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Hi everyone.

We have installed several FMB125 trackers and are now observing the data that is coming in. We are seeing some strange values in the altitude records and, since we live near see we assume the values are somehow overflowing and should in fact be negative. Unlike the longitude and latitude, where it is explained in the codec how to figure whether a position is negative, there is no mention of this for altitude.

Has anyone experienced this? In the example payload below, the altitude value is 0xFFEC (65516), clearly not valid.

00000000         | preamble
00000044         | records
08               | codec id
01               | number of records
00000176a918a7b0 | timestamp
00               | priority     
082e79df         | longitude
1b25a98a         | latitude
FFEC             | altitude
00ec             | angle
05               | satellites
0005             | speed
... rest of payload
000c05ef01f0011505c800450105b5000fb6000d422f80430e7044008f02f1000072ba10000003f300010000c7b9

I will be thankful for any information.

Marko

1 Answer

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by

Hello,

Could you please send the full payload without any separation "As received from device"?

sending more than one record will be appreciated.

Best Regards,

Mahmoud A.M Khalil

by

Hi Mahmoud, thank you for your interest. Here are some examples:

65524

0000000000000044080100000176b2e907a800082eff451b26606bfff4004a0a0018000c05ef01f0011505c800450105b5000bb60007423014430fa544000002f1000072ba100004eb13000100003e75

65525

0000000000000044080100000176b2e90f7800082f04ce1b265daffff5005a09000f000c05ef01f0011505c800450105b5000cb60007423019430fa544000002f1000072ba100004eb200001000079ec

65530

0000000000000044080100000176b2e9368800082f174b1b2659a6fffa005c0a0020000c05ef01f0011505c800450105b5000bb6000742301e430fa544000002f1000072ba100004eb4a000100009348

65531

0000000000000044080100000176b2e94a1000082f37101b265a09fffb00590a0034000c05ef01f0011505c800450105b5000cb60007423010430fa544000002f1000072ba100004eb8a000100000fa7

65533

0000000000000044080100000176b2e955c800082f4c171b2658fffffd00660a0031000c05ef01f0011505c800450105b50009b60006423010430fa544000002f1000072ba100004ebb40001000061b9

65534

0000000000000044080100000176b2e95d9800082f595f1b2655bdfffe00710a0033000c05ef01f0011505c800450105b50009b6000642300e430fa544000002f1000072ba100004ebd000010000dea7

65535

0000000000000044080100000176b2e9c32800082fe5591b264dddffff0066090027000c05ef01f0011505c800450105b50010b60008423016430fa544000002f1000072ba100004ece100010000795f

65534

0000000000000044080100000176b2e9d6b000082ff9981b264a48fffe00700a0025000c05ef01f0011505c800450105b50009b60006423016430fa544000002f1000072ba100004ed16000100009973

65535

0000000000000044080100000176b2e9e6500008300b2c1b264289ffff007b0b001f000c05ef01f0011505c800450105b50009b60006423010430fa544000002f1000072ba100004ed40000100007cb4

by

Hello,

First, thank you for share the needed info. Here, I will reply to the first two payloads, the rest will be similar.

0000000000000044080100000176b2e907a800082eff451b26606bfff4004a0a0018000c05ef01f0011505c800450105b5000bb60007423014430fa544000002f1000072ba100004eb13000100003e75

FFF4 = -12 (12 meter under sea level)

0000000000000044080100000176b2e90f7800082f04ce1b265daffff5005a09000f000c05ef01f0011505c800450105b5000cb60007423019430fa544000002f1000072ba100004eb200001000079ec

FFF5 = -11 (11 meter under sea level)

In order to convert this value to decimal, you have to use Decimal from signed 2's complement conversion. please do a search for this topic in your search engine "Two's Complement to Decimal Conversion" and surely you will have more understadning about this. "read this article"

I hope that you reached your answer and solved your problem.

Best Regards,

Mahmoud A.M Khalil