Almanac Fleet

Almanac Fleet sends a fresh satellite almanac to your Sensative Square Trackers over the air.

A GNSS almanac is the list of which satellites are where. A tracker uses it to know where to look in the sky, so a device with an up-to-date almanac gets a position fix quickly and uses far less battery doing it. The almanac goes stale over time, and a tracker with an old one can take minutes to find a fix, or fail to find one at all.

Previously the only way to refresh it was to hold an NFC phone against each device. Almanac Fleet does it remotely, over the same LoRa network the devices already use, to as many devices as you like at once.

Before you start

Almanac Fleet is not switched on for everyone. If you do not see Almanac Fleet in the main menu, ask your Yggio administrator to enable Almanac Fleet access on your user account. It is a per-user setting, so it has to be enabled for each person who needs it, and you will need to sign out and sign back in before it appears.

You also need:

• Write access to every device you want to push to. Devices you can only view are rejected.

• Devices that are Sensative VSM LoRa trackers. Other device models do not accept the almanac.

• Devices connected through a ChirpStack or Netmore network server. Yggio cannot send almanac messages through Actility Thingpark or The Things Network, so devices on those are skipped with a note on the row.

  On Netmore the almanac messages are sent unconfirmed, because its downlink API has no confirmed option. The transfer is driven by the device's own checksum replies either way, so a lost message is still resent - Yggio just takes a little longer to notice it went missing, which can make a push over Netmore slower on a poor link.

How long a push takes

The almanac is about 2.5 kB, which is large for LoRa. It is split into numbered chunks and sent one at a time, and each device confirms a chunk before the next one is sent. How many chunks a device needs depends on its data rate (DR), which reflects how good its radio link is:

Data rate	Chunks needed	Realistic duration
DR0 - DR2	52	Hours
DR3	23	Tens of minutes
DR4	12	Tens of minutes
DR5	11	Tens of minutes

Devices at DR0 - DR2 are far from a gateway. They will get there eventually, but the transfer is slow and competes with the device's normal reporting. If you have a mixed fleet, consider setting a minimum data rate of DR3 and pushing to the weak-signal devices separately.

Over Netmore the messages go out unconfirmed (see above), so a push on a weak link can take longer than the table suggests.

Pushes continue in the background. You can close the page, or your laptop, and come back later.

Starting a push

Pushes are started from your devices, not from the Almanac Fleet page. There are two ways.

Several devices at once

1. Open Devices from the main menu.
2. Tick the devices you want to push to.
3. In the bar that appears at the bottom, choose Almanac push from Select action.
4. Choose the LNS connector the devices belong to, and optionally a Minimum data rate to leave out weak-signal devices. Leave the rest alone unless you have a reason to change it:
   • Almanac refresh interval - how long Yggio may reuse an almanac it has already downloaded before fetching a new one.
   • Assist position strategy - Last known GPS position gives the tracker a hint about roughly where it is, which speeds up the first fix. Devices that have never reported a position are simply sent the almanac without a hint.
5. Press Start push.

One device

Open the device, go to LoRa control, and use the GNSS almanac push section there.

Watching progress

The Almanac Fleet page lists your pushes, newest first, with the status of each one and how many of its devices are done. Press View on a row to open it.

The detail view shows each device with a status and a chunk count such as 14 / 23. Click a device row to see per-chunk detail: which chunk is in flight, what the device confirmed, and when.

Device statuses:

Status	Meaning
pending	Queued, not started yet
sending gps time, sending assist pos	Sending the two small set-up messages
chunking, awaiting ack	Transferring; waiting for the device to confirm a chunk
retrying	A chunk was not confirmed and is being sent again
done	The device confirmed it received and stored the almanac
skipped	Below your minimum data rate, or on a network Yggio cannot send almanacs through; nothing was sent - the row says which
failed	Gave up after repeated retries; see the error on the row

The summary line also counts unconfirmed devices. These finished the transfer but never explicitly confirmed the final message, so the almanac probably arrived but Yggio cannot promise it. If a device stays unconfirmed and its position fixes are still slow, push to it again.

A push is slow by nature, and a device that is asleep or out of coverage holds up its own transfer without affecting the others. Nothing is wrong if a job sits at the same chunk for several minutes.

Stopping a push and cleaning up

Removing a push is how you stop it. On the Almanac Fleet page, tick the pushes you no longer need and press Remove selected, or press Remove all to clear the whole list at once; you can also remove the push you are looking at from its own page.

Removing a running push stops Yggio sending anything further to its devices, but messages already handed to the network operator may still arrive, so a device can be left with a partial almanac. Pushing to it again fixes that - a fresh push always restarts from the beginning.

The list keeps every push until you remove it, so it is worth tidying now and then.

Keeping the almanac up to date automatically

Rather than remembering to push an almanac every few weeks, you can let Yggio do it. Turn Automatic almanac updates on for a device and Yggio starts a push for it on its own whenever its almanac is older than the interval you chose.

An automatic push is the same transfer as one you start by hand, with the same settings and the same progress rows on the Almanac Fleet page, so you can see exactly what happened and when.

How many days between updates

A device almanac stays usable for about 80 days, so anything comfortably inside that works. 30 days is the recommended interval and is filled in for you: it leaves well over twice the margin you need, while spending the 2.5 kB transfer's downlink airtime only once a month.

Shorten it if your trackers need the fastest possible position fix and their battery and airtime budget allows more traffic. Lengthen it if downlink airtime is scarce. The interval is per device, so a mixed fleet can have different schedules.

Turning it on

There are three places to do it, and they all set the same thing.

On one device. Open the device, go to LoRa control, and use the Automatic almanac updates section. It shows when the device was last pushed to and when the next automatic update is due, so it is also where you come back to check or change the schedule.

On many devices at once. Open Devices, tick the ones you want, then choose Automatic almanac updates from Select action. Saving here replaces whatever settings those devices already had rather than editing them one by one, which the page warns you about before you save.

While starting a push by hand. Both push forms have an Also keep the almanac up to date choice. Turning it on subscribes the devices you are pushing to, so the common case - "send one now, and keep it fresh from here on" - is one action instead of two.

On a single device's push form the choice opens on that device's current setting, so leaving it alone changes nothing and switching it off cancels its subscription. On the device list's push form it always opens off and can only ever subscribe - it never cancels, because a selection can hold devices with different settings and unsubscribing them all silently would be the wrong default. To cancel in bulk, use the Automatic almanac updates action instead.

What the device needs

The same as a push by hand, because that is what an automatic update is:

• A Sensative VSM LoRa tracker.
• A ChirpStack or Netmore network server. Yggio cannot send almanac messages through Actility Thingpark or The Things Network at all, so a device on one of those can never be updated. Yggio refuses to switch automatic updates on for such a device and tells you which ones.

If a device moves to another network server after you subscribed it, Yggio notices on the next attempt, stops trying, and says so on the device's Automatic almanac updates section - rather than retrying something that cannot work. Save the settings again once the device is back on a supported network server and it resumes.

What Yggio needs from you

Subscribing a device commits Yggio to sending downlinks to it later, when nobody is there to approve them. So it asks for the same access starting a push by hand does: write access to the device, and access to send through the network server connector the messages will go through. Each automatic push then runs with the access of whoever turned the subscription on

• worth knowing if that person later loses access to the device, because their automatic updates stop rather than silently continuing.

The LNS connector you choose is only used for devices that have no connector of their own; a device that has one is always pushed through that.

Turning it off

Set Automatic almanac updates to Off and save, in any of the same three places. On a push form, leaving Also keep the almanac up to date off while pushing to a device that is already subscribed cancels its subscription - so if you only want to push once without changing the schedule, use the Automatic almanac updates section rather than the push form to check what it is set to first.

Turning it off stops future automatic pushes. It does not stop a push already running; remove that from the Almanac Fleet page as usual.

Things worth knowing

• A manual push counts. Pushing to a subscribed device by hand resets its clock, so the next automatic update is a full interval away rather than days later.
• A new subscription pushes soon. A device that has never had an almanac pushed to it is due immediately, so expect a push within about ten minutes of subscribing it.
• Nothing overlaps. A device that is already receiving an almanac, or an app upgrade, is left alone and picked up on a later check. The reason appears on the device's Automatic almanac updates section.
• Skipped devices are not marked as updated. A device on a network server Yggio cannot send almanacs through receives nothing, and its clock does not move, so it stays visibly overdue instead of looking permanently up to date.
• Automatic pushes are not instant. Yggio checks for due devices every few minutes, so a device becomes due some minutes before its push starts.

If an automatic update does not happen

What you see	What it means
No Automatic almanac updates section on a device page	That device is not a Sensative VSM LoRa tracker, or it is not connected through a ChirpStack or Netmore network server, or Almanac Fleet access is not enabled on your account.
"connectorId is required when enabling automatic almanac updates"	Choose an LNS connector before saving. Yggio needs to know where to send the messages when nobody is present to pick.
"Not authorized to push to devices"	You have view-only access to one of the selected devices. The device is named in the message.
"Not authorized to send downlinks through connector"	You cannot send through the network server connector one of the devices uses. Ask whoever administers that connector.
"The last automatic update could not be started" on a device	The most recent check could not start a push - usually a transfer already in progress, or access that has since been lost. The reason is shown with it, and Yggio tries again.
A subscribed device is never pushed to	Check that its subscription still shows as on, and that the person who turned it on still has access to the device and its connector.
"Automatic almanac updates have stopped for this device"	A push reached the device and could send nothing - almost always a device that has moved to a network server the almanac cannot go through. Fix that, then save the settings again to resume.
"Automatic almanac updates need a network server that can carry almanac downlinks"	One or more of the selected devices is on a network server other than ChirpStack or Netmore. The message names them.

If something goes wrong

What you see	What it means
No Almanac Fleet in the menu	Access is not enabled on your account, or you have not signed out and back in since it was. Ask your Yggio administrator.
"Almanac fleet push is not enabled for your account"	Same as above.
A device is rejected when you start the push	You have view-only access to it, or it already has a push running.
No GNSS almanac push section on a device page	That device is not a Sensative VSM LoRa tracker, or it is not connected through a ChirpStack or Netmore network server.
Every device sits at pending	The push has not begun, or the connector cannot reach the network operator. Contact support if it does not move.
A device is failed	It did not confirm chunks after several attempts, usually poor coverage or an offline device. Try again later, or exclude it with a minimum data rate.