The TA124 Bessel-Thomson Reference Filter is the highest-data-rate model in Pico Technology’s current Bessel-Thomson reference filter family. It is intended for engineers working with high-speed optical transmission systems, telecom interfaces and networking signals where receiver-oriented waveform characterisation is required.
Pico identifies TA124 for two standard data rates:
- 2.488 Gb/s for OC48 / STM16
- 2.500 Gb/s for InfiniBand 2.5G
It is used in the electrical path after optical-to-electrical conversion, not directly in the optical fibre path.
Correct Measurement Position
The correct measurement chain is:
Optical transmitter → Optical transmission path → O/E converter → TA124 Bessel-Thomson filter → Sampling oscilloscope
Pico states that connecting the appropriate BT filter between the O/E converter output and scope input enables the oscilloscope to display a waveform representative of what an equalised optical receiver would see.
This is the most important technical point to explain clearly on the product page.
Designed for 2.488 Gb/s OC48 / STM16
The TA124 supports the 2.488 Gb/s data rate associated with:
- OC48
- STM16
- SONET transmission systems
- SDH transmission systems
- Optical telecom interfaces
- Fibre-optic communication equipment
Typical measurement applications include optical transmitter analysis, eye-diagram evaluation, telecom interface verification and laboratory research.
Designed for 2.500 Gb/s InfiniBand 2.5G
The same TA124 reference filter is also specified for:
- 2.500 Gb/s
- InfiniBand 2.5G
This makes the accessory suitable for high-speed networking and communication measurements in addition to SONET/SDH optical testing. Pico explicitly maps both 2.488 Gb/s and 2.500 Gb/s applications to TA124.
Bessel-Thomson Reference Receiver Response
The TA124 should not be described merely as a generic signal filter.
Its role is to provide the appropriate reference receiver response for the selected communication rate.
This helps produce more meaningful measurements of:
- Eye opening
- Rise time
- Fall time
- Signal transitions
- Pulse shape
- Overshoot
- Undershoot
- Timing behaviour
- Receiver-oriented waveform quality
The filter limits the measurement response in a controlled way so the waveform is more representative of the communication receiver being modelled.
Optical Eye-Diagram Measurements
The TA124 is suitable for high-speed eye-diagram analysis after optical-to-electrical conversion.
Engineers can use the resulting waveform to study:
- Eye height
- Eye width
- Crossing position
- Transition quality
- Rise and fall behaviour
- Pulse symmetry
- Timing variation
- Signal quality
Using the correct bit-rate-specific reference filter is important because the measurement bandwidth can influence the apparent shape of the eye.
Compatible PicoScope Platforms
Pico Technology currently lists compatibility with:
- PicoScope 9221A
- PicoScope 9231A
- PicoScope 9321
These oscilloscopes are explicitly named by Pico for use with its Bessel-Thomson reference filter range.
Electrical Filter, Not an Optical Filter
The TA124 acts on the electrical signal after O/E conversion.
It should not be described as:
- An optical fibre filter
- An optical attenuator
- An optical-to-electrical converter
- An optical receiver
- A calibration standard
- A standalone measurement instrument
This distinction will improve both technical accuracy and search relevance.
Fixed Reference Filter
The TA124 is a fixed, data-rate-specific measurement accessory.
It does not need:
- USB control
- Software configuration
- PicoSDK
- User-selectable filtering
- Network connectivity
- Electronic switching
The required response is selected simply by choosing TA124 for the applicable communication rate.
Bessel-Thomson Filter Family
Pico currently lists the following family.
| Model |
Bit Rate |
Communication Standard |
| TA120 |
51.8 Mb/s |
OC1 / STM0 |
| TA121 |
155 Mb/s |
OC3 / STM1 |
| TA122 |
622 Mb/s |
OC12 / STM4 |
| TA123 |
1.250 Gb/s |
GBE |
| TA124 |
2.488 Gb/s |
OC48 / STM16 |
| TA124 |
2.500 Gb/s |
InfiniBand 2.5G |
Why Correct Filter Selection Matters
Each filter in Pico’s BT family is matched to a specific serial data rate.
Choosing the wrong model can affect the apparent:
- Rise time
- Fall time
- Eye opening
- Pulse shape
- Overshoot
- Timing behaviour
- High-frequency waveform content
For OC48/STM16 at 2.488 Gb/s or InfiniBand 2.5G at 2.500 Gb/s, TA124 is the correct Pico reference filter.
Applications
The TA124 is suitable for:
- OC48 transmitter testing
- STM16 signal characterisation
- InfiniBand 2.5G testing
- Optical eye-diagram analysis
- SONET and SDH system development
- Optical transceiver testing
- Fibre-optic system validation
- Telecom equipment testing
- High-speed networking development
- Optical module characterisation
- Production optical testing
- Research and development
- University optical communication laboratories
Why Buy from RevineTech?
RevineTech can supply the TA124 for high-speed optical and telecom measurement setups and assist with selection of compatible PicoScope instruments, O/E conversion hardware and related accessories.
