlight .
– D o not im m e r se t he ba t t e r y in w a t e r .
– D o not use or st or e t h e ba t t e r y inside a ve hicle dur ing h ot w e a t he r .
– D o not dr op or punct u r e t he ba t t e r y.
– D o not ope n t he ba t t e r y or sh or t - cir cuit it s cont a ct s.

W ARN I N G - Avoid cont a ct w it h t he r e cha r ge a ble Lit hium - ion ba t t e r y if it
a ppe a r s t o be le a k ing. Ba t t e r y fluid is cor r osive , a nd cont a ct w it h it ca n
r e sult in pe r sona l inj u r y a nd/ or pr ope r t y da m a ge .
To pr e ve nt inj u r y or da m a ge :
– I f t he ba t t e r y le a k s, a void cont a ct w it h t he ba t t e r y fluid.
– I f ba t t e r y fluid ge t s int o your e ye s, im m e dia t e ly r inse your e ye s w it h
cle a n w a t e r a nd se e k m e dica l a t t e nt ion. D o n ot r ub your e ye s!
– I f ba t t e r y fluid ge t s ont o you r sk in or clot hin g, im m e dia t e ly use cle a n
w a t e r t o w a sh off t he ba t t e r y fluid.

W ARN I N G - Cha r ge a nd use t he r e cha r ge a ble Lit hium - ion ba t t e r y only in
st r ict a ccor da nce w it h t he inst r uct ion s. Cha r gin g or usin g t he ba t t e r y in
una u t h or iz e d e quipm e n t ca n ca use a n e x plosion or fir e , a nd ca n r e sult in
pe r sona l inj ur y a n d/ or e quipm e n t da m a ge . To pr e ve nt inj ur y or da m a ge :
– D o not cha r ge or use t he ba t t e r y if it a ppe a r s t o be da m a ge d or le a k in g.
– Cha r ge t he Lit hium - ion ba t t e r y only in a Tr im ble pr oduct t ha t is spe cifie d
t o cha r ge it . Be sur e t o follow a ll inst r uct ions t h a t a r e pr ovide d w it h t he
ba t t e r y cha r ge r .
– D iscon t inue cha r ging a ba t t e r y t ha t give s off e x t r e m e he a t or a bu r ning
odor .
– Use t he ba t t e r y only in Tr im ble e quipm e n t t h a t is spe cifie d t o use it .
– Use t he ba t t e r y only for it s int e nde d use a n d a ccor ding t o t he
inst r u ct ion s in t he pr oduct docum e n t a t ion .

Connecting SPS receivers to a vehicle battery

12

Getting Started Guides

W ARN I N G – Use ca ut ion w he n conne ct ing ba t t e r y ca ble 's clip le a ds t o a
ve hicle ba t t e r y. D o not a llow a ny m e t a l obj e ct or j e w e lr y t o con ne ct ( shor t )
t he ba t t e r y's posit ive ( + ) t e r m ina l t o e it he r t he ne ga t ive ( - ) t e r m ina l or t he
m e t a l of t he ve hicle conne ct e d t o t he ba t t e r y. This could r e sult in high
cur r e n t , a r cing, a nd high t e m pe r a t ur e s, e x posing t he use r t o possible
inj ur y.

W ARN I N G - W he n conn e ct ing a n e x t e r na l ba t t e r y, such a s a ve hicle
ba t t e r y, t o a n SPS r e ce ive r , be sur e t o use t he Tr im ble ca ble w it h pr ope r
ove r - cur r e nt pr ot e ct ion int e nde d for t his pur pose , t o a void a sa fe t y ha z a r d
t o t he use r or da m a ge t o t he pr oduct .

Changing the Radio module

SPS882 only

Trimble requires that you do not change from one version of a radio door
assembly to another, for the following reasons:
• The regulatory compliance requirements will be violated.
Operating such a product is illegal.
• The internal connector on the radio is not intended for
multiple insertions or extractions. It may be damaged or break if
overused.
• The seal integrity of the whole GPS receiver is compromised
when the radio is removed. Users do not have the facilities to test
the integrity of the seal.
• If the unit is outside of warranty, you can purchase another
radio door, which must be installed by a Trimble authorized
Service Provider. There are hardware limitations to this, so be
very careful, especially with the 900 MHz doors.

Ca u t ion - Be ca u se of in st a lla t ion pr oble m s a n d cou n t r y r e gu la t ion
issu e s, Tr im b le doe s n ot se ll r a dio door s t o e n d u se r s. Tr im ble
a u t h or iz e d Se r v ice Pr ovide r s m u st com ply w it h cou n t r y r e gu la t ion s
a n d in st a ll t h e cor r e ct r a dio on ly in d e fin e d a n d a cce pt e d r e ce iv e r s.
I nst a llin g a r a d io in a n on - sp e cif ie d GPS p r oduct or de v ice voids a n y
w a r r a n t y of t h e r a d io a n d of t h e GPS pr odu ct . I t a lso su b j e ct s t h e
se r v ice pr ovide r t o pe n a lt ie s se t for t h b y v a r iou s g ove r n m e n t
a ge n cie s. Tr im ble sh a ll a ssu m e n o lia b ilit y for r a dios u se d in n on -
a u t h or iz e d pr odu ct s.

Wet locations

SPSx61 only

W ARN I N G - This pr oduct is not int e nde d t o be u se d out door s or in a w e t loca t ion
w he n it is pow e r e d by t he Pow e r ove r Et he r ne t ( POE) int e r fa ce , or by t he e x t e r na l
pow e r su pply.

13

SNM910 Site-Net Modem Getting Started Guide

W ARN I N G - The e x t e r na l pow e r a da pt or a nd it s a ssocia t e d pow e r cor d a nd plu g a r e
not int e n de d t o be inst a lle d out door s, or in a w e t loca t ion.

Use of Power over Ehternet

SPSx61 only

W ARN I N G - W he n t his pr oduct is con ne ct e d t o a Pow e r ove r Et he r ne t conne ct ion,
t he sou r ce of t he Et he r n e t pow e r m ust m e e t I EEE 8 0 2 .1 1 a f, a nd it s D C out pu t
( Et he r ne t pow e r sou r ce ) m ust be com ple t e ly isola t e d fr om e a r t h gr oun d ( floa t ing) ,
or a sh ock ha z a r d m a y e x ist .

W ARN I N G - The e x t e r na l pow e r a da pt or a nd it s a ssocia t e d pow e r cor d a nd plu g a r e
not int e n de d t o be inst a lle d out door s, or in a w e t loca t ion.

1. 900 MHz radios are not used in Europe.
2. 2.40 GHz radios are available initially only for Japan.

SNM910 Site-Net Modem: What's in the box

list of items.

I tem Pa r t N um be r

SNM910 Site-Net Modem: Setting up a SIM card and IP address

Types of SIM cards

<which ones are suitable>

Obtaining a SIM card

How does a user get a card?

IP addresses

14

Getting Started Guides

Cable with DC Power from 12 V
59044 7-pin Lemo Serial
plug car battery
Power to host
Cable with DC Serial-to-serial for
67384 7-pin Lemo devices from AC
plug Moving Base applications
adapter
Adapter with Power from AC USB(B) socket and
57167 26-pin
DC plug adapter Ethernet socket
Adapter with Power from AC Serial and Ethernet
57168 26-pin
DC plug adapter socket
2 x Serial, Ethernet
Cable with DC Power from AC
77070-00 26-pin plug, USB(A) plug, 1PPS
plug adapter
(BNC)
Cable with DC Power from AC 2 x Serial, Ethernet
78235-00 26-pin
plug adapter socket

Using the SNM910 Site-Net Modem with the SPS Receivers

Using the SNM910 Site-Net Modem with the SPS Receivers

I n t h is se ct ion :

• Web interface
• Front panel < < lin k y e t t o b e done > >
• Setting up an iBase
• Setting up an SPS rover receiver

Configuring the SNM910 site-net modem for use with SPS receivers

SPSx 6 1 a nd SPSx 5 1 only

How to connect to host using a web browser.
Which web browsers are supported.
Description of web UI pages which are releavant to the SNM910:
• GPRS modem
• Network

17

SNM910 Site-Net Modem Getting Started Guide

• PPP
• I/O
Not e –

Heading

Setting up a SNM910 site-net modem for use with a SPS rover receiver

SPSx 6 1 a nd SPSx 5 1 only

Photo of typical rover with an SNM910 on a marine vessel
step-by-step instructions
Not e –

Heading

Connecting a SNM910 site-net modem to an SPS receiver using the Web interface

SPSx 6 1 a nd SPSx 5 1 only

How to connect to host using a web browser.
Which web browsers are supported.
Description of web UI pages which are releavant to the SNM910:
• GPRS modem
• Network
• PPP
• I/O
Not e –

Heading

Using the SNM910 Site-Net Modem with the SNB900R Radio Modem

Use cases for a SNM910 site-net modem

Detail some use cases (line art of long road job with SNM910/SNB900 used for
CMR rebroadcast)
Not e –

18

Getting Started Guides

Heading

SNB900 front panel

Description of front panel on host SNB900 that relate to the SNM910

Not e –

Heading

Setting up a 900 MHz rebroadcaster

<photo of SNM910/SNB900 using AC supply in office>
<photo of SNM910/SNB900 using DC supply in field>
Mounting options - Tripod, benchtop, lighting pole
Step-by-step instructions

Not e –

Heading

Getting the best performance

Choosing the best location for radio and cellular.

Not e –

Heading

Connecting a SNM910 site-net modem to an SNB900 radio-modem using the Web
interface

How to connect to host using a web browser.
Which web browsers are supported.
Description of web UI pages which are releavant to the SNM910:

19

SNM910 Site-Net Modem Getting Started Guide

• GPRS modem
• Network
• PPP
• I/O
Not e –

Heading

20

SNM910 Site-Net Modem Getting Started Guide

Is the cumulative phase count of the GPS or GLONASS
ca r r ie r ph a se
carrier signal at a given time.

A wireless adaptor that connects a laptop computer to a
cellular phone system for data transfer. Cellular modems,
which contain their own antennas, plug into a PC Card
ce llu la r m od e m s
slot or into the USB port of the computer and are
available for a variety of wireless data services such as
GPRS.

Compact Measurement Record. A real-time message
format developed by Trimble for broadcasting corrections
CM R/ CM R+
to other Trimble receivers. CMR is a more efficient
alternative to RTCM.

A real-time message format developed by Trimble for
transmitting more statellite corrections resulting from
CM Rx more satellite signals, more constellations, and more
satellites. Its compactness means more repeaters can be
used on a site.

A statistical measure of the variance of two random
variables that are observed or measured in the same
cova r ia n ce mean time period. This measure is equal to the product
of the deviations of corresponding values of the two
variables from their respective means.

Also called geodet ic dat um . A mathematical model
designed to best fit the geoid, defined by the relationship
between an ellipsoid and, a point on the topographic
surface, established as the origin of the datum. World
geodetic datums are typically defined by the size and
shape of an ellipsoid and the relationship between the
center of the ellipsoid and the center of the earth.
Because the earth is not a perfect ellipsoid, any single
da t u m datum will provide a better model in some locations than
in others. Therefore, various datums have been
established to suit particular regions.
For example, maps in Europe are often based on the
European datum of 1950 (ED-50). Maps in the United
States are often based on the North American datum of
1927 (NAD-27) or 1983 (NAD-83).
All GPS coordinates are based on the WGS-84 datum
surface.

Withdrawal of all electrical energy to the end-point
de e p disch a r ge
voltage before the cell or battery is recharged.

D GPS See real-time differential GPS.

Differential correction is the process of correcting GPS
data collected on a rover with data collected
simultaneously at a base station. Because the base
diff e r e nt ia l cor r e ct ion station is on a known location, any errors in data
collected at the base station can be measured, and the
necessary corrections applied to the rover data.
Differential correction can be done in real-time, or after

22

SNM910 Site-Net Modem Getting Started Guide

Features can be classified as surface or non-surface
features, and again as points, lines/breaklines, or
boundaries/areas.

The program inside the receiver that controls receiver
fir m w a r e
operations and hardware.

Global Orbiting Navigation Satellite System. GLONASS is
a Soviet space-based navigation system comparable to
GLON ASS the American GPS system. The operational system
consists of 21 operational and 3 non-operational satellites
in 3 orbit planes.

GN SS Global Navigation Satellite System.

General Serial Output Format. A Trimble proprietary
GSOF
message format.

H D OP Horizontal Dilution of Precision. HDOP is a DOP value that
indicates the accuracy of horizontal measurements. Other
DOP values include VDOP (vertical DOP) and PDOP
(Position DOP).
Using a maximum HDOP is ideal for situations where
vertical precision is not particularly important, and your
position yield would be decreased by the vertical
component of the PDOP (for example, if you are
collecting data under canopy).

The primary L-band carrier used by GPS and GLONASS
L1
satellites to transmit satellite data.

The secondary L-band carrier used by GPS and GLONASS
L2
satellites to transmit satellite data.

A modernized code that allows significantly better ability
L2 C
to track the L2 frequency.

The third L-band carrier used by GPS satellites to
transmit satellite data. L5 will provide a higher power
L5
level than the other carriers. As a result, acquiring and
tracking weak signals will be easier.

Some applications such as vehicular-mounted site
supervisor systems do not require Precison RTK accuracy.
Location RTK is a mode in which, once initialized, the
Loca t ion RTK
receiver will operate either in 10 cm horizontal and 10 cm
vertical accuracy, or in 10 cm horizontal and and 2 cm
vertical accuracy.

Every single NTripSource needs a unique mountpoint on
an NTripCaster. Before transmitting GNSS data to the
M ou n t poin t
NTripCaster, the NTripServer sends an assignment of the
mountpoint.

Moving Base is an RTK positioning technique in which
both reference and rover receivers are mobile.
M ovin g Ba se Corrections are sent from a “base” receiver to a “rover”
receiver and the resultant baseline (vector) has
centimeter-level accuracy.

24

Glossary

MTSAT Satellite-Based Augmentation System. A satellite-
based augmentation system (SBAS) that provides a free-
M SAS to-air differential correction service for GPS. MSAS is the
Japanese equivalent of WAAS, which is available in the
United States.

Interference, similar to ghosts on an analog television
screen, that occurs when GPS signals arrive at an
antenna having traversed different paths. The signal
m ult ipa t h traversing the longer path yields a larger pseudorange
estimate and increases the error. Multiple paths can arise
from reflections off the ground or off structures near the
antenna.

National Marine Electronics Association. NMEA 0183
defines the standard for interfacing marine electronic
navigational devices. This standard defines a number of
N M EA
'strings' referred to as NMEA strings that contain
navigational details such as positions. Most Trimble GPS
receivers can output positions as NMEA strings.
Networked Transport of RTCM via Internet Protocol
(NTrip) is an application-level protocol that supports
streaming Global Navigation Satellite System (GNSS) data
N Tr ip Pr ot ocol
over the Internet. NTrip is a generic, stateless protocol based
on the Hypertext Transfer Protocol (HTTP). The HTTP
objects are extended to GNSS data streams.
The NTripCaster is basically an HTTP server supporting a
subset of HTTP request/response messages and adjusted
to low-bandwidth streaming data. The NTripCaster
accepts request messages on a single port from either
the NTripServer or the NTripClient. Depending on these
N Tr ipCa st e r messages, the NTripCaster decides whether there is
streaming data to receive or to send.
Trimble NTripCaster integrates the NTripServer and the
NTripCaster. This port is used only to accept requests
from NTripClients.

An NTripClient will be accepted by and receive data from
an NTripCaster, if the NTripClient sends the correct
N Tr ipClie n t
request message (TCP/UDP connection to the specified
NTripCaster IP and listening port).

The NTripServer is used to transfer GNSS data of an
NTripSource to the NTripCaster. An NTripServer in its
simplest setup is a computer program running on a PC
that sends correction data of an NTripSource (for
N Tr ipSe r ve r example, as received through the serial communication
port from a GNSS receiver) to the NTripCaster.
The NTripServer - NTripCaster communication extends
HTTP by additional message formats and status codes.

The NTripSources provide continuous GNSS data (for
N Tr ipSou r ce example, RTCM-104 corrections) as streaming data. A
single source represents GNSS data referring to a specific
location. Source description parameters are compiled in

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SNM910 Site-Net Modem Getting Started Guide

the source-table.

The OmniSTAR HP/XP service allows the use of new
generation dual-frequency receivers with the OmniSTAR
service. The HP/XP service does not rely on local
reference stations for its signal, but utilizes a global
Om n iSTAR
satellite monitoring network. Additionally, while most
current dual-frequency GPS systems are accurate to
within a meter or so, OmniSTAR with XP is accurate in 3D
to better than 30 cm.

Position Dilution of Precision. PDOP is a DOP value that
indicates the accuracy of three-dimensional
measurements. Other DOP values include VDOP (vertical
PD OP DOP) and HDOP (Horizontal Dilution of Precision).
Using a maximum PDOP value is ideal for situations
where both vertical and horizontal precision are
important.

Postprocessing is the processing of satellite data after it
has been collected, in order to eliminate error. This
post p r oce ssin g
involves using computer software to compare data from
the rover with data collected at the base station.

Also known as r eal- t im e differ ent ial corr ect ion or DGPS.
Real-time differential GPS is the process of correcting
GPS data as you collect it. Corrections are calculated at a
base station and then sent to the receiver through a radio
link. As the rover receives the position it applies the
corrections to give you a very accurate position in the
field.
r e a l- t im e dif fe r e n t ia l GPS Most real-time differential correction methods apply
corrections to code phase positions.
While DGPS is a generic term, its common interpretation
is that it entails the use of single-frequency code phase
data sent from a GPS base station to a rover GPS
receiver to provide sub-meter position accuracy. The
rover receiver can be at a long range (greater than 100
kms (62 miles)) from the base station.

A rover is any mobile GPS receiver that is used to collect
r ove r or update data in the field, typically at an unknown
location.

Roving mode applies to the use of a rover receiver to
Rovin g m ode collect data, stakeout, or control earthmoving machinery
in real time using RTK techniques.

Radio Technical Commission for Maritime Services. A
commission established to define a differential data link
for the real-time differential correction of roving GPS
receivers. There are three versions of RTCM correction
RTCM messages. All Trimble GPS receivers use Version 2
protocol for single-frequency DGPS type corrections.
Carrier phase corrections are available on Version 2, or
on the newer Version 3 RTCM protocol, which is available
on certain Trimble dual-frequency receivers. The Version
3 RTCM protocol is more compact but is not as widely

26

Glossary

supported as Version 2.

real-time kinematic. A real-time differential GPS method
RTK that uses carrier phase measurements for greater
accuracy.

Satellite-Based Augmentation System. SBAS is based on
differential GPS, but applies to wide area
SBAS (WAAS/EGNOS/MSAS) networks of reference stations.
Corrections and additional information are broadcast via
geostationary satellites.

SNR. The signal strength of a satellite is a measure of the
information content of the signal, relative to the signal’s
sig n a l- t o- n oise r a t io
noise. The typical SNR of a satellite at 30° elevation is
between 47 and 50 dBHz.

The satellite skyplot confirms reception of a differentially
corrected GPS signal and displays the number of satellites
sk yplot
tracked by the GPS receiver, as well as their relative
positions.

SN R See signal-to-noise ratio.

Sou r ce - t a ble The NTripCaster maintains a source-table containing
information on available NTripSources, networks of
NTripSources, and NTripCasters, to be sent to an
NTripClient on request. Source-table records are
dedicated to one of the following:
• data STReams (record type STR)
• CASters (record type CAS)
• NETworks of data streams (record type
NET)
All NTripClients must be able to decode record type STR.
Decoding types CAS and NET is an optional feature. All
data fields in the source-table records are separated
using the semicolon character.

A type of receiver that uses three carrier phase
t r ip le fr e qu e n cy GPS
measurements (L1, L2, and L5).

Universal Time Coordinated. A time standard based on
UTC
local solar mean time at the Greenwich meridian.

Virtual Reference Station. A VRS system consists of GPS
hardware, software, and communication links. It uses
data from a network of base stations to provide
corrections to each rover that are more accurate than
corrections from a single base station.
VRS
To start using VRS corrections, the rover sends its
position to the VRS server. The VRS server uses the base
station data to model systematic errors (such as
ionospheric noise) at the rover position. It then sends
RTCM correction messages back to the rover.

Wide Area Augmentation System. WAAS was established
W AAS by the Federal Aviation Administration (FAA) for flight
and approach navigation for civil aviation. WAAS

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SNM910 Site-Net Modem Getting Started Guide

improves the accuracy and availability of the basic GPS
signals over its coverage area, which includes the
continental United States and outlying parts of Canada
and Mexico.
The WAAS system provides correction data for visible
satellites. Corrections are computed from ground station
observations and then uploaded to two geostationary
satellites. This data is then broadcast on the L1
frequency, and is tracked using a channel on the GPS
receiver, exactly like a GPS satellite.
Use WAAS when other correction sources are unavailable,
to obtain greater accuracy than autonomous positions.
For more information on WAAS, refer to the FAA website
at http://gps.faa.gov.
The EGNOS service is the European equivalent and MSAS
is the Japanese equivalent of WAAS.

World Geodetic System 1984. Since January 1987, WGS-
84 has superseded WGS-72 as the datum used by GPS.
W GS- 8 4
The WGS-84 datum is based on the ellipsoid of the same
name.

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Document Created: 2017-11-11 18:10:35
Document Modified: 2017-11-11 18:10:35

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