Arcam DiVA DT81 Buku Pegangan - Halaman 7

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Selection mode

Press the

button four times to access the Selection

Mode menu. This can be used to change the way services are

selected when scrolling with the rotary controller or when using

the

and

buttons on the remote control.

To change between 'AUTO' and 'MANUAL', turn the rotary

controller and press

to conﬁ rm the setting: the tuner

SELECT

reverts to displaying the service name.

With the selection mode set to manual, the displayed service

name is selected by pressing the

or the

button on the remote control. When the selection

BAND

mode is set to auto, the displayed service is automatically

selected after 2.5 seconds.

TUNER BYPASS switch

The front panel Tuner Bypass switch is used to switch between

this tuner's

and the audio output of an FM tuner

AUDIO OUTPUT

attached to the

FM TUNER INPUT

continues to output the audio signal from the currently selected

digital service on the DT81.

A note on Programme types

The Programme Type (PT) label is the short description

displayed below the service name.

Two different PT labels are transmitted: Static PT and

Dynamic PT. The static PT is the service 'genre' and does

not change. Radio 4's static PT for example is 'Current affairs'.

The dynamic PT reﬂ ects the current programme's content (for

example, for Radio 4 typical dynamic PTs include 'Drama',

'News', etc.).

When a service is selected, the dynamic PT is displayed; at

other times the static PT is shown. This means that Radio 4

will say 'Current affairs' while scrolling through services, then

may change to 'Drama' when that service is selected. The tuner

works this way because it cannot update dynamic PTs for a

multiplex to which it is not currently tuned.

Note also that, for secondary services, the tuner displays the

parent's static PT, since a dynamic PT would not be relevant.

A note on Secondary services

Primary services can have one or more secondary services

attached to them. These tend to be temporary; sporting

events like football matches for example may be broadcast

as secondary services. Services that have secondary services

attached to them are indicated by a

rotary selector clockwise will then reveal these services. The

secondary services themselves are indicated by a

You need to select a main service in order to see if there

are secondary services attached. The BBC is currently not

distinguishing between primary and secondary services, to

work with tuners that do not support secondary services. The

effect of this is to make those services appear twice in the list,

once as primary and once as secondary.

Note that only primary services can be attached to a preset.

Dynamic label

This is a 128 character block of scrolling text used by most

broadcasters to display programme information (such as song

titles, useful phone numbers and website addresses).

button on the tuner

SELECT

sockets. The digital output

symbol. Turning the

symbol.

Signal quality meter

The signal quality meter is a simple bargraph which gives a

quick visual guide to reception quality. Technically, it is an

inverse measure of the Viterbi error rate, with zero errors at

full scale (all segments are lit) and 300 errors/second (with

all segments off). When reception is marginal, the number of

segments displayed becomes a very sensitive function of the

received signal strength and can be used to optimize the aerial

position.

Engineering mode

The DT81 digital radio tuner has two modes – in addition

to User Mode (in which the unit powers up) it also offers

an Engineering Mode that allows you to view technical

information about the currently selected service.

To access Engineering Mode, press

simultaneously. 'ENGINEERING MODE' is brieﬂ y displayed. From

Engineering Mode you can return to User Mode by pressing

and preset

simultaneously again.

SELECT

Once in Engineering Mode, each of the eight preset buttons

shows different technical information:

Preset 1: Ensemble frequency. This is the carrier frequency

of the currently selected ensemble.

Preset 2: Service data rate. This is the data rate of the

current service in kilobits per second: the higher the number,

the better the sound quality.

Preset 3: Service start and end CU numbers. The start

and end CU (Capacity Unit) numbers indicate the service's

position within the ensemble.

Preset 4: Viterbi error/CRC failure count. The Viterbi rate

indicates the amount of error correction that is going on. Audio

decoding normally works transparently with Viterbi rates up

to about 200; above this, audible degradation of the signal

may be noticeable. The CRC (Cyclic Redundancy Check) failure

count indicates the amount of uncorrected errors. Any ﬁ gure

above zero may mean audio disruption.

Preset 5: Signal strength (AGC). A measure of raw RF

strength at the receiver front end.

Preset 6: Transmitter ID information. This shows the IDs

(identities) of all the transmitters detected for the current

ensemble. DAB radio uses multiple transmitters for the same

signal and can add together for better results. If you turn the

rotor you can see how many transmitters are being picked up

and their respective ﬁ eld strengths on a scale of 1 to 7.

Preset 7: Audio mode. This shows that the selected

programme is being transmitted in Stereo, Joint Stereo or

Mono mode. (Joint stereo is an MPEG audio mode where the

data for one channel is sent along with data representing the

difference between the two channels. It allows a lower data rate

to be used, but is not as good quality as true stereo.)

Preset 8: Transmission mode. This indicates which of four

possible methods of encoding/decoding transmissions is used

in the current service. This information may be useful to

engineers in diagnosing certain unusual problems.

and preset

SELECT

DT81