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1.2.2
Audio and Data Transmission Characteristics
The F270X series operates by accepting the audio signal at the RJ11 connector from the exchange and
digitizing it, using an A/D converter. This signal is then multiplexed with data (RS-485 or RS-422) signals
coming from the RJ45. The combined signal is applied to a light pulse and transmitted over fiber optic or 4-wire
twisted pair cable to the remote F271X series unit.
The remote F271X series unit converts the light pulse (in cases of fiber optic connection) back into an
electrical signal, demultiplexes the combined data / audio signal and applies the digitized signal to an A/D
converter to recover the audio signal. The separated data and audio signals are then sent to their respective
destinations. The outgoing signal path (subscriber-to-exchange) is similar. The audio signal is digitized and
multiplexed together along with the data (RS-485 or RS-422) signals and transmitted to the F270X series unit.
Finally, the F270X Modem recovers the audio and data signals.
The Model F270X / F271X transmits analog signals of 300 to 3400Hz and full duplex asynchronous or
isochronous data (RS-485 or RS-422) signals up to 64Kbps and is fully transparent.
1.2.3
Physical Characteristics
Model F270X / F271X FOM II Series Tele-Data Modems measure 7.0 x 0.85 x 11.8in, HWD, (17.78
x 2.2 x 29.98cm) and are designed to be mounted in a variety of VERSITRON enclosures and chassis (see
Table 1 for dimensions of enclosures and chassis). "Desktop" options include both single- and dual-card
enclosures. Rack mount options include a 2-card and 20-card 19” standard rack mountable chassis. For
either desktop enclosure or 2-card rack mount chassis, each F270X / F271X unit requires a wall transformer,
VERSITRON Model PSAC08 (US) or PSAC09 (European), providing 12 VDC, 1A. The one-pin power
connector for electrical input is on the back of the card. There are two RJ11 jacks for the telephone and
copper interface (used in applications where there is no fiber optic cable), a RJ45 jack for EIA RS-485 or RS-
422 data connection and two ST connectors for the fiber optic interface, also on the back of the card as shown
in Figure 1.3. For HF-20 chassis installations, power is provided by VERSITRON Model AC150W Power
Supply / System Monitor. One AC150W utilizes two slots in the HF-20. Two AC150W units are
recommended for power redundancy. Both F270X and F271X models have six indicator LEDs: power
(PWR), off-hook (HOOK), ring signal (RING), loop detection (LOOP), reverse battery signal (RBAT), and
alarm (ALM). No audible alarm is available.
Model #
(Part #)
Dimensions (WHD)
Description
Power Supply Required
*¹
HF-1
(19052)
7.1 x 1.3 x 11.6in
(3.3 x 18.0 x 29.5cm)
Single Card Standalone Enclosure
PSAC08 PSAC09
(LTWPD1210PLX) (LTWPD1210EPL)
HF-2*²
(19053)
7.1 x 2.3 x 11.6in
(5.9 x 18.0 x 29.5cm)
Dual Card Standalone Enclosure
PSAC08 PSAC09
(LTWPD1210PLX) (LTWPD1210EPL)
HF-2SS*²
(19629)
19.0 x 1.7 x 13.8in
(4.3 x 48.0 x 35.0cm)
2-Slot Rack Mount Chassis
PSAC08 PSAC09
(LTWPD1210PLX) (LTWPD1210EPL)
HF-20
(19032)
19.0 x 7.0 x 11.6in
(17.8 x 48.0 x 29.5cm)
20-Slot Rack Mount Chassis
AC150W
(19320-03)
*¹ Note:
US Model - PSAC08; European Model - PSAC09
*² Note:
One Power Supply per Modem required.
TABLE 1: DIMENSIONS OF ENCLOSURES AND CHASSIS
