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TTM 01-G Manual / October 2018
7
Inputs and Outputs
ANT: Antenna Port (SMA connector)
The “ANT” antenna input provides an interface for an external active antenna. The antenna should be
connected using a high quality, low loss 50 Ω low loss coaxial cable. The centre conductor
can supply 5 Vdc (100
mA max.) to power an active antenna. The antenna voltage will automatically fold back to limit the output
current under fault condition.
Care should be taken to ensure that the connector is not cross threaded when attaching the antenna lead-in
cable. The connector should be tightened firmly by hand only. Do NOT over-tighten! Ensure the antenna
SMA male connector center pin is straight before plugging in.
Antenna Cable Considerations
The TTM 01-G antenna port expects a signal with a gain of at least 15 dB, and no more than 35 dB, with 20 – 35
dB being the optimal gain range.
All antenna cables will introduce some signal loss in the antenna installation system, which will be dependent on
cable length. The total gain of the antenna installation should fall within the ranges specified below. The total
gain is calculated by the gain of the antenna (Tekron supplied antenna provides 40 dB gain) minus the antenna
cable loss.
Figure 2 - Recommended antenna cable loss range
Note:
The above figures are based on an average GNSS signal strength of -130 dBm at sea level and assumes
that the Tekron supplied antenna is used.
CNT-240
32.8 dB/100 m (10dB/100ft). Plus 1 dB/connector
Approximate optimum length range: 15m to 60m (50 ft –
197 ft)
Approximate maximum length range: 15m to 76m (50 ft –
250 ft)
CNT-400
16.73 dB/100 m. Plus 1 dB/connector
Approximate optimum length range: 30m to 120 m (99 ft –
394 ft)
Approximate maximum length range: 30m to 150m (99 ft –
493 ft)