What type of GPS antenna should I use? |
For recreational and traveling purposes, standard GPS receiver antennas can be classified into two groups:
1. Upright antennas (Quadrifilar helix antennas):
Rectangular in shape, mostly visible and external to the main housing
of the receiver. They can detect satellites right on the horizon. They
cannot normally detect satellites directly overhead and should be held
upright for best reception
2. Patch antennas
Patch Antennas are made from a flat patch internal to the antenna's
housing. They can detect satellites directly overhead but cannot detect
satellites on the horizon. They should be held flat for best reception.
The M7 GX receiver will work with a
typical passive antenna, but performance (acquisition speed and signal
tracking) will be improved if an "active" antenna is used. Active
antennas actively amplify the GPS signal before sending it to the M7 GX's GPS receiver. This also helps compensate for the signal loss through the cable.
The M7 GX
applies 3.0-3.3 V DC on the center-conductor of the GPS antenna
connector. This voltage is used to power and active GPS antenna.
 Do not plug a GPS antenna that connects the center-conductor to ground into the M7 GX. The M7 GX transponder provided DC power to the antenna on the center conductor of the coax cable. Thus, the center conductor should not be grounded.
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