HM Firmware Revision History

This model is not capable of firmware updates in the field so no files are available for download. Contact Lectrosonics if you need a firmware update.


HM v2.5 - 23 December 2014

Unit now turns itself off when battery voltage is too low for stable operation. This eliminates noises in the audio just before the battery fails completely, and also prevents repeated power cycling at the end of battery life.

HM v2.4 - 23 December 2014

Added 25 kHz tuning step mode. Also applied minor cosmetic fixes to user interface and factory serial commands, and slightly improved dynamic tracking accuracy in compatibility mode 6.

HM v2.3 - 03 December 2012

Shaped battery telemetry signaling for slightly lower noise floor. Also added new factory diagnostic functions.

HM v2.2 - 20 September 2012

Increased power level (and thus the accuracy) of the microprocessor brownout detection circuit.

HM v2.1 - 15 August 2012

Added powerup delays, checksums and multiple read attempts to ensure robustness of non-volatile memory. Created a protected memory storage class for crucial system setup and calibration parameters. No user-apparent changes were made since v2.0.

HM v2.0 - 27 February 2012

Introduced new hardware variant with backlight feature.

HM v1.6 - 29 December 2010

Increased battery telemetry adjustment range and scaling, and added autorepeat to the battery telemetry adjustment screen, for faster and easier factory alignment and fewer component changes. No user perceptible changes were made; however, upgrading to this (or newer) versions will require recalibration of the battery telemetry adjustment.

HM v1.5 - 10 October 2010

Added 10 dB additional gain control range. Also added optional audio polarity inversion feature. Fixed factory diagnostic "rolloff=" serial command.

HM v1.4 - 23 September 2009


  • Adjusted battery warning thresholds for LED indicator.
  • Adjusted power off timings to ensure receivers have enough time to mute before carrier turns off.
  • Added new serial commands for testing department.

HM v1.3 - 18 August 2009

DSP code, which formerly worked only on the TMS320VC5402 DSP, is now also compatible with the TMS320VC5402A. Firmware may be used on logic boards populated with either DSP. Nothing else has changed since v1.2.

HM v1.2 - 06 August 2009

Audio mute status is now correctly displayed in RF-off mode. Improved accuracy of compatibility mode 3.

HM v1.1 - 23 April 2009

First production release.