Micro Seven, Inc.

LS100-2J, 2-line telephone line simulator with true line impairment option


Front and rear panels of LS100-2J are shown above.    


The Micro Seven’s model LS100-2J simulates long distance telephone circuit, which includes frequency attenuation characteristics, random noise, and envelope delay distortion. It also contains 30 Hz ring signal, dual-frequency call progress tones, and long-digit bi-directional telephone number.

The Line Impairment condition is programmable by dialing a 3-digit telephone number among four different telephone line condition.

By a dialing a different telephone number, a different telephone line condition is simulated. The line impairment condition includes frequency attenuation characteristics, random noise (white noise), and envelope delay distortion. Note that the envelope delay distortion is very critical for high-speed modem communication. The random noise amplitude is adjustable by turning a potentiometer through a front panel hole.

LS100-2J has just been redesigned to include serial interface option for programming line impairment conditions and random noise amplitude while transmitting data. LS100-2J also includes most of features in model LS100-2A to include dual frequency call progress tone/single frequency call progress tone, programmable telephone number, stutter dial tone, distinctive ringing features, etc. The potentiometer adjustment for random noise amplitude has been eliminated on the rear panel.



-True Line Impairment Circuit to test high-speed modems

-simulates the worst-case telephone line conditions

-programmable line impairment condition

-envelope delay distortion, frequency attenuation characteristics, and random noise

-testing analog modems including high-speed modems


-quick testing of modems under the worst-case condition

-testing and demonstration of fax machines and modems under different line impairment conditions

-Windows-compatible software for programming



Note 1: all programmed parameters including telephone numbers are stored in non-volatile memory.

Note 2: LS100-2J is exactly same as LS100-2A with Line Impairment Options 1 and 2, and serial interface option

DialingTelephone Numbers: 1. Single-digit primary telephone number
2. Secondary programmable telephone number

3. A bi-directional telephone number is installed

Frequency Attenuation Characteristics relative to 1 kHz:
+12 dB +/- 1.5 dB @ 300 Hz
+ 8 dB +/- 2.0 dB @ 500 Hz
+ 8 dB +/- 1.5 dB @ 2500 Hz
+12 dB +/- 1.5 dB @ 3000 Hz
Above Band (>3000 Hz): 80 dB/octave roll-off to 50 dB holding to 10 kHz
Below Band (<300 Hz): 24 dB/octave roll-off

Full Envelope Delay Characteristics: 800-2600 Hz: 1750 micro seconds nominal
300-3000 Hz: 3000 micro seconds nominal at both band edges

Partial Envelope Delay Characteristics: 800-2600 Hz: 1250 micro seconds nominal,
300 to 3000 Hz: 2000 micro seconds nominal at both band edges

Random Noise (white noise): adjustable by control software between -60dBm and -20dBm.

Programming Line Impairment Option

One of the following five circuit conditions may be selected by dialing a unique telephone number or using control software:

1. Full Line-Impairment Condition, power-up default condition
It includes frequency attenuation characteristics, full envelope delay, and random noise.

2. Partial Line Impairment Condition
It includes frequency attenuation characteristics, partial envelope delay, and random noise.

3. Line Impairment Condition without Envelope Delay Distortion

4. 20dB insertion losses between lines

5. No line impairment condition.

Distinctive ringing features: four types 

DTMF dialing: -13 dBm to +5 dBm per a frequency, and no more than 4 dBm difference between frequencies.
DTMF dialing detection time: 45 ms

Pulse dialing:

Break period: 45 to 75 ms (60 ms nominal)
Make period: 30 to 60 ms (40 ms nominal)

Line characteristics:

Input impedance at 1 kHz: 600 ohms +/- 5%

Signal Range: -45 to +5 dBm
Bandwidth noise: 2mV P-P max. (-60 dBm) (full bandwidth mode)
Signal Bandwidth: 150 HZ to 5 kHz (full bandwidth mode)

Off-hook impedance requirement:

400 ohms maximum DC, 600 ohms nominal AC

Disconnect Signal (programmable):

There is interruption of loop current for 0.5 sec when the other line terminates a call. For example: assuming that the line 1 and 2 are connected. The loop current of line 1 is interrupted for 0.5 sec when the line 2 hangs up.

Network delay (programmable)

Selection of dual Frequency Call Progress tone:

Dial Tone: 350 Hz + 440 HZ continuous.
Ring-back Tone: 440 Hz+480 Hz, 2 sec ON/4 sec OFF.
Busy Tone: 480 Hz + 620 Hz, 0.5 sec ON/0.5 sec OFF.
Signal Power: - 20 dBm nominal.

Single frequency call progress tone:

480Hz, -20 dBm nominal.

Ring Signal:

90 VRMS 30 Hz square wave
Frequency: 16 to 68 HZ
Interval: nominally 2 sec ON/4 sec OFF
Distinctive Ring Features: User programmable for four different ringing patterns.
It is set as 2 sec on/4 sec off as a power-up default condition.

Serial interface option: RS232C interface including 9-pin D-sub M/F cable and control software for programming

Transmit Power Adjustment Potentiometers: It attenuates the signal output from the line between 0 to -40 dB range.

Line Input Jacks: USOC-RJ11-C, standard modular phone jacks

Power Requirement: 100-130 VAC, 50/60 HZ

Note: 230V power unit is also available.

Fuse: 0.15A, 3AG, SLOBLO

Dimensions: 8.35" W x 2.5" H x 7.25" L

Weight: 3.5 lbs.

Environmental: Operating temperature: 0 to 45 degree C Humidity: 85% RH at 45 degree C

Warranty/Service: 6 months limited warranty. Service is performed at the factory, usually within 10 working days.

Options: 1. USB/RS232 adapter
2. 230V AC power option

The new Windows version of programming software, W2J.EXE, is available as a standard accessory. The screen display as shown below when the factory default file “DEFAULT2J” is downloaded from PC. Programming of line impairment parameters, telephone numbers, saving/loading of programmed parameters, enabling/disabling of PBX mode, stutter (dial) tones, dual frequency call progress tone/single frequency call progress tone, disconnect signal period length, and network delay.


Micro Seven, Inc.

1095-K N.E. 25th Hillsboro, OR 97124 U.S.A.
fax: 503-693-9742