User Manual Part 1

User Guide to Q4000/QPRO
Document Number 1135-4713 Rev G
THIS DOCUMENT CONTAINS CONFIDENTIAL AND PROPRIETARY INFORMATION OF QUAKE GLOBAL CORPORATION. IT MAY BE USED BY
RECIPIENT ONLY FOR THE PURPOSE FOR WHICH IT WAS TRANSMITTED AND WILL BE RETURNED UPON REQUEST OR WHEN NO LONGER NEEDED
BY RECIPIENT. DISCLOSURE TO UNAUTHORIZED THIRD PARTIES OR DUPLICATION WITHOUT THE EXPRESS WRITTEN PERMISSION OF QUAKE
GLOBAL IS PROHIBITED.
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CONFIDENTIAL
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RF antennas connected to QUAKE modems should not be mounted closer than six feet
to each other. There is a risk of overpowering the receiver if two modem antennas are
moun
ted too closely to one another.
3 Antenna setup
3.1 Antenna recommendations
3.1.1 ORBCOMM
3.1.1.1 Voltage Standing Wave Ratio (VSWR)
VSWR is a measure of how well the antenna is matched to the receiver/transmitter port(s). It is a
measure of how much power is reflected from the antenna back to the transmitter output. If power
is reflected back to the transmitter, it is being lost as heat.
• 1:1 – best case. This is a perfect match between the cable and antenna.
• 1.5:1 – good.
• > 2:1 – poor match. The antenna is both not receiving signals as efficiently as possible,
and is prevented from radiating as much power as the transmitter PA is capable of
putting out.
We recommend using an antenna with less than 2:1 VSWR. Use of an antenna with larger
VSWR results in decreased messaging performance. Satisfactory operation can be achieved with
a VSWR as high as 3:1; however, message delivery latencies could be increased by 100% or
more. To determine the optimal VSWR and antenna for your specific application, we recommend
testing various antennas, cabling, and mounting options over an extended period to determine
which gives the best results.
An ORBCOMM antenna must be 50 ohm 137-150.05 MHz. Due to the fairly wide frequency
range used by ORBCOMM and the variety of installation factors between antenna size, cost, and
performance, it is not practical to achieve a VSWR of below 1.5:1 throughout the entire frequency
range. To tune an antenna to ORBCOMM frequencies, the transmit band is best at 149 MHz.
3.1.1.2 ORBCOMM satellite basics
• Direction of travel – West to East.
• Degrees of elevation – For Contiguous United States (CONUS): 85% of the time, satellite will
be between 5˚ and 45˚ elevation.
• Satellite Footprint ~ 3000 miles.
• Pass is 10 to 12 minutes for regions between 20° and 50° latitude - North and South
Hemisphere.
Note: