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Feature #6347

open

mobile: support data calls @ 300 bps and 1200/75 bps (TCH/[FH]2.4)

Added by fixeria 28 days ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
OsmocomBB mobile (host)
Target version:
-
Start date:
01/27/2024
Due date:
% Done:

0%

Resolution:
Spec Reference:
Tags:
CSD

Description

Currently we implement data rates starting from 2400 bps and higher, but not 300 bps and 1200/75 bps.
The problem is that those rates are not specified in ITU-T Rec. V.110, which defines 600 bps as the minimum synchronous data rate.

According to 3GPP TS 44.021, section 4.1, the 300 bps user data signalling rate shall be adapted to a synchronous 600 bps stream.
Also, "Incoming asynchronous data is padded by the addition of stop elements" -- this means that we pad bits after stop bit(s):

pad bits = ((600 / 300) - 1) * (start + data + parity + stop)

This logic most likely needs to be implemented in the soft-UART module of libosmocore.git.


Related issues

Related to OsmocomBB - Feature #4396: Circuit Switched Data (CSD) Support in osmocom-bbResolvedfixeria02/13/2020

Actions
Actions #1

Updated by fixeria 28 days ago

  • Related to Feature #4396: Circuit Switched Data (CSD) Support in osmocom-bb added
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