Rx Measureme Nts T Ile - Aeroflex 3900 Series Option Manual

T E T R A M S S y s t e m
Rx M ea su r e m ent s T i l e
The Recei ver S ensit ivity o f th e mobil e may be test ed usin g a BER mea su rement in which PR BS
fr ames sent t o t he mo bile by t he Test Set ar e ret urned to it by the R F t ransmissio n f rom the mobile.
The Test Set then compar es th e dat a th at it r eceived w ith the data tha t it sent . T his r equir es th e
mobile to b e in a specia l mode in w hich it sen ds ba ck a ll th e tr aff ic fr ames t hat i t r eceives. Thi s
mode may be e nabled w ith the Te st Set and mobi le in T1 Test Mode , or w it h the T est Se t and mob ile
in T T Loo pback Mode .
In TET RA MS, mobile recei ver t esting is pe rfor med o n th e speech Tra ffic Cha nnel u si ng TT
Loopba ck Mode a fter a mobile has per for m ed a Test Mode R egist rati on an d a d uplex ca ll has been
set up . Mobi le re ceiver t esting for othe r t yp es of ch annels is suppor ted by the T ETR A MS T1 System
using T1 Lo opback Mod e w ith the mob ile in T1 Test Mode.
T 1 T e s t M o d e o r T T L o o p b a ck M o d e m a y n o t b e s u p p o r t e d b y m o b i l e u n d e r t e s t .
The Rx Me asuremen ts Til e show s th e r esults o f B ER , R BE R and ME R measur ements mad e on the
recei ver of the mobile und er test. The mobil e must supp ort th e T ETR A Test Mode ( TT) R F Loopback
funct ion t o use this feat ure. I t may be ne ce ssary t o per for m a Test Mo de R egistr ati on bef ore the RF
Loopba ck funct ion ca n be used.
Af ter a mobile t hat su pport s TT L oopback ha s perf ormed a Test Mo de R egistr ation (if requ ired) , it is
necessar y to set u p a d uplex ca ll fr om or to the mobile, and to comma nd t he mobil e int o Loo pback
Mode ( eithe r B ER TT Loopback o r R BE R T T Loo pback). Whe n a dup lex call wit h Loopb ack enable d
is not conf igur ed, t he R x Measur ement s Tile indicat es Loo pback N ot On and does no t show a ny
measure m ents a s show n in Fig. 5-9 .
F i g . 5 - 9 T E T R A M S R x M e a s u r e m e n t s T i l e - L o o p b a c k O F F
When the mobile is p erf orming BE R TT Loopba ck, t he R x Mea su rement s Til e show s t he B ER r esult s
for the thr ee d iffer ent classes o f bit s in the TET RA speech fra me . Class 0 bit s have no pr otect ion
and are likely t o r esult in non -zer o BE R measur ements a t a higher R F Gene rato r Le vel than the
Cla ss 1 an d C lass 2 bits, whi ch have some er ror cor recti on capa bility.
When the mobile is per for mi ng R BE R TT L oopback, the Rx Measuremen ts Ti le show s t he R BE R
resul ts for t he Class 0 and C lass 1 bits in the T ETR A speech f rame, an d t he MER result f or th e C lass
2 bi ts. In RB ER TT Loopba ck, w hen t he mob ile de tects err ors i n th e C lass 2 bits, it e rases two
complete speech fr ames and indicat es th is er asure in t he Loo pback da ta. The refo re, the RB ER
resul ts for t he Cla ss 0 and C lass 1 bits do not include any speech f rames in w hich Cla ss 2 bi t err ors
resul ted in er asure.
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