Rohde and Schwarz CMU200v10 Data Sheet

Application notes

Universal Radio Communication Tester CMU200

GSM power measurement –

versatile, fast and accurate

Measurement speed and accuracy – these are the key criteria in production because
they determine test times and thus throughput. Universal Radio Communication
Tester CMU 200 [*] (FIG 1) optimizes the two parameters for each application. How
this rapid tester helps you to cut down on measurement times is demonstrated
here by the example of power measurements on GSM mobiles.

FIG 1 Universal Radio Communication Tester
CMU200 optimally matches measurement
requirements in GSM mobile-phone produc­tion

Optimized in every case

GSM specifi cations state how much
power a mobile may emit as a function
of power control level (PCL), together
with the time characteristic a mobile
must comply with (FIG 2). The latter
again depends on PCL. CMU200 per­forms all the measurements required for
this – fast and extremely accurately.

Power versus frequency

CMU200 allows GSM-conformant
measurement of the power character­istic in all frequency bands:

• GSM400 with option CMU-K20

• GSM900 with option CMU-K21

• GSM1800 with option CMU-K22

• GSM1900 with option CMU-K23

CMU200 records several bursts (1 to

2000) of a mobile and from these finds
the minimum, maximum and average

Photo 43238/10

power characteristic. In manual opera­tion, detailed analysis is simplified by a
zoom function, markers and auxiliary
lines. To allow immediate verification
of compliance with GSM specifications,
the tester automatically positions the
power versus time template over the
measured burst and detects and marks
violations of limits and specifications
(FIG 2). The template is automatically
adapted to the particular power control
level. The user can define template

FIG 2

CMU200 auto-

matically positions

power versus time

template over mea-

sured power charac-

teristic and checks

compliance with

specified values.

Tolerance violations

are marked by fail

indicators and

measured values

highlighted in red

and tolerance limits to match mobile­specific requirements. In short, with
CMU200 you can check at a glance
whether the power characteristic of a
mobile is go or nogo.

The pass/fail indicators are available

also in remote control. So, on the
remote-control computer, you can deter­mine immediately, without elaborate
analysis, whether or not a mobile con­forms to GSM specifi cations. Plus, you

24 News from Rohde &Schwarz Number 167 (2000/II)

Application notes

can read out the complete power char­acteristic – minimum, maximum and
average – or selected parts of it. In
the latter case, CMU200 also detects
the minimum, maximum and average
power values of the selected part. This
special feature allows time-optimized
recording of especially critical parts
of the power characteristic and makes
it very easy to trace power ripple of
the useful part.

In the production of GSM mobile
phones, peak power measurement is
suffi cient in many cases. It allows,
for example, very fast adjustment of
a mobile, followed only by a com­pliance check of the power versus
time template. CMU200 comprises
power meters of different bandwidths
to perform such peak power measure­ments.

Power versus slot

But this is by no means all this fast
new tester has to offer. Another impor­tant measurement is power versus slot
(FIG 3), which is of interest in particu­lar in testing multislot mobile phones.
Here CMU200 measures the average
power of eight successive timeslots in
realtime. It is not possible to carry out
GSM-conformant power measurement
and template verification in such a short
time, so the tester only evaluates part
of the power ramp and from this cal-

FIG 4

Hopping in fre-

quency, CMU200

changes power

from highest

through to lowest

power control level

(PCL). All PCLs are

measured in one go

SACCH power change is sent to mobile

Multiframe

(approx. 500 ms)

Multi-measure­ment IEEE-bus
command is
executed

Multiframe

(approx. 500 ms)

Idle multiframe is
inserted while
mobile is waiting
for execution of
command

culates the average power. The train­ing sequence is not determined in this
measurement, nor is the power versus
time template checked. Experience has
shown, however, that results obtained
in this way are usually sufficient in GSM
mobile-phone production.

Power versus PCL

When measuring power versus PCL,
CMU200 shows unbeatable perform-

ance, ie time economies. In no more
than two or three seconds, it deter­mines the power of a mobile phone
at all power control levels on three dif­ferent GSM channels. Using conven­tional methods (channel and power
change followed by measurement of
power versus time), this would take
more than 30 seconds. Hopping in
frequency, CMU200 changes power
from the highest through to the lowest

PCL 5

13 frames

15 steps of 13 frames: approx. 900 ms

Combined with

hopping

Configurable

channels A, B, C

PCL 19

PCL (FIG 4) and detects the power
in realtime by the same method as
in measurement of power versus slot.

The power measured on three differ-

ent channels is output in table form for
each PCL (FIG 5). In doing this, the
tester automatically takes into account
the PCLs supported by the mobile.

CMU200 also incorporates sophis­ticated selftest functions, which are
described on the next two pages.

Rudolf Schindlmeier

LITERATUR
[*] Mittermaier, Werner; Schmitz, Walter:

Universal Radio Communication Tester
CMU200 – On the fast lane into the mobile
radio future. News from Rohde&Schwarz
(1999) No. 165, pp 4–7

Reader service card 167/09

FIG 3 Power versus slot measurement determines power in all eight
timeslots of a frame – an interesting function for multislot mobiles

News from Rohde&Schwarz Number 167 (2000/II) 25

FIG 5 CMU200 measures power through all PCLs of mobile on three
different GSM channels in just two or three seconds