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Basic modules

DSS1. Digital Speech Memory Module

DSS1. Digital Speech Memory Module

At a Glance:

  • 6 memory addresses for speech recording:
    • Up to 8 banks in RAM memory (volatile)
    • Up to 8 banks in flash memory (permanent)
  • Write protection feature for speech memory
  • Ringing tone detector, e.g. for railway radio
  • Synchronisation mode for redundant systems

The module DSS1 makes it possible to save recurring verbal announcements and to output them on call stations and loudspeaker circuits.

For this there are eight memory banks available each on RAM and flash chips.

The module has four independent sets which can all be run in different modes of operation. This way different functions can be realized on a DSS1. Each set can simultaneously access each of the 2 x 8 memory banks.

Application Description:

Application example for the DSS1 with PA and intercom systems
Fig. Application example for the DSS1 with PA and intercom systems

The DSS1 module can be used as speech memory in all DVS-21 applications in which a minimum of a call station or a loudspeaker circuit (LK) are included. The DSS1 module is used, for example, as ringing tone detector for switching on of radio modules at Deutsche Bahn AG. Here preset sound frequencies are detected and correspondingly interpreted.

Function Description:

The principle functions are illustrated in the following block diagram.

Block diagram DSS1
Fig. Block diagram DSS1

The DSS1 consists essentially of a control unit and the RAM and the flash chips. The module communicates over the PCM bus on 8 of 64 traffic channels (VKW). Here the following allocation applies:

  • Set 1 low frequency: Recording VKW 26 and playback VKW 22
  • Set 2 low frequency: Recording VKW 27 and playback VKW 23
  • Set 3 low frequency: Recording VKW 28 and playback VKW 24
  • Set 4 low frequency: Recording VKW 29 and playback VKW 25

The module is available in two variations which only differ in terms of their soft-ware:

  • Ringing tone detector
  • Speech memory

Variation "Ringing tone detector":

This variation is currently in use at the Deutsche Bahn AG and serves to switch on radio modules.

Basic arrangement of a DVS-21 for ringing ton analysis
Fig. Basic arrangement of a DVS-21 for ringing ton analysis

The DSS1 checks cyclically whether a signal is pending from the radio module on the low frequency line. If a radio subscriber sends a call signal, the fre-quency is determined from it internally and compared to the three values stored in the EPROM. Each of these frequencies is allocated to a line. When there is a match then the corresponding line is sent to the DVS-21 and the right DVS-21 subscriber is called.

In order to make a connection between the DVS-21 subscriber and the radio module (and thus the corresponding radio subscriber) the radio module needs a control line as switch criteria. This is sent over the 24LI with the pressing of the appropriate range button on the call station, regardless where the connec-tion request originated. The connection is only terminated after the delete but-ton is pressed or after a timeout. To speak, the DVS-21 subscriber must keep the speaking button pressed, and to listen, let go again.

Optionally the sending of a free line signal and a busy signal can be selected in the configuration software (ICS). If the subscriber being called is currently speaking, a short signal is sent twice, otherwise a long signal is sent. Further-more the limit values of the ringing tone (level and frequency) can be changed in the ICS software.

The following frequencies are available per default:

  • 1520 Hz
  • 1750 Hz
  • 2135 Hz

Other frequencies are possible for special cases.

Variation "Speech Memory":

In this variation, three further modes of operation can be selected in the con-figuration software:

  • Speech Memory
  • Sync Master
  • Sync Slave

The features on the card depend on the mode of operation.

Mode of Operation "Speech Memory"

In this mode of operation texts can be recorded on one or several banks (up to 60s for one text). Here the beginning and end of a speech recording are precisely defined in terms of time, and public address is terminated when the text ends.

The texts or tones are recorded in analogue form through a 4NSA on the DSS1.

The RAM memory is designed for recurring announcements over a short period of time. Texts can be recorded directly through a ProCom call station. These are retained until the DVS-21 is switched off or until new texts are re-corded over them.

Recording on the flash memory can only be done with a detour over the RAM chip. It is possible to write announcements from the RAM directly into the flash memory. The memory content of the flash chip is retained, how-ever, also after the DVS-21 is switched off.

The option "write protection" can be activated in order to prevent uninten-tional deletion of the flash memory.

The memory times are distributed as follows:

Memory Type Time/Bank Number of Banks Total Time
RAM volatile 7.5 s 8 60 s
Flash permanent 7.5 s 8 60 s
Flash - ,, - 1 x 15 s
6 x 7.5 s
7 - ,, -
Flash - ,, - etc. 6 - ,, -

Examples of memory distribution

Modes of Operation "Sync Master" and "Sync Slave"

A redundant public address system can be built with two DVS-21 systems in order to ensure adequate public address capabilities for possible disrup-tions.

Example: A redundant DVS-21 system
Example: A redundant DVS-21 system

To do this the loudspeaker circuits (LK) are arranged in an alternating way with the loudspeakers of system A and B (LK 1A / LK 1B and LK 2A / LK 2B) in or-der to ensure adequate public address capabilities in the case of a disruption. Announcements are triggered or made e.g. through or using a call station in parallel operation. Because of running times, output through the loudspeakers in both systems can become superimposed and unintelligible.

To solve this there is an additional synchronisation line between the two

DVS-21 systems (4NSA – 4NSA).

The DSS1 of the first system is set to the mode "Sync Master" and that of the second system to the mode "Sync Slave". A 1 kHz signal is continuously transmitted by the master. This signals operation-ready status to the slave sys-tem. If an announcement is triggered, the master simultaneously transmits a 2 kHz signal together with the announcement and the slave system simultane-ously begins the announcement.

These modes of operation are configured as option in the ICS.

The Front Plate Symbols and their Meaning:

The System Blinker The System Blinker
Addressing from processor taking place
I/O Input/Output
BUS output works as push-push operation with the system blinker
BUS input works as push-pull operation with the system blinker
01 - 03
13 - 15
Status Display Set 1
04 - 06
16 - 18
Status Display Set 2
07 - 09
19 - 21
Status Display Set 3
10 - 12
22 - 24
Status Display Set 4

LED Displays (depending on the set):

Set-related arrangement of the front plate LEDs
Set-related arrangement of the front plate LEDs

LED Illumination Function Description
Delete
Flash
Delete flash
Delete
Flash
Delete terminated with success
Recording
RAM to Flash
Transfer terminated
Recording
RAM to Flash
Inactive
Special Cases
Recording
RAM to Flash
If this pattern appears imme-diately following the copy command, there is no flash in the socket or the flash is defective
Recording
RAM to Flash
When this pattern appears, then the flash was delivered write protected. Either use a new flash or remove write pro-tection in a special copy device
Recording
RAM to Flash
When this pattern appears then the flash has been write protected through ICS. The respective option checkmark must be removed

Technical Data:

Operating Voltage: +/-5 V (control)
Operational Current (+5V): 6 mA
Weight: 300 g
Installation Height: 3HE
Installation Width: 6TE