8.4Synchronization

The AES42 standard describes the following two modes for synchronizing the microphone with the receiver (e.g. a mixing console or the DMI-2 Digi- tal Microphone Interface).

Mode 1: The microphone operates asynchronous- ly, using the sampling rate of its internal quartz oscillator. In this case, a sample rate converter is required at the receiver.

Attention: This mode should be used only when it is not possible to use mode 2 synchroniza- tion, since signal quality can be expected to be impaired by standard sample rate converters (in terms of dynamic range and latency time).

Mode 2: The microphone operates synchronously with a master word clock. This can be an external word clock, or the internal word clock of the DMI-2. In this case, a frequency/phase comparison with the master word clock is carried out in the AES 42 receiver. A control signal is generated which is transmitted via the remote control data stream to the microphone, where it controls the frequency of the internal quartz oscillator.

Via the BNC output, the internal word clock generator can be used to synchronize additional DMIs and connected equipment, such as a mixing console.

Problem

▶ Possible causes

▶ Solution

The “DATA VALID” LED is not lit up,

No valid data stream – Cause:

Check to ensure a continuous

even though a microphone is con-

The microphone cable connection

cable connection.

nected and switched on. (The RCS

 

is faulty or too long.

Comply with the recommended

“AES 42 PWR” display is lit up).

 

maximum cable length and

 

 

 

 

required cable quality, as appli-

 

 

cable for the selected word clock

 

 

frequency. Avoid unnecessary

 

 

transition points (connectors). See

 

 

Section 8.2, Cables.

 

The microphone is defective.

Use a microphone that is in good

 

 

working order.

The “SYNC LOCKED” LED blinks

The microphone has not been

Select a word clock frequency that

continuously. (Blinking for a short

synchronized because the se-

it is supported by all of the con-

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9. Troubleshooting

Problem

▶ Possible causes

▶ Solution

The RCS does not indicate that a

The DMI is not recognized by the

 

microphone is switched on and

RCS software. – Cause:

 

connected to the DMI, even though

The DMI was not switched on

Do not start the RCS until the DMI

the “DATA VALID” LED on the DMI

at the time when the RCS was

has been switched on; or execute

is lit up.

started.

the command Options/DMI and

 

 

 

then close the window again.

 

An ID has been used that is not

Currently only the IDs 0, 1, 2 and

 

currently supported by the RCS,

3 are supported. Set the ID by

 

or the same ID has been used for

means of the coding switch on the

 

more than one DMI.

back of the DMI; each DMI must

 

 

have a different ID!

 

The ID has been changed while the

After an ID is changed, the DMI

 

DMI was in operation.

must be restarted. Then restart

 

 

the RCS; or execute the command

 

 

Options/DMI and then close the

 

 

window again.

 

Incorrect interface setting (USB,

Select the correct interface in the

 

COM1 or COM2).

RCS via the command Options/

 

 

Communication.

The “Ext. Word Clk” LED is not lit

No word clock signal has been

Check the source of the word clock

up, even though an external word

detected.

signal and the cable connection.

clock has been connected.

 

 

The “Ext. Word Clk” LED blinks

A word clock signal is present,

Check the word clock frequency or

continuously. (Blinking for a short

but has not been interpreted as a

select another source for the word

period following activation of an

valid signal. This can occur, for ex-

clock signal. Alternatively, remove

external word clock is normal, and

ample, if the word clock frequency

the external word clock and use

indicates that the synchronization

deviates by more than ±50 ppm

the DMI internal word clock as the

process is being carried out).

from the nominal value.

master word clock for the signal

 

 

chain.

16

 

 

period during the synchronization

lected word clock frequency is not

nected microphones.

process is normal).

supported.

 

The “SYNC LOCKED” LED is not lit

The microphone is operating in

Set a sampling rate for synchro-

up.

asynchronous mode. (This is indi-

nous mode or set “Sync to Ext.

 

cated by the letter “a” preceding

Word Clk”.

 

the frequency display in the RCS

 

 

word clock window).

 

 

The microphone supports only

Use a microphone that can be

 

“mode 1” in accordance with the

synchronized (e.g. any Neumann

 

AES 42 standard, i.e. it cannot be

Solution-D series microphone).

 

synchronized.

 

Functions cannot be controlled via

Control via the user port has not

In the RCS system menu, “Func-

the user port.

been activated.

tion controlled by user port”

 

 

must be activated for the relevant

 

 

functions.

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