Manual - 8500A Series Peak Power Meter - Giga-tronics

Remote Operation
Remote State
As in the regular PPM operation mode, the instrument must be in the REMOTE state to accept any
commands over the GPIB or to output any data. However, unlike the standard PPM operation, the front
panel is fully active while in the REMOTE state and more Menu options will become active in 1018B
emulation (see the Front Panel Menus discussion in this section). This imposes two requirements for the
operator. One is the fact that a cursor delay will be accepted on either the front panel or over the GPIB.
The most recent cursor delay will determine the measurement. The other difficulty is that a measurement
and not a menu prompt must be displayed on the screen for the instrument to be able to collect data. If
the controller tries to collect data while the PPM has a front panel menu displayed, the PPM will take no
action until it returns to displaying data on the front panel. Then it will collect and output the data. Also,
there is no return to local escape sequence while in REMOTE since the front panel is not locked out.
There is no local lockout feature either.
Serial Poll
The serial poll feature operates similar to the 1018B serial poll function. The only time SRQ is asserted
is if an output is ready and the value of the status byte is zero.
Front Panel Menus
The front panel menu will include three options regarding GPIB control when in the 1018B emulation
mode. These options represent capabilities which can be set on the 1018B front panel, but not on the
PPM in general usage. This is because each of these options are directly controllable over the GPIB in
normal PPM usage.
Disable/Enable SRQ:
Update on Trigger
Reset/Continuous:
End 1018B
Emulation Mode:
This allows the SRQ capability to be enabled or disabled with the same effects
as the SRQE and SRQD PPM GPIB commands. Whatever option is offered,
enable or disable, will be the opposite of the current state.
This sets the Output Mode. The choice offered will be the opposite of the
current mode. Upon entering the 1018B emulation mode, the Output Mode
will be set to Update on Trigger Reset.
This prompt will replace the menu prompt that initiated the 1018B Emulation
Mode.
Analog Output
When using the PPM in the 1018B Emulation Mode, it should be kept in mind that the 1018B instrument
has a 10 mV/dB Analog Output while the PPM has 100 mV/dB. If the 10 mV/dB output of the 1018B is
required, a 10:1 resistive L attenuator can be placed on the PPM’s output.
Two Detectors
The Model 8502A has two detectors instead of only one as does the 1018B. When in the 1018B
Emulation Mode, either detector can be used with the choice made through the front panel. It is up to the
operator to know which detector is active when the command is given over the GPIB to change cursor
delay or to take a measurement. If both detectors are active, the instrument will ignore any GPIB
commands and not be able to output any data.
Reference Delay, Correction of Carrier Frequency, and Offset vs 1018B Direct Mode
A correction will always be made on the carrier frequency. However, to simulate the 1018B direct mode
if desired, the reference delay and offset features of the PPM can be negated by setting both to zero via
the front panel.
Manual No. 20790, Rev C, November 1998 3-39
Superceded by Revision D, March 2009