Versitron F270XA User manual

F271XA
Fiber-Optic
Telephone Modem
Technical Manual
Revision B
© August 2011
VERSITRON, Inc.
83 Albe Drive / Suite C
Newark, DE 19702
www.versitron.com
Safeguarding Communications Since 1958

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PROPRIETARY DATA
All data in this manual is proprietary and may not be disclosed,
used or duplicated, for procurement or manufacturing purposes,
without prior written permission by VERSITRON.
VERSITRON LIFETIME WARRANTY
All VERSITRON products are covered by a Lifetime Warranty against defects in materials and workmanship. This coverage
is applicable to the original purchaser and is not transferable.
We repair, or at our option, replace parts/products that, during normal usage and operation, are proven to be defective during
the time you own the products, provided that said products and parts are still manufactured and/or available. Such
repair/replacement is subsequent to receipt of your product at our facility and our diagnostic evaluation and review of the unit.
Advance replacements are not provided as part of the warranty coverage.
This warranty does not cover damage to products caused by misuse, mishandling, power surges, accident, improper installation,
neglect, alteration, improper maintenance, or other causes which are not normal and customary applications of the products
and for which they were not intended. No other warranty is expressed or implied, and VERSITRON is not liable for direct,
indirect, incidental or consequential damages or losses.
In the unlikely event a warranty issue should arise, simply contact us at 302-894-0699 or 1-800-537-2296 or via e-mail to
[email protected]m and obtain a Return Material Authorization (RMA) number. Reference this number on the outside of
the shipping container and return the unit (shipping charges prepaid) to us for diagnostic review and repair/replacement as
determined solely by VERSITRON. We pay the shipping charges to return the repaired unit or a replacement unit to you.
CAUTION!!!! WARNING!!!!
DO NOT CONNECT THE F271XASUBSCRIBER UNIT TO THE PBX SIDE OF
THE CIRCUITAS THIS MAY RESULT IN DAMAGE TO THE F271XA.
SUCH DAMAGE IS NOT COVERED BY THE WARRANTY.

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1 DESCRIPTION OF EQUIPMENT
1.1 INTRODUCTION
This manual provides general and detailed information on the installation and operation of
the Model F271XA Fiber-Optic Telephone Modem. Section 1 provides a general description of
the equipment. Section 2 provides installation instructions. Section 3 provides operating
instructions. Section 4 provides the theory of operation. Section 5 provides maintenance and
troubleshooting information. Figure 1 and Figure 2 provide an overall view of the Telephone
Modems.
Figure 1: Front View, F271XA (Top Unit)
Figure 2: Rear View, F271XA

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1.2 DESCRIPTION OF EQUIPMENT
1.2.1 Functional Characteristics
The Model F271XA Telephone Modem is an extender for subscriber (telephone handset)
connected telephone lines. These units are designed to be used with Model F270XA, which supply
an exchange (PBX or direct dial service from a telephone company) interface. When configured
in this way, the modems provide a fiber optic link for regular, 2-wire analog telephones. The main
characteristics of the Model F271XAare:
Transparent extension of telephone lines.
SFP Based optics.
Supports data up to 14.4kbps via dial-up modem or facsimile.
Model F270XA and F271XA modem pairs use SFP optic modules to achieve transmit
distances of up to 20km over a single pair of fiber-optic cable. Alternatively, these telephone
modems can be used in a VMX20 Versimux II chassis, which can multiplex up to 19 telephone
modems on a single pair of fiber-optic cables.
1.2.2 Audio Transmission Characteristics
The F271XA accepts a telephone audio signal on the RJ11 connector from the subscriber,
digitizes it with an analog-to-digital converter. The digital samples are then encoded and applied
to the SFP for transmission over the fiber-optic cable.
The remote F270XA unit decodes the signal from the SFP module, and applies the samples
to a digital-to-analog converter to recover the analog audio. The converse occurs in the other
direction for the F271XA.
The telephone modem transmits analog signals of 300 to 3400Hz.
1.2.3 Physical Characteristics
The telephone modems measure 7.0" wide x 0.84" high x 11.6" deep (17.8 x 2.1 x 28.9 cm)
and are designed to be mounted in a variety of VERSITRON enclosures and chassis (see Table 1
for dimensions of enclosures and chassis). "Desktop" option is a single-card enclosure. Rack-
mount options include a 2-Slot and 20-Slot 19” standard rack-mountable chassis. For either
desktop enclosure or 2-Slot rack-mount chassis, each F271XA unit requires a wall transformer,
VERSITRON Model PSAC08 (US) or PSAC09 (European), providing 12 VDC, 1.0A. The one-
pin power connector for electrical input is on the back of the card. There is a RJ11 jack for the
telephone line on the front of the card. There is an SFP module slot on the back of the card for the
SFP fiber-optic interface. For HF-20A chassis installations, power is provided by VERSITRON
Model AC300WR Power Supply / System Monitor, through the twelve pin connector (P1). For
Versimux II installations power is provided to the VMX20 chassis by VERSITRON Model
AC300WR Power Supply / System Monitor, through the twelve pin connector, and the link
connection is provided by the backplane connector (J5). In Versimux II installations the SFP
module will be deactivated, and link communications will occur over the backplane connector J5.
Therefore, the SFPneed not be populated in Versimux IIinstallations. Both F270XAand F271XA
models have eight indicator LEDs as described in Table 2.

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Table 1: Dimensions of Enclosures and Chassis
Model #
(Part #)
Dimensions
Description
Power Supply Required*¹
HF-1
(19052)
1.3" H x 7.1" W x 11.6" D
(3.3 x 18.0 x 29.5 cm)
Single-Card Desktop Enclosure
PSAC08 PSAC09
(LTWPD1210PLX) (LTWPD1210EPL)
HF-2SS
(19629)
1.7" H x 19.0" W x 13.8" D
(4.3 x 48.0 x 35.0 cm)
2-Slot Rack-Mount Chassis*²
(Side-by-Side)
PSAC08 PSAC09
(LTWPD1210PLX) (LTWPD1210EPL)
HF-20A
(32406)
7.0" H x 19.0" W x 11.6" D
(17.8 x 48.0 x 29.5 cm)
20-Slot Rack-Mount Chassis
AC300WR
(32410)
VMX20
(32458)
7.0" H x 19.0" W x 11.6" D
(17.8 x 48.0 x 29.5 cm)
20-Slot Rack-Mount Chassis
(19-Multiplexed Slots)
AC300WR
(32410)
*¹ Note: US Model –PSAC08; European Model –PSAC09
*² Note: One Power Supply per Modem required.
Table 2: Front Panel Status LEDs
Link
Not Used
TX
Not Used
RX
Not Used
System
Port 1

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1.3 Telephone Modem Specification:
1.3.1 General Specifications:
Models
F270XA /F271XA
Dimensions
(7H x 7/8W x 11L) (17.8 x 2.1 x 27.9 cm)
Weight
0.28 kg (10.0 oz)
Operating Temperature
0to 50C (32to 100F)
Humidity
Up to 95% relative humidity (non-condensing)
Altitude
Up to 10,000 ft
1.3.2 Electrical Interface:
Models
F270XA /F271XA
Power Requirements
12VDC, 1.0Amp
Phone Connectors (Tip & Ring)
RJ11, 2-Wire Twisted Pair
Audio Signal
Analog, 300Hz to 3.4Khz
Idle Channel Noise
- 65dBm
Single Frequency Distortion
- 46dB
2nd Harmonic Distortion
- 55dB
Talk Battery
44 to 52 VDC
Loop Current
40mA max (off hook)
Ring Signal
92Vpeak(max), 15 to 67Hz
Line Impedance
600Ω
1.3.3 Fiber-Optic Interface:
See SFP module datasheet.
1.3.4 Major Features:
Intercom or Ring Down Application with two Subscribers, F271XA
Will accept a variety of SFP modules for Fiber-optic interface
VERSITRON Versimux II compatibility.
Supports data up to 14.4kbps via dial-up modem or facsimile.
NOTE: F270XAand F271XA are not backward compatible with F270X and F271X

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2 INSTALLATION
2.1 GENERAL
This section contains detailed information on the installation and initial checkout of the
F271XA Telephone Modem. Section 2.2 contains general information on site selection and
mounting. Section 2.3 contains the description for selecting different options on the modem.
Sections 2.4 and 2.5 contain detailed instructions for connecting Model F271XA products to
your system. Section 2.6 contains initial checkout procedures.
2.2 SITE SELECTION AND MOUNTING
The Model F271XA products are designed to be used as an interface extender for analog
subscriber (phone handset) lines. When connecting the F271XAto a system, thecopper and fiber-
optic cable should be securely installed so as to prevent accidental disconnection. Care should be
taken to ensure that the copper and fiber-optic cables are not mechanically separated from the
modem during operation. When installed in either desktop chassis or in the dual-card rack-mount
chassis, space for the power transformer must also be provided.
2.3 SWITCH AND JUMPER SETTINGS
There is one set of switches and two jumpers provided for configuration of selectable
options. Switch and jumper locations are shown in Figure 3. Switch and jumper settings are as
follows:
2.3.1 Modem Configuration Settings
The F271XA has one user selectable configuration setting. For ring-down operations (i.e.
subscriber to subscriber) SW1-1 is set to the 'ON' position. In the 'OFF' position the subscriber
card will be set for normal operation.
Table 3: SW1 Switch Settings
Position
On
Off
SW1-1
Ring-down Operation
Normal Operation
SW1-2
Factory setting*
SW1-3
Factory setting*
SW1-4
Factory setting*
SW1-5
Factory setting*
SW1-6
Factory setting*
SW1-7
Factory setting*
SW1-8
Factory setting*
* Note: Factory settings as indicated. Do Not Change.

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2.3.2 SFP Module Settings
There are no user configurable SFP settings
Table 4: SFP Rate Jumper Settings (J2)
Jumper
Jumped
Functional Description
J2
Off*
Do Not Change
*Note: Factory Setting: Do Not Change
2.3.3 Default Jumper
The remaining jumper (J1) is open and should not be changed.
2.4 Power Requirements
The F271XA products are designed to operate from an AC power transformer or a DC
power source in the range of +10 to +16 VDC.
2.4.1 Installation with AC Power
Before inserting the VERSITRON power transformer, PSAC08 (US) or PSAC09 (EUR),
Figure 3: Switch and Jumper Locations
Illustration 3: Switch and Jumper Locations

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Figure 4: DC Power Supply Connection
into an AC power source, the plug should be connected to the Telephone Modem. There are no
special tools required.
2.4.2 Installation with DC Power
DC power may be used instead of a power transformer. This requires a 2.5 mm socket, J3
(location shown in Figure 3) with the positive voltage on the center and the common on the
concentric supplying 12VDC at 1.0Aas shown below (Figure 4):
2.5 INTERFACE WIRING
Table 5 and Table 6 list the interface wiring for F271XA telephone modems. The
RJ11 is used with a single line 2-wire telephone as shown in Table 5. The barrel connector (J3) is
wired in parallel with the 12-pin connector (P1) for power. When installing the telephone modem
in a standalone or dual-card rack-mount chassis, a power transformer is plugged into barrel jack
(J3). When installing the Telephone Modem in a 20-Slot rack-mount chassis (HF-20Aor VMX20)
with optional power supplies (AC300WR) the 12-pin connector (P1) is used. Wiring for the 12-
pin connector is shown in Table 6. Hard Metric Type-C connector (J5) is used for backplane
communications, when the Telephone Modem is placed in a VMX20 chassis. Figure 3 identifies
the locations for the 12-pin power connector (P1), modular power jack (J3), and HM Type-C (J5)
connector.
Table 5: Telephone/Analog Wiring
Pin Number
Signal Designation
Color
1
Not Used

2
Not Used

3
Ring
Green
4
Tip
Red
5
Not Used

6
Not Used

Table 6: (P1) Chassis Power/Alarm Wiring
Pin Number
Signal Designation
1
+12 VDC
2
+12VDC
3
Signal Ground
4
Signal Ground
5
Signal Ground
6
Frame Ground (Chassis)
7
System Alarm Interface
8
Signal Ground
9
Signal Ground
10
+12 VDC
11
+12 VDC
12
+12 VDC

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2.5.1 Fiber-Optic Cable Installation
After the electrical and digital interface cables have been wired according to sections 2.4
and 2.5 , insert the SFP module into the SFP cage (Z1) and attach the fiber-optic cable to it (see
Figure 3 for location of Z1). The SFP module slides into the RFI Cage label side up. There will
be a slight click when it locks into place. After the SFP module is installed the fiber-optic cable
can be installed. The cable must be an LC type connection. The cable should be oriented with the
thumb tab at the top. When completely inserted the tabs will click into place.
2.6 Initial Checkout Procedure
F271XA telephone modems contain no power on/off switch. Once power is connected, the
Modem will go through its power-up sequence. When the System LED (see Table 2) is lit the
Modem is ready for use. Before beginning system operation check the following to verify proper
installation:
1. Verify that the power plug is seated fully into the Modem or the Modem is seated fully in the
rack-mount enclosure (HF-20A or VMX20).
2. Verify that the fiber cable is connected on each end.
3. Verify that the Link LED (see Table 2) is lit when the fiber-optic cable is connected and the
units, both local and remote, are powered.
If a malfunction is detected during the initial checkout procedure, refer to Section 5 for
information on isolating the malfunction in the unit.

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3 OPERATION
3.1 Introduction
This chapter contains a description of the operating controls and indicators associated with
the telephone modems. Since the F271XAis designed for continuous and uninterrupted operation,
there are no setting requirements after the unit is operational. Once the unit is powered up it should
remain in service as long as required.
3.2 Status Indicators
There are five indicators used on the F271XA: Link Status(Link), Transmit Data(TX),
Receive Data(RX), System Status(System), and a multi-function LED for the telephone port (see
Table 7 for descriptions).
Table 7: Status Indicators
LEDs*
Color
Function
Link
Green
Indicated the remote link is active and synchronized
TX
Green
Indicates transmit data
RX
Green
Indicates receive data
System
Green
Indicates System is active and configured (ready for operation)
1
Red
Indicates the following :
Off: Phone is On-Hook
On: Phone is either Off-Hook or Call is in progress
Flashing: Phone is ringing.
* See Table 2 for LED mapping

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4 THEORY OF OPERATION
4.1 Introduction
The F271XA is a subscriber side telephone modem with an SFP port for fiber-optic
connections. These Modems are designed to work with F270XAexchange side telephone modems
or another F271XA in pairs and interface with audio grade signals. These units are housed in
VERSITRON FOM II chassis: HF-1, HF-2SS and HF-20A or in a VMX20 Versimux II chassis.
Chassis descriptions are found in section 1.2.3 .
4.2 Power Supply and Alarm Circuit
4.2.1 Power Supply Circuit
When 12VDC is applied to the circuit, the unit should draw between 200mA and 1000mA
depending on the modem state. The unit has a series of switching power supply circuits, which
converts 12V to 3.3VDC, 1.8VDC, and 1.2VDC.
4.2.2 Alarm Circuit
This unit does not have an alarm circuit. Therefore, the Alarm signal on the P1 connector
will not be driven by this unit.
4.3 Functional Description
The unit consists of the following circuits:
4.3.1 –Ring Detection
4.3.2 –Ring-Down
4.3.3 –Analog-to-Digital Conversion
4.3.4 –FPGA
4.3.5 –Fiber-Optic Transceiver Circuit
4.3.6 –Backplane Transceiver Circuit
4.3.1 Ring Detection
The F271XA detects, through its FPGA, a ring signal coming through the fiber interface for
the telephone port and then enables the ringing signal.
4.3.2 Ring-Down
In a ring-down configuration the F271XA detects an off-hook condition and asserts the ring
signal for transmission over the fiber to the down-stream F271XA. On the other end the F271XA
handles the ringing signal as described above ( 4.3.1 ).
4.3.3 Analog-to-Digital Conversion
Analog to Digital conversion is handled by the phone CODEC chipset. A 16-bit sample is
gathered at an 8kHz sampling rate. On the return side Digital to Analog conversion is handled in
a similar way.

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4.3.4 FPGA
The FPGAis used to transmit the digitized audio signal from the telephone port. In essence,
it is an asynchronous-to-synchronous converter encoded using proprietary VHDL programming
designed at VERSITRON. A 8.192MHz Oscillator, Y1, provides the clock input to the FPGA.
The FPGA also performs configuration operations for the phone CODEC chipset.
4.3.5 Fiber-Optic Transceiver Circuit
Fiber-optic communications are handled by the SFP module. The power for this module is
isolated from the other power circuits through filters. This helps reduce the supply noise being
coupled into the SFP module. The SFP interfaces directly with the FPGA.
4.3.6 Backplane Transceiver Circuit
Backplane communications are handled by the FPGA. Upon insertion of the unit into a
Versimux II chassis the SFP module will be disabled, and serial communications will occur across
the backplane connection (J5).

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5 MAINTENANCE AND TROUBLESHOOTING
5.1 Introduction
This chapter contains general information designed to isolate a malfunction in the Model
F271XAto a replaceable unit. These units are not equipped with redundancy. Therefore, a failure
in one of these units would interrupt service.
5.2 Fault Isolation
The steps in Table 8 should be taken to check a non-operating modem. Contact
VERSITRON Customer Service for additional diagnostic assistance or to arrange for repair as
necessary.
Table 8: Non-Operational Indicators
STATUS INDICATOR
PROBABLE CAUSE
CORRECTIVE ACTION
System Status (System) LED is
OFF
No AC power
Check that both ends of the transformer are
connected
Over current condition
Power off the unit for a few minutes and retry
Other
Contact VERSITRON for assistance
Link Status (Link) LED is OFF
Incorrect optical signal level received at
receiver input
1. Check that fiber-optic cables are properly
connected
2. Check that the remote unit power is on and the
fiber-optic connectors are properly attached
3. Check that the SFP module on each end is
seated properly
4. Contact VERSITRON for assistance
Ports Indicator LED is ON
Possible problems ranging from a
telephone set in an Off-Hook position to
a problem with the Off-Hook circuit
Check if the telephone set receiver is seated in the
cradle correctly. If this is not the case, contact
VERSITRON for assistance
Modem is not working properly
Default jumpers and switch settings are
not set properly
1. Check if SW1 positions are all off
2. Check that jumper J2 is off
3. Contact VERSITRON for assistance