Arcam Alpha 10 - Manual (Page 7)

Technical notes
1. This product is normally supplied with a moulded mains plug
already fitted to the lead. If for any reason the plug needs to be
removed, it must be disposed of immediately and securely, as it is a
potential shock hazard when inserted into a mains socket.
This unit is double insulated and does not require an earth.
NOTICE FOR U.K. CUSTOMERS ONLY
The mains inlet socket does not have an earth pin but for
convenience the mains lead is a standard 3 wire type. You should
connect the green and yellow wire as described below to prevent
the risk of this wire touching either of the other two wires within
the mains plug.
If the plug is removed then the remaining lead must be rewired as
follows:
• The blue wire must be connected to the terminal which is
coloured blue or marked with the letter N.
• The brown wire must be connected to the terminal which is
coloured brown or marked with the letter L.
• The green and yellow wire must be connected to the
terminal which is coloured green and yellow, or marked with
the letter E or the safety earth symbol.
• When replacing the fuse in the supplied moulded mains plug,
the integral fuse holder/cover must always be refitted. Use a
5 amp fuse.
2. A NOTE ON PROGRAMME TYPES
The programme type (PT) label is the short description displayed
below the service name. It is important to note that there are two
different PTs transmitted, these being static PT and dynamic PTThe
static PT is the service 'genre' and does not change. Radio 4's static
PT for example is'Current affairs'.The dynamic PT changes from one
programme to the next, and reflects the current programme.Typical
dynamic PTs for Radio 4 for example are '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.
It is also important to note that secondary services share their PTs
with their parent service. For secondary services the tuner displays
the parent's static PT (Dynamic would not be relevant).
3. 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 '> >' symbol.Turning the rotary selector clockwise will
then reveal these services. The secondary services themselves are
indicated by a'< <’symbol.You must select the main service in order
to see if there are secondary services. At present (March '99) the
BBC is signalling secondary services as primary in addition to
secondary, so as 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: It is only
possible to set a primary service to a preset and not any secondary
ones attached to it.
4. USER MODE / ENGINEERING MODE
There are 2 modes - User Mode and Engineering Mode. The unit
always powers up in User Mode, the operation of which is described
in the main body of the handbook.
Engineering Mode enables the user to view technical information
about the currently selected service. To access Engineering Mode
press SELECT and preset button 7 simultaneously.
The display will show ENGINEERING MODE briefly. Once in
Engineering Mode you can go back to User Mode by pressing
SELECT & preset 7 again. In Engineering Mode each of the 7 preset
buttons will show different technical information about the selected
service.
Preset I: Ensemble frequency. The carrier frequency of the
currently selected ensemble.
Preset 2: Service data rate.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 (capacity unit) numbers.This
indicates the services position within the ensemble.
Preset 4: Viterbi error/ CRC failure count. Viterbi rate indicates the
amount of error correction that is going on.The audio decoding will
normally work correctly with viterbi rates of up to approximately
200. Above this, audible degradation of the signal may become
apparent. The CRC (cyclic redundancy check) count indicates the
amount of uncorrected errors. If this is above zero then you will also
hear severe audio disruption.
Preset 5: Signal strength (AGC). A measure of raw RF strength at
receiver front end.
Preset 6: Transmitter ID information. 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 best results. If you turn the rotor you can see how many
transmitters are being picked up.
Preset 7: Audio Mode: stereo/mono etc., shows that the selected
programme is being transmitted in stereo, joint stereo or mono
modes.
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