tutorials

Parts / Assembly - Locator

Ground based tracking is the essence of successful recovery. So long as we know where our payload is once it lands we should have a successful launch. Over at the shop, you can buy an SMS based locator. Here is a quick description of how to use it. Make sure you’re familiar with it before launch day!

PLEASE NOTE: These locators operate over the GSM network, also known as 2G. This service is being depreciated in certain countries, notably Australia, Canada and the USA, where it is now only available from some network providers. If you’re not sure whether this will work in your country, please get in touch with us on the Forum or by email at info@sentintospace.com.

THE SIM CARD

The device uses a Standard size SIM card. If you can only purchase a micro or nano SIM, you will need an adapter kit – these can be found online and in most phone shops and generally cost less than £1/$1.

Before putting the SIM into the device, you’ll need to ‘activate’ it. Put some credit onto the card, put it into a phone and use the card to make and receive a call. Once this is done, the card is ready to be installed into your locator.

FITTING THE BATTERY AND SIM CARD

Flick the catch, lift the battery out and install the sim card as above. Before using the device, it should be fully charged. 
Charging can take up to 12 hours for the first charge and then around 3-5hrs for future charges. Try to leave it charging for this long (even if it tells you it’s full!)

FLASHING LIGHTS

Once you have installed the SIM and the battery and turned the device on, you’ll want to test it out. To do so, take the device outside and place it in clear view of the sky, so that the GPS chip can get a fix on its location from several satellites.

It may take up to 10 minutes on first use for the device to connect to both the GSM network (to cummunicate to you) and the GPS network (to know its location). The green light on the side will blink once every 3 seconds when mobile network coverage is achieved and double blink when GPS lock has been established.

LOCATING

tracker txtTo locate the device, simply call the number of the SIM card and the locator will send an SMS with location coordinates. The Google maps link will take you directly to the location.
google maps arrowBe aware that on some mobile versions of Google maps, the coordinates appear as the nearest road. On a computer browser, a green arrow will show the precise coordinates location.

TIPS AND TRICKS

Some places don’t have good mobile network coverage (and some have none at all!). For our flights we often use two SMS trackers to increase our odds of landing in good network coverage. The extra weight is offset with peace of mind!
When you call the tracker, if it has coverage, it will ring 3 times and then hang up. It will then send an SMS with coordinates. You will get straight to voicemail if it is out of coverage. Check that you’re predictions are likely to land you in an area of coverage in advance. In the USA you can use this tool to check for coverage.
Mobile phone networks don’t reach very high! You’ll need to wait until the payload lands before you know exactly where it is. We normally go to the predicted landing site whilst the balloon is in the air and then wait for the tracker to respond to calls.

The most common problem people experience is from the unit failing to connect to a cellular network and/or return a text message. The most frequent cause of this is that the SIM card has not been activated or used within a mobile handset. Although credit can be added and the SIM remotely activated online, the SIM will need to be placed within a mobile handset and used before being introduced into the tracking unit. It is good practice to make and receive a call from the mobile handset before making the exchange. This appears to have the effect of notifying the carrier that the SIM is now in use and allowing full activation of the card.

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