Amateur Television (ATV)





In mid-2015, MDARC converted the downlink transmitter of its ATV system to be fully digital. We are now able to transmit multiple channels of HD quality content in the same bandwidth that the old analog transmitter required. This also means that a digital receiver is needed to receive the MDARC ATV signal. Analog reception is no longer operational. Our uplink receiver can now handle both analog and digital, however. So if you are transmitting into our system in analog, your existing analog equipment will still work.

Check into the ATV net on Thursday @ 20:00 hours local on W6CX 147.06 MHz + 100 PL repeater.

System Outputs:
MDARC's digital ATV (DATV) repeater transmits on 1244.5 MHz.
You may also watch us live on the Internet at http://www.mdarc.org/activities/repeaters/atv/atv-stream.

You may also find it at www.w6cxatv.net/live or http://www.batc.tv/ch_live.php?ch=2&id=305.

System Inputs:
The repeater's receiver provides multiple inputs for you to transmit into; one digital and four analog:

Digital = 1292.5 MHz

Analog inputs:
  • 1270 MHz FM
  • 1289.25 MHz AM
  • 915 MHz FM
  • 427.25 MHz AM

Receive Equipment

So what do you need to receive MDARC's DATV signals? Here's a short list:
  • High gain antenna tunable to 1240 MHz . Vertical polarity.
    Most ATV-ers recommend a yagi pointed at Mt. Diablo's North Peak.
  • RG-6 or better coax
  • DC blocking adapter
  • Digital TV receiver: DVB-S2 with HDMI and Composite out
  • HDMI or Composite video monitor or TV
  • HDMI or composite cable, depending on the interface between the DVB receiver and your monitor.
You may also need one or more adapters to convert from the antenna connector (usually an N-type) to the F-connector on the RG-6 coax.

Transmit Equipment

If you are planning to buy or build an ATV transmission system, MDARC recommends going digital. You will need:
  • Color camera.
  • Line level audio.
  • DATV Express board with all needed hardware (see their web page for details, www.datv-express.com).*
  • Downeast Microwave 1200 Amp. 50mw to 3 W. or equal (see http://www.downeastmicrowave.com/).
  • LMR400 or better coax.
  • 1290 MHz high gain yagi antenna. Vertical polarity.
  • Various other cables to connect it all together.
*Some of us are using instead a Harmonic MV-50 Encoder w/ Harmonic PSM-3600 Satellite Modulator.

Some needed specs:
  • DVB-S
  • QPSK 3/4
  • Symbol rate 2.222 MB/s
Other settings are in a flux right now.

More Information:
Subscribe to these Yahoo groups:

MDARC Digital ATV Repeater Block Diagram