Saturday, 31 October 2020

WinLink VARA Setup with Icom IC-7300

Hi everyone,

This is a technical post.  It updates one of our most popular posts "WinLink Setup with Icom IC-7300".

We'll describe how we setup our IC-7300 HF/SSB to use the new VARA modem protocol on WinLink.  VARA offers faster data communication than the older ARDOP and WinMor protocols.  One does have to pay the VARA author US$69 to use the high data rates.

Downloading a SailDocs GRIB file

VARA must be downloaded and installed separately.  Download it here.  We installed it at C:\apps\VARA but the default is C:\VARA.

With VARA installed open WinLink Express.  To setup VARA open a 'Vara HF WinLink' session.  Configure Settings ... VARA TNC Setup and then Settings ... Radio Settings as below...

VARA TNC Setup

Radio Settings

Key to configuring VARA is setting audio levels.  Setting microphone (Rx) level is easy since VARA provides a VU meter.  For us, speaker (Tx) level was harder.

Initially 'Tuning' using the VARA SoundCard drive level tool caused interference in the USB cable which confused the IC-7300.  Once we realised what was happening it was simple to re-run the USB cable via a quieter path (it was already fitted with RF chokes) and set the volume.  We settled on a lower volume than the graphic in the tool recommends.

Setting VARA Tx Level

Overall our three transmit volume levels are -25dB in VARA, 100% in the Windows Volume Mixer and 50W IC-7300 transmit power.  The first two are shown in the image above.

The screenshot below shows our IC-7300 transmitting during a VARA session.  It's at a lower level than recommended but is working well.


Transmitting VARA

Once setup we've found VARA very easy to use.  We'll use WinLink to obtain mid-ocean weather forecasts by downloading SailDocs GRIB files.  So that's what we tested.

We carried out initial tests on 20m (14MHz Amateur Band) to stations 600nm away in Switzerland and 1000nm away in Sweden.  Zen Again was in her pen at Premier Gosport Marina, which is far from optimal since we're surrounded by other yacht masts.

WinLink RMS stations

The screenshot below shows us communicating with S50ARO in Sweden.  The 100% Windows Volume Mixer level is visible.  It is labelled VARA, while in the drive level tool the label is SoundCard.

VARA session with Speaker Volume Mixer

The screenshot below shows us connecting with SK5UM.  The SNR dial shows the received signal is marginal but the message gets through.

Starting session to download GRIB email

The screenshot below shows the GRIB email being downloaded.  The upper horizontal green bar shows progress.  The red columns show the transfer rate being achieved as the session progresses.

GRIB email download in progress

The screenshot below shows the session terminating.  The transcript shows 1315 bytes downloaded in 13 seconds.  We were impressed at the download speed given the poor circumstances.

5700 Bytes/Minute download speed

It's interesting that VARA can exceed 20kBytes/Minute in reasonable conditions.  That's faster than Pactor3 or Iridium Go!.

We expect to use HF/SSB WinLink as a backup to an Iridium Go!.  One reason for this is we like PredictWind forecasts and routing.  PredictWind data can't be carried over WinLink since it is commercial.


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