Vaisala CT25K - Data Message No. 3

Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
38
20TH LINE
L↵ End-of-Text and CRLF.
4.4.3 Data Message No. 3
This message contains a line which has one bit for each range gate at 100 ft
resolution. It is intended for printer-type black-and-white graphical recorders
such as Vaisala DR21, DR23, DD50 with printer, etc. The message is derived
from Message no. 2 by setting a threshold for the range and sensitivity
normalized backscatter profile and reporting signal exceeding this threshold
as a 1, and otherwise as a 0. The bit line gets split into groups of four
successive range gates, which are then transmitted as a string of 64
hexadecimal characters 0...F.
Message format example:
(
CTA2033
J
↵ 1st line 11 char.
30 01230 12340 23450 FEDCBA98↵ 2nd line 31 char.
00002204FFEFFF8C00000000627EEFFF310000000335A0BFFFFF100000000000↵
3rd line 66 char.
L
↵ 4th line 3 char.
-------------------
total 111 characters
Transmission time and size :
0.46 s at 2400 baud (10-bit char.)
26.64 kbytes/h, 639 kbytes/d, 19.18 Mbytes/mo. at 4 msg./min.,
uncompressed.
Message interpretation:
1ST LINE
Identical to that of Message No. 1 except that the second to last digit which
identifies the message number, is always 3.
2ND LINE
Identical to that of Message No. 1
3RD LINE
Example:
00002204FFEFFF8C00000000627EEFFF310000000335A0BFFFFF100000000000↵
64 hexadecimal characters 0...F, each bit in its binary format representing one
of four subsequent range gates at 100 ft (30 m) resolution. Bit is set to "1" if
its internal unscaled value (in units of (10,000 km srad)
-1
, ref. message no. 2)
exceeds 1,000 *
100
/
SCALE
, i.e. maximizing the value of parameter SCALE to