INSTALLATION AND MAINTENANCE MANUAL
LYNX
E1 FAMILY
LICENSED & SPREAD SPECTRUM RADIOS
JUNE 2001
PAGE 3-66
SECTION 3: INSTALLATION & ADJUSTMENTS
For precision measurement of transmit output power, it is best to
connect an RF power meter to the antenna port. The PWR port
voltage may not provide enough precision. This is especially
important where EIRP limits apply to the installation.
In cases of no EIRP limits, the radio transmitter output power
can be adjusted to maximum for installation, except for very
short paths using very high gain antennas, where excessive
power may not be advised.
Don’t forget that the RF output port should be terminated at all times when
power is applied to the Lynx radio. Therefore, disconnect power to the radio
before connecting a power meter and reapply power once connected.
Often, an RF power meter may have a limit to the input power that it can
measure without damage. It is advised to place a calibrated fixed value RF
attenuator (typically 20 dB or more) between the Lynx radio and the power
meter to assure proper operation and safety for the RF power meter. The
value of this fixed attenuation can then be added to the value of the RF
power meter reading to obtain the actual Lynx radio transmitter output
power.
9.
Connect a voltmeter across the GND and RSL front panel test points. This voltage reading
corresponds to the Received Signal Level (RSL) of the near-end radio. In other words, RSL is the
“amount” of signal the near-end radio is receiving from the far-end radio. Since the antennas have
not been finely aligned, it is not expected at this time that the RSL will read very high. However, at
this point it can be verified that some communication is taking place between the two
LYNX
terminals. Use the RSL voltage reading to align the antennas. Align one antenna at a time in
accordance with Section 3.10. Complete alignment of both ends of the radio link before going
further.
The RSL voltage output on the radio's front panel will output a
voltage range over the full receiving capability of the radio
(approximately 10 VDC at 0 dBm to 0.0 VDC at threshold).
The
Lynx
radio has a unique feature of allowing measurement of the far-end RSL from the near-end
radio. This is only possible if the
Lynx
radios are communicating (the RSL is above threshold). The
far-end RSL can be used to verify that adjustments to local antenna alignment are corresponding to
the far-end radio reception. Far-end RSL is measured by pressing and holding the DISPLAY FAR
END front panel button. While this button is held, the RSL voltage indicates the RSL of the far-end
radio. RSL of both ends should be verified to be within approximately 2 dB of predicted value (see
Section 3.3.3). There are several factors that can contribute to low RSL:
- Incorrect antenna alignment (aligned on a lobe and not on the main signal)
- Improper polarization alignment of antennas (horizontal vs. vertical)
- Transmission line problems (loose connections, bent or damaged cables, lossy adapters)
