HP 8920A - Forward Control Channel Message and Filler Buffers

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S:\HP892XX\USRGUIDE\manual\encoscrn.fb
Chapter 10, Signaling Encoder (AF Generator 2)
MPT 1327 Encoder
Forward Control Channel Message and Filler Buffers
This control is only available using IBASIC commands; it is not displayed on the
MPT 1327 Encoder screen.
The encoder screen
Test Mode field selects the type of signal being transmitted
by the signaling hardware (as explained in
"Test Mode" on page 406). The most
important modes are the
Control and Traffic modes.
In the
Control mode the Test Set continuously generates a slotted aloha forward
control channel, as defined and controlled from IBASIC. In
Traffic mode the
Test Set generates individual messages, as defined and controlled from IBASIC.
These modes are central to testing MPT 1327 RUs. An RU must acquire and
validate a control channel. It must also be instructed, by control channel signaling,
to proceed to a traffic channel before any RF or audio measurements can be
performed.
During testing it is necessary to generate the forward control channel
continuously; initially, for the RU to acquire and validate the control channel for
exchanging the necessary call setup signaling; thereafter, for the RU to remain
locked onto the control channel, awaiting exchange of further signaling. This also
prevents the RU from re-entering control channel acquisition procedures.
The exception to this is when the RU-under-test is participating in a test call on a
traffic channel. It is not necessary to maintain the control channel signaling during
test calls as there is only one RU in the test environment and it is on a traffic
channel.
As there is only one RU, the control channel signaling comprises a fixed slotted
aloha sequence with occasional variations to send specific messages (such as
requests for registration (RQR), broadcast messages (BCAST), ahoy messages
(AHY)).
The filler buffer contains the repeating pattern of the forward control channel. It
also contains a message buffer from which selected timeslots in the filler buffer
can be replaced on a one-off or repeating basis.