Arcam DT81 manual Troubleshooting, Display shows ‘No Signal’

Troubleshooting

1.Display shows ‘Service not found’ when attempting to select a service

This can happen when the tuner has an ensemble stored that is no longer available. For example when the tuner is first shipped it has the BBC ensemble stored, and if it is used in another country then that ensemble will not be available. In this situation one should perform a search.

Note that re-configuration of services within an ensemble is handled without having to perform a search, so if services are added or removed from the ensemble it is not necessary to perform a search. Therefore ‘Service not found’ may also appear when an attempt is made to select a service that has been removed from the ensemble. Normally redundant services are automatically removed from the list but occasionally they are not. If this happens, simply select another active service to remove redundant services fom the list of available services and from any stored presets.

The other situation when the tuner may fail to select a service is when the signal strength is insufficient. When a service is not selected it is possible to view the signal strength in Engineering Mode (provided an attempt has been made to select a service from the required ensemble) . Generally the meter needs to be past the ‘E’ in ‘Strength’ for reliable reception.

We strongly recommend that an external aerial is used for the best possible performance. If the signal strength is marginal then an indoor aerial will only work some of the time, as the signal quality is affected by weather and the time of day.

Note: There will be situations where some ensembles are strong and others are weak. With a good aerial you may be able to weakly pick up some ensembles from outside their normal coverage range.

2. Display shows ‘No Signal’

This message is displayed if a signal at the required frequency is missing. Note that it may take some time (about one minute) to show the message. If you have removed the aerial and this message appears, reconnect the aerial and reselect a service to restore operation.

3.Display shows ‘No services stored’ at the end of the search

This will happen when the signal strength is insufficient due to either a poor aerial or lack of an available DAB signal.

4.Audio is lost and display shows ‘signal weak – muted’ This happens when the signal becomes weak. A better aerial is required.

5.Audio is lost and display shows ‘Service ended’ or ‘Arcam DAB Tuner’

This occurs if the selected service is no longer broadcast – in practice this will rarely happen. Select another active service.

6.Display shows ‘No service stored’ when a preset button is pressed

This message is shown if a service has not been assigned to a preset button or if that service has been removed from the ensemble, even temporarily. If ensemble components are only partially detected (due to weak signal strength) then the tuner sometimes decides that a service has been removed and the preset is deleted.

Notes on data rate and sound quality

The tuner supports MPEG audio data rates up to 256 kb/s which is the maximum rate as defined by the ETSI specification for DAB radio.

Data rates transmitted are generally lower than this because broadcasters prefer to include a high number of services within the available bandwidth. Higher compression factors are used to lower data rates, reducing audio quality.

Most stereo services operate at 192kb/s at present, and this has been found to give very high quality audio (though 256kb/s is even better).

Some speech-based services use mono in order to reduce the data rate and some apply higher compression as well. It is also common to find that different services have different audio quality even though they operate at the same data rate. This is due to differences in the audio processing techniques used in the transmission chain. Generally speaking, audio

is transmitted without applying dynamic range compression (DRC) – unlike FM broadcasts. DAB uses a system whereby the coefficients for DRC are transmitted separately, so that the tuner can apply the compression itself. This is beneficial because the listener can decide whether or not to apply DRC: most hi-fi enthusiasts do not. However some DAB broadcasts have some form of DRC applied directly to the audio and this generally impairs audio quality.

DT81

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