71
11. Two-WireReturnLoss.
The 2-wire return loss is computed
using the following equation:
r = -20
log (2V
M
/V
S
),
where: Z
D
= The desired impedance; e.g., the characteristic
impedance of the line, nominally 600
.
(Reference Figure 6).
12. OverloadLevel(4-Wireport).
The overload level is specified at
the 4-wire transmit port (V
TXO
) with the signal source (E
G
) at
the 2-wire port, I
DCMET
= 23mA, Z
L
= 20k
(Reference Figure
7). Increase the amplitude of E
G
until 1% THD is measured at
V
TXO
. Note that the gain from the 2-wire port to the 4-wire port
is equal to 1.
13. OutputOffsetVoltage.
The output offset voltage is specified
with the following conditions: E
G
= 0, I
DCMET
= 23mA, Z
L
=
∞
and is measured at V
TX
. E
G
, I
DCMET
, V
TX
and Z
L
are defined
in Figure 7. Note: I
DCMET
is established with a series 600
resistor between tip and ring.
14. Two-Wire to Four-Wire (Metallic to VTX) Voltage Gain.
The 2-
wire to 4-wire (metallic to V
TX
) voltage gain is computed using
the following equation.
G
2-4
= (V
TX
/V
TR
), E
G
= 0dBm0, V
TX
, V
TR
, and E
G
are defined
in Figure 7.
15. Current Gain RSN to Metallic.
The current gain RSN to Metallic
is computed using the following equation:
K = I
M
[(R
DC1
+ R
DC2
)/(V
RDC
- V
RSN
)]
V
RDC
and V
RSN
are defined in Figure 8.
K, I
M
, R
DC1
, R
DC2
,
16. Two-Wire to Four-Wire Frequency Response.
The 2-wire to
4-wire frequency response is measured with respect to E
G
= 0dBm
at 1.0kHz, E
RX
= 0V, I
DCMET
= 23mA. The frequency response is
computed using the following equation:
F
2-4
= 20
log (V
TX
/V
TR
), vary frequency from 300Hz to
3.4kHz and compare to 1kHz reading.
V
TX
, V
TR
, and E
G
are defined in Figure 9.
17. Four-Wire to Two-Wire Frequency Response.
The
2-wire frequency response is measured with respect to
E
RX
= 0dBm at 1.0kHz, E
G
= 0V, I
DCMET
= 23mA. The fre-
quency response is computed using the following equation:
4-wire
to
F
4-2
= 20
log (V
TR
/E
RX
), vary frequency from 300Hz to
3.4kHz and compare to 1kHz reading.
V
TR
and E
RX
are defined in Figure 9.
18. Four-Wire to Four-Wire Frequency Response.
The 4-wire to
4-wire frequency response is measured with respect to
E
RX
= 0dBm at 1.0kHz, E
G
= 0V, I
DCMET
= 23mA. The fre-
quency response is computed using the following equation:
F
4-4
= 20
log (V
TX
/E
RX
), vary frequency from 300Hz to
3.4kHz and compare to 1kHz reading.
V
TX
and E
RX
are defined in Figure 9.
19. Two-Wire to Four-Wire Insertion Loss.
The 2-wire to 4-wire
insertion loss is measured with respect to E
G
= 0dBm at 1.0kHz
input signal, E
RX
= 0, I
DCMET
= 23mA and is computed using
the following equation:
L
2-4
= 20
log (V
TX
/V
TR
).
where: V
TX
, V
TR
, and E
G
are defined in Figure 9. (Note: The
fuse resistors, R
F
, impact the insertion loss. The specified
insertion loss is for R
F
= 0).
20. Four-Wire to Two-Wire Insertion Loss.
The 4-wire to 2-wire
insertion loss is measured based upon E
RX
= 0dBm, 1.0kHz
input signal, E
G
= 0, I
DCMET
= 23mA and is computed using
the following equation:
L
4-2
= 20
log (V
TR
/E
RX
).
where: V
TR
and E
RX
are defined in Figure 9.
21. Two-Wire to Four-Wire Gain Tracking.
The 2-wire to 4-wire
gain tracking is referenced to measurements taken for
E
G
= -10dBm, 1.0kHz signal, E
RX
= 0, I
DCMET
= 23mA and is
computed using the following equation.
G
2-4
= 20
log (V
TX
/V
TR
) vary amplitude -40dBm to +3dBm, or
-55dBm to -40dBm and compare to -10dBm reading.
V
TX
and V
TR
are defined in Figure 9.
22. Four-Wire to Two-Wire Gain Tracking.
The 4-wire to 2-wire
gain tracking is referenced to measurements taken for
E
RX
= -10dBm, 1.0kHz signal, E
G
= 0, I
DCMET
= 23mA and is
computed using the following equation:
G
4-2
= 20
log (V
TR
/E
RX
) vary amplitude -40dBm to +3dBm,
or -55dBm to -40dBm and compare to -10dBm reading.
V
TR
and E
RX
are defined in Figure 9. The level is specified at the
4-wire receive port and referenced to a 600
impedance level.
23. Two-WireIdleChannelNoise.
The 2-wire idle channel noise at
V
TR
is specified with the 2-wire port terminated in 600
(R
L
)
and
with
the
4-wire
receive
Figure 10).
port
grounded
(Reference
24. Four-WireIdleChannelNoise.
The 4-wire idle channel noise at
V
TX
is specified with the 2-wire port terminated in 600
(R
L
).
The noise specification is with respect to a 600
impedance
level at V
TX
. The 4-wire receive port is grounded (Reference
Figure 10).
25. Harmonic Distortion (2-Wire to 4-Wire).
The harmonic distor-
tion is measured with the following conditions. E
G
= 0dBm at
1kHz, I
DCMET
= 23mA. Measurement taken at V
TX
. (Reference
Figure 7).
26. Harmonic Distortion (4-Wire to 2-Wire).
The harmonic distor-
tion is measured with the following conditions. E
RX
= 0dBm0.
Vary frequency between 300Hz and 3.4kHz, I
DCMET
= 23mA.
Measurement taken at V
TR
. (Reference Figure 9).
27. ConstantLoopCurrent.
The constant loop current is calculated
using the following equation:
I
L
= 2500 / (R
DC1
+ R
DC2
).
28. StandbyStateLoopCurrent.
The standby state loop current is
calculated using the following equation:
I
L
= [|V
BAT
| - 3] / [R
L
+1800], T
A
= 25
o
C.
29. GroundKeyDetector.
(TRIGGER) Increase the input current to
8mA and verify that DET goes low.
(RESET) Decrease the input current from 17mA to 3mA and
verify that DET goes high.
(Hysteresis) Compare difference between trigger and reset.
30. PowerSupplyRejectionRatio.
Inject
(50Hz to 4kHz) on V
BAT
, V
CC
and V
EE
supplies. PSRR is
computed using the following equation:
a
100mV
RMS
signal
PSRR = 20
log (V
TX
/V
IN
). V
TX
and V
IN
are defined in
Figure 12.
HC5526