DMR TA APRS not working for Southern or Western hemisphere

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VK3KYY
Posts: 7481
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

DMR TA APRS not working for Southern or Western hemisphere

Post by VK3KYY » Sun Nov 13, 2022 10:43 pm

Does anyone know how I can get in contact with the Brandmeister developers, because sending "In Call GPS" via DMR to BM only works correctly for positive values of Latitude and Longitude.

Negative values e.g. Southern or Western hemispheres, result in invalid locations being reported by https://aprs.fi

The BM Self Care settings only seem to support Motorola or Hytera GPS data, but I can't find any information online about whether their data format is different from the ETSI standard data format.

According to the ETSI standard the GPS information is send in the last TA 'phase" of 7 bytes

The first 4 bytes are the Longitude and the last 3 bytes are Latitude.

Actually first byte also contains accuracy information and reserved binary bits, so that most of the Longitude data is sent in bytes 1,2 and 3


Sending 0xFFFFFF in the Latitude bytes should result in a position of -0.000001 deg i.e south, but results in a large positive value on APRS.fi, which is out of range.

So either the hemisphere data is sent in a different byte entirely, or one of these 2 systems is not working correctly :-(

Edit.

I tried posting to the aprs.fi Google group, but my question was rejected by the moderators, as not being applicable to the aprs.fi website :-(

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YT5HOK
Posts: 213
Joined: Sat Nov 16, 2019 11:36 am
Location: Belgrade, KN04FR

Re: DMR TA APRS not working for Southern or Western hemisphere

Post by YT5HOK » Mon Nov 14, 2022 8:32 am

VK3KYY wrote:
Sun Nov 13, 2022 10:43 pm
Does anyone know how I can get in contact with the Brandmeister developers...
Sent you an e-mail.

We can continue here, after you decide how to proceed.

Cheers!

VK3KYY
Posts: 7481
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: DMR TA APRS not working for Southern or Western hemisphere

Post by VK3KYY » Mon Nov 14, 2022 8:46 am

YT5HOK wrote:
Mon Nov 14, 2022 8:32 am
VK3KYY wrote:
Sun Nov 13, 2022 10:43 pm
Does anyone know how I can get in contact with the Brandmeister developers...
Sent you an e-mail.

We can continue here, after you decide how to proceed.

Cheers!
Thanks.

I received your email. I will reply

VK3KYY
Posts: 7481
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: DMR TA APRS not working for Southern or Western hemisphere

Post by VK3KYY » Tue Nov 15, 2022 11:43 am

I had a conversation on Telegram with the BM dev and it looks like BM may need to release an update to resolve this issue

I'm going to do some tests tomorrow to confirm

VK3KYY
Posts: 7481
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: DMR TA APRS not working for Southern or Western hemisphere

Post by VK3KYY » Fri Nov 18, 2022 8:47 am

This has feature has now been added.

I will probably need to make more changes to allow greater precision of manual data entry, and also possibly add a flag to the codeplug channel data to allow this as a per channel setting.

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