Pacific Crest ADL Sentry, Руководство пользователя

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21 ADL Sentry User Guide
Scrambling
To demodulate a digital transmission, a receiver must synchronize itself with the
transmitter. This can be hard to do when the transmitter sends a long series of one’s or
a long series of zeroes. But if every nth character in the transmission were switched, a
one to a zero or a zero to a one, and if the receiver is expecting this, it can more quickly
synchronize itself with the transmission. This is essentially what Scramble Control does
and why we recommend you leave it on for all radios. However, if some of the radios in your
system are not Pacific Crest or Trimble radios, you may need to turn Scrambling off.
Note - Trimble protocols require Scrambling. With a Trimble protocol selected, you are unable
to turn scrambling off.
Forward Error Correction
Forward Error Correction places extra bits in the transmitted data so receivers can check
for transmission errors. Although data throughput is adversely affected, using Forward
Error Correction can greatly improve range and so is strongly recommended.
Tips and Techniques for Best
Performance
Antenna
Antenna placement is critical for good performance. Range and coverage is directly
proportional to the height of the transmitting and receiving antennas in addition to
antenna gain. Where possible, select a reference station location that takes advantage of
terrain to get the transmitting antenna as high as possible.
Always use the telescoping antenna mast and raise the antenna as high as is practical and
safe given terrain and wind conditions.
Antennas are excellent conductors of electricity, so use extreme caution when operating
near power lines and other sources of electric current or during stormy weather.
Do not use a gained antenna if doing so increases the radio’s Effective Isotropic Radiated
Power beyond the limit of your license.
Line loss
Line loss from connectors and cables between the radio and antenna decreases the output
power transmitted by the antenna, thereby decreasing the signal’s range. To minimize line
loss, please check the loss-per-length of cable to be used. For every 3 dB of line loss, the ERP
(Effective Radiated Power) decreases by half. For example, if you have a 4 W radio and a line
loss of 3 dB in your cable and antenna, the power effectively radiating from the antenna is 2
W. Every 6 dB of loss reduces the radio’s effective range by 50%.