Rohde & Schwarz 1094.0006.50, Руководство по эксплуатации

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CTS55 RF Connection
1094.0006.55 8.1 E-4
8 RF connection
8.1 RF Connection of the Mobile Phone Using a Cable
The RF cable used should ideally be of low-loss, high-grade quality. Manufacturers of mobiles mostly
provide an RF cable that comes with a mating plug for the RF socket on the mobile. Kits for in-vehicle
fitting are often offered with handies. In this case the car antenna cable can be connected to the CTS for
carrying out the tests. A check should always be made to see whether all plugs and sockets used for the
RF connection mate with one another. A cable connection that is not mechanically sound causes a large
increase in the attenuation and thus leads to erroneous measurements at high frequencies. When
working with a good cable connection (attenuation less than 0.5 dB), the "Coupler" key can be set to
"off".
With the "Coupler" key set to the "off" position, all measurements will be carried out without taking the
set attenuations into account, that is attenuation is zero. If the cable is of higher attenuation, it is
advisable to set the toggle key for the coupler to "on" in the main menu to allow entry of the expected
attenuation.
8.2 RF Connection of the Mobile Phone Using an Antenna
Coupler
Operation with an antenna coupler is the not the best method of connecting to the CTS. The reason lies
in the physical principles involved. The attenuation between a coupler and a mobile phone antenna
strongly depends on the physical form of the antenna. Other factors affecting the attenuation are
whether the antenna is bent and inadvertent movement in the coupler during testing. In order to obtain
reproducible measurements on output power or sensitivity, it is necessary to work with an accurately
defined attenuation.
Reproducibility can normally be guaranteed by means of a cable connection. The use of a coupler is
expedient if the mobile is not provided with an RF connection. When working with an antenna coupler it
is necessary to set the "Coupler" toggle key to "on" in the Home menu. Measurements are run in this
case with the coupler attenuation taken into consideration. Details of setting the coupler attenuation can
be found in section 9.9.5. The coupler attenuation can be set separately for the input and output
attenuation with reference to the tester. R&S supply an appropriate coupler (Part CTD-Z10, 800 to 1000
MHz and CTS-Z10, 800 to 2000 MHz).
If an antenna coupler is required, the correct coupling attenuation values must be set. In order for the
user not to have to re-enter the correct coupling attenuation values, when changing the type of mobile or
the antenna coupler, a list is implemented in the CTS, which contains user-definable types of mobiles
with their coupling attenuation values (see section 9.9.5). When changing the mobile phone or the
antenna coupler, the user simply has to select the type of mobile, it’s coupling attenuation values are
taken from the stored list and displayed.
If no antenna coupler is used (toggle for coupler in the main menu is in the "off" position), it is
nevertheless advisable to select the correct type of mobile, since the name of the mobile appears in the
printer report also the level for the sensitivity and the BER measurements is defined for the mobile type.