Reference Between Signal Data And Screen Display - Hameg Instruments HM5014-2 Manual Del Usuario

Detailed description of #bm1 command
#BM1(CR) = block mode (transfers 2048 data byte via
RS-232 interface)
The transfer data consist of 2048 byte: trans_byte [0] up to trans_byte
[2047]
The 2048 data byte contain 2001 signal byte, the center frequency
parameter and a check sum for the signal byte.
The signal data allocate the following transfer data byte.
trans_byte[n] = sig_data[n] ( n = 0 bis n = 2000):
trans_byte[0] = sig_data[0]
trans_byte [2000] = sig_data[2000]
The check sum is a 24 bit value ( = 3 Bytes ) and generated as follows:
Checksum = sig_data[0] +sig_data[1] + ... sig_data[1999] + sig_data[2000]
(sum of all signal data)
The 24 bit check sum allocates the following transfer data byte:
trans_byte[2044] = 1.Byte of checksum [MSB]
trans_byte[2045] = 2.Byte of checksum
trans_byte[2046] = 3.Byte of check sum [LSB]
The center frequency parameter is allocated to the following transfer
data byte:
trans_byte [2016] = 'C'; trans_byte [2017] = 'F'; trans_byte [2018] = 'x';
trans_byte [2019] = 'x'; trans_byte [2020] = 'x'; trans_byte [2021] = 'x';
trans_byte [2022] = '.'; trans_byte [2023] = 'x'; trans_byte [2024] = 'x';
trans_byte [2025] = 'x'; (x= '0' to '9') Example: CF0623.450
(These bytes are not being used for check sum calculation)
The last sign is always CR ( Carriage Return)
trans_byte[2047] = 0D hex (Carriage Return)
All unused bytes are set to „00 hex".

Reference between signal data and screen display

The signal data are the result of 2001 analog/digital conver-sions
during one sweep.
X-Position: The analog value of the fi rst byte „sig_data[0]" is displayed
at the trace start position (left). The following values are displayed
linearly until sig_dat[2000] is reached, which is displayed at the trace
end position (right). The frequency of each signal data (sample) can be
calculated from center frequency and span.
Frequency (x) = (Center Frequency – 0.5 * Span) + Span * x/2000
X = 0... 2000 (Position of sample = sig_data[x])
Y-Position: The 8 bit value (hex: 00 bis FF) of each memory location for
sig_data[x] has the following relation to the screen:
1C hex (28 dec) coincides with the lowest horizontal graticule line.
E5 hex (229 dec) coincides with the upmost (reference level) graticule
line.
The a/d converter dependent resolution allows for 25 different Y po-
sitions/div.
In combination with 10dB/div the resolution is 0.4 dB and in case of
5dB/div it is 0.2dB.
The level (y) of a signal position can be calculated:
For y< 229 (Ref-Level position):
Level in dBm (y) = ref-level (dBm) – ((229-y) x 0.4 dB) at 10dB/Div
For y > 229 ( Ref-Level position):
Level in dBm (y) = ref-level (dBm) + ((y-229) x 0.4 dB) at 10dB/Div
R S - 2 3 2 I n t e r f a c e – R e m o t e C o n t r o l
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Subject to change without notice