Buying signal filters for a shielded room or EMC chamber is not simply a matter of choosing the cheapest filter or the one with the highest attenuation.

The filter needs to match the actual signal system.

If the specification is incomplete, the wrong filter may be selected, causing unnecessary redesign, communication problems, or installation changes later.

Before requesting a quotation, we recommend confirming the following 10 specifications.

1. Don’t Start With Price

Price should not be the first selection criterion.

The first question should be:

What signal needs to pass through the shielded wall?

Typical applications include:

• Telephone
• Fax
• Fire alarm
• Access control
• Temperature monitoring
• Humidity monitoring
• Environmental monitoring
• Air-conditioning control
• Intercom
• Network communication
• Gigabit network
• Multi-wire control

Different applications can require different filter configurations.

A lower-priced filter is not necessarily a suitable replacement if its electrical characteristics do not match the application.

2. Confirm the Signal Type

When requesting a quotation, describe the actual signal.

For example:

4-wire temperature and humidity signal

is much more useful than:

4-wire signal filter

Similarly:

8-line Gigabit Ethernet

is more useful than:

8-wire network filter

This allows the manufacturer to identify the appropriate filter architecture more accurately.

Noordin’s current product range includes dedicated configurations for temperature/humidity, network, Gigabit network, telephone, fire alarm, access control, monitoring, and multi-wire applications.

3. Confirm Rated Voltage

The voltage requirement should be provided clearly.

Examples include:

• 24 VDC
• 48 VDC
• 100 VDC
• 0–250 VAC/DC

The filter should be selected according to the actual electrical system.

For example, the GSF423-1 is rated at 100 VDC and 1 A, while several other models in the range are specified for 0–250 VAC/DC.

Do not assume that all signal filters have the same voltage rating.

4. Confirm Current

Current is equally important.

Provide:

• Normal operating current
• Maximum operating current
• Any startup or transient current if applicable

The Noordin range includes different current ratings, including 0.3 A and 1 A configurations, depending on the model.

For custom multi-wire systems, providing the current for each signal group can help the manufacturer recommend the appropriate design.

5. Confirm the Number of Lines

The number of lines determines the basic filter configuration.

Common configurations include:

• 1 line
• 2 lines
• 3 lines
• 4 lines
• 8 lines
• Customized multi-wire

For example:

GSF-T2
2 lines

GSF423-1
4 lines

GSF-V8
8 lines

GSF-V8/1000
8 lines

GSF-N*C
Customized number of lines

The current Noordin product range provides these different configurations for communication and control applications.

6. Confirm the Required Frequency or Bandwidth

This is one of the most important purchasing specifications.

A filter must allow the required signal to pass.

The required passband should therefore be provided whenever possible.

Examples in the existing product range include:

• 20 kHz
• 100 kHz
• 200 kHz
• 6 MHz
• 10 MHz

depending on the specific model.

If the customer does not know the required filter bandwidth, provide the original equipment or communication interface specification.

This allows the filter supplier to evaluate the application before recommending a model.

7. Don’t Purchase Only by “High Attenuation”

This is an important purchasing mistake.

A filter with a very high attenuation figure may sound attractive.

But attenuation is only one part of the specification.

The filter also needs to maintain the required signal transmission.

For example, a filter used for temperature monitoring and a filter used for Gigabit network communication cannot be selected using the same criteria.

The purchasing process should therefore consider:

Signal transmission + Filtering performance + Electrical rating + Mechanical installation

rather than attenuation alone.

8. Confirm the Installation Method

Before ordering, confirm how the filter will be installed.

Important information may include:

• Shield wall thickness
• Mounting method
• Filter dimensions
• Terminal type
• Connector type
• Cable entry direction
• Number of filters
• Available installation space
• Grounding/bonding method

For shielded rooms, the filter should be integrated into the shielding boundary.

Mechanical compatibility is therefore just as important as electrical compatibility.

9. Don’t Forget the Quantity and Future Expansion

For a new EMC chamber or shielded room, don’t only calculate today’s requirements.

Consider future expansion.

For example, the project may initially require:

• 4 temperature signals
• 8 control signals
• 8 network lines
• 4 access-control lines

But additional monitoring or control systems may be added later.

Providing the complete signal list to the filter supplier allows the design to consider future requirements.

For larger projects, a signal schedule is highly recommended.

Example Signal Schedule

Signal	Lines	Voltage	Current	Bandwidth	Quantity
Temperature	4	24 VDC	0.1 A	Project specific	2
Humidity	4	24 VDC	0.1 A	Project specific	2
Access Control	2	24 VDC	0.5 A	100 kHz	2
Fire Alarm	2	24 VDC	0.5 A	200 kHz	4
Network	8	100 VDC	1 A	10 MHz	2
Gigabit Network	8	100 VDC	1 A	High-speed	2

The exact values should always be based on the actual equipment.

10. Ask About Customization Before Finalizing the Design

Not every shielded-room project can use a standard configuration.

A project may require:

• Special voltage
• Special current
• Special number of lines
• Custom dimensions
• Special connector
• Custom housing
• Special mounting arrangement
• OEM labeling
• Customized filtering characteristics

Noordin states that customized signal-filter solutions are available, including customized multi-wire configurations. The product range also supports OEM/ODM requirements.

Therefore, if the standard model does not exactly match the project requirement, it is better to discuss customization before changing the system design.

What Information Should You Send When Requesting a Quote?

To obtain a faster and more accurate quotation, send the following information:

1. Application:
EMC chamber / shielded room / shielded cabinet / other

2. Signal type:
Telephone / alarm / control / monitoring / network / other

3. Number of lines:
2 / 4 / 8 / customized

4. Rated voltage:
For example, 24 VDC or 100 VDC

5. Rated current:
For example, 0.3 A or 1 A

6. Frequency or bandwidth:
For example, 20 kHz / 200 kHz / 10 MHz / network speed

7. Quantity:
Number of filters required

8. Installation:
Panel-mounted / bulkhead / shield-wall installation

9. Mechanical requirements:
Dimensions, connectors, mounting holes, etc.

10. Special requirements:
OEM, customized model, special materials, test reports, or other project requirements

The more complete the information, the easier it is for the manufacturer to recommend the appropriate filter.

Final Purchasing Checklist

Before placing an order, confirm:

• Signal type
• Number of lines
• Rated voltage
• Rated current
• Signal bandwidth
• Communication speed
• Required filtering performance
• Filter dimensions
• Connector/terminal configuration
• Installation method
• Quantity
• Customization requirements
• Required documentation

A signal filter is a relatively small component, but it can have an important role in maintaining the electromagnetic integrity of a shielded facility.

The best purchasing process is therefore not:

“Find a filter with the lowest price.”

It is:

“Define the signal first, then select the filter.”

Signal Filters for Communication and Control

Noordin Etech provides signal filters for communication and control applications in shielded rooms, EMC chambers, shielded cabinets, and other electromagnetic isolation environments.

The current product range includes standard and multi-wire configurations for control, monitoring, communication, network, and Gigabit network applications.

Contact us with your signal specifications, and we can recommend a suitable configuration for your project.

Fore more informa：Don’t Install a Signal Filter Without Checking These 7 Parameters