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Feature #6347
openmobile: support data calls @ 300 bps and 1200/75 bps (TCH/[FH]2.4)
Status:
New
Priority:
Normal
Assignee:
-
Category:
OsmocomBB mobile (host)
Target version:
-
Start date:
01/27/2024
Due date:
% Done:
0%
Resolution:
Spec Reference:
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.
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