The case of the missing beacons!

Several of us have noticed over the last few weeks that in certain conditions beacons from ViewRanger seem to not appear on Social Hiking (usually these missing beacons are visible on the BuddyBeacon Portal, but not always). I have done a bit of digging and found the problem (and implemented a temporary fudge on Social Hiking to fix it)

The main problem seems to be that sending a manual beacon does not send any beacons waiting to be sent when the phone was out of signal (or in aeroplane mode – but more on that later!), which then conflicts with how Social Hiking handles connections with ViewRanger.

As an example, let’s say you have BuddyBeacon updating every 2 minutes. Every 2 minutes, your phone sends your position to the Viewranger servers. Every 10 minutes, the Social Hiking server connects to Viewranger and asks for all beacons received since the latest beacon in the database. In normal conditions Viewranger would return five beacons, and Social Hiking would take the latest timestamp to use for the next request.

When out of signal, your phone will store each scheduled beacon. Each time Social Hiking requests your latest beacons, none will be received, and the server will try again in another 10 minutes (incidentally this update time is set to be improved, which will  make this issue worse). However if you send a manual beacon, your stored beacons will not be sent until your next scheduled beacon, which means that the Social Hiking server will only receive the manual beacon and will use that timestamp for the next request – effectively ignoring the stored beacons when they are later sent to the Viewranger server.

In the short-term, I have added a fudge which gives eight hours grace when checking for new beacons – in effect your last eight hours worth of beacons are always imported each update (the majority of which will be discarded as duplicates). This unfortunately means that it will be impossible to delete beacon sent within the last eight hours from Social Hiking (as they would just get pulled back in from Viewranger – it is already impossible to delete your last beacon, which is  always returned by Viewranger).

I will be contacting Viewranger about this issue, as based on discussions I have had with people, we have all assumed that sending a manual beacon would also send any stored beacons. I had a problem on my last walk where I was out of signal for the last leg. On returning to the car I sent a manual beacon before turning off BuddyBeacon – as the missing beacons were not sent with the manual beacon, they were lost when BuddyBeacon was turned off (although I guess it is possible that they might reappear when I next switch on BuddyBeacon – again something to clarify with Viewranger)

The problem and fix above does not effect InstaMapper, which does not have a send manual beacon feature.

Aeroplane Mode

Something that has been discussed recently is whether the ‘Send Old Positions’ function of Viewranger effectively allows you to switch your phone to aeroplane mode to conserve battery but still store beacons which you can then effectively send in bulk periodically.

I have run some tests using Viewranger on Android, as have other users, and it certainly seems to work fine (there were problems, but these related to the problems above). However it would appear that aeroplane mode on an iPhone seems to disengage GPS. No tests have been carried out on Symbian.

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3 Comments on "The case of the missing beacons!"

  1. Lighthiker says:

    I can confirm that Aeroplane mode on the iPhone switches GPS off, too. Unfortunately there is no workaround inside iOS. The only solution is if you are willing to jailbreak your iPhone and install SBS Settings (http://www.youtube.com/watch?v=QfJiUdCf5lI) afterwards which allows you to switch on/off GSM, Bluetooth, WIFI and GPS independly.

  2. Jonathan Quirk says:

    Offline mode on a Nokia 5800 (Symbian S60 5th edition) keeps the GPS working.

  3. daylightgambler says:

    Thanks Jonathan – I have raised the manual beacon issue with ViewRanger, and they have confirmed it doesn’t affect the latest Symbian version.

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