Describe a typical error-detection scheme used in telemetry packets.

• A. Packets include a header with address and length, payload, and CRC; the receiver recomputes CRC to verify integrity and requests retransmission if error.
• B. Packets include the payload only.
• C. Packets rely on end-to-end encryption for error detection.
• D. Packets are validated by a separate system external to the link.

Answer: (A)

The key idea is to detect errors right where the data travels: by including a CRC (cyclic redundancy check) or similar checksum in each telemetry packet, along with a header and payload. The receiver uses the same CRC calculation on the received header and payload and compares it to the CRC value stored in the packet. If they match, the data is likely intact; if they don’t, a transmission error is detected.

This works well in telemetry because random bit flips from noise can be caught by the CRC, and including a header with address and length lets the receiver verify not only the data integrity but also that the packet is intended for the right destination and has the expected size. When an error is detected, the system can request a retransmission, which provides reliability over imperfect channels.

Relying on the payload alone offers no mechanism to know if bits were corrupted. End-to-end encryption focuses on confidentiality and may provide some integrity checks, but it isn’t designed as the primary, efficient link-level error detector for noisy channels and can add unnecessary complexity. A separate external system validating packets adds latency and is not typical for just detecting errors on the link.