GSE Status (DVB-S2/S2X)

There are two types of traces in the Trace > Data > Demod menu that display component carrier data: CCn (component carrier is fixed), and Display CC (component carrier is dynamically selected using the Carrier Aggregation > Selected CC for Trace Display parameter). See About Demod Per-Carrier Trace Types for more information.

The GSE Status trace shows the PDUs recovered from the baseband frame plus summary counters for decode problems. For DVB-S2/S2X, GSE (Generic Stream Encapsulation) decapsulation is always performed. You can also choose to measure BER Bit Error Ratio - A ratio of the number of errors to data bits received on a digital circuit. on the decapsulated PDU (protocol data unit) The data unit exchanged between peer entities of the same protocol layer. On the downward direction, it is the data unit generated for the next lower layer. On the upward direction, it is the data unit received from the previous lower layer. bits (after GSE) instead of the raw frame bits, using the Reference Bits Plane control.

GSE Status is a type of Matrix Table that provides selectable column visibility and copy/paste and export functionality to share rows of content or complete tables to applications like email, text editing or spreadsheet programs.

Three aggregate counters are shown above the GSE Status table:

Total PDUs — Number of GSE PDUs found in the frame(s).
PDU CRC Cyclic Redundancy Check Failures — Count of PDUs whose CRC-32 check failed.
BBHEADER CRC Failures — Count of BBHEADER (CRC-8) failures.

The GSE Status table has one row per PDU:


PDU index within the result.	Decode status of the PDU: Pass — the PDU was reassembled and its GSE CRC-32 passed. Fail — the PDU's GSE CRC-32 was checked and failed (corrupt data). N/A — a single-packet PDU that carries no GSE CRC-32; its integrity is covered instead by the baseband-frame CRC and forward error correction. This is the normal state for an unfragmented PDU, not an error. Timeout — a fragmented PDU was started but its final fragment never arrived within the reassembly window, so the partial PDU was discarded. Preempted — a new fragment stream started for the same Fragment Id before this PDU finished (its end fragment was lost), so the partial PDU was discarded. Malformed — the PDU's end fragment was too short to contain the CRC-32 trailer, so the PDU was discarded. Length Mismatch — the reassembled PDU's length did not match the total length declared in its header, so the PDU was discarded. Invalid Length — the GSE packet could not be parsed: its declared length runs past the data field, or a header was too short for its mandatory fields. No Start — a continuation/end fragment was seen with no in-flight Start fragment. This is expected and common when you begin demodulating partway through a stream (the Start fragment was before the capture). Consecutive such fragments of the same PDU are collected into a single row, with the Fragments count showing how many were seen. No End — a reassembly was started (Start seen) but the capture ended before its End fragment arrived. Distinct from Timeout, which covers only a fragment stream that exceeded the 256-frame reassembly window. Unsupported Stream — the baseband frame is not standard GSE (for example a Transport Stream or GSE high-efficiency-mode stream), so it was not decapsulated. On rows that recover no payload (No Start, No End, Timeout, Preempted, Malformed, Length Mismatch, Unsupported Stream), the Offset and Length cells show * instead of 0, and Protocol Type shows * when unknown (no Start header parsed).	GSE Fragment Id (the reassembly key, 0–255) that ties this PDU's row to its fragments in the stream. Shows *** for a single-packet (unfragmented) PDU, which has no Fragment Id.	Number of fragments the PDU was reassembled from.	Bit offset of the PDU within the decapsulated stream.	PDU length, in bits.	Index of the first baseband frame (BBFRAME) in which a fragment of this PDU was seen.	Index of the last baseband frame in which a fragment of this PDU was seen. For a completed PDU these are its start/end frames; for No Start / No End they are just the first/last fragment actually observed.	GSE Protocol Type field (displayed in hex).

PDU #

PDU Status

Fragment ID

Fragments

Offset (bit)

Length (bit)

First Frame

Last Frame

Protocol Type

PDU index within the result.

Decode status of the PDU:

Pass — the PDU was reassembled and its GSE CRC-32 passed.
Fail — the PDU's GSE CRC-32 was checked and failed (corrupt data).
N/A — a single-packet PDU that carries no GSE CRC-32; its integrity is covered instead by the baseband-frame CRC and forward error correction. This is the normal state for an unfragmented PDU, not an error.
Timeout — a fragmented PDU was started but its final fragment never arrived within the reassembly window, so the partial PDU was discarded.
Preempted — a new fragment stream started for the same Fragment Id before this PDU finished (its end fragment was lost), so the partial PDU was discarded.
Malformed — the PDU's end fragment was too short to contain the CRC-32 trailer, so the PDU was discarded.
Length Mismatch — the reassembled PDU's length did not match the total length declared in its header, so the PDU was discarded.
Invalid Length — the GSE packet could not be parsed: its declared length runs past the data field, or a header was too short for its mandatory fields.
No Start — a continuation/end fragment was seen with no in-flight Start fragment. This is expected and common when you begin demodulating partway through a stream (the Start fragment was before the capture). Consecutive such fragments of the same PDU are collected into a single row, with the Fragments count showing how many were seen.
No End — a reassembly was started (Start seen) but the capture ended before its End fragment arrived. Distinct from Timeout, which covers only a fragment stream that exceeded the 256-frame reassembly window.
Unsupported Stream — the baseband frame is not standard GSE (for example a Transport Stream or GSE high-efficiency-mode stream), so it was not decapsulated.

On rows that recover no payload (No Start, No End, Timeout, Preempted, Malformed, Length Mismatch, Unsupported Stream), the Offset and Length cells show *** instead of 0, and Protocol Type shows *** when unknown (no Start header parsed).

GSE Fragment Id (the reassembly key, 0–255) that ties this PDU's row to its fragments in the stream. Shows *** for a single-packet (unfragmented) PDU, which has no Fragment Id.

Number of fragments the PDU was reassembled from.

Bit offset of the PDU within the decapsulated stream.

PDU length, in bits.

Index of the first baseband frame (BBFRAME) in which a fragment of this PDU was seen.

Index of the last baseband frame in which a fragment of this PDU was seen. For a completed PDU these are its start/end frames; for No Start / No End they are just the first/last fragment actually observed.

GSE Protocol Type field (displayed in hex).

The GSE Status result stays populated for rejected or zero-PDU frames (for example, a failed BBHEADER CRC): the per-PDU table is empty, but the counters still report what happened so you can see why a frame produced no payload.