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Advanced Repeater Systems

D-Star Repeater Control

The Advanced Repeater Systems D-Star Repeater Controller (DRC) allows the Radio Amateur to build High-Performance, Stand-Alone D-Star Repeaters with suitable receivers and transmitters, without a computer.

Click for Schematic and Installation Instructions.

The DRC can be used to make a Stand-Alone D-Star Repeater or linking a new repeater to an existing D-Star Repeater or Compatible Hot-Spot or Node Adapter.

If you have an ICOM D-Star repeater on a site without access to the Internet, you can now install a Low-Cost, Stand-Alone, D-Star Repeater and link it to your ICOM repeater.  This can save your expensive ICOM repeater system from potential lightning and powerline surge damage by keeping the system at a safe location with Internet access.

The DCR utilizes a high-performance GMSK modem (the CMX-589) with a Phased Locked Loop (PLL) data extraction.  The DCR is designed for fast data acquisition and data lock to less than 6 dB Signal to Noise (S/N).  Further, if the signal fades or temporary drops, the DRC continues to process the signal in a Free-Run mode for over 200 clock cycles before returning to the Acquire Mode.

Received Data is Delayed approximately 250 milliseconds (mS) to allow the Repeater Transmitter to stabilize and allow listening Receivers to open.

The DRC instantly responds and faithfully repeats any GMSK (D-Star) signal, unlike some Stand-Alone Hot-Spots that utilize microcontroller firmware that can freeze and lock-up, and ignore transmissions if the Header is missed or signal fades. 

The DRC does not utilize microcontroller firmware (only highly reliable Programmable Gate Arrays (PGA) ) or any component that can cause a lock-up or require a Header to repeat a received GMSK signal.  Below is the demodulated waveform of a Motorola Micor with an ARS DRC.

The Bit Time (BT) is set to 0.45 which with +/- 1.2 kHz deviation, meets the GMSK spectrum mask for 12.5 kHz channel spacing. 

The DRC features: 

  • Stand-Alone Operation
  • DB-9 Male Connector
  • Optional Direct Connection for Low Profile Installations
  • Small Size PCB just 2.00" x 2.75" 
  • No Computer Required
  • No Receiver Carrier Operated Switch (COS) Input
  • No Microcontroller or Firmware to Freeze or Lock-Up
  • High-Performance Phase Locked Loop (PLL) Data Extraction
  • PLL Acquire, Lock and Free-Run Modes
  • Low 35 mA current draw
  • Operates from +10 to +14 volts DC
  • 250mS Digital Data Delay for accurate Header retransmission
  • Generates Transmitter Key (Open Collector Active Low)
  • Single Discriminator Receiver Connection
  • High Input Impedance (>100K)
  • Adjustable Input and Output Data Levels
  • High Level Transmit Data Output (> 5 Vpk-pk)
  • LEDs for Power, S/N, Lock, Free-Run and Tx Key
  • Receiver Level Test Point
  • Transmit Data Polarity Jumper Selectable
  • AC Coupled Analog Audio Shunt Mute Switch
  • Activity (Active High) Output Indicator
  • Charge (Data) Pump Waveform Generator
  • BT Set to 0.5 for 12.5 KHz Channel Operation
  • BT Modifiable down to 0.3 for narrow channel operation
  • Easy Installation and Set-up

Installation is straight forward but does require the use of Receivers and Transmitters that are either designed for data transmissions, meet certain technical requirements, or can be modified for 4800 bps GMSK. 

DC Blocking capacitors should have time constants less than 5Hz and data paths must be free of DC transients.  Greater time constants or turn on (unsquelch and transmitter keying) transients can cause Header corruption and increased Bit Error Rate (BER).

Receiver Intermediate Frequency (IF) Filters must be linear with minimal Group Delay and distortion across the GMSK passband.  It is preferable that the IF bandwidth be designed for +/- 2.5 kHz narrowband deviation. Although good results can be obtained using a traditional wideband (+/- 5 kHz) receiver, these should not be used for channel spacing less than 20 kHz.  The DRC input should be directly connected to the receiver discriminator to avoid any potential low-frequency corners from audio circuits.

Most analog radios can be modified for data and many current Amateur Radio units have 9600 bps data ports that are compatible with the DRC.

The Transmitter Modulator should be a Direct FM type (or closely replicate the operation of a Direct FM modulator).  Phase Modulators cannot be used for GMSK.  Radios capable of Digital Coded Squelch (DCS) can usually be modified by injecting the GMSK transmit data into the same location as the DCS (with the DCS disabled).  Synthesized Radios require two-point modulation which includes Direct FM of the reference oscillator.

The connector configuration is the same as the Dutch Star and Moen Star Board Node Adapters, except they are generally powered from the USB connector whereas the DRC is powered from Pin 9.

The DRC DB-9 female connector pins:

  1. Transmitter Data Output
  2. N/C
  3. Receiver Discriminator Input
  4. Transmitter Key (PTT)
  5. Ground
  6. N/C
  7. Active High Logic Output
  8. Tx Audio Mute (AC coupled analog audio mute)
  9. Power Input (10 - 14 Vdc)

It is highly recommended that you have your radio service manual with schematic and access to radio test equipment (oscilloscope, deviation meter, service monitor...) to properly set-up the DRC.

Please note that the DRC does not provide repeater identification.  It is intended to be a repeater receiver to transmitter interface device.  However, your D-Star radio or node adapter can provide the repeater identification in D-Star, or you can install one of the many CW identifiers or analog repeater controllers to provide an analog identification.

Below is a 100-watt Motorola Micor mobile converted to an Amateur Radio D-Star Repeater with a DRC.

This is a Dual Mode D-Star and Analog Repeater with encode/decode Digital Private Line (DPL or DCS).  This DRC board was supplied without the DB-9 male connector to allow installation of the Micor cover.  The small board to the right of the DRC is a vintage 1993 ARS CW IDer.  This unit is a stand-alone repeater linked to the D-Star Gateway via a V2 Node Adapter Board and a Micor mobile radio as a link.

Below is a Motorola MSR 2000 with a DRC, configured as a dual mode repeater.  The DRC and repeater controller are installed in a rack mount enclosure.

The DRC is used in combination with an Micro Computer Concepts RC-100 repeater controller to select and/or disable either the analog or the digital mode.

The DRC has been installed and tested with many different radios including
Motorola, General Electric and Amateur Radios from ICOM, Yaesu and Kenwood, all with excellent results.

The DRC is completely assembled and tested and includes detailed installation instructions.  A DB-9 female connector and cable is required to interface with your repeater.  Contact ARS with your specific application. 

Price: $159 plus $10 shipping anywhere in the U.S.

International Orders please contact ARS for shipping quote.

                                  Advanced Repeater Systems

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