Atec HP-Agilent-8904A - Manual (Page 6)

6
Communication signaling
In addition to the extra channels,
Option 001 also adds four sequence
modes to the 8904A: tone sequence
mode, DTMF sequence mode, digital
sequence mode, and Hop Ram sequence
mode. These modes make the 8904A a
powerful tool for generating sequences
used in communications signaling.
Tone sequence mode allows entry of
16 unique sine wave tones, each with
an “on-time” and “off-time.” From
these 16 tones, sequences can be built
up to a length of 750 tones. The mini-
mum on and off time duration is 800 µs
with 10 µs resolution, while the maxi-
mum value is 655.35 ms. Timing accu-
racy is better than ±20 µs. When no off-
time is specified, tone sequence mode
will switch to the next tone frequency
in a phase continuous manner
without
discontinuities.
DTMF (Dual Tone Multi Frequency)
mode allows generation of sequences
up to 750 telephone type signals in
length. In DTMF mode, the 8904A can
generate the 16 standard frequency
pairs as defined by Bell Telephone (Bell
technical reference publication No.
48005). Minimum timing periods for
DTMF are 1 ms, with 10 µs resolution.
Digital sequence mode can generate
digital bit streams up to 3,000 bits in
length. Minimum period in the digital
mode is 100 µs with 10 µs resolution.
On and off “levels” in the digital mode
can be set to any value for simulating
different logic families and asserted
“high” or asserted “low” logic conven-
tions. For ease of entry, data may be
entered in binary, octal, or hexadeci-
mal formats. All three modes contain
extensive sequence-editing features,
and three control modes: single se-
quence, continuously repeat sequence,
and manual step-through sequence.
Hop Ram sequence mode offers a mix
of the capabilities of the tone and dig-
ital sequence modes. This mode allows
entry of 16 signal states, each with an
associated amplitude, frequency, and
phase value. Sequences of up to 750
tones can be built if all 16 states are
used, or up to 3,000 tones if only two
of the states are used. A unique burst
function allows the pattern to be re-
peated a specified number of times
from 1 to 127. Unlike the other se-
quence modes, Hop Ram sequence
mode allows you to use any of the six
standard waveforms available in the
8904A: sine, square, ramp, triangle, dc
or white Gaussian noise. Instead of
selecting the timing in terms of milli-
seconds, Hop Ram sequence mode sets
timing in terms of frequency. This
allows the generation of patterns
which have precise baud rates such
as 1200, 2400, 4800, or 9600.