HAMTV from the ISS - How to contribute to the ARISS Merger

What is the ARISS Merger?

Due to the technical challenges of providing a reliable HamTV downlink at the venue of an Educational ARISS contact, we use a merger facility to stream the live HAMTV signal from a network of co-operative ground stations.

A central server runs a software process developed by Phil Heron MI0VIM whereby individual segments of the MPEG Audio+Video Transport stream are sourced from whichever stations have that segment available. This allows two 'lossy' stations to produce a perfect stream to the venue (under ideal conditions).

The ground stations contribute by streaming the MPEG-TS from their local receivers up to the server. To ease the logistics of this over unreliable network connections a custom client software is used.

Server Instances

Operational - Used for the educational contacts, streamed publicly on https://live.ariss.org/hamtv Only _live_ ISS downlink can be streamed through this server.

Test - Used for ground station and merger testing and development, often with replayed recordings or artificial test signals.

How would I join the ARISS Merger ground station network?

Firstly check that your station is functional and meets the requirements lower down this page.

Then please send ARISS Operations hamtvops@ariss-i.org an email with the following details, and we'll start your onboarding process.

• Typical pass length seen
• Typical maximum MER seen
• Receiver configuration
• Operating System for your Merger Client Software

The details of the qualification and onboarding process are constantly revised by ARISS Operations and may be subject to change at any time. We'll request and assess details on your station including the following:

• Performance of your internet connection to the Merger server
• Likelihood of availability for supporting educational contacts

The final step will be a series of dry-run ISS passes over your ground station feeding the test instance of the ARISS Merger.

If all looks good - we'll set you up to contribute to the main feed for the next Educational Contact near you!

Station Requirements

Internet Connection

The UDP streaming of the Transport Stream is latency-sensitive. We strongly suggest using a wired network connection.

At least 5Mbps of Internet Upload bandwidth is required for reliable streaming.

Receiver Configurations

Microsoft Windows

• Minitioune v0.7 / v0.8 / v0.9
  • Yes. This can be used with UDP streaming to 'dvbpush' running on the same PC.

• Minitioune v1.0
  • No. This software appears to have problems with unicast UDP streaming.

• Satdump
  • Yes, using 'ISS HAMTV to UDP', this can stream to dvbpush running on the same PC. Not at this time, due to issues with uncorrected errors in the TS output.

• Open Tuner (ZR6TG)
  • Yes, although the configuration can sometimes be less intuitive than alternatives.

Linux

• BATC Portsdown
  • Yes.

• BATC Ryde "Set-top box"
  • No, not yet. The author is working on it.

• Longmynd
  • Yes, stream the UDP to the linux client.

• Satdump
  • Yes, using 'ISS HAMTV to UDP', this can stream to the linux client. Not at this time, due to issues with uncorrected errors in the TS output.

macOS

There is currently no support for macOS

'dvbpush' Windows Client Software

Download: https://live.ariss.org/hamtv/software/dvbpush-v18-bin.zip

Configuration

Accessed by 'File' -> 'Preferences'

• Callsign: Unique per-groundstation identifier
• Key: Issued to you by ARISS Operations
• Server Host: Normally 'live.ariss.org'
• Server Port: For test this must be '9978', for operational this must be '5678'
• Input Port: This is the UDP port from your receiver application, such as Minitioune or Satdump.
• Repeat Port: The client will repeat the TS out on this port, to allow you to stream to VLC or such simultaneously.
  • If you're not using the Repeat Port then you must set it to '0'.

Example configuration of Minitioune

• A target address of '127.0.0.1' must be used. The client does not support multicast at this time.
• The UDP port can be anything, but must match to 'Input Port' configured in dvbpush.

Example of success

Key things to look out for:

• dvbpush
  • 'Upload' is 'Online' - this indicates that your Callsign, Key, Server Host, and Server Port are all correct.
  • 'DVB' is 'Receiving' - this indicates that the client is receiving UDP MPEG-TS from the receiver.
  • 'Upload':'Received' increases every 10s - this is the server reporting back how many packets it has received.
  • 'Upload':'Lost' increases every 10s - this is the server reporting back how many packets have been lost in upload. This should be <0.1% of the 'Received'.

Known Issues

• The Upload 'Lost' field may report '4294967295' - this is a bug on the server, and actually means zero!
• If you're not using the 'Repeat' port then you must set this to zero, else the application may unexpectedly terminate.
• In some setup sequences the dvbpush client may report a large number of 'large packet' errors and cease to upload. In this case you'll have to force-quit dvbpush, and restart dvbpush.

Using the BATC Portsdown to upload to the Merger

The ability to uplink a locally received HamTV signal to the merger has been added to the Portsdown 4 (fully functional from software update 202510040). It can be selected from Menu 3, ISS HamTV RX Merger.

To set up for the merger, enter the frequency to tune to (usually 2395 MHz unless you are using a downconverter), the tuner input (A for the top socket, B for the bottom socket), the LNB voltage required (off, 13 or 18), your call (generally in uppercase), and the passkey. The region button is used to select one of 4 regional servers (Europe, America, Asia or Australia), or the Test server. For testing select the test server and make sure that you are using the test passkey. You will need to change the passkey when connecting to the live server.

To connect, press “Connect to Merger”. The button will turn green and stay green if you have successfully connected. If it just flashes green and goes back to blue, then that indicates a problem with the connection. Check your internet connection, call and passkey and try again.

Once you have connected, you will also see an indication on the online webpage. You can then press RX to start the receiver. The receiver behaves in a similar fashion to the normal Portsdown receiver. If you receive HamTV and send packets to the merger, you will see the statistics on the webpage.

If you select the receiver without first connecting to the merger, you will get a warning, but you can go on to run the receiver without a connection.