6.7.3
Custom Installation - Antenna Recommendations
This section provides key recommendations when selecting an antenna for a custom antenna installation with the
GridTime 3000.
The following recommendations should be considered when selecting an antenna for a custom antenna installation:
• Select an amplified active antenna with integral low-noise amplifer (LNA) to ensure good performance under
nominal signal reception.
• Select a dual-band antenna that is compatible with at least one of the supported GNSS constellations.
• Use an active antenna that can be powered with less than 5V and under 80 mA, accounting for cable and in-line
component losses.
6.7.4
Custom Installation - Cable recommendations
This section provides key recommendations when selecting an antenna cable for a custom antenna installation with
the GridTime 3000.
The following recommendations should be considered when selecting an antenna cable for a custom installation:
• Select a cable with shielding against radio frequency (RF) interference
• Select a cable that is compatible with your antenna
• Ensure the cable is terminated with a TNC connector – you may need to terminate the cable yourself
• Use a low-loss 50 Ω coaxial cable
6.7.5
All Installations - Connection Recommendations
This section provides key recommendations on how to safely connect an antenna cable to the GridTime 3000.
• Safe cable grounding techniques should be used on the RF cable.
• A lightning arrestor should be installed in-line with the antenna cable to protect the device from lightning strikes
• The GNSS cables should only be connected once the device’s chassis is properly earth grounded
• Follow local building electrical codes for grounding the device’s chassis
DANGER
To avoid serious personal injury or death, use extreme caution when installing the antenna near, under, or
around high voltage lines.
6.7.6
All Installations - Antenna Placement Recommendations
This section provides recommendations on positioning the GNSS antenna in your installation for optimum timing
performance.
• Mount the antenna outside, preferably on the roof with an unobstructed view of the sky
• Do not mount the antenna near a wall or other obstruction that may impact the sky view.
• Do not mount the antenna near other RF emitters such as satellite dishes or WiFi routers
• Mount the antenna well above roads or parking lots.
• For a multi-antenna installation, place antennas at least one meter apart from one another.
To achieve the highest level of accuracy it is recommended the antenna is provided with an RF gain between 15
to 35 dB and positioned in an area with an unobstructed view of the sky and in a low multipath environment. If the
antenna is not placed in the correct environment and these conditions are not met, the device may require a longer
GNSS acquisition window or will prevent the GNSS input from being used.
6.7.7
All Installations - Delay Compensation
This section describes how to compensate for the signal propagation delay through an antenna installation.
Ensure that the cable delay on the device is set to compensate for the total propagation delay through the antenna
and cable, and any lightning arrestors or in-line amplifiers in the installation. Time synchronization to GNSSs will be
inaccurate by the value of the propagation delay error if left uncompensated.
Installation
©
2022 Microchip Technology Inc.
and its subsidiaries
Manual
DS00004572A-page 53
