- 2069 Chaitra · 2 marks
Role of hybrid transformer
Short answer
A hybrid transformer couples a two-wire subscriber line to four-wire transmit and receive paths. Its balancing network, matched to the line impedance, stops the received signal leaking into the transmit path, preventing echo and singing. It provides about 3 dB loss in each through path.
Explain the role of Hybrid transformer or circuit in case of telecommunications.
A hybrid transformer (or hybrid circuit) is the interface between the two-wire subscriber line and the four-wire transmission/switching path.
Its roles:
- 2W→4W: passes the subscriber's speech from the two-wire line to the four-wire transmit (GO) path.
- 4W→2W: passes the received speech from the four-wire RETURN path to the two-wire line.
- Isolation: with a balancing network equal to the line impedance, it prevents the received signal from leaking into the transmit path (high transhybrid loss). This stops echo and singing on long four-wire circuits.
- Each through path has about 3 dB loss.
It is used in telephone sets (sidetone control), line cards of digital exchanges and the ends of trunk/carrier circuits.
✓ Answer checked by Claude Opus 5.5 (high effort)
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