1. Home
2. News
3. No signal, no problem: The secret behind the Attenuation Test

No signal, no problem: The secret behind the Attenuation Test

The Attenuation Test tool is essential for certifying the deployment and response of cabling and distribution equipment (splitters, etc.) in a television distribution plant, whether in MDUs (Multi-Dwelling Units) or cable networks.

It involves injecting test pilots at the headend and verifying their reception across all floors and every branch of the wiring, all the way to the outlets.

With PROMAX equipment, the attenuation test can be performed on live installations or even without waiting for a real signal to be present

This test can be performed “in-service” (avoiding interference with operational signals) or prior to signal availability, certifying that the infrastructure will perform correctly once the antenna and headends are operational.

Additionally, PROMAX equipment features pilot signal generation for Terrestrial, Satellite, and CATV bands, meeting the requirements of global telecommunications legislations.

Hold on! Isn't a real signal required for cable testing?

By conducting an attenuation test via a pilot generator, you can verify the wiring performance of a whole building, gaining benefits over using live signals:

• On new infrastructure: Certify ICT-2 or DUCTOS compliance without needing the antenna or headend equipment on-site yet.
• During upgrades or repairs, you ensure proper network rollout regardless of whether the antenna and headends are connected.
• You can perform maintenance on live installations without interfering with services by inserting pilots into vacant frequencies.
• You can test cabling performance at different frequencies (since copper response varies depending on the frequency).

And last but not least: Regulations (such as ICT, DUCTOS, or RITEL) strictly require a pilot generator for official certification.

Noise generators VS Pilot generators

While legislation mandates pilot generators at set frequencies for certifying installations, noise generators are discouraged due to the following drawbacks:

• They occupy the full frequency range, preventing in-service testing due to interference with real-time traffic (in contrast, pilot generators enable testing in free frequency slots).
• Noise generators lack the signal stability necessary for accurate certification.

Using a noise generator on a working installation is a bad practice: it creates interference with the live signal

From the headend to the outlet

The workflow for performing an attenuation test is simple: Calibrate, connect, and measure. You only need a pilot frequency generator and a calibratable field strength meter such as the TV EXPLORER NG.

1. Calibration. Zeroing.

In the “Attenuation Test” mode, make sure the meter is monitoring the exact frequencies emitted by the pilot generator. Connect both units, perform a reference set (zeroing) on the meter, and define the maximum allowable loss per pilot.

Using the PROMAX RP-110 allows you to adjust pilot frequencies and output levels to your preferred spectrum gaps. This is ideal because, when working on a live installation, you can utilize free spectral slots without interrupting the service.

2. Pilot signal generation at the system headend

... or any other point, though it is used at the headend 99% of the time. When using the PROMAX RP-110 pilot generator, the equipment runs independently for 5 hours using its internal battery. With the RP-080, it can be RF-powered from the field strength meter.

3. Verifying pilot reception at subscriber outlets

Test the pilot reception levels at user points with the “Attenuation Test” function. The more points you certify, the better (it is nearly instantaneous with PASS/FAIL mode!). At the very least, you must check one outlet for every branch of the distribution system. Key focus points:

• First outlet from the headend: Too much signal here can saturate the receivers.
• ... and the end-of-line outlet for each branch: Ensuring adequate signal levels here confirms the integrity and robustness of the trunk network.

Conclusion: Stop measuring, start CERTIFYING!

Testing an installation only after the antenna is up or the operator has enabled the signal is like testing a security system by waiting for a thief. With the TV EXPLORER NG Attenuation Test, you get the peace of mind that everything will be fully operational the moment the signal goes live.

Top professionals don't just fix; they prevent by design.

PROMAX is a leading manufacturer of test and measurement systems, broadcast and TV signal distribution equipment. Our product lines include measuring instruments for cable TV, satellite TV, broadcast, wireless and fibre optics networks, FTTH and GPON analyzers. DVB-T modulators, IP streamers or IP converters (ASI, DVB-T) are among the company’s latest developments.