Lectrosonics DMTH4 Reference Manual
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Lectrosonics DMTH4 Reference Manual

Digital telephone hybrid
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DMTH4
Digital Telephone Hybrid
Fill in for your records:
Serial Number:
Purchase Date:
REFERENCE MANUAL
Rio Rancho, NM, USA
www.lectrosonics.com

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Summary of Contents for Lectrosonics DMTH4

  • Page 1 REFERENCE MANUAL DMTH4 Digital Telephone Hybrid Fill in for your records: Serial Number: Purchase Date: Rio Rancho, NM, USA www.lectrosonics.com...
  • Page 2 DMTH4 LECTROSONICS, INC.

  • Page 3: Important Safety Instructions

    Digital Telephone Hybrid Important Safety Instructions This symbol, wherever it appears, alerts you 14) Refer all servicing to qualified service personnel. to the presence of uninsulated dangerous Servicing is required when the apparatus has been voltage inside the enclosure -- voltage that damaged in any way, such as power-supply cord or may be sufficient to constitute a risk of shock.

  • Page 4: Introduction

    DMTH4 Introduction Lectrosonics is proud to introduce the DMTH4, our most advanced digital telephone hybrid. The DMTH4 is an integral part of our DM Series of digital audio processors and interfaces easily with a standard telephone line to add telecon- ferencing capability to any sound system.

  • Page 5: Table Of Contents

    DMTH4 Output Compressor Commands ......52 DM Output Limiter Commands ..........53 DM Programmable I/O Commands ........54 DMTH4 Rear Panel Control Commands ......57 DMTH4 Telephone Interface Commands ......59 DMTH4 Codec Interface Commands ........63 DM Command Grammar Rules ..........65 FCC Part 68 Compliance ............

  • Page 6: Echo And Echo Cancellation

    Two digital acoustic echo cancellers are provided in the DSP can do a decent job of identifying the far-end audio DMTH4 to further reduce the return of local signals to and subtracting it from the transmitted signal, but this is the far-end.
  • Page 7 A gain proportional automatic mixer applies the most An important final note on the DMTH4 is the fact that the gain to the most active microphone with smooth, echo canceller will never “diverge” (lose convergence).

  • Page 8: General Overview

    DM Series system. Each output receives signals from the mixing and the DMTH4 is no different. The focus and purpose matrix, the pink noise generator or the tone generator is to meet the requirements of modern applications and as needed for setup, diagnostics or operation.

  • Page 9: Digital Matrix

    DMTH4 Functional Block Diagram Digital Matrix The digital matrix provides signal routing and commu- Submix nication with other devices in the system, and applies Power of the Mix automatic mixing and level control.

  • Page 10: Lecnet2 Software

    DMTH4 LecNet2 Software Input Processing Software is included with the DMTH4 and available Each input channel provides individual stages for gain, for download from the website at: www.lectrosonics. filtering and compression. com. The software is used primarily for setup, with the Input Gain configuration saved on file and into the unit’s memory...

  • Page 11: Output Processing

    Digital Telephone Hybrid Output Processing Output Compressor and Limiter Output Source Select A versatile compressor and limiter are provided at each The TEL, CODEC and AUX outputs can each be set to output to control the average level and dynamics of the receive a signal from the pink noise generator, the tone audio signal, and restrict the maximum output level to generator, the expansion outputs or from the master unit...

  • Page 12: Dynamic Compressor

    0. 1 tension reduces gradually as the senses recover. The time [sec] DMTH4 compressor effectively acts in the same manner. DSP controlled, variable attack time is based upon values A dynamic, variable attack time is applied by the DSP to generated by an RMS detector to follow the ears natural apply an optimal rate as the signal transient arrives.

  • Page 13: Dmth4 Controls And Features

    POWER POWER On/Off Switch Note: The DMTH4 is shipped from the factory configured as a Master unit. The Power On/Off Switch is used to turn the DMTH4 on (1) or off (0). Mode Switch USB Port If a unit configured to run in slave mode doesn’t detect...

  • Page 14: Control Panel Overview

    DMTH4 for simple operational scenarios or trouble- last recalled. shooting purposes. Every function of the device can be monitored and adjusted in real time. The control panel can connect to the DMTH4 over a serial port, a USB port, or a network connection. Tabs Menu Bar Status Bar LECTROSONICS, INC.

  • Page 15: Special Key Functions

    Status Bar Offline: Displayed when the control panel is opened but the computer is not connected to a DMTH4. Menu options for features that require a connection to a DMTH4 will be disabled in this mode. Connected: Displayed when the control panel is opened with the computer connected to the DMTH4.

  • Page 16: Dmth4 System Setup Tabs

    Channel Activity/Gain, Output Channel Activity, Tele- (enabled when DMTH4 is connected to computer sys- phone Interface/Acoustic Echo Canceller and Codec tem) and the ability to initiate and accept telephone calls.
  • Page 17 Dial button - Click to dial the telephone number displayed in the telephone number list. It is enabled only when the control panel is connected to a DMTH4. If the telephone interface is not connected to the line, it will be automatically connected before the number is dialed.

  • Page 18: Inputs Tab

    DMTH4 Inputs Tab The Inputs Tab is used to setup and control the inputs to the DMTH4. The tab is divided into three functional sec- tions: TEL, CODEC and AUX. TEL Input Section CODEC Input Section AUX Input Section Gain Control Slider...
  • Page 19 Digital Telephone Hybrid Rio Rancho, NM...

  • Page 20: In Filters Tab (Input Filters)

    DMTH4 settings are stored to a filter settings, with a separate page for each input chan- preset in nonvolatile memory. nel. If connected to a DMTH4, changes made in this tab take effect immediately. As always, the changes are not Filter Set...
  • Page 21 Digital Telephone Hybrid Name Description Filter Set Notebook Filter Number - One of six tabs used to select the filter number. One of six different filters (cont) (see Filter Type) can be applied to each filter number. Input Select Set of three tabs to select input to which filters will be applied: TEL, CODEC and AUX. Frequency Response Each input channel page contains a graph which displays two plots: Graph...

  • Page 22: In Comp Tab (Input Compressor)

    As always, the changes are not tings, with a separate page for each input channel. If permanent unless the DMTH4 settings are stored to a connected to a DMTH4, changes made in this tab take preset in nonvolatile memory. Status...
  • Page 23 Digital Telephone Hybrid Name Description Gain Reduction Displays the reduction in gain (in dB) resulting from compressor activity. Meter Amplitude Each input channel page contains a graph which displays three plots: Response Graph A fixed plot for the 1:1 amplitude response used for reference (dashed grey line) The amplitude response of the compressor (orange line) Total response, the amplitude response of the compressor plus makeup gain (blue line) These plots contain handles which can be used to change the threshold level (or-...

  • Page 24: Matrix Tab

    As always, the changes pages, one for the main matrix and one for the expan- are not permanent unless the DMTH4 settings are sion matrix. If connected to a DMTH4, changes made in stored to a preset in nonvolatile memory. Matrix...
  • Page 25 Digital Telephone Hybrid Name Description Gain Step (dB) - Sets the step rate for increasing or decreasing the crosspoint gain. De- Crosspoint Setting Controls (cont) fault is 1dB. Range can be adjusted from 1dB to 10dB. Automix Mode - Selects the automix mode for the crosspoint. Four modes are available: Auto - mixes the input applied to the crosspoint into the output channel using the Adaptive Proportional Gain automixing algorithm in the normal manner.

  • Page 26: Out Source Tab (Output Source)

    DMTH4 Out Source Tab (Output Source) The DMTH4 is designed to be an integral component of Pink Noise or 1 kHz Tone). a DM Series chain, so each of the audio output chan- The Out Source tab selects the output channel sig- nels can be thought of as a processing pipeline whose nal source.
  • Page 27 Digital Telephone Hybrid Rio Rancho, NM...

  • Page 28: Out Filters Tab (Output Filters)

    Six different filter types are available for each of the six output filters. If connected to a DMTH4, changes made in this tab take effect immediately. As always, the Filter Set...
  • Page 29 Digital Telephone Hybrid Name Description Filter Set Notebook Filter Number - One of six tabs used to select the filter number. One of six different filter (cont) types can be applied to each output filter. Input Select Set of three tabs to select output to which filters will be applied: TEL, CODEC and AUX. Frequency Response Each output channel page contains a graph which displays two plots: Graph...

  • Page 30: Out Comp/Lim Tab (Output Compressor/Limiter)

    The compressor and limiter implementa- If the computer is connected to a DMTH4, changes tions are based on an RMS level detector controlled by made in this tab take effect immediately. As always, the a single time constant parameter.
  • Page 31 Digital Telephone Hybrid Name Description TEL (cont) Compressor Parameters (cont): Ratio - The compression ratio is displayed here and can be adjusted from 1:1 (dis- played as “Off”) to 50:1 (displayed as “INF:1”). Makeup Gain - The makeup gain value is displayed here and can be adjusted from 0dB to a limit which is a function of the threshold and compression ratio.

  • Page 32: Outputs Tab

    This tab is used to set the output levels for the TEL, permanent unless the DMTH4 settings are stored to a CODEC or AUX channel outputs from the DMTH4. If preset in nonvolatile memory. connected to a DMTH4, changes made in this tab take Output Channel Mute Comp/Lim...
  • Page 33 Digital Telephone Hybrid Name Description CODEC (cont) Attenuation control : (CODEC and AUX outputs only) Allows attenuation of the output signal. For normal operation, 0 dB (no attenuation) should be selected. If attenuation by 20 or 40 dB is selected, the output audio is attenuated by those amounts in the analog output amplifier stage.

  • Page 34: Rear Panel Control Tab

    The DMTH4 has 11 programmable inputs which can input and output audio channels. This is an additional be used to control a wide variety of DMTH4 functions. gain value that is added to the “main” gain value for a Depending on the assigned function, the inputs may channel to give the total gain applied.
  • Page 35 When certain functions have been selected and the control panel is connected to a DMTH4, the Test button is enabled. Pressing this button simulates a contact closure on the programmable input and is very useful for testing the function. The following function types...
  • Page 36 Display the status of the corresponding programmable input when a function has been as- Programmable signed and the control panel is connected to a DMTH4. For the Analog Gain Control func- input status indica- tions, the indicator glows red when the voltage applied to the input is in the upper half of tors the allowable 0 to 5VDC range.
  • Page 37 Digital Telephone Hybrid Name Description Programmable Programmable Output Function Select: Selecting a function type from the Function list Outputs Notebook causes the controls used to setup the specific feature or features of that function to appear in below the list. These feature(s) vary according to the nature of the programmable output function values.

  • Page 38: Tel/Codec Tab

    TEL and one for the CODEC interface. If the computer memory and shared between all presets. Changes is connected to a DMTH4, changes made in this tab to the telephone book are always permanent. take effect immediately. As always, the changes are not...
  • Page 39 Mute Both Tx and Rx - Mute both transmit and receive audio when Privacy is engaged. Telephone Acoustic Echo Canceller (AEC) controls display the status of the AEC (when the Acoustic Echo control panel is connected to a DMTH4) and allow it to be enabled or disabled. The controls Canceller and indicators are: Enable AEC/Disable AEC - Configures the AEC as enabled for normal operation, or as disabled for testing purposes.
  • Page 40 (dash, dot, left and right parenthesis) allowed as delimiters to improve readability The following controls are enabled only when the control panel is connected to a DMTH4. Add button - Click to open a dialog box allowing a new telephone book entry to be made.
  • Page 41 Telephone number list - Used for typing in the telephone number to be dialed when the “D” Telephone Interface button is clicked. It is enabled only when the control panel is connected to a DMTH4. This control has a “memory”. Once a number has been dialed, additional numbers may be typed controls (cont) in without losing previously entered numbers.
  • Page 42 DMTH4 Name Description Codec Interface Codec interface control is allowed only when the control panel is connected to a DMTH4. controls Connect/Disconnect - Toggles the connection state of the interface. Connection LED - Glows red when Codec Interface is connected.

  • Page 43: Serial Interface And Control Commands

    The preset location to be modified is specified by using the address syntax. Addresses must The only wildcard available for use with the DMTH4 be in the range 1 to 24. No data is transferred. commands is the “*”. This wildcard is used to mean “all”...
  • Page 44 This command is used as a query to read the user This command may be used as a query to determine if the DMTH4 is operating as a Master or as a Slave. It defined device description, or as an update to set the description.
  • Page 45 Digital Telephone Hybrid store (store settings to preset) Examples: Request Response This command is used to store current settings to a premsk?<CR> OK 2<CRLF> Query memory preset. The preset location to be updated is specified by using the address syntax. Addresses must premsk=5<CR>...

  • Page 46: Dmth4 Audio Input Commands

    DMTH4 DMTH4 Audio Input Commands iniv (input phase invert) This command is used as a query to read the input channel phase invert status, or as an update to set the Command Description status. The input channel is specified by using the ad-...
  • Page 47 Digital Telephone Hybrid inmttog (input mute toggle) This command is used as a simple command to toggle the input channel mute status. The input channel is specified by using the address syntax. Addresses must be in the range 1 to 3. Example: Request Response...

  • Page 48: Dmth4 Matrix Crosspoint Commands

    DMTH4 DMTH4 Matrix Crosspoint Commands means that the crosspoint is in BACKGROUND mode means that the crosspoint is in AUTO mode Command Description If an entire row is being transmitted then the data type is array of integer of size 24. In this case the value 99...

  • Page 49: Dmth4 Audio Output Commands

    Digital Telephone Hybrid DMTH4 Audio Output Commands outattn (output attenuation) This command is used as a query to read the output attenuation value, or as an update to set the value. The Command Description output channel is specified by using the address syntax.
  • Page 50 DMTH4 outsrc (output signal source) This command is used as a query to read the output signal source status, or as an update to set the status. The output channel is specified by using the address syntax. Addresses must be in the range 1 to 3. The data...

  • Page 51: Dmth4 Input Compressor Commands

    Digital Telephone Hybrid DMTH4 Input Compressor Commands incprat (input compressor ratio) This command is used as a query to read the ratio, or as an update to set the ratio. The input channel is specified Command Description by using the address syntax. Addresses must be in the...

  • Page 52: Dmth4 Output Compressor Commands

    DMTH4 DMTH4 Output Compressor Commands outcprat (output compressor ratio) This command is used as a query to read the ratio, or as an update to set the ratio. The output channel is speci- Command Description fied by using the address syntax. Addresses must be...

  • Page 53: Dm Output Limiter Commands

    Digital Telephone Hybrid DM Output Limiter Commands Command Description outlmtc Output limiter time constant outlmthr Output limiter threshold level Note: All commands are terminated with an ASCII carriage return character (hex code 0x0D), represented by <CR> in the examples. All responses are terminated with an ASCII carriage return, line feed pair (hex codes 0x0D, 0x0A), represented by <CRLF>...

  • Page 54: Dm Programmable I/O Commands

    DMTH4 DM Programmable I/O Commands prgindef (programmable input definition) This command may be used as a query to read a pro- grammable input definition, or as an update to modify Command Description the definition. The programmable input is specified by...
  • Page 55 Digital Telephone Hybrid Function Target Values Examples: Request Response Analog input gain control A sequence of zero or more integers in the range 1 to 8. These identify prgindef(9)?<CR> OK{4,1,3,4,10}<CRLF> Query which input channels are to be (Function “Analog output controlled by the function.
  • Page 56 DMTH4 Examples: prgout (programmable output state) Request Response This command is used as a query to read a program- prgoutdef(8)?<CR> OK{3,1,3,4}<CRLF> Query mable output state. The programmable output is specified (Function “Monitor active by using the address syntax. Addresses must be in the preset”...

  • Page 57: Dmth4 Rear Panel Control Commands

    Digital Telephone Hybrid DMTH4 Rear Panel Control Commands rpingnmin (rear panel audio input gain minimum) This command is used as a query to read the rear panel input gain minimum, or as an update to set the gain Command Description minimum.
  • Page 58 {0,-5,99}<CR> OK<CRLF> mask which specifies which settings are restored and which are not. This mask has the same format as the preset mask. (See also DMTH4 General Commands, rpoutgnmin premsk.) (rear panel audio output gain minimum) Example:...

  • Page 59: Dmth4 Telephone Interface Commands

    Digital Telephone Hybrid DMTH4 Telephone Interface Commands telautoans (telephone auto answer) This command may be used as a query to determine the status of the telephone auto answer feature. It may also Command Description be used as an update to enable or disable auto answer.
  • Page 60 DMTH4 telconnchm (telephone connection chime) Examples: Request Response This command may be used as a query to determine teldtmf=”3”<CR> OK<CRLF> Update the status of the telephone connection chime feature. It may also be used as an update to enable or disable teldtmflv (telephone DTMF level) the connection chime.
  • Page 61 Digital Telephone Hybrid telflash (flash telephone hookswitch) telprivmod (telephone line privacy mode) This command may be used to “flash” the telephone This command may be used as a query to read the pri- hookswitch (momentarily break and then re-make the vacy mode setting for the telephone line interface.
  • Page 62 DMTH4 telringing (telephone ringing status) This command may be used as a query to determine if an incoming telephone call is detected by the telephone line interface. The data type is integer, either “1” meaning true (ring pulses detected), or “0” meaning false.

  • Page 63: Dmth4 Codec Interface Commands

    Digital Telephone Hybrid DMTH4 Codec Interface Commands codconn (codec connection status) This command may be used as a query to determine the connection status of the codec interface. It may also be Command Description used as an update to make or break a connection to the...
  • Page 64 DMTH4 codpriv (codec privacy) This command may be used as a query to determine the privacy status of the codec interface. It may also be used as an update to enable or disable the privacy feature on the codec interface. The data type is integer, either “1”...

  • Page 65: Dm Command Grammar Rules

    Digital Telephone Hybrid DM Command Grammar Rules Augmented BNF[1] Rules for the Lecnet2 command grammar: OCTET = %x00-FF; <any 8-bit sequence of data> CHAR = %x01-7F; any US-ASCII character except NUL (1 - 127) UPALPHA = %x41-5A; any US-ASCII uppercase letter “A”..”Z” LOALPHA = %x61-7A;...

  • Page 66: Fcc Part 68 Compliance

    If trouble is experienced with this equipment, please sive REN on the telephone line may result in the devices contact Lectrosonics, Inc. at (800) 821-1121 for repair not ringing in response to an incoming call. In most, but and/or warranty information. If the trouble is causing...

  • Page 67: Specifications And Features

    Digital Telephone Hybrid Specifications and Features Connectors: Echo Canceller (3 Total): (2 Acoustic) - 126 mS tail time Audio I/O: 5-pin “Phoenix” type (1 Line) - 30 mS tail time Expansion: RJ45 Logic I/O: DB25 Will never diverge, regardless of signal type Serial: Standard USB and mini TRS (i.e.

  • Page 68: Service And Repair

    There are no adjustments inside that will make a malfunctioning unit start working. LECTROSONICS’ Service Department is equipped and staffed to quickly repair your equipment. In warranty repairs are made at no charge in accordance with the terms of the warranty. Out-of-warranty repairs are charged at a modest flat rate plus parts and shipping.
  • Page 69 Digital Telephone Hybrid Rio Rancho, NM...
  • Page 70 This warranty does not apply to used or demonstrator equipment. Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any defective parts without charge for either parts or labor. If Lectrosonics, Inc. cannot correct the defect in your equipment, it will be replaced at no charge with a similar new item.

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