R&S 1129.7246.03, Руководство по эксплуатации

Страница: 239 / 855

R&S ESU Instrument Functions
Analyzer Mode
4.208 Operating Manual 1302.6163.12 - 03
Gated statistics configuration example:
A statistics evaluation has to be done over the useful part of the signal between t3
and t4. The period of the GSM signal is 4.61536 ms
The instrument has to be configured as follows:
4.8.13.5 Measurement of Carrier/Noise Ratio C/N and C/No
Using the carrier/noise measurement function, the R&S ESU determines the C/N
ratio which can also be shown normalized to a 1 Hz bandwidth (function C/No).
To determine the noise power, a channel at the set center frequency is examined.
The bandwidth of the channel is fixed by means of the
CHANNEL BANDWIDTH
function.
The largest signal in the frequency span is the carrier. It is searched when the func-
tion is activated and is marked by means of the
REFERENCE FIXED marker. The
noise power of the channel is subtracted from the signal level obtained (C/N), and in
the case of a C/No measurement it is referred to a 1 Hz bandwidth.
There are two methods for measuring the carrier/noise ratio:
1. The carrier is outside the channel examined:
In this case, it is sufficient to switch on the desired measurement function and to
set the channel bandwidth. The carrier/noise ratio is displayed on the screen.
t1 External positive trigger slope
t2 Begin of burst (after 25 µs)
t3 Begin of useful part, to be used for statistics (after 40 µs)
t4 End of useful part, to be used for statistics (after 578 µs)
t5 End of burst (after 602 µs)
Trigger Offset t2 - t1 = 25 µs now the gate ranges are relative to t2
Range 1 Start t3 - t2 = 15 µs start of range 1 relative to t2
Range 1 End t4 - t2 = 553 µs end of range 1 relative to t2