FREEDOM OF COMMUNICATION
USER MANUAL
G.shdsl+ modem with G.703 interface
TAHOE 671
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TABLE OF CONTENTS
1. Introduction ......................................................................... 1
2. Interfaces ............................................................................ 2
3. Modem configuration using built-in keyboard and LCD .4
4. Configuration using serial console ................................... 10
5. Technical data .................................................................... 12
6. Declaration of Conformity ................................................. 13
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®
Tahoe 671 (G.shdsl+ / G.703 modem)
User Manual
http://www.tahoe-group.com/
Firmware version 1.2.6
®
©2004 Tahoe . All rights reserved.
Other trademarks of other companies are used only for explanation and to
the owner's benefit, without intent to infringe.
®
Tahoe assumes no responsibility for any errors or omissions that may appear in
®
this document. Tahoe makes no commitment to update the information
contained here, and may make changes at any time without notice.
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1
1. Introduction
Thank you for purchasing the Tahoe 671 modem. We did our best
to ensure highest reliability and performance of our products. Devoting
many years of research and development we are proud to provide a
superior quality device unfolding new possibilities for the use of the
copper lines.
®
Tahoe 671 is a G.shdsl+ modems allowing data transmission
with speeds up to 2048 kbps over a 2-wire line. Thanks to powerful
TCPAM-32 modulation throughputs and ranges are much higher than
using HDSL technique. TCPAM-16 modulation is also available to provide
compatibility with other manufacturers’ products.
The modem is equipped with a G.703 interface that may work in
both framed or unframed mode. In the first case only selected timeslots
may be transmitted over long lines where the throughput of 2048 kbps
cannot be achieved.
The modem may be managed using a built-in LCD and keyboard,
using a serial console or remotely through the DSL line.
The system firmware is stored in the Flash memory - it is possible
to update it through the serial console. The configuration is stored in the
EEPROM memory.
2
2. Interfaces
Following connectors are found on the rear panel of the modem:
2.1. G.shdsl
It is a 6-pin RJ-11 connector used to connect the leased line. The
line should be connected to the two central pins (3 and 4). The
polarization of a line is not important.
2.2. Serial console
The RS-232 serial console is used for modem management. It has
a DB9/M connector and works as a DTE, i.e. a null-modem cable should
be used to connect it to a PC. Only three lines (written in bold) are
necessary for transmission. Terminal settings are 9600 bps, 8 data bits, 1
stop bit, no parity, no handshaking.
Pin Name
1
DCD
2
3
4
5
6
RXD
TXD
DTR
GND
DSR
Description
carrier detect, transmission readiness signaling
data received from the PC
data sent by the modem to the PC
active, when the PC is switched on
signal ground
active, when the modem is switched on
7 RTS
used by the PC to inform that is has data to send
8 CTS
used by the modem to permit data transmission
9 RI
ring indicator (signal used in telephone modems)
G.shdsl
serial
console
G.703
power
switch
power
connector
O
I
Pin Function
1
2
3
4
5
6
line
line
-
-
-
2
2.1
2.2
3
2.3. G.703
The G.703 port has a RJ-45 connector. The G.703 standard
doesn’t specify the connector pinout, but the pinout used in Tahoe
devices is the most common in the industry, thus in most cases a regular
straight patch-cord may be used to connect the card to the external
device.
Anyway the pinout should be carefully checked before connecting
the DCE device. The RX+ pin of the card should be connected to the TX+
pin of the other device, the RX- pin to the TX- pin, TX+ to RX+ and TX- to
RX-.
2.3
Pin Signal
1
Tx+
2
3
4
5
6
Tx-
-
Rx+
Rx-
-
7
8
-
-
4
3. Modem configuration using built-in
keyboard and LCD
The easiest way to configure a modem is to use the four-button
keyboard and the LCD. After switching the power on, an information
about the modem type, the line throughput and state will be displayed:
Four-letter code in the bottom right describes the DSL line state:
¡ BOOT - booting of the G.shdsl transceiver
¡ IDLE - transceiver inactive
¡ DOWN - transceiver active, line not synchronized
¡ SYNC - line synchronized, data may be transmitted
The G.703 link status is described using two letters in the upper
right corner of the LCD. In case of unframed mode letters “UC” may
appear. Letter “U” signals the unframed mode and “C” means that the
carrier signal was detected.
In the case of unframed mode letters “SC” may appear there.
Letter “S” means that the modem is synchronized to the E1 stream.
Letter “C” again signals, that the carrier was detected. If only “C” is
displayed, then the G.703 signal is present, but the converter is unable to
synchronize to it. Perhaps the signal detected is an unframed signal.
On the right of the display there is a keyboard with “up”, “down”,
“Escape” and “Enter” keys. By pressing up/down buttons you may
browse the configuration menu:
¡ speed setting
¡ modem type setting (Master/Slave)
¡ line modulation selection
¡ CRC4 setting
¡ G.703 port line coding, sensitivity and range
¡ test loopbacks
¡ console throughput
¡ language selection
¡ storing settings in the EEPROM memory
¡ connection reset
¡ modem reset
Each pressing of the “Escape” button causes the return to the
Tahoe 671 UC
2048 kb/s BOOT
3
5
primary display with modem type and state. Pressing of the “Enter”
button selects given menu option.
3.1. Throughput setting
After pressing Enter the throughput may be set using up/down
buttons. It may be chosen from 128-2048 kbps range. In the framed
mode the first number depicts the DSL line speed, while the second one
- a sum of G.703 timeslots used for transmission. It is 64 kbps lower
than the first one, because the DS0 synchoronization timeslot is also
being transmitted over the DSL line, while it is not used for the data
transmission over the G.703 link.
When the throughput is set to 2048 kbps (1984) and “up” button
is pressed the letters “unfr” will appear in the brackets. It means that
the unframed mode is enabled and whole 2048 kbps are used for data
transmission.
In the framed mode the selection of G.703 timeslots used for
data transmission is done automatically depending on the throughput
set. Timeslots 0 (synchronization) and 16 (signaling) are selected first,
then the subsequent timeslots from 1 to 15 and from 17 to 31:
NOTE: The same throughput must be set on both modems.
Line rate:
2048 kb/s (1984)
Throughput Timeslots used
128 kbps 0, 16
192 kbps
256 kbps
...
1024 kbps
0, 1, 16
0, 1, 2, 16
...
0, 1, 2, 3,..., 13, 14, 16
1152 kbps
0, 1, 2, 3,..., 13, 14, 15, 16
0, 1, 2, 3,..., 13, 14, 15, 16, 17
... ...
1984 kbps 0, 1, 2, 3,..., 28, 29, 30
2048 kbps 0, 1, 2, 3,..., 28, 29, 30, 31
1088 kbps
Line rate:
2048 kb/s (unfr)
3.1
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3.2. Modem type
After pressing Enter the modem type may be selected - either
Master (HTU-C) or Slave (HTU-R). After selecting the type and pressing
Enter again the connection will be reset and renegotiated with new
settings.
NOTE: Always one modem has to be set as a Master and the
other one as a Slave.
3.3. Line coding
After pressing Enter the G.shdsl line coding (signal modulation)
may be chosen. The number (32 in the example above) means the
number of values encoded in one symbol (32 - 5 bits per symbol). The
higher this number is, the lower is the signal frequency, which gives
better immunity for signal attenuation and higher reach.
The second part - PAM or TCPAM - means either the Pulse
Amplitude Modulation or Trellis Coded Pulse Amplitude Modulation.
The latter is more efficient.
It is recommended to use the 32-TCPAM modulation, which
provides the best results. The remaining line codings are available to
provide compatibility with others’ manufacturers equipment. The 32TCPAM allows throughputs from 256 kbps to 2048 kbps, while 16TCPAM - from 128 kbps to 2048 kbps.
The “Auto” setting forces use of 32-TCPAM for speeds higher
than or equal to 256 kbps per line and 16-TCPAM for lower rates.
3.4. CRC4 checksum
After pressing “Enter” the CRC4 transmission and checking may
Line coding:
32-TCPAM
3.2
3.3
Modem type:
Master / HTU-C
3.4
CRC4:
on
be either enabled or disabled.
3.5. G.703 coding
The G.703 port may use one of two available codings - HDB3 and
AMI. The first one is used in most cases, the second one is provided for
compatibility only.
3.6. G.703 receiver sensitivity and range
The G.703 port’s receiver sensitivity (thus port range) may be
changed - either -12dB (50m) or -43 dB (2000m)
3.7. Test loopbacks
The test loopback are useful to diagnose the network problems.
Two kinds of loopback are available:
¡ towards DSL - packets received from the G.shdsl line are sent back
to it
¡ towards PCM - packets received from the G.703 port are sent back
to it
3.8. Console throughput
Different console port throughputs may be chosen - 9600,
19200 or 38400 bps. Be sure to set the same throughput on the modem
and the PC.
7
3.5
3.7
G.703 line code:
HDB3
G.703 port range
2000m
Loopback:
disabled
Console port:
9600 bps
3.6
3.8
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3.9. Language selection
After pressing “Enter” the language used on the LCD and the
serial console may be changed.
3.10. Write configuration to EEPROM
Every change to the configuration will be lost after reboot or
power off unless the settings are written to the EEPROM. After reaching
this option just press Enter to save them.
3.11. Connection reset
After pressing Enter the G.shdsl link will be disconnected and
negotiated again.
3.12. Modem reset
After pressing Enter the whole modem is rebooted. If some
settings were not saved to the EEPROM, they will be lost.
3.13. Line parameters
The “Esc” button returns to the main screen (with modem type,
throughput and link state). While having this screen displayed, you
may press Enter to display line attenuation in dB (proper value appears
only after the line synchronizes):
3.10
3.9
Connection reset
(press Enter)
Modem reset
(press Enter)
Line attenuation:
12.5 dB
3.11
Language:
English
3.12
Write config
to EEPROM
3.13
9
Pressing Enter again will show so-called Noise Margin (or SignalNoise Ratio). This is the difference between the useful signal and the
background noise. It may be used to estimate, how much the line rate
may be increased without causing any problems with the
synchronization.
When the NMR is less than 0 dB modems will be unable to bring
the link up.
It is the best practice to keep the NMR equal to or higher than 78 dB, so the error rate will be unnoticeable. Otherwise the packets will
be lost due to bit errors and the retransmission would be necessary,
thus decreasing the overall effective throughput.
Pressing Enter again will return to the main screen with the
throughput and modem state.
Noise margin:
6.0 dB
10
4. Modem configuration using the serial
console
After connecting the converter to a PC, running a VT-100 terminal
emulation software and switching the modem on a menu will appear:
Up and down arrows may be used to navigate through the menu.
Either Enter or right arrow should be pressed to select an option. To
confirm a changed parameter press Enter. To cancel a parameter change
press left arrow.
All options are identical to the LCD options described in point 3.
However two options were added - “Manage remote modem” and
“Refresh screen”.
4
firmware version
and compilation date
time elapsed since
power-on or reboot
log containing most important
information about modem status
main menu G.703 port state DSL parameters DSL state
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4.1. Manage remote modem
It is possible to manage the remote modem through the DSL line.
First the modems must reach the synchronized state. Then after
selecting this option modems will establish a connection in so-called
Embedded Operations Channel (EOC, separate from the main data
channel).
A blinking message will appear on the top of the screen informing
that the connection was made. Now all the options on the screen concern
the remote modem. They may be changed and stored to the EEPROM.
The “Manage remote modem” option will change to “Return to
local modem”. Selecting it will cease the remote management.
4.2. Refresh screen
When a working converter is connected to the PC’s serial port the
screen contents may be incomplete - selecting this option or pressing
Ctrl+L will refresh the screen.
4.1
4.2
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5. Technical data
¡ processor:
Motorola MC68302
¡ G.shdsl interface:
connector: RJ-11
standards: ITU G.991.2 (G.shdsl)
ITU G.994.1 (G.hs)
modulations: TCPAM-32, TCPAM-16, TCPAM-8, TCPAM-4,
PAM-16, PAM-8, PAM-4, PAM-2
¡ throughput:
128 - 2048 kbps
¡ G.703 interface:
framed according to G.704 or unframed
balanced, 120W, RJ-45 connector
throughput: 64-1984 kbps or 2048 kbps
line coding: AMI, HDB3
signaling: FAS, CCS, CRC4
receiver sensitivity: -12 dB / -43 dB
range: 50m / 2000 m
¡ serial console:
RS-232, DB9/M connector
¡ dimensions:
200 mm (width) x 45 mm (height) x 130 mm (length)
¡ power supply:
15 V, 230 mA, 3,5W
external power supply included
¡ environmental conditions:
storage: temperature -20°C to 65°C
humidity 5 to 95%
operation: temperature 0°C to 40°C
humidity 0 to 85%
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6. Declaration of Conformity
We declare that the product Tahoe 671 complies with the
regulations of the following European Directives:
¡ 73/23/EEC low voltage safety requirements
¡ 89/336/EEC EMC requirements
¡ 99/5/EEC radio & telecommunication terminal
equipment requirements
The compliance of Tahoe 671 with the requirements of the above
mentioned directives is ensured by complete application of the following
harmonized European Standards:
¡ EN 60950:2000
¡ EN 55022:1998
¡ EN 61000-6-1:2002
¡ EN 61000-6-3:2002
Signed: Piotr Kaczmarzyk
Position: Director
Signature:
Date: 2 Feb 2004
Place: Wroclaw, Poland
TAHOE
Piotr Kaczmarzyk
ul. Uniwersytecka 1
50-951 Wroclaw, Poland
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®
TAHOE
Uniwersytecka 1
50951 Wroc³aw, Poland
phone +48 50 100 7362
fax +48 71 344 2642
http://www.tahoe-group.com/
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