Open EricAndrechek opened 1 year ago
Please look up APRS101.PDF, telemetry specification in Chapter 13. The !" base91 decodes to a decimal value of 1. Whether the LSB of an integer is left or right is an implementation detail of your computer but does not affect the spec. :) But the intention of the spec here is that the !" base91 decodes to a decimal value of 1 (only the of the integer LSB is 1), and in this case the first bit of APRS telemetry (B1) is 1.
In the classic APRS telemetry the first bit B1 is the first character in the ASCII telemetry string ("10000000"). In Mic-E telemetry it's encoded as a single integer and the LSB is B1.
Per the apr base91 comment telemetry spec (also at he.fi), section 3.9 says:
Then, later, in the examples it is given:
I could be misunderstanding, but it was my understanding that in binary, the LSB was the right-most bit. Wouldn't this mean that in the given example B1 would be 0? I guess I am confused as to whether the binary representation goes from B8-B1 like
87654321
or from B1-B8 like12345678
. If B1 were the LSB I would think it would be87654321
but in the example, it seems to go12345678
. Could I get some clarity here? Also, I am assuming, but would appreciate some clarity as well, as to where the 9-13 reserved bits would then go.Thanks!