Aeroflex 2050T SERIES Spezifikationen PDF herunterladen (Seite 14)

formance is poor.

QQ44..44::

What is the IFR 2968 generating when it is set to 'test

tone'?

AA44..44::

It is generating a TETRA encoded version of a 1 kHz tone,

representing a level of approximately 12 dB below the theoretical

maximum output level. The test tone is pre-computed data that is

stored in the 2968, hence the frequency and level are fixed. It is

not generated in real time from an audio signal since the 2968

does not have a TETRA codec.

The 1 kHz test tone that the 2968 generates is the result of exten-

sive simulation work to obtain the best result; however, TETRA

mobiles will not necessarily be able to reproduce a perfect steady

1 kHz tone from this data. TETRA codecs are not good with steady

tones, and are subject to level fluctuations.

QQ44..55::

Can I use the 2968 TETRA test tone for audio SINAD meas-

urements?

AA44..55::

Yes. Although the 1 kHz tone may be reproduced in a

TETRA receiver with some amplitude fluctuations, it generally

results in a SINAD >26 dB, particularly when measured through a

CCITT psophometric filter. This can be a useful work-around if the

mobile under test does not provide access to a means of meas-

uring Bit Error Rate for testing RF receiver sensitivity. Refer to the

2968 TETRA supplement issue 10, chapter 4, page 35 for details.

QQ44..66::

Can I use the 2968 to test audio at frequencies other than

1 kHz?

AA44..66::

Yes, if you test audio transmit and audio receive together,

using a duplex call and talk-back in the IFR 2968. Refer to A4.3

above for details.

Section 5 Q&A: Functional testing of TETRA mobiles

QQ55..11::

Can the IFR 2968 test text messaging, as with SMS text

messages in GSM?

AA55..11::

Yes, with the Phase 3.2 software. The TETRA equivalent of

SMS is known as SDS-TL (Short Data Service - Transport Layer)

and it handles text messaging in a similar (but not identical) man-

ner to GSM. TETRA mobiles can send and receive text messages

using either the standard TETRA 8-bit text coding scheme or the

GSM-compatible 7-bit text coding scheme. GSM 7-bit text coding

enables TETRA mobiles on TETRA networks to send or receive

text messages to or from GSM mobiles on GSM networks. The IFR

2968 can send and receive text messages using either 7-bit or 8-

bit text coding. SDS-TL is also used for other applications besides

text messaging, and the IFR 2968 allows you to send and receive

your own user-defined content as hex data. For details refer to the

2968 Phase 3.2TETRA supplement issue 10, chapter 4, pages 24

to 28, and chapter 3, pages 20 to 26.

QQ55..22::

Can the IFR 2968 support 16-bit UCS2 and Cyrillic text

messages?

AA55..22::

Yes, but it will not decode or display these alphabets - use

the 'type 4 data in hex' facility to send messages or view received

messages in these formats.

QQ55..33::

What is the 'commanded registration' function used for?

AA55..33::

Commanded registration is of limited use. This is a TETRA

function in which the network requests information from a TETRA

mobile that is already registered to the network. N.B. it does not

and can not force a TETRA mobile to register to the IFR 2968

when the essential network parameters do not match the mobile

(see A6.4 and A6.10 below). The commanded registration func-

tion requests the mobile to re-register and supply its full ITSI

(MCC, MNC, SSI) and report its group attachments. IFR originally

included this function in the IFR 2968 because there was no clear

definition of the circumstances under which TETRA mobiles would

supply this information. However, the requirements that are now

defined in the TIP make this function of limited usefulness: the

mobile only performs a normal registration to its home network,

so the MCC and MNC are already known; the mobile performs

attachment of its selected group or its multiple groups at the time

of registration so the groups are already known. Some TETRA

mobiles do not support this function, so you are recommended

not to use it for normal testing on the IFR 2968.

QQ55..44::

What is the 'TT test confirm' function used for?

AA55..44::

'TT test confirm' is used for mobiles that implement the

'TETRA Test' (TT) mode for performing an extended (test mode)

registration, and the [ TT test confirm ] softkey should be pressed

after TT test mode has been enabled on the mobile and the

mobile has registered to the IFR 2968. It requests the mobile to

supply its TEI, power class and receiver class, as well as confirm-

ing the TT test mode selection on the mobile, thus enabling it to

use TT BER / RBER loopback during a duplex call for measuring

receiver sensitivity. For details refer to 'TT test mode' in the 2968

Phase 3.2 TETRA supplement issue 10, chapter 4, page 41.

QQ55..55::

What is the SYSTEM SET-UP: MOBILE PARAMETERS menu

used for?

AA55..55::

This menu has four items: SSI, GSSI, power class and receiv-

er class. For explanation, refer to the 2968 Phase 3.2 TETRA sup-

plement issue 10, chapter 3, pages 34 and 35.

• SSI: normally obtained from the mobile at registration

and does not need to be entered. The 2968 uses this

value when making private or phone calls to the mobile,

so if you change it then the mobile should not respond

to the call set-up.

• GSSI: normally obtained from the mobile's attachment of

the selected group at registration, or subsequently, and

does not need to be entered. The 2968 uses this value

when making group calls to the mobile, so if you change

it to a value that does not match one of the mobile's

attached groups then the mobile should not respond to

the call set-up.

• Power class: obtained automatically from the mobile if it

responds to a TT test mode extended registration, oth-

erwise the value should be entered manually to match

the power class of the mobile under test. This parameter

is used to determine the maximum power level expect-

ed from the mobile using open loop power control, and

it is used in autotest to determine the level for the mobile

high power level test pass/fail.

• Receiver class: obtained automatically from the mobile if

it responds to a TT test mode extended registration. This

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