> For the complete documentation index, see [llms.txt](https://docs.ceruleansonar.com/c/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ceruleansonar.com/c/ethernet-rov-locator/multi-unit-operation-swarms/multi-unit-2x1-1.md).

# Multi-Unit 2x1:1

The Multi-Unit 2x1:1 case has two independent transmitters on ROVs or divers, with each transmitter on a different channel. A separate receiver tracks each transmitter. 

The position of each transmitter is updated once per second.

If a topside GPS is associated with each receiver, the absolute (latitude/longitude) position of each transmitter can be known.

**The Mk II Autosync model is the only ROVL model that can operate on two channels.** In order to maintain clock synchronization, all four units must surface and re-acquire the GPS signal periodically (every hour or two).

{% hint style="info" %}
The 2x1:1 case is supported by Cerulean software. Additionally, users can write their own software to make use of the positional information created.
{% endhint %}

<figure><img src="/files/rMCdM1STheiq2vroArWo" alt=""><figcaption><p>Two independent receivers, each tracking their own independent transmitter</p></figcaption></figure>