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VF Input/Output Interfaces for T1 / E1 Products
     

VF Input/Output interfaces are provided for the following platforms:

  • USB based tProbe™ T1 E1 Unit -  supports only 3.5mm balanced (stereo) analog interfaces with varying impedances
  • PCIe Based Express T1 E1 Cards - supports 3.5mm balanced (stereo) analog interfaces with varying impedances. 
  • Universal T1 E1 Cards - supports 3.5mm unbalanced (or mono) analog interfaces. 
  • USB based Portable T1 E1 Units - supports 3.5mm unbalanced (or mono) analog interfaces and also an RJ-22 telephone handset interface. 
 
 
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User's Guide
 
pdf
Product Brochure
 
pdf
Frequency Calibration Procedure User Guide
 
View Presentation
 
pdf
Terminate, Bridge,
Monitor Design-tProbe™

Latest T1 E1 Software Ver 10.3.23 is Now Available | Download Now!

Monitoring VF Interfaces application is included with T1 E1 Basic Software

Caution:  Do NOT connect balanced (stereo) signals to unbalanced (mono) signals, i.e. do not connect VF signals between different GL platforms.  If you must, then use only mono cables.

Additional details for each are provided below. 


VF Interfaces in tProbe™ T1 E1 & Express T1 E1


GL's tProbe T1/E1 and Express T1/E1 Analyzer products are equipped with VF inputs and outputs via 3.5 mm connectors.  Primary functionality of these connectors is to connect to external equipments or accessories.  Input signal is digitized (at 8 Khz, uLaw/A-Law) and inserted into selected timeslot of T1/E1. Higher sampling rates (16KHz for 8/16 bits) are under development. Higher resolution at 8 kHz and 16 bits is also available.

An output audio signal is dropped from the selected timeslot of T1/E1. These interfaces offer many termination modes so that it can be compatible with connected source or sink devices under test. This paper describes details about 3.5mm jack connectivity details and also various impedances offered for termination mode. It is important to select correct impedance settings using Analyzer GUI or scripts so that source and sink present same resistive load and analog signal flow as expected.

VF interfaces on these GL's hardware are balanced interface, which means that analog signal is presented and expected on Tip and Ring of the connector and shield (sleeve) is grounded to chassis as depicted in the following diagrams. It is important to use stereo 3.5mm audio cables when inter-connecting other equipments or accessories into these connectors.

Balanced Audio Cable
A balanced cable uses Tip, Ring for Audio signal and cable shield for the ground.

VF Input:

VF Output:

VF Tx Rx Gains

VF Tx Gains

Supports: -12 dB to +59 dB in 0.5dB Steps Gain (0.1 dB steps can also be accommodated
in tProbe™)

VF Rx Gains

Supports: -63.5 dB to +9 dB in 0.5dB Steps Attenuation (0.1 dB steps can also be
accommodated in tProbe™)

VF TX and RX IMPEDANCES

GL's analyzer allows users to select various VF terminations, gain, drop, and insert options within VF Dialog bar as shown below. User should select appropriate impedance settings as per their application.

VF Imped/Mic
Selection
VF Input
Impedance
VF Output
Impedance

135

135 Ohms

135 Ohms

150

150 Ohms

150 Ohms

600

600 Ohms

600 Ohms

900

900 Ohms

900 Ohms

High

>50K Ohms

600 Ohms

Mic+Headset

1K Ohms+
Mic Power

900 Ohms

Typical Applications for VF

Typical Application   VF Imped/Mic
Selection
Recommended
Connectivity

Telephony Audio Equipments


600

VF Out jack to Equipment In

VF In jack to
Equipment Out

Old Telephony Audio Equipments


900

VF Out jack to Equipment In

VF In jack
to Equipment Out

Connecting VF Input and Output to Sound Card


900

-VF Out jack to Line In
-VF In jack to Speaker

Non-Intrusively Bridge over VF Line


High

-VF In jack to bridge on line

Connecting Headset with Microphone for communication over T1/E1 Timeslot


Mic+Headset

VF-In jack to Mic
VF-Out jack to Headset

 

Wideband Copper Equipments

 

135 or 150

VF Out jack to Equipment In

VF In jack
to Equipment Out

VF Signal Measurements

tProbe™ VF IN (8 KHz Mu-law encoding) connected to Sage 930A Out using 3.5mm Stereo Cable.
The table below provides a comparison of the VF signal measurements against different impedances between tProbe™ and Sage 930A.

Note: For the below measurements the gain on the VF dialog bar is set to the 0 reference level.

VF Imped/Mic
Selection
VF Output
Impedance on Sage 930A
1004 Hz Signal Level from Sage-930A tProbe T1
VF IN
Level in Spectral Display dBm
tProbe T1
VF IN
S/N in Spectral Display

135

150 Ohms

-10 dBm

-10.8

36.5

 

 

-15 dBm

-15.9

33.8

 

 

-20 dBm

-21.0

29.6

150

150 Ohms

-10 dBm

-10.3

36.9

 

 

-15 dBm

-15.4

31.3

 

 

-20 dBm

-20.6

29.2

600

600 Ohms

-10 dBm

-9.9

39.8

 

 

-15 dBm

-14.9

38.7

 

 

-20 dBm

-19.9

36.6

900

900 Ohms

-10 dBm

-10.0

38.9

 

 

-15 dBm

-15.0

37.7

 

 

-20 dBm

-20.0

37.3

 

 

-

 

 

High

600 Ohms

-10 dBm

-7.3

36.6

 

 

-15 dBm

-12.4

37.5

Special Mic+Headset testing:
Mic (VF IN) <-> Headset (VF OUT) Looped back using Stereo Cable
1004 Hz Signal Sent at different levels from Tx Tone application in (TS-0 Insert on TS-1 Drop on TS-0)

Mic+Headset

 

-15 dBm

-4.9

34.4

 

 

-20 dBm

-9.9

33.7

 

 

-25 dBm

-14.9

32.1

 

tProbe™ VF IN Connected with Edirol UA-1ex Soundcard Out Port using 3.5 mm Stereo or Mono Cable:

The table below provides a comparison of the VF signal measurements against different cables between tProbe™ and Edirol UA-1ex Soundcard.

Note: When connected against soundcard, there are many factors which affects true output level like Software Volume Control, Sound Card Volume Control etc.

For the below measurements the gain on the VF dialog bar is set to the 0 reference level.

VF Impedance Sound Card
Line Output
Stereo 1004 Hz at -10 dBm
Cable tProbe T1
VF IN
Level in Spectral Display dBm
tProbe T1
VF IN
S/N in Spectral Display
Sage 930A Level Measurement
dBm

900

 Phase Reversed L/R Signal

Stereo

-12.4

37.7

-12.3

900

Phase Reversed L-R Signal

Mono

-13.9

39.4

-14.0

* 900

Non-Phase Reversed L-R Signal

Stereo

-47.0

 

-47.0

900

Non-Phase Reversed L-R Signal

Mono

-15.1

39.1

-15.2

900

Stereo Music File

Stereo

Sound OK

 

 

* This is expected result because of same signal fed to Left and Right channel and will be in same phase and will be canceled at transformer input.

 

tProbe™ VF IN Connected with connected with PC Sound card using 3.5mm Stereo or Mono Cables.

The table below provides a comparison of the VF signal measurements against different cables between tProbe™ and PC Soundcard.

For the below measurements the gain on the VF dialog bar is set to the 0 reference level.


VF Impedance
Sound Card
Line Output
Stereo 1004 Hz at -10 dBm
Cable tProbe T1
VF IN
Level in Spectral Display dBm
tProbe T1
VF IN
S/N in Spectral Display
Ameritec AM5XT Level Measurement
dBm

900

 Phase Reversed L/R Signal

Stereo

-9.9

39.1

 

900

Phase Reversed L-R Signal

Mono

-14.6

37.1

-14.4

*900

Non-Phase Reversed L-R Signal

Stereo

-47.0

 

-47.0

900

Non-Phase Reversed L-R Signal

Mono

-14.6

36.5

-14.4

900

Stereo Music File

Stereo

Sound OK

 

 

* This is expected result because of same signal fed to Left and Right channel and will be in same phase and will be canceled at transformer input.

tProbe™ VF IN Connected with External Microphone:

Recommended gain of 25 dB on VF-Insert.
Observe signal in spectral display and also drop output to Headset via different timeslot to listen what is spoken on microphone.

tProbe™ VF IN (8 KHz 16-bits encoding) Connected with Sage 930A Output

The table below provides a comparison of the VF signal measurements against different impedances between tProbe™ and Sage 930A.

All the measurement were done after recording 8kHz 16-bits signal into file and than opening that file into Adobe Edition for analysis.

VF Imped/Mic
Selection
VF Output
Impedance on Sage 930A
1004 Hz Signal Level from Sage-930A tProbe T1
VF IN
Level in dB (Adobe Edition) Stats Peak
Next Largest Peak
In dB
(In Adobe Audition)
Average Noise Floor in dB (Adobe Audition)

135

150 Ohms

-10 dBm

-13.98

-66.27

-84

 

 

-15 dBm

-19.04

-66.82

-84

 

 

-20 dBm

-24.19

-66.56

-84

150

150 Ohms

-10 dBm

-13.51

-74.96

-86

 

 

-15 dBm

-18.54

-74.96

-86

 

 

-20 dBm

-23.74

-74-96

-86

600

600 Ohms

-10 dBm

-13.18

-74.74

-96

 

 

-15 dBm

-18.16

-79.44

-101

 

 

-20 dBm

-23.14

-88.53

-102

900

900 Ohms

-10 dBm

-13.25

-69.93

-92

 

 

-15 dBm

-18.24

-74.01

-108

 

 

-20 dBm

-23.23

-80.80

-108

 

 

-

 

 

 

High

600 Ohms

-10 dBm

-10.57

-67.17

-96

 

 

-15 dBm

-15.52

-77.83

-94

 

 

-20 dBm

-20.55

-81.01

-101

 


VF Interfaces in USB T1 E1 & Universal T1 E1

GL's USB T1/E1 and Universal T1/E1 Analyzer products are also equipped with VF inputs and outputs via 3.5 mm connectors.  Primary functionality of these connectors is to connect to external equipments or accessories.  Input signal is digitized (at 8 Khz, uLaw/A-Law) and inserted into selected timeslot of T1/E1.

An output audio signal is dropped from the selected timeslot of T1/E1. These interfaces offer only standard 600 Ohms termination mode so that it can be compatible with connected source or sink devices under test.

VF interfaces on these GL's hardware are unbalanced (mono) interfaces, which means that analog signal presented and expected on Tip and Shield of the connector and Ring is not used (unconnected) as depicted in the following diagrams.  It is important to use Mono 3.5mm audio cable when inter-connecting other equipments or accessories into these connectors.

VF Input


VF Output

VF Tx Rx Gains for USB analyzer

VF Tx Gains

Range: -7.2dB to +18.2dB selectable gain in 0.1dB steps
Level: 0.0dBm ± 0.1dBm

VF Rx Gains

Range: -18.0 dB to +7.3 dB selectable gain in 0.1dB steps
Audio Insertion: Selected DS0 replaced with inserted audio from VF Input with selected gain.
Audio Monitoring: Built-in Speaker or external speaker
Volume Control: User specified software controller

VF Tx Rx Gains for Universal Board

VF Tx Gains

Level: 0.0dBm +/- 0.1dBm
Range: –7.2 dB to +18.2 dB selectable gain in 0.1 dB steps

VF Rx Gains

Audio Monitoring: Built-in Speaker.
Audio Insertion: Selected DS0 replaced with inserted audio from VF Input
Range: 18.0 dB to +7.3 dB selectable gain in 0.1 dB step.
Volume Control: User specified software controller

VF Tx and RX IMPEDANCES

GL's analyzer allows users to control VF gain, drop and insert options within VF Dialog bar as shown below.

User Setting Receive Setting Transmit Setting
600Ohms 600Ohms Calibrated to 600Ohms

VF Signal Measurements

USB T1 E1 VF IN connected to Ameritec AM5XT using Mono Cable - Typical VF Measurements are as shown below

VF Impedance VF Output
Impedance Ameritec AM5XT
1004 Hz Signal Level from Ameritec AM5XT

USB T1
VF IN
Level in Spectral Display dBm

USB T1
VF IN
S/N in Spectral Display

600

600 Ohms

-10 dBm

-9.0

39.8

 

 

-15 dBm

-15.1

37.5

 

 

-20 dBm

-20.0

37.1




Summary of Cable Requirements between GL T1E1 products

  tProbe™ Universal T1 E1 USB T1 E1

tProbe

Balanced or Mono

Mono

Mono

Universal T1 E1

-

Mono

Mono

USB T1 E1

-

-

Mono

Dual UTA HD

Balanced or Mono

Mono

Mono

 

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