SAES-T-830 PDF – Voice Frequency Loop Transmission Objectives

This article is about SAES-T-830 which is about Voice Frequency Loop Transmission Objectives and download SAES-T-830 PDF for telecommunication and electrical engineers, supervisors and project managers, telecom QCs, telecom QC Supervisors. This is saudi aramco standards of Telecommunication Engineering based on international codes and standards and useful for telecom and electronics engineering knowledge to get job as engineers, QC Supervisors and QC managers, Engineering managers and technicians.

SAES-T-830 PDF Download

SAES-T-830

Voice Frequency Loop Transmission Objectives

The SAES-T-830 standard outlines the minimum mandatory requirements for voice frequency loop transmission objectives and defines the parameters associated with circuits used for voice frequency transmission. It sets the guidelines and criteria for ensuring reliable and high-quality voice communication over the transmission circuits.

The standard addresses various aspects related to voice frequency transmission, including but not limited to:

1. Transmission Objectives: It defines the objectives that voice frequency loop transmission should meet. These objectives typically include parameters such as signal quality, noise levels, attenuation, echo control, and transmission performance.
2. Circuit Parameters: The standard specifies the parameters associated with voice frequency transmission circuits. This may include parameters like frequency response, impedance, loop loss, distortion, signal-to-noise ratio, and crosstalk. These parameters ensure that the transmission circuits meet the required performance standards.
3. Loop Length: The standard may provide guidelines or limitations on the maximum loop length for voice frequency transmission. Loop length affects the signal quality and attenuation, and it is important to ensure that the transmission objectives are met within the specified loop length.
4. Test Methods: The standard may describe the test methods and procedures for measuring and evaluating the performance of voice frequency transmission circuits. These tests help verify compliance with the specified parameters and ensure that the transmission objectives are achieved.

By defining these minimum mandatory requirements, SAES-T-830 aims to ensure consistent and reliable voice frequency transmission over communication circuits. It provides a common framework for design, installation, and evaluation of voice transmission systems, promoting quality and interoperability in telecommunications networks.

Industry Codes and Standards for SAES-T-830

The SAES-T-830 standard for voice frequency loop transmission objectives may reference or incorporate industry codes and standards to ensure compliance and alignment with best practices. Some of the industry codes and standards that may be relevant to SAES-T-830 include:

1. American National Standards Institute (ANSI): ANSI develops and publishes various standards related to electrical and electronic systems. While specific ANSI standards related to voice frequency loop transmission objectives are not mentioned, ANSI standards in the electrical and telecommunications domain may provide guidance on relevant aspects.
2. IEEE C2: IEEE C2 is a standard published by the Institute of Electrical and Electronics Engineers (IEEE) that addresses the safety requirements for electric power systems in industrial and commercial installations. While not directly related to voice frequency transmission, it can provide guidelines for electrical safety considerations in the design and installation of communication systems.
3. National Electrical Safety Code (NESC): The NESC is a set of safety standards published by the Institute of Electrical and Electronics Engineers (IEEE) and the National Electrical Safety Board (NESB). It provides guidelines for the installation, operation, and maintenance of electric supply and communication lines, including requirements for grounding and protection against electrical hazards.
4. National Fire Protection Association (NFPA): NFPA publishes various codes and standards related to fire safety. NFPA 70, also known as the National Electrical Code (NEC), is a widely adopted standard that covers the installation of electrical systems, including communication systems. It provides requirements for wiring, grounding, and protection against electrical hazards.

These industry codes and standards, including ANSI/IEEE C2, NESC, and NFPA 70 (NEC), can complement SAES-T-830 by providing additional guidance and requirements for electrical safety, installation practices, and overall compliance with industry best practices. It is important to consult the specific editions and sections of these codes and standards that are applicable to the design and installation of voice frequency loop transmission systems.

Design

In the design section of SAES-T-830, there are several requirements related to various parameters associated with voice frequency loop transmission. Here’s a summary of the design requirements:

5.1 Loss:

• The maximum loss at 1000 Hz should not exceed 8.5 dB.
• If user loops are used for data transmission, the loss requirement may vary based on the specific data circuit requirements.

5.2 Loss versus Frequency:

• The bandwidth of the subscriber loops should fall between 300 Hz and 3300 Hz.
• For long voice frequency cable pairs, the loss slope should not exceed 6 dB, with the loss at 2800 Hz not being more than 6 dB greater than the loss at 1000 Hz.
• For conditioned long voice frequency cable pairs (with voice frequency repeaters), the loss slope should not exceed 2.5 dB. Data transmission circuits may require equalized gain to improve the slope of the cable pairs.

5.3 Noise – Steady State:

• The noise level at the user set should not exceed 20 dBrnC (measured using weighting filters).

5.4 Crosstalk:

• The objective for user loops is to have a crosstalk index not exceeding 0.1 for 99% of circuits.
• The crosstalk coupling loss at 1000 Hz should be a minimum of 77 dB when measured at either end of a user loop.

5.5 Echo and Return Loss:

• The return loss for loops, when measured against 900 ohms + 2 µF, should be a minimum of 8 dB for Echo Return Loss (ERL) and a minimum of 5 dB for Source Return Loss (SRL).

These design requirements ensure that voice frequency loop transmission systems meet specified criteria for loss, bandwidth, noise, crosstalk, and echo/return loss. Compliance with these requirements helps maintain satisfactory voice communication quality and performance.

5.6 Impedance:

• Electronically derived circuits (originated from a switch using solid-state devices) should have a 900-ohm impedance.
• The choice of user loop impedance takes into account the impedance of existing equipment and cable pairs.
• Telephone sets typically have an impedance of approximately 600 ohms, which varies with frequency and current magnitude.
• Non-loaded cables have an impedance that varies with length, frequency, and gauge.
• H88 loaded cables have specific impedances at 1000 Hz depending on the gauge.

5.7 Impulse Noise:

• The impulse noise should not exceed 15 counts in 15 minutes at a threshold of 54 dBrnC when measured at the central office.
• Impulse noise is less of a concern for voice transmission due to the ear’s limited response to fast noise spikes and the presence of varistors in telephone sets.
• However, impulse noise becomes important when user loops are used for data transmission as it can cause errors.

5.8 Delay Distortion:

• The envelope delay distortion should not exceed 100 µs between any two frequencies over the band from 1000 Hz to 2400 Hz for data transmission speeds greater than 300 bits/second.
• No specific objective is provided for speeds under 300 bits/second or for speech transmission.
• Speech signals are generally insensitive to delay distortion, but data transmission may be affected by phase distortion and other characteristics.
• The envelope delay of 24 gauge H88 loaded cable is provided as an example.

5.9 Nonlinear Distortion:

• Nonlinear distortion should be at least 25 dB lower than the original signal.
• Nonlinear distortion arises from nonlinear elements in transmission equipment and includes harmonic and intermodulation distortion.
• Nonlinear distortion has a negligible effect on speech transmission but may impair data transmission.
• Distortion can be expressed as a percentage, and the relationship to dB is provided as an example.

5.10 Transmission Contrast:

• When changing from one type of facility to another, the loss of the user loop should not increase by more than 3 dB.
• User complaints may arise when there is a difference in transmission performance between existing telephone facilities and the new circuit being replaced, even if both circuits are within design limits.
• Transmission contrast, particularly a change in loss, can cause user complaints.

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