Synchronisation
Note
This article is valid only for 52/RM4200D, 52/XR devices.
For related information on 52/XD, 52/XC or 52/XS devices see 52/XC/XD/XS Synchronisation
On the Synchronisation tab, you can configure different synchronisation options for the device.
You can adjust the sample rate of a device (System Sample Rate) to 48 kHz or 44.1 kHz.
Important
Even if the device works with external synchronisation, you have to set the correct sample frequency here, because the internal Quartz PLL can not adjust correctly to the external clock otherwise.
You can define two synchronisation sources, Sync Source 1 and Sync Source 2. The option configured under Sync Source 1 is the primary synchronisation source. If this one fails, the system automatically changes to the source configured under Sync Source 2. If this one fails too, the system switches to the internal clock of 48 kHz or 44.1 kHz.
The following options are available for the external synchronisation of a 52/RM4200D DSP Frame. Please find more information on the synchronisation of a 52/XR MADI Router on 52/XR Synchronisation Module.
Warning
configuration Slot 1-8 must be at least one Digital I/O Module RM420-111
Slot 10: RM420-848M or RM420-848L or RM420-848M + RM420-424S
| available sync source 1, 2 | function |
|---|---|
| Internal | • Internal synchronisation source 48 kHz or 44.1 kHz. |
| AES <Slot.Port:Label> | • The synchronisation is taken from the incoming AES data stream if a valid AES signal is received. |
| BNC Wordclock | • TTL wordclock Input 48 kHz or 44.1 kHz. |
Slot 10: RM420-848M + RM420-421S
| available sync source 1, 2 | function |
|---|---|
| Internal | • Internal synchronisation source 48 kHz or 44.1 kHz. |
| AES <Slot.Port:Label> | • The synchronisation is taken from the incoming AES data stream if a valid AES signal is received. |
| BNC Wordclock | • TTL wordclock Input 48 kHz or 44.1 kHz. |
| MultiChannel | • The synchronisation is taken from the incoming MADI data stream if a valid MADI signal is received. |
Slot 10: RM420-848M + RM420-422S
| available sync source 1, 2 | function |
|---|---|
| Internal | • Internal synchronisation source 48 kHz or 44.1 kHz. |
| AES <Slot.Port:Label> | • The synchronisation is taken from the incoming AES data stream if a valid AES signal is received. |
| BNC Wordclock | Important You can not use this option, because the BNC connector is not available due to mechanical space constraints! |
| MultiChannel MADI 1 | • The synchronisation is taken from the incoming MADI data stream of the MADI port 1 (top) if a valid MADI signal is received. |
| MultiChannel MADI 2 | • The synchronisation is taken from the incoming MADI data stream of the MADI port 2 (bottom) if a valid MADI signal is received. |
Slot 10: RM420-848M + RM420-422S Option for redundant MADI
(see also Redundant MADI)
| available sync source 1, 2 | function |
|---|---|
| Internal | • Internal synchronisation source 48 kHz or 44.1 kHz. |
| AES <Slot.Port:Label> | • The synchronisation is taken from the incoming AES data stream if a valid AES signal is received. |
| BNC Wordclock | Important You can not use this option, because the BNC connector is not available due to mechanical space constraints! |
| MultiChannel | • The synchronisation is taken from the incoming MADI data stream of the MADI port 1 (top) if a valid MADI signal is received. If the MADI signal in port 1 is not valid, the system switches to MADI port 2 (bottom) automatically if a valid signal is received there. The active MADI signal of the corresponding logic function is used. The signal is toggled automatically only if configured appropriately. |
Note
If you configure a digital input of the RM420-111 module as synchronisation source, it does not matter whether you have enabled the sample rate converter for this input under DSP Frame I/O or not. (See also DSP Frame I/O – Configuring the DSP Frame)
Important
Please notice the following limitations when connecting external sync sources:
- In order to keep the Quartz PLLs used for external synchronisation working correctly, the external clocks have to be in the range of ±75 ppm around the selected sample rate of 48 kHz or 44.1 kHz.
- External sync sources can exclusively be feed via the slots 1 to 10, synchronisation via the slots 11 to 30 is technically impossible.
- If MADI interfaces are used, the systems connected among each others have to work using the same internal clock frequency (44.1 kHz or 48 kHz).
- If three RM420-422 modules are used at the same time, synchronisation can be done only by MADI, AES3/EBU or internally. The reason for this is that the RM420-422 modules (Dual-MADI) have no BNC connector due to space limitations.
Select the Slot 10 as Output check box to use the BNC port on slot 10 as TTL wordclock output. This is only possible if the option BNC Wordclock is not selected in one of the sync sources. In these cases, the BNC connector works as input.
The BNC ports of the slots 20 and 30 are always defined as TTL wordclock outputs and can synchronise other devices. Generally, all TTL wordclock outputs, all digital AES3/EBU outputs and all MADI outputs of the system use the same sample rate frequency, depending on the configuration and status of Sync Source 1 and Sync Source 2.
If you use a DSP frame with several DSP modules, each module always uses its own synchronisation. The modules in backplane 2 and 3 synchronise themselves to the module in backplane 1, in this case.
If you use several backplanes and at least one external sync source at the same time, though, on rare occasions and under certain conditions, problems with synchronisation can occur if the sync source is switched.
In such cases, clear the Disable VCXO on BP2/3 check box. This way, the Quartz PLL on the backplanes 2 and 3 is disabled and the sync range is enlarged. At the same time, the transient period of these backplanes is reduced. Enable this option if you want to minimise noise on the outputs of the backplanes 2 and 3 when switching the sync source.
Important
Backplane 1 is always the synchronisation master, backplanes 2 and 3 are slaves and need to synchronise themselves to the master.
If backplane 1 itself gets its synchronisation from an external source and this source fails, it will switch over to its second synchronisation source, sync source 2. After that, the backplanes 2 and 3 need to synchronise themselves again, but only after the signal on backplane 1 has become stable again. This whole process takes some time.
While backplane 1 is switching its synchronisation source and stabilizing itself again, the audio links between backplane 1 and 2 and backplane 1 and backplane 3 are cut. This happens only for a few milliseconds, until the system has synchronized itself again completely. During this time, distortions may happen on the audio links and the DSP frame may give warning messages about the state of the audio links. Also, D/A converters and AES3/EBU outputs on backplanes 2 and 3 may output distortion noise. The reason for that is the re-synchronisation of the system. The option Disable VCXO on BP2/3 shortens the time necessary for this process by setting the PLL to a much shorter adjustment time than usual.
However, you should activate this option only if the DSP frame contains more than one backplane, if it is synchronized from an external signal and if you are experiencing problems when switching synchronisation. If this is not the case, do not change anything!
Select the Varispeed check box to synchronize the systems to an external clock with a variable frequency between 40 kHz and 48.2 kHz.
Configuration Examples
The following table contains some examples for different synchronisation options:
| sync source 1 | sync source 2 | application |
|---|---|---|
| Internal | Internal | • As stand-alone system with internally supplied clock. |
| BNC Wordclock | Internal | • Synchronisation on incoming TTL wordclock signal. The device and its digital outputs are working synchronously to the external clock. • In case of a failure of the incoming TTL wordclock signal, the system works with the internal clock source. |
| AES <1.1.01:CD> | Internal | • Synchronisation source is the AES3 input signal on slot 1, port 1 (labelled CD here). The device and its digital outputs are working synchronously with the incoming AES signal. • In case of a failure of the incoming AES signal, the system works with the internal clock source. |
| Multichannel | Internal | • Synchronisation on incoming MADI signal. The device and its digital outputs are working synchronously with the incoming MADI signal. • In case of a failure of the incoming MADI signal, the system works with the internal clock source. |
| Multichannel | BNC Wordclock | • Synchronisation on incoming MADI signal. The device and its digital outputs are working synchronously with the incoming MADI signal. • In case of a failure of the incoming MADI signal, the system works with the incoming TTL wordclock source. |
| Multichannel | AES <1.1.01:CD> | • Synchronisation on incoming MADI signal. The device and its digital outputs are working synchronously with the incoming MADI signal. • In case of failure of the incoming MADI signal, the system works with the AES signal on slot 1, port 1 (labelled CD here). |
| BNC Wordclock | Multichannel | • Synchronisation on incoming TTL wordclock signal. The device and its digital outputs are working synchronously with the external clock. • In case of failure of the incoming TTL wordclock signal, the system works with the incoming MADI signal. |
Example 1: Several devices are networked via MADI, synchronisation via MADI:
Desctiption:
- Internal system clock of the router is distributed to the three attached mixers via MADI. The router is sync master.
- Mixers 1 to 3 are sync slaves.
| device | sync source 1 | sync source 2 |
|---|---|---|
| Router | Internal | Internal |
| Mixer 1 | Multichannel | Internal |
| Mixer 2 | Multichannel | Internal |
| Mixer 3 | Multichannel | Internal |
Example 2: Several devices are linked via MADI, synchronisation via MADI, the router is supplied via BNC with the TTL house clock.
Desctiption:
- TTL wordclock signal connected to router via BNC; distributed to the 3 connected mixers via MADI. The router is sync master for the clock distribution via MADI.
- Mixers 1 to 3 are sync slaves.
| device | sync source 1 | sync source 2 |
|---|---|---|
| Router | BNC Wordclock | Internal |
| Mixer 1 | Multichannel | Internal |
| Mixer 2 | Multichannel | Internal |
| Mixer 3 | Multichannel | Internal |
Example 3: Several devices are linked via MADI, the clock is centrally distributed via TTL wordclock:
Description:
- TTL-Wordclock is connected to the router and 3 mixers via central house clock distribution.
- Router and Mixer 1 to 3 are sync slaves.
- If the central clock distribution fails, synchronisation is done by MADI. The router acts then as sync master for the mixer.
| device | sync source 1 | sync source 2 |
|---|---|---|
| BNC Wordclock | BNC Wordclock | Internal |
| Mixer 1 | BNC Wordclock | Multichannel |
| Mixer 2 | BNC Wordclock | Multichannel |
| Mixer 3 | BNC Wordclock | Multichannel |
52/XR Synchronisation Module
A 52-6710 Synchronisation Module comes with three connectors. These are two BNC connectors and one RJ45 jack.
The BNC connectors can be used to establish a TTL wordclock or AES3/EBU connection. The upper BNC connector is dedicated as input, but the lower BNC jack can be switched to be an output. Use BNC cables with a characteristic wave impedance of 75 Ohm. AES3/EBU synchronisation is also possible via the RJ45 jack.
Beside these options it also possible to synchronise the 52/XR MADI Router via the MADI ports 3.1 and 13.1. Moreover, the 52/XR can be synchronised internal.