[share information] usage of an external bluetooth receiver

[UH1169]

in short terms, i want to share these information, in case its of interest to somebody.
as a was disappointed with gps accuracy even under medium difficult conditions, i tested an external BT receiver.
here are my results, after tracking car trip, let it avtivated while shopping and for trailrunning.

external BT Device: NAVILOCK BT-821G
80 grams , 90 euro, changeable battery, no protection / IP / MIL cert

constellation A
HAFURY A7, cheap fone, very bad builtin gps capabilities, no protection, ca. 160gr, ca 16cm, android 9, Oruxmaps GP 7.5.8

coupling variant
worked very good and stable using the coupling method: mocked location provider with the app "Bluetooth GNSS - GPS, Galileo, GLONASS and BeiDou".
accuray (used in car): most of the time, 1m, you see on which side of the street you have been. (!)
stability BT connection: no cut offs
stability / accurcy of GPS signal: even in the building (light build rooftop), the signal was accurate (!)

coupling variant
direct coupling without mock/BT App.
which means: phone setting location is off (!), BT coupled to the external GPS device
this worked too


constellation B

motorola defy plus (2011) , Android 2.3, Oruxmaps 6.0.5
118 gram, 11cm, IP67, shockproof (tested for years, its unbreakable), removable battery
(rooted, underclocked etc.)

trailrunning, mediumdifficult conditions, direct coupling without additional app, GPS Setting in Phone is off, flight mode activated.

setting orux: timeinterval 4sec,distance interval 0m, accuracy limit 0m

recording time: 3h

battery level 70% before (it displays in 10% steps), battery level 70% after 3h recording !!!!

accuracy of the recorded track: very high. always 1meter accuracy, sometimes 2m.
update in a second test (2:30h recording time) the navilock was fixed on the belt of the rucksack, not on top of the shoulder but a little bit downwards. with this setup some more inaccuracies occurred, with this some recorded sections of the track have 2-3m offset and go in parallel. i suspect for real good accuracy the mount point of the device is very important, on (front) top of the shoulder in the former testcase produced a more exact result

in a small tunnel , it still had accuracy

a section where a came back after 1h both tracks are recorded without offset !!!!

noticed one inaccuracy: for 25km/3h after a change in direction, for about 200m, the accuracy was 5m.

the recorded trail 95% of the time sits exactly on the map's pathes, like it was drawed/prepared by hand an not have been recorded.

in every constellation: no cutoff of the BT connection, BT worked reliable (short distance), i didnt tested it with phone in the chest pocket (front of body) and the receiver in the bag (back).