APPENDIXC
AMPLITUDE CONVERSIONS
The HP Model 8569B Spectrum Analyzer reads signal levels in dBm. The following equations allow conversion from dBm to dBm V or dBV in a 500 system.
CONVERSION EQUATIONS
dBm
+
107 dB
= dB/-lV dBm
+
47 dB
= dBmV dBmV
+
60dB
= dBV
If it is desired to convert from logarithmic units to linear units, then the equations given below will be useful. Keep in mind that the logarithmic levels are all referenced to linear units.
To calculate a linear level, simply take the antilog of the logarithmic level.
dBm dBm to P(mW)
=
P
10 log-w' P
= dBm log-l--
1m 10 dBmV dBmV to V(mV)
=
V
20 log--, V
= dBmV log-l--
1 mV 20 dBp,V to V(p,V) dBp,V
=
20 log
V
- 1 p,
V' V
= log-l dB V
--p,-
20
Figure C-I can be used to convert from dBm to voltage in a 500 system.
Conversion from dBm to volts can be made whether the
AMPLITUDE SCALE is in LOG or LINear. To read voltage on the HP 8569B, position the signal on the REF-
ERENCE LEVEL line of the CRT. Read the REF
LEVEL in dBm and find its equivalent voltage from the conversion chart (Figure C-I). The REF LEVEL calibration can be changed from dBm to dB/-lV by means of an internal jumper (Appendix D).
That is:
o
dBm referenced to 1 mw
o
dBmV referenced to 1 mV
o
dB/-lV referenced to I/-lV dBm
-20 40
-30 30
-40 20
, , ;
V
-50 10
V
~:,..-
/
-60 0
,,;
V
-70 -10
. /
~
:,..-
-80 -20
-90 -30
10mV
V
lOIlV l00mV lOO1JV
1 V
1mV
Voltage (rms)
Figure Col. Converison Cban - Converts from dBm to Voltage in
son
. /
~
~
~
,,~
10V
10mV
43
APPENDIX D
OPTION STATUS INTERFACE
Certain options on the HP 8569B can be enabled by means of a single jumper per option.
The jumper socket (12) is part of the Option Status Interface, located on the A7 Input/Output Assembly. A diagram showing the location of J2 is shown in Figure D-I.
Figure D-l. Option Status Jumpers
~
WARNING'
Positioning of the option jumpers requires working on the instrument with protective covers removed and should be done only by a qualified service techni· cian who is aware of the potential shock hazard. To avoid electrical shock, the line
(mains) power cable should be
dtseon-
nected before removing the protective covers from the spectrum analyzer.
Four (4) options are available on the OPTION STATUS
INTERFACE.
I.
Minimum Resolution Bandwidth
Pin A to Pin I (100 Hz Bandwidth)"
Pin B to Pin 2 (I kHz Bandwidth)
NOTE
The Minimum Resolution Bandwidth option is not usable with Option 002 instruments.
2.
Display Units - Reference Level
Pin C to Pin 3 (dBm)·
Pin D to Pin 4
(dB~V)
3.
Display Resolution - Center Frequency
Pin E to Pin 5 (100 kHz)·
Pin F to Pin 6 (1 MHz)
4.
Reference Position for Normalized Response
(INP-B-A)
Pin G to Pin 7·
(Center Horizontal Graticule Line)
Pin H to Pin 8
(Top Horizontal Graticule Line)
·No connection needed, default condition.
44
APPENDIX E
SYNTAX REFERENCE GUIDE
This Syntax Reference Guide is intended to provide, in detail, the required forms of command to be used when addressing the analyzer from an external HP-IB controller, and to describe precisely the resulting HP-IB output from the analyzer. It is important to keep in mind that this guide is written from a controller point of view, as user-generated programs will always be executed in the controller, not in the spectrum analyzer.
A pictorial flow representation is used to delineate the sequence of bytes or blocks of traffic across the bus.
Literal ASCII characters are bold and shown in rounded envelopes. These are transmitted exactly as shown.
Items enclosed by rectangular boxes are blocks of bus traffic which require further explanation. Those used repeatedly are described immediately below; others are dealt with on a command by command basis.
I
Output
I
UNL TA21 LAI8: UNListen, Talk Address 21,
Listen Address 18 (analyzer factory-set select code=18) (ASCII code: ?U2)
I
Enter
I
UNL LA21 TAI8: UNListen, Listen Address 21,
Talk Address 18 (ASCII code: ?5R)
I
Additional Commands
I
Additional analyzer commands
(two letter mnemonics) may follow within the same "Output" statement
Note that data bytes passed across the bus originate from the controller (controller is talker) until an "Enter" block is transmitted at which time the analyzer generates any succeeding data (analyzer is talker).
In several cases, two commands are used in an identical fashion and are listed together. Each pair performs the same function either on lower or upper lines of text (e.g.,
AL and AU) or on Trace A or Trace B (e.g.,
AP and BP).
Only the usage of the first command listed is described; the second command may simply in substituted in its place.
A reference in a command description to a "digit" should be understood to be the ASCII code for the character
1,2,3,4,5,6,7,8,9,orO.
The analyzer is able to ignore extra delimiters such as
(carriage return) and
"'R l.f:
(linefeed) at several points in a command sequence to the analyzer.
On the other hand, every byte indicated as output from the analyzer, i.e., data which immediately follows an "Enter" block, must be read by the controller or the analyzer will not be able to resume normal operation.
All commands which return values to the controller, except for the binary transfer commands, BA, BB, and MS, are terminated by transmitting an LF with the interface bus line EOI (End or Identify) pulled true. The commands
BA, BB, and MS send no terminating LF, but the EOI line is pulled true during transmission of the fmal byte of the returned data sequence. (The final byte is the 962nd byte for BA and BB and is the only byte for MS.)
Pressing RESET on HP·IB controllers generates an interface clear (IFC) command on the bus, which unaddresses the analyzer.
In case an illegal two-character mnemonic is entered (i.e., one which is not part of the analyzer's command set), a message appears on the upper annotation line:
SYNTAX ERROR
To remove the message, send a command AU, or press
CLEAR/RESET and hold it in until the annotation returns to the control setting mode.
AL. AU
Display lower line, display upper line control settings
Y
Additional Commands
r-J
Returns labeling above graticule on CRT to the control setting mode after an LL or LU command. (AU = upper line, AL = lower line)
AP. BP Output coordinates of trace A, trace B peak x~: x,y coordinates (0-480, 0-820) of peak response on trace
(AP
= trace A,
BP = trace B). Format is two 3-digit numbers separated by a comma: d d d , d d d
L.--.J
L.--.J
x
Y
If the peak value occurs at two or more horizontal positions, the leftmost point is returned.
45
AT
Output RF Input Attenuation CS
Output annotation
AU
Atten:
See
AL
0 to 70 for Attenuation in dB
BA. BB
Output trace A, output trace B byte values
Ctrl settings: A 126·character string, represents two 63-<:haracter lines of control setting labels (or LL or LV generated labels) as they are displayed above the graticule on the analyzer CRT. Refer to LL, LV for a table of the character set.
OG Output display mode
BB
BP
CF
Trace out: 481 trace values (962 bytes) in doublebyte format (BA
= trace A, BB
= trace
B): value number ab
1 ab
2 ab
3 ab ab
480481 where a and b are 8-bit bytes. Ten bits are required to specify trace values from 0 to 820 display units. 800 represents full-scale deflection. 801-820 are overrange values. The first byte in each number (a) represents the most significant two bits. The second byte
(b) represents the least significant eight bits of this lO-bit value. For example, to represent 820, the pair of 8-bit bytes would be: a
=
00000011 b
=
00110100
Therefore, when a BA or BB command initiates a byte transfer over the interface, the resulting pairs of bytes must be recombined in the controller to yield meaningful data. Normally, the first byte is either shifted or rotated 8 bits to the left (or multiplied by 256 = 2
8
) and added to the second byte to effect the recombination.
See
BA
See AP
Output Center Frequency
Frequency: -50000000 to 22600000000 for
Center Frequency in Hz
OM
Flag:
=
0 for normal mode
=
I for Digital Average mode
Output detection mode
Flag: lA, IB
= 0 for Peak Detection mode
=
1 for Sample mode
Input trace A, input trace B integer values
Trace in: value number
Up to 481 values in the range 0-975.
Only the integer portion of the number is used. Values will be displayed at the appropriate levels on the CRT except negative values, which will be blanked. The trace values are to be separated by commas, the last value followed by a serni-colon except when a full 481 values are sent, in which case the final serni-colon is optional. For example, an input of 300 values would look like this: v, v, v,......
v, v;
2 3 299 300 where v
=
1 to 3 digits
A carriage return before the terminating linefeed is optional and is ignored. If the trace values and commas are sent as a string, do not attempt to send additional commands following in the same
'Outputstaternent.
46
IB
See
IA
RB
Output Resolution Bandwidth
LG
Output Amplitude Scale
Res BW: 100 to 3000000 for Resolution
Bandwidth in Hz
Ampl Scale:
=
10, 5, 2, or I for LOG scale (dB/ division)
= 0 for LINEAR scale
RL
Output Reference Level
LL, LU
Input lower line, input upper line message
BGBB~
Additional Commands
p~
Text: Up to
63 ASCII characters to appear on upper line (LU) or lower line (LL) of labeling above graticule on CRT.
Term: An ASCII terminating character ETX,
4=,
~ or any byte in the range
o
to 31 decimal.
Ref Level:
=
60 to -112 for Reference Level in dBm
167 to -5 for Reference Level in dBpV*
=
172 to -172 for relative level of center graticule in dB with
INP-B-+AON
8569B Display Character Set
32-.63
M~5
H~~
!
II
*$%&' ( )
*+, -.
/0123456789:
<
=
>?
@ABCDEFGHIJKLMNOPQRSTUVWXYZ
,]A
'abcdefghjjklmnopqrstuvwxyz
:)~i
*Character 32 Is a blank
LU
MS
See
LL
Output value of sweep flag
SF Start sweep and set sweep flag
B---0
Y
Additional Commands
~
•
Triggers sweep, sets MS flag sweep, MS flag
=
1.
At completion of
=
O.
(SF may not be used when analyzer is in analog or mixed sweep mode.) During the sweep triggered by SF, the MS command may be used to test whether the sweep is in progress or complete. All other analyzer commands sent by the controller during the sweep for which the MS flag = 1 will be accepted and ignored by the analyzer. The MS command is the only command that has meaning during an SF·triggered sweep.
See the example at the end of this appendix.
NS
Flag: = 0 for sweep completed
= 1 for sweep in progress
The MS (mid-sweep) flag should be used only following an SF command and refers only to the single sweep triggered by that command. If the
MS flag is tested when there has been no SF command, the flag has no meaning and a zero value is returned.
SP
Span:
Output INP-B-+A state
Output Frequency Span/Div
=
1000 to 500000000 for Span in
Hz/division
0 for Zero Span
=
=
-1 for Full Span
-2 for 1.7-22 GHz Span
Flag: = 0 for INP-B-+A OFF
=
1 for INP-B-+A ON
*See Appendix D for conversion from dBm readout to dBpV.
47
