QMDL Analysis Guide Capture & Post-processing
Everything you need to know about the QMDL (Qualcomm DiagMonitor Log) format: internal structure, field capture, post-processing workflow and conversion to Excel, CSV or HLOG. The definitive reference for mobile network engineers.
In a nutshell
QMDL (Qualcomm DiagMonitor Log) is the standard diagnostic log format for Qualcomm chipsets. It records Layer 3 messages (RRC, NAS), radio metrics (L1/L2) and system events in a timestamped binary file. This guide covers the format structure, field capture methods and the complete post-processing workflow to Excel, CSV or the encrypted HLOG format.
What is the QMDL format?
QMDL is a binary file format developed by Qualcomm to record diagnostic data emitted by the mobile chipset via the DIAG interface (/dev/diag serial port). This format has been used by the entire mobile network testing ecosystem for over 15 years and remains the de facto standard for log exchange among field engineers.
Each QMDL file contains a continuous stream of diagnostic packets captured in real time during a measurement session. These packets cover all layers of the protocol stack: from L1 physical measurements (RSRP, RSRQ, SINR) to L3 signaling messages (RRC, NAS, SIP) through L2 transport metrics (PDCP, RLC, MAC).
QMDL is compatible with the major post-processing tools on the market: QCAT (Qualcomm CATS Analysis Tool), QXDM, and test suites such as TEMS and Nemo. HiCellTek exports natively to QMDL format to ensure interoperability with existing workflows.
Internal structure of a QMDL file
The fundamental components of a Qualcomm log file.
File header
The file begins with a header containing the format version, chipset identifier, capture start date and time, and active log masks. This header allows post-processing tools to identify the format and select the correct decoder.
Sub-packets
The file body is composed of sequential sub-packets. Each sub-packet contains a log type (log code), a size, a system timestamp and the raw data. Log codes follow the Qualcomm nomenclature: 0xB0C0 for LTE RRC, 0xB0E0 for LTE NAS, etc.
Timestamps
Each sub-packet carries a timestamp in milliseconds since system boot. Synchronization with GPS time (when available) allows geotagging each event. This temporal precision is essential for correlation with radio measurements.
Log masks
Log masks define which message types are captured. A mask that is too broad generates large files; a mask that is too narrow may omit critical information. HiCellTek provides preconfigured mask profiles tailored to each scenario (L3 troubleshooting, RF audit, throughput benchmarking).
Capturing QMDL logs with HiCellTek
HiCellTek accesses the Qualcomm DIAG interface directly on the Android smartphone to capture diagnostic packets in real time. Unlike traditional solutions that require a PC connected via USB, capture runs entirely on the mobile device.
Capture is configured by selecting a mask profile (full L3, RF only, VoLTE, or custom) and enabling GPS synchronization if needed. Logs are stored locally on the device and can be exported to QMDL, Excel, CSV or the encrypted HLOG format at any time.
The integrated Layer 3 decoder allows you to visualize and filter captured messages in real time, without waiting for post-processing. The engineer can thus identify a problem (attach reject, handover failure, bearer drop) immediately in the field.
Post-processing workflow: QMDL to Excel/CSV
The traditional QMDL post-processing workflow follows these steps: field capture, file transfer to a PC, opening in QCAT or QXDM, applying filters, and exporting filtered data to CSV or text. This process can take several hours for lengthy measurement campaigns.
HiCellTek simplifies this workflow by enabling direct Excel export from the device. L3 messages are decoded and organized in separate tabs: RRC, NAS, L1 metrics, L2 stats. GPS coordinates are included for each event, enabling immediate mapping without third-party tools.
For teams that maintain an existing QMDL workflow, HiCellTek also exports in standard QMDL format, compatible with QCAT and established post-processing chains. The generated QMDL file contains the same log codes and structure as a capture produced by a traditional tool.
QMDL vs HLOG: format comparison
| Criteria | QMDL | HLOG v1 |
|---|---|---|
| Developer | Qualcomm | HiCellTek |
| Encryption | None (plaintext) | chiffrement authentifié |
| Integrity | Not verified | Cryptographic signature |
| Compatibility | QCAT, QXDM, TEMS, Nemo | HiCellTek Cloud, export to QMDL/Excel |
| Size | Standard | Compressed (30 to 50% smaller) |
| Geotagging | Optional (tool-dependent) | GPS integrated by default |
| Post-processing | Requires PC + software | Decoded on device or cloud |
Related resources
FAQ: QMDL Format
What exactly is a QMDL file?
A QMDL (Qualcomm DiagMonitor Log) file is a proprietary Qualcomm binary log format. It contains raw diagnostic messages captured via the Qualcomm chipset's DIAG interface: Layer 3 messages (RRC, NAS), L1/L2 radio metrics, system events and internal logs. It is the reference format used by field engineers for post-processing and network troubleshooting.
How do you open and analyze a QMDL file?
QMDL files are traditionally analyzed with QCAT (Qualcomm CATS Analysis Tool) or QXDM. HiCellTek allows you to capture DIAG logs directly on the Android handset and export them in QMDL format for compatibility with existing tools, or directly in Excel/CSV for immediate analysis without additional software.
What is the difference between QMDL and HLOG?
QMDL is an open Qualcomm format, compatible with third-party tools (QCAT, QXDM). HLOG is HiCellTek's proprietary format, encrypted with chiffrement authentifié, which preserves the integrity and confidentiality of field captures. HLOG can be converted to QMDL or Excel from the HiCellTek cloud for post-processing.
What is the typical size of a QMDL file?
Size depends on capture duration and active message filters. A 30-minute capture with all L3 messages and radio metrics typically generates between 50 and 200 MB. With detailed L1/L2 logs enabled, the size can reach 500 MB per hour. HiCellTek allows filtering captured messages to reduce file size.
Capture and export QMDL directly in the field
HiCellTek captures Qualcomm DIAG logs and exports to QMDL, Excel, CSV or encrypted HLOG. No more connecting a PC via USB to capture field logs.