Scan Repeater Universal Drive-Unit

Scandinavian Micro Systems

  • SR03-01 converts serial heading data to analog synchro signals for driving virtually any type of Mechanical Synchro Repeater
  • A truly flexible unit when you need to exchange your old Gyro Compass
  • SR03-01 connects to 24V DC Mains and generates all required synchro signals internally, both the reference signal and the phase signals

SR03-01 is a Universal Drive-Unit for Mechanical Synchro Repeaters

SR03-01 converts serial HEADING data to analog Synchro Signals. It can drive up to 12 Mechanical Synchro Repeaters of virtually any signal type and gear ratio.

The unit requires only 24V DC Power and a serial data signal with Heading information on NMEA or other data format. All other signals, such as Synchro Reference and Phase signals, are generated internally with the correct voltages and frequency.

You can program the SR03-01 at the time of installation, by selecting from a list of Mechanical Repeaters types such as: Amur, Anschütz, Hokushin, Kurs, Microtecnica, Plath, Sperry, Tokimec, Yokogawa, etc.

SR03-01 accepts two independent HEADING data inputs and has a Compass Compare function with automatic switchover from Primary to Secondary Heading. SR03-01 can even be used in a Redundant Configuration with automatic switch-over between two independent SR03-01 units.

This ScanRepeater™ is a 3rd generation Lehmkuhl Repeater Unit; Built on 25 years of experience with units such as LR22 & LR40

Power Requirements

24VDC (18-32), 16 Amps.

Heading Input

SR03-01 has two (2) NMEA input ports for receiving Heading Data.
Heading #1 is the Primary Heading Input.
Heading #2 is the Secondary Heading Input and can be connected to a back-up compass.

Automatic Switchover

SR03-01 will always use Heading # 1 (Primary Heading), but will switch to the Heading # 2 (Secondary Heading), if Primary Heading fails or has an alarm.

If the difference between Primary and Secondary Heading is larger than a pre-set value, the user is required to confirm the switch-over manually.

The Heading input selected is always used to generate the Synchro Output signal and it is also re-transmitted to the "outside world" as serial data in the NMEA format.

Compass Compare

The Compass Compare function is already a part of the Automatic Switchover procedure and used if the Primary Heading fails. However - if the Compass Compare function is activated there will be an alarm as soon as the difference between Heading #1 and Heading #2 is greater than a pre-set value. This Preset Compare Value is set to 2.5 degrees, but can be edited.

Synchro Output

SR03-01 generates all required Synchro Reference and Phase signals to drive virtually any Mechanical Synchro Repeater operating with a gear ratio of 1X, 36X, 90X or 360X.

SR03-01 can be programmed at the time of installation. The selection is permanently stored (Flashed). Therefore if power is lost the unit will always output the correct Synchro Signals when it is turned on again.


SR03-01 has a signal output for automatic switchover from the primary to a secondary SR03-01, back-up unit.

Two SR03-01 units can then be connected in a redundant configuration.

A separate communication port is included for aligning two SR03-01 units in Redundant Configuration.

In special cases a Synchro Ref. input signal can be connected in order to phase-synchronize two or more SR03-01 units.

Auto Recover

SR03-01 has battery back up to retain critical information in case power is lost. When Power is restored, the unit will automatically align the Mechanical Repeaters to the correct Heading.

Alarm Functions

SR03-01 has several alarm detection modes, the most important are:

  • Missing/faulty Serial Data input
  • Input Protocol Error
  • Output Over-Load
  • Internal Temperature is too high

Alarm Display - Reporting

Alarms are displayed and reported as follows:

  • The Main Control Panel has an LCD display that shows the alarm status and cause. In addition there is an Alarm Buzzer and a blinking Red Light and Re-set Button.
  • A dedicated Relay Contact output, with a Normally Closed (NC) and a Normally Open (NO) Relay Contact
  • One full duplex RS422 serial data alarm channel, using NMEA $--ALR, and $--ACK sentences.
  • An optional Remote Control Unit is available. It can be console mounted on the Bridge and will display the SR03-01 status and Alarms.

Signal Processing

SR03-01 has a soft start control when the Synchro signals are engaged.

It also has a built in load test that will detect if a Mechanical Repeater is stuck and give a Warning (non-critical alarm)SR03

01 employs various filtering techniques to achieve smooth rotation of the Mechanical Repeaters with a minimal heading delay. It works with heading data refresh rates from one update per second and up to over 50 updates per second with "Fast NMEA".

Control Panel

The SR03-01 has a built in Control Panel for easy set-up and configuration. The Control Panel consists of a LCD display and three Menu Control Buttons, a Synchro ON/OFF switch, an Alarm Buzzer and a red Alarm Lamp/Button.

In normal operation the Control Panel Display shows heading received on Heading #1 (H1) and Heading #2 (H2) and which of the two drives the Synchro and NMEA output signals. It also displays the difference between H1 and H2, the temperature inside the unit and the 24V DC current consumption.

H1(359,3)-->S Out(359,3)
H2( 0,3) H1-H2( -1,0)
S: 500Hz(115/0-90)V 360X
+36'C 2.7 Amp

Normal Mode - Status Display

In an alarm situation the relevant error information will be shown in the display and the red lamp will be flashing.

Special 24V AC Lamp Output

A special 24V AC Lamp output signal can be connected for driving the light bulbs on certain Hokushin/ Yokogawa Repeaters. Please note that this will reduce the number of Mechanical Repeaters that can be connected to SR03-01.

Remote Control Unit (SR03-03)

An optional Remote Control Unit (SR03-03) can be connected to the unit via a dedicated RS422 port.

Typically the Remote Control Unit will be installed on the Bridge.

The SR03-03 is almost identical to the built-in Control Panel described above, except that you cannot change or turn off the Synchro Output signals from the Remote Control Unit.

SR03-01 with Optional Secondary Gyro
SYSTEM DIAGRAM:  SR03-01 with Optional Secondary Gyro, Remote Control Unit & Centralized Alarm Monitoring.

SR03-01 units in redundant configuration
SYSTEM DIAGRAM: Showing how two (2) SR03-01 units can be connected in a Redundant Configuration.


Technical Specification

MAIN Technical Specification

Supply Voltage: 24 VDC (18 - 32 VDC), Max 16 Amp
Synchro Voltages Ref: 24-120 V / Phase: 0-20 .... 0-90 V
Synchro Frequencies 50Hz to 500 Hz
Power Consumption: Max 40 - 250 W, depending on load
Approvals (scheduled for May 2006): By DnV and according to:IEC 60945,
IEC 61162-1, IEC 61162-2

Environmental Specification

Environmental: Operating: - 15 °C to + 55 °C
  Storage: - 20 °C to + 70 °C

Physical Specification

Physical Enclosure Aluminum Enclosure / IP 23
Physical Net Size W x H x D: 300 x 420 x133 mm.
Physical Max Size W x H x D: 300 x 483 x136.5 mm.
Physical Mounting Use 4 x M8 Bolts.
Mounting DIM Center-to-Center 269 mm x 457 mm
Net / Gross Weight 9,0 kg / 10.0 kg

Physical SERIAL DATA Ports

Heading 1 port RS422 Opto-isolated (RX only)
Heading 2 port RS422 Opto-isolated (RX only)
Remote Control Unit Full Duplex RS422, RX+ & RX- (Opto-isolated)
+ TX+ & TX- RS422 Driver.
Centralized Alarm Monitoring (CAM) Full Duplex RS422, RX+ & RX- (Opto-isolated)
+ TX+ & TX- RS422 Driver.
CAN-1 & CAN-2 Proprietary Control for future use.

BAUD RATE on each Port is individually selectable

Baud Rates 4800, 9600, 19200 & 38400 b/sec
Heading IN Refresh Rate 1 time per sec - to max 50 times per sec.
Heading OUT Refresh Rate 10/sec(4800/9600/19200), 50/sec(38400)

HEADING Data INPUT Formats / Protocols

NMEA sentences $-THS, $-HDT, $-HDG, $-HDM, $PPLAN
Anschütz ST20/22 Course-Bus protocol
Tokimec / Robertson RGC11 protocol
Lehmkuhl / Robertson SKR80 / LR22 / LR40 protocol


NMEA sentence $HEHDT, x.x, T,*h<CR><LF>


Relay Alarm Outputs 2 x 1 Amp Relay Contacts (NO / NC)


Serial Alarm - NMEA RS422 Full Duplex $--ALR, and $--ACK


Redundancy Control 2 x 1 Amp Relay Contacts (NO / NC)
Redund. Sync. Ctrl CAN-bus - Proprietor protocol.


Synchro Reference R1, R2: 50V to 120V
Synchro Phases S1, S2, S3: from 0-20V to 0-90 V
Synchro Frequency 50Hz to 500 Hz
Synchro ROT Max. 20 deg / sec
Synchro Load Max 150W (approx 12 Mechanical Repeaters)
Angular Accuracy 1X Accuracy is better than +/- 0.4 deg


24 V AC Max LOAD: 60 W
Special transformer connection
When driving Hokushin repeaters with 50/60Hz 50/60 V
Ref (0 to 68/82phase), a special 24V AC signal can be
connected for providing light in the mechanical repeaters.
NB! Will reduce the allowed #of repeaters

Possible Combinations

Mfg Gear Freq.
Ref / Phase Volt
--- 36/90/360X 50 50V / 0...20 V
--- 36/90/360X 60 60V / 0...24 V
--- 36/90/360X 50 50V / 0...68 V
--- 36/90/360X 60 60V / 0...82 V
--- 1/36/90/360X 50 96V / 0.. 75 V
--- 1/36/90/360X 60 115 V / 0..90 V
--- 1/36/90/360X 400 115 V / 0..90 V
--- 36/90/360X 500 115 V / 0..52 V

Other combinations can be programmed on Request.

Typical Selection by Manufacturer

AMUR 360X 500 Hz 115V (0 to 52V)
AMUR 360X 60 Hz 115V (0 to 52V)
Anschütz 360X 50/60 Hz 50/ 60 (0 to 20/24)
Hokushin 360X 50/60 Hz 50/ 60 (0 to 68/82)
Hokushin Separate 24VAC is provided for light in repeaters
Kurs 360X 50/60 Hz 115V (0 to 52V)
Microtecnica 360X 50/60/400 Hz 96/115 (0 to 75/90)
Microtecnica DC 360X 50/60 Hz 96/115 (0 to 75/90)
Plath 360X 50/60 Hz 50/ 60 (0 to 68/82)
Sperry 360X 50/60 Hz 96/115 (0 to 75/90)
Tokimec 360X 50/60 Hz 96/115 (0 to 75/90)
Tokimec 90X 50/60 Hz 96/115 (0 to 75/90)
Yokogawa 360X 50/60 Hz 96/115 (0 to 75/90)
Yokogawa DC 360X 50/60 Hz 96/115 (0 to 75/90)


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