ZED-F9T - Integration Manual
UBX-RXM-SFRBX message. Data bits 1 to 8 are always a hamming code, whilst bits 81 to 84 are a
string number and bit 85 is the idle chip, which should always have a value of zero. The meaning of
other bits vary with string and frame number.
The fourth and final 32 bit word in the UBX-RXM-SFRBX message contains frame and superframe
numbers (where available). These values aren't actually transmitted by the SVs, but are deduced by
the receiver and are included to aid decoding of the transmitted data. However, the receiver does
not always know these values, in which case a value of zero is reported.
The four words are arranged as follows:
Figure 24: GLONASS subframe words
In some circumstances, (especially on startup) the receiver may be able to decode data from a
GLONASS SV before it can identify the SV. When this occurs UBX-RXM-SFRBX messages will be
issued with an svId of 255 to indicate "unknown".
3.8.1.4 BeiDou
For BeiDou B1I D1, B1I D2, B2I D1, B2I D2 signals, there is a fairly straightforward mapping between
the reported subframe and the structure of subframe and words described in the BeiDou ICD. Each
subframe comprises ten data words, which are reported in the same order they are received.
Each word is arranged as follows:
Figure 25: BeiDou subframe word
UBX-19005590 - R01
3 Receiver functionality
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