QRP Labs QMX User Manual

You can disable this automatic protection feature by setting the GPS protection mode parameter
to DISABLE.
5.12 CW Decoder menu
The Decoder menu contains a number of configuration parameters relating to the CW decoder,
which are described below. Some of these parameters control some aspects of the decoder
behaviour. Some constructors may find it interesting to experiment with these settings and see if
you can improve the performance of the CW decoder in your specific circumstances. For example,
some stations may experience more noise interference than others, depending on your location
etc.
Note that the Decoder is able to decode the Morse prosign symbols AR, KN and SK/VA. When
shown in the decoded text section of the display, they appear as two characters, for example AR.
When using the keyer to enter text into message menus, the two characters are prefixed by the _
character to indicate to the QMX that when replaying the message, the following two characters
should be strung together without any gap.
Noise blnk.
10
This parameter defines the duration of the noise blanker in milliseconds. The microcontroller’s 24-
bit stereo I Q ADC samples audio at 48ksps (thousand samples per second). Blocks of 32
samples are analysed by an implementation of the Goertzel algorithm (kind of a single bucket of a
Fourier Transform), which results in a digital filter bandwidth of 250Hz. In other words, it results in
a measurement of the amplitude 250 times per second, i.e. once every 4 milliseconds. The
amplitude is analysed by logic which compares it to a threshold amplitude to decide if a tone has
been detected or not. Impulse noise that generates shorter pulses than the noise blanker
parameter, is ignored.
If the noise blanking period is too short, then noise impulses will not be blanked effectively. On the
other hand, if the noise blanking period is too long, then it will impair the decoder’s ability to
decode high speed Morse. For example, 24wpm Morse has dits lasting 50 milliseconds.
Speed avg.
07
The duration of dits and dahs is measured in order to define a threshold at which to define a tone
burst as a dit or a dah, and whether to define no tone at all as an inter-symbol, inter-character or
inter-word gap. The measurement of this timing is implemented via an exponential moving
average, whose averaging duration is determined by this parameter (the weight of each new
measured symbol in the accumulated average).
If the exponential moving average is too fast (the parameter value is too low) then noise etc will
throw off the timing averages too easily. If the exponential moving average is too slow (the
QMX operang manual; rmware 1_00_012 25

QRP Labs QMX Specifications

General

Brand	QRP Labs
Model	QMX
Category	Transceiver
Language	English

Summary

1. Overview of Features

QMX Portability

Highlights the small size and low current consumption for portable operations.

Synthesised VFO Tuning

Details the VFO tuning using a Si5351A chip and rotary encoder, with two VFOs.

CW Keyer and Break-in

Explains the integrated lambic keyer and full/semi break-in operation.

2. Connectors

Paddle Connector Functions

Details the 3.5mm stereo jack for paddle, GPS data, and microphone input.

Audio and DC Power Connectors

Describes the 3.5mm audio output and 2.1mm barrel jack DC input.

3. Display Elements

4. Operator Controls

4.1 Tune Rate

Explains how to adjust the VFO tuning rate using the rotary encoder.

4.2 Keyer Speed

Details how to adjust the CW keyer speed using the 'Select' button and encoder.

4.3 RIT

Explains how to adjust Receiver Incremental Tuning (RIT) using double-click and encoder.

4.4 VFO Mode

Describes selecting between VFO A, VFO B, and Split modes for operation.

5. Menu System

5.1 Saving Current Operating Parameters

Stores current operating conditions like VFO frequency, mode, and keyer speed upon power down.

5.3 Editing Configuration Parameters

Details the process of editing menu parameters using the rotary encoder and buttons.

5.8 Audio Menu

Controls audio settings like volume step and sidetone volume and its absolute/relative mode.

5.11 Keyer Menu

Configures CW keyer settings like mode, swap, weight, and auto-space.

5.16 Protection Menu

Configures protection features like SWR protection, threshold, and supply voltage monitoring.

5.19 Factory Reset

Resets the radio to its default factory configuration, erasing all custom settings.

5.20 Update Firmware

Guides the user through rebooting into bootloader mode for firmware updates via USB.

6. Operating QMX on Digital Modes

WSJT-X Configuration

Step-by-step guide for configuring WSJT-X for audio and CAT control with QMX.

7. Firmware Update Procedure

Entering Bootloader Mode

Explains methods to enter firmware update mode, including button presses and jumpers.

8. Terminal Applications

PC Terminal Emulator Setup

Guides setting up terminal emulators like PuTTY for connecting to QMX.

8.5 Band Configuration

Details configuring parameters for each amateur radio band, including frequencies and PTT.

8.6 Hardware Tests Menu

Accesses tools for optimizing and testing hardware, including filter sweeps and diagnostics.

8.7 PC and CAT Menu

Covers PC interface and CAT commands, including system config and input analysis.

9. Resources

10. Document Revision History