Rohde & Schwarz CMU-K20, Руководство по эксплуатации

Страница: 148 / 646

Non Signalling: Connection Control CMU-K20/K21/K22/K23/K24
1115.6088.12 4.70 E-11
Max.
Level
The Max. Level softkey sets the maximum expected input level (overload level).
This level corresponds to the maximum peak envelope power (PEP) of the GSM
signal that the CMU is able to measure. For GSM signals, the PEP is very close to
the average burst power (low crest factor), however, it is appropriate to allow for a
display margin of a few dB. Input levels exceeding the
Max. Level overdrive the
input path and cause invalid results (“– – –“).
In the table-oriented version of the Analyzer tab, either manual or automatic setting
of the input level can be selected. The behavior of the Max. Level softkey depends
on the way the input level is set:
•
In manual mode, the input level is indicated in the input field to the left of the
softkey. This field can be activated and the level can be changed by pressing
the
Max. Level softkey. Note the remarks on external output attenuation on p.
4.76 .
•
If autoranging is selected, Auto is indicated in the input field to the right of the
softkey. Max. Level is not active. To change the input level and mode, the
table-oriented Analyzer tab must be opened by pressing the Analyzer hotkey
again.
Remote control
[SENSe:]LEVel:MAXimum <Level>
RF
Channel
The RF Channel softkey defines the channel number and frequency of the
measured signal. The assignment between channel numbers and frequencies is
defined in the GSM specification for both directions of transmission (uplink and
downlink). Therefore, it is sufficient to enter only one value (frequency
or channel
number), the other one is automatically adjusted.
The following tables contain the channel assignment in the uplink direction (i.e.
from mobile to base station/CMU). Compared to the downlink, all channel
frequencies are shifted by a constant frequency offset depending only on the GSM
band (duplex spacing, see
Table 4-5 on p. 4.77 ). Channel numbers which are not
listed in the tables are not assigned.
Table 4-4 GSM channels in uplink direction
Frequency
/ [MHz]
Channel GSM400
Band
Frequency
/ [MHz]
Channel GSM900
Band
0.2
↓
450.4
---
↓
---
–
0.2
↓
876
---
↓
---
–
450.6
↓
457.4
259
↓
293
GSM 450 band
876.2
↓
880
955
↓
974
R-GSM band
(European railway
netw.)
457.6
↓
478.8
---
↓
---
880.2
↓
889.8
890.0
975
↓
1023
0
E-GSM band
(extended GSM)
479.0
↓
485.8
306
↓
340
GSM 480 band
890.2
↓
914.8
1
↓
124
P-GSM-Band
(primary GSM)
486.0
↓
2700
---
↓
---
–
915
↓
2700
↓
---
–
深圳德标仪器
135-1095-0799