Keysight N5227B Service Guide 5-39
Theory of Operation
Receiver Group Operation
A16 SPAM Board (Analog Description)
The A16 SPAM board contains digital and analog circuitry. For digital
“A16 SPAM Board (Digital Description)” on page 5-45
In this assembly, the IF signals (A, B, C, D, and R for 4-port models and A, B,
R1, and R2 for 2-port models) from the A24 IF multiplexer board go through a
gain stage where small signals are amplified to ensure that they can be
detected by the analog-to-digital converter (ADC).
All input signals are sampled simultaneously by the ADCs, where they are
converted to digital form. The ADC conversions are triggered by timing signals
from the digital signal processor (DSP) in response to commands from the
central processing unit (CPU). The digitized data is processed into magnitude
and phase data by the DSP and sent to the CPU random access memory (RAM)
by way of the peripheral component interconnect (PCI) bus.
The processed and formatted data is finally routed to the display, and to the
general-purpose interface bus (GPIB) for remote operation. Refer to
Processing and Digital Control Group Operation” on page 5-42
information on signal processing.
6
DCOM
Digital ground
7
PulseSyncIn
Pulse generator synchronization trigger input (TTL)
8
RFPulseModIn
RF source pulse modulation drive input (TTL)
9
DCOM
Digital ground
10
Pulse1Out
Programmable pulse train output #1 (TTL)
11
Pulse2Out
Programmable pulse train output #2 (TTL)
12
Pulse3Out
Programmable pulse train output #3 (TTL)
13
Pulse4Out
Programmable pulse train output #4 (TTL)
14
NC
No connect
15
DCOM
Digital ground
Table 5-5
PULSE I/O Connector Pin Assignments
DB-15 Female Connector
Pin
Name
Description
