Satellite Comms - another try

I have previously integrated 2-way satellite IOT communications into the Voyager Sailing Drone design.

Swarm Space 

I started with a modem for Swarm Space. But before I commenced integration they announced to imminent shutdown of the constellation. I did nothing more with this modem.

Astrocast

I purchased the Astronode S+ device from Astronode through Mouser.
The Astronode S+ is a small-footprint, low power and very effective IOT modem. Their constellation consists of a few LEO satellites, so they are visible only a few times per day.

Once integration was completed, Astronode advised me of the "commercial service contract" fee of US$500 per month.
For some reason, the only fees documented on their website for connectivity were the data usage fees ranging from US$1.30 to US $6 per month.  
A fee of $500 per month changes from being a reasonable hobby project to being only a serious commercial enterprise.
As at Feb 2026, it is unclear if Astronode is still a trading entity.

I have been continually monitoring the Satellite IOT marker looking for  low power, small footprint devices with low cost connectivity and data usage fees.

Monogoto with Murata and Skylo

Then I happened upon a YouTube video by Laurens Slats from Monogoto.
They provide a service marrying together the Murata 1SC NTN modem, with access to geo-stationary satellites via Skylo. The costs are under $10 per month for my usage, so it fine for hobby projects.
Using geo-stationary satellites means that the satellite is always accessible (assuming it is not obscured).

The Murata 1SC is available within an evaluation board.

This costs around US $100 through Monogoto. It is small and low power.

Murata 1SC Development Board

The Murata 1SC Dev Kit does have some design problems which compromise its use when deployed in an operational system:

• It lacks any mounting holes, and so must be clamped in place.
• It has level-shifting interface circuity on board, which consume just over 20mA while the board is powered up. The Murata 1SC does go to sleep and consumes very little power, by the persistent 20mA minimum is the largest current sink in the Voyager Sailing drone, with the exception of the steering servo.
• The Murata 1SC supports 3.3Vdc, but the Dev Kit only support 5Vdc.
• The main connector looks like a standard 16-pin IDC ribbon cable connector.
  But its not. It has a 2mm pitch, rather than the more standard 2.54mm or 0.1" pitch.

In future, I will update the Voyager Controller board to provided switched 5Vdc to allow for powering off the whole Dev Kit board when idle, to significantly reduce power consumption.

The first step was addressing the main issues of installation on a sailing drone, being the antenna.

The antenna supplied with the kit is a multiband antenna, designed to address the different bands used by the Skylo service around the world.

The multiband antenna is pictured below. It doesn't easily fit with the existing equipment bay, and would need considerable effort to deploy and also handle immersion in sea water.

Multiband Antenna included in the Dev Kit

Australia is in the Band 255 region for the Skylo NTN service. This band is close to the GPS L-Band.

I wanted to see if a standard GPS patch antenna could be used with the Murata 1SC Dev Kit in Australia.

Of course, a standard GPS patch antenna is an active device.  I stripped out the active components and attached an SMA pigtail directly to the antenna element to allow for testing with the Dev Kit.

I tried this process on two different sizes of GPS patch antenna.
The 25mm passive patch antenna works well.
The smaller patch antenna could not establish a connection, and was of no use.

Testing with Passive Patch Antennae.

The Murata 1SC Dev Kit mounted above the main board within the equipment housing, including the 25mm passive patch antenna.

The Murata 1SC Dev Kit lifted up on the hinge to reveal the main board below.

I found the documentation of the AT commands provided by Murata was only a subset of the commands available.
The additional AT commands to aid the development were obtained from here:
we-online.com/components/media/o691492v410 Manual-um-acm-adrastea-i-2615011136000 %28rev1.2%29.pdf

 Testing in the back yard is generally good with mostly reliable communications.

I still need to perform on-water testing to ensure good communications while under sail on the local lake.

 

I have set up dedicated UDP listener software to receive and decode the telemetry packets.
At this stage I’m sending around 60 bytes of data, at regular intervals.

It then checks to see if there are outbound commands queued up, and waiting to be sent.
This allows for commands to be sent to change the mission waypoints or other parameters.
They can only be sent in response to the vessel sending a periodic telemetry update.

On-water testing results to follow...