TimeTools T Series Manual de usuario

T-Series NTP Network Time Server

GPS/GNSS Antenna Installation Guide

Models Covered: T100, T 00, T550

Ducument Number: T1202-02

18 November 2020

The latest version of this user guide can be obtained from TimeToolsLtd.com.

GPS/GNSS Antenna Installation Guide Page 2

WARNING:

Comply with all health and safety standards when installing a GNSS

antenna.

Do not work at heights without a fall protection device.

Do not install or maintain the antenna or cabling when there is a risk

of lightning or electrical storms.

CAUTION:

Before installing and configuring any T-Series NTP server

appliance, please read the manuals and retain for future reference.

Please follow all instructions and heed all warnings.

Full product documentation can be found at TimeToolsLtd.com.

While reasonable efforts have been taken in the preparation of this document to ensure its accuracy, TimeTools Limited

assumes no liability resulting from any errors or omissions in this manual, or from the use of the information contained

herein.

All claims based on information publicly available at time of printing.

All product or service names mentioned in this document are trademarks of the companies with which they are

associated.

GPS/GNSS Antenna Installation Guide Page

Table of Contents

1. Introduction................................................................................................................................................ 5

2. Antenna Ty es........................................................................................................................................... 6

2.1. T- 040 Permanent-Mount GPS L1 Antenna (T100, T 00 models).........................................................................6

2.2. T- 740 Permanent-Mount Multi-Constellation Antenna (T550 models)...................................................................6

2. . Mounting bracket (T- 070/T- 740 Antennas)..........................................................................................................7

3. Antenna Placement.................................................................................................................................... 8

4. Antenna Cabling........................................................................................................................................ 9

4.1. Typical Minimum and Maximum Cable Length (T- 040, T- 740 Antennas)............................................................9

4.2. Routing Cable.......................................................................................................................................................... 9

4. . Coax Cable Minimum Bend Radius.........................................................................................................................9

4.4. Connector Types................................................................................................................................................... 10

4.5. Longer Cable Runs................................................................................................................................................ 10

4.5.1. GPS Amplifiers..............................................................................................................................................10

4.5.2. GPS Over Fibre Solutions............................................................................................................................. 11

5. GNSS Antenna Surge Protection............................................................................................................ 12

5.1. Grounding Coax Cables........................................................................................................................................1

6. Ty ical GPS/GNSS Installation............................................................................................................... 14

7. Indoor O eration...................................................................................................................................... 15

8. GPS/GNSS Receiver Site Survey and Signal Lock...............................................................................16

8.1. Signal Lock Problems............................................................................................................................................ 16

9. Ti s and Trouble Shooting...................................................................................................................... 17

GPS/GNSS Antenna Installation Guide Page 4

Revision History

Date Doc. Rev. Changes

27-Jan-17

18-Nov-20

T1202-01

T1202-02

Initial release.

Updated surge-suppressor and coaxial cable grounding installation instructions.

GPS/GNSS Antenna Installation Guide Page 5

1. Introduction

A good antenna, together with a good installation, is vital for getting the best performance from a GPS/GNSS receiver.

This guide explains the requirements for the antenna and provides recommendations for a good installation.

The T-Series NTP Server has an integrated GPS/GNSS receiver. An external antenna provides synchronisation with

global navigation satellite systems. GPS/GNSS solutions can be utilised anywhere in the world.

Ideally, the GPS antenna should be roof mounted with a 60-degree unobscured view of the sky. As a rule of thumb, the

better the view of the sky, the more chance of a good consistent signal lock. However, satisfactory operation can often be

achieved by citing the antenna on the side of a building, on a window sill or in some circumstances indoors.

GPS/GNSS Antenna Installation Guide Page 6

2. Antenna Ty es

The antenna receives the GNSS satellite signals and amplifies them for transmission along a coax cable to the receiver.

The GNSS signals are spread spectrum signals in the 1551MHz to 1614MHz range and do not penetrate conductive or

opaque surfaces. Therefore, ideally, the antenna should be located outdoors with a clear view of the sky.

TimeTools supplies two different types of antenna with T-Series NTP servers:

T- 040 Permanent-Mount GPS L1 Antenna - T100 and T 00 models.

T- 740 Permanent-Mount Multi-Constellation Antenna - T550 model.

2.1. T-3040 Permanent-Mount GPS L1 Antenna (T100, T300 models)

The T- 040 Permanent Mount GPS L1 Antenna is supplied with T100 and T 00 models.

The antenna is a professional grade, permanent mount GPS L1 antenna, specially designed for professional precision

timing applications. The T- 040 features a custom high performance, wide band patch element, a 40dB gain LNA stage

and a high rejection out-of-band SAW filter. It provides ±10MHz bandwidth centred on 1575.42 MHz and covers the GPS

L1 and SBAS (WAAS/EGNOS/MSAS) signals, and it provides great axial ratio, excellent circular polarized signal

reception, great multipath rejection and great out-of-band signal rejection.

The T- 040 is housed in a permanent mount industrial-grade weather-proof enclosure.

2.2. T-3740 Permanent-Mount Multi-Constellation Antenna (T550 models)

The T- 740 Permanent Mount Multi-Constellation Antenna is supplied with T550 models.

The T- 740 is a precision high gain multi-GNSS antenna covering the BeiDou B1, Galileo E1, GPS L1, GLONASS L1

and SBAS (WAAS, EGNOS, QZSS & MSAS) frequency band (1557 to 1606 MHz). It provides truly circular polarized

signal reception through the entire bandwidth of the antenna, thereby providing superior multipath signal rejection. It is

especially designed for precision timing applications.

The T- 740 features a three stage Low Noise Amplifier, comprised of one input LNA per feed, a mid section SAW to filter

the combined output, and a final output gain stage.

The T- 740 is housed in a permanent mount metal base with two nickel coated nuts and a weatherproof

enclosure.

Fig. T- 040 and T- 740 Antenna and Dimensions.

GPS/GNSS Antenna Installation Guide Page 7

2.3. Mounting bracket (T-3070/T-3740 Antennas)

TimeTools provides a mounting bracket for use with T- 070 and T- 740 antennas. The bracket can be used to mount the

antenna to a vertical surface such as a wall or fascia. The mount is also supplied with a 1.5” V-bolt, which can be used to

mount the antenna to a pole or mast, if required.

Fig. MT4-GPS Mounting Bracket – Supplied 1.5 inch V-Bolt Not Shown.

GPS/GNSS Antenna Installation Guide Page 8

3. Antenna Placement

GNSS signals can only be received with a direct line of sight between antenna and satellite. The antenna should see as

much as possible of the total sky.

Seen from the northern hemisphere of the earth, more satellites will be visible in the southern direction rather than in

northern direction. The antenna should therefore have open view to the southern sky. If there are obstacles at the

installation site, the antenna should be placed south of the obstacles, preferably, in order not to block sky-view to the

south.

If the installation site is in the southern hemisphere of the earth, then the statements above are reversed – more

satellites will be visible in the northern direction.

For installations near to the equator, satellites are visible directly overhead.

Partial sky visibility often causes poor Dilution of Precision (DOP) values due to the geometry of the visible satellites in

the sky. If the receiver can only see a small area of the sky, the DOP has a high degree of uncertainty and will be worse

compared to a condition with better geometric distribution. It may happen that a receiver is seeing 6 satellites, all close

together, and still get a much worse DOP than a receiver which sees 4 satellites, but all in different corners of the sky.

The receiver’s DOP filter rejects fixes with high DOP (high uncertainty), therefore it can take longer to get the first

acceptable fix if sky visibility is partly obstructed.

WARNING:

Any local installation regulations for rooftop antennas in the country

where the antenna is installed must be observed.

GPS/GNSS Antenna Installation Guide Page 9

4. Antenna Cabling

TimeTools can provide pre-terminated cables for use with GPS and multi-GNSS antennas.

Optional pre-terminated cable lengths of 10m, 0m, 50m and 100m are available for the T- 040 and T- 740 antennas,

supplied with the T100, T 00 and T550 models .

Customers are free to source and utilise their own cables, if required, provided TimeTools recommendations are

observed.

4.1. Ty ical Minimum and Maximum Cable Length (T-3040, T-3740 Antennas)

GPS and multi-GNSS antenna systems utilise coax cable and are sensitive to both cable type and length. Coax cable

and connectors with an impedance of 50 ohms should be utilised. The table below provides the minimum and maximum

cable lengths for the T- 040 and T- 740 antennas, supplied with T100, T 00 and T550 models.

Cable Ty e Minimum Cable

Distance

Maximum Cable Distance

RG58 C/U 7m 6m

LMR195 10m 50m

LMR400 0m 1 0m

LMR600 45m 210m

Table: Minimum and maximum cable lengths for T- 040 and T- 740 antennas (supplied with T100, T 00, T550).

4.2. Routing Cable

CAUTION:

Be careful not to damage cable. Take care to avoid sharp bends or

kinks in the cable, hot surfaces (for example, exhaust manifolds or

stacks), rotating or reciprocating equipment, sharp or abrasive

surfaces, door and window jambs, and corrosive fluids or gases.

4.3. Coax Cable Minimum Bend Radius

Modern coax cables can be quite easily damaged. Bending, stretching and kinks in the cable can affect the

characteristics of the cable.

Observing the minimum bend radius for a cable can be critical to the correct installation of coax cables. This is especially

so if the cable passes through walls or other structures.

In order to maintain the specified characteristics of the coax cable, each cable type has a recommended minimum bend

radius. As a general rule, the minimum bend radius is five times the diameter of the cable. For a list of cable types and

there associated minimum bend radius, please see the table below.

Cable Ty e Minimum Bend Radius

RG58 26mm

LMR195 1 mm

LMR400 26mm

LMR600 9mm

Table: Typical minimum bend radius of common cable types.

An installer must take care to only use moderate force on the cable, especially when feeding cables through walls and

GPS/GNSS Antenna Installation Guide Page 10

other structures.

A particular weak spot is where the coax connector mates with the cable. Exerting force on the connector can not only

damage the cable, but also damage the termination of the connector itself.

Where cable routing involves tight bends, it may be prudent to utilise a right-angle connector.

4.4. Connector Ty es

TimeTools GPS and Multi-GNSS systems utilise coax cable and connectors of 50 ohm impedance. Both cable and

connector specification should have an operating frequency of at least 1575 MHz.

The T-Series NTP server and T- 040/ T- 740 antenna require a TNC type male connector on the attached cable.

Optional T-AD200-8 GPS amplifier and SPP-GPS surge suppressor require N-type male connectors on the attached

cable.

Pre-terminated 100m cable (TCX-100) is terminated with N-type male connectors and is provided with N-type female to

TNC male pigtails (short cable lengths of RG58 for converting N-type connectors to TNC).

4.5. Longer Cable Runs

Longer coax cable runs can be accommodated by the use of GPS amplifiers. Alternatively, GPS over fibre solutions can

be provided to transmit GPS signals very long distances over optical fibre.

4.5.1. GPS Am lifiers

A GPS amplifier (T-AD200-8) is a small weather-proof device that is inserted in-line on the coax cable. The amplifier

casing is 55 mm long and 41 mm in diameter. It requires no external power supply. The amplifier boosts the signals from

the antenna to utilise longer cable runs.

Ideally, amplifiers should be located at equidistant intervals along the cable run. A single amplifier should be located at

the mid-point of the cable length. If two amplifiers are utilised, one should be located at one-third of the length of the

cable, the second at two-thirds.

Cable Ty e Maximum Cable Distance with

Single GPS Am lifier

Maximum Cable Distance with Two

GPS Am lifiers

LMR400 250m 70m

LMR600 90m 570m

Table: Maximum cable lengths with amplifier for T- 040 and T- 740 antennas (supplied with T100, T 00, T550).

TimeTools T-AD200-8 GPS amplifier requires N-type male connectors to be installed on connecting cables.

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