B&K 4070A Dtmf Detection Mode, Dtmf detection on Ext Mod input 3 # a, Dtmf detected digits

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5.17 DTMF Detection Mode

Introduction

Dual Tone Multi Frequency detection mode decodes and displays the Touch-tone dialing tones according to ANSI T1.401-1988 Section 7.2 standard. Input test signal could be applied to the External Mod Input for DTMF decoding. Once a DTMF digit has been detected, it will appear on the LCD display and will also be sent to the RS-232 terminal port.

The input signal must be 10 Vp -p or less. If the input signal exceeds 10 Vp -p, the waveform will distort and adversely affect the DTMF detector. The DTMF detector in the 4070A features an AGC algorithm, which boosts low-level signals (20 mVp -p or greater) to detect low-level DTMF tones.

For reliable detection, each DTMF digit must be present for a minimum of 100 mS. There must also be a minimum silent period of 100 mS between each DTMF digit.

The Ext Mod In input is high impedance (about 30KO). If your system expects this signal to be terminated, place a resistor (of the appropriate terminating resistance) across this input.

*** Caution ***

Do NOT connect the Ext. Mod In input directly to a telephone line. High voltages exist on a telephone line, which will cause permanent damage to the 4070A. Input levels above ±25 V may damage the 4070A. See appendix A for a suitable telephone line interface.

Background

Each DTMF dialing tone consists of two sinusoids of different frequencies, which are added together to form the output waveform. These frequencies were chosen so that they are not harmonically related. The table of each dialing digit and its associated Dualtone frequencies could be listed in 5.16

DTMF Detection Mode Parameters

The DTMF Detection mode has the following front panel display:

1

DTMF detection on Ext Mod input:

1 2 3 # A 4

Figure 5.17-1: DTMF Detection mode display

1. DTMF detected digits

All detected digits appear on this line of the display. The display shows up to 40 detected digits.

When the 41st digit is detected, this line of the display is cleared and the new digit is printed on the left hand side. All detected digits are sent to the terminal port. By connecting a computer to the terminal port, the 4070A can be

used as DTMF detection peripheral. See the example program in Appendix A.

2. RS-232 Port

All DTMF detections are printed to the terminal port. When a DTMF digit is detected (the digit 6 is given here as an example), a carriage return and a linefeed plus the following text is sent to the terminal:

DTMF: 6

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BK Precision 4070A User Manual Rev.2.2

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Contents User’s Manual Page Model 4070A User’s Manual +K Precision CorpTable of Contents Arbitrary waveform system Warranty informationRemote operation DC Operation OptionIntroduction Description Feature summary ModesSync out connector Installation and setupSIG Out connector External Modulation In connector External Trigger/Gating/FSK/BPSK input RS232 Interface connector External Reference Input / Ext Arb. Clock connectorExternal Arb Sync In / Out connector Line in connectorField arrow keys Mode keyOperating controls and keys Recall / Store keyNumeric keys 0 to 9, Trigger keyÉ, ê, è, ç keys Clear key One Touch Mode KeysMHz/dBm, KHz/Vp-p/Sec, Hz/mVp-p/mS keys Changing frequency Operating mode selectionOperating guide Changing levelModifying an existing value Changing valuesEntering a new value Basic Sinewave CW Mode Mode descriptionsSinewave Mode 000,000.00 Hz 10.0 dBm Internal AM Mode External AM Input gain 000,000.00 Hz PEP level -10.0 dBm External AM ModeExternal AM Mode Parameters Input GainInt FM 1,000 Hz Pk dev 10,000 Hz 000,000.00 Hz 10.0 dBm Internal FM ModeInternal FM Mode Parameters Peak Frequency DeviationExternal FM Mode Parameters External FM ModeExternal FM Pk dev 10,000 Hz 000,000.00 Hz 10.0 dBm Peak Phase Deviation Internal PM ModeInternal PM Mode Parameters Int PM 1,000 Hz Pk dev 180 deg 000,000.00 Hz 10.0 dBmExternal PM Mode Parameters External PM ModeExternal PM Pk dev 180 deg 000,000.00 Hz 10.0 dBm Sweep Mode Up / Down sweep Sweep timeMark Frequency Internal FSK ModeInternal FSK Mode Parameters Space FrequencyExt FSK Mark 1,000,000.00 Hz Space 2,000,000.00 Hz 10.0 dBm External FSK ModeExternal FSK Mode Parameters Ext FSK InputBurst Mode Trig Ton 10,000 mS 000,000.00 Hz Off 10.0 dBm Burst Mode IntroductionBurst frequency Int SSB 1,000 Hz Upper Sideband 000,000.00 Hz 10.0 dBm Internal SSB ModeInternal SSB Mode Parameters Upper/Lower Sideband selectionsExternal SSB Mode Parameters External SSB ModeExternal SSB Upper Sideband 000,000.00 Hz +10.0 dBm Dtmf Generation Mode Parameters Dtmf Generation ModeDtmf generation # Duration 200 mS Delay Level -10.0 dBm BackgroundDtmf Delay Dtmf DurationDtmf detection on Ext Mod input 3 # a Dtmf Detection ModeDtmf Detection Mode Parameters Dtmf detected digitsPower Level Power & Voltage Measurement ModePower & Voltage Measurement Mode Parameters Voltage LevelRemote Mode Arbitrary ModeOther mode Internal Bpsk Mode Parameters Internal Bpsk ModeInt Bpsk 1,000 Hz 000,000.00 Hz 10.0 dBm External Bpsk Mode Parameters External Bpsk ModeExternal Bpsk 000,000.00 Hz 10.0 dBm Dualtone Generation Mode 10,000 Hz F2 Ton 000 mS Toff 10.0Dualtone Examples Data Modulation Mode Parameters Data Modulation ModeUsing the Data Modulation Mode Baud RateDownloading Modulation Message Data Example MessageTriggering the Transmission Saving the MessageStart End 1,000,000.00 Hz 10.0 dBm Voltage Controlled Oscillator VCO ModeVCO Mode Parameters End FrequencyRemote Operation ConnectingChecking your connection with Hyper Terminal Remote Control Operation Remote Control Programming Rules× Ø Remote Control CommandsReset 4070A to Sine wave mode Returns CE1,0 Enable, Disable LCD echo to terminal K1.0 Enable, Disable front panel keys and rotary knobReport hardware and software versions ? or H Print help menu Linear Trig Up Time 10,000 mSF0-9 Move cursor to field 0 to Return a CRemote Control Examples ExampleQuick Start Guide Arbitrary Waveform ModePin 9-pin cable Pin 25 pin cable adapter Introduction to the Arbitrary Waveform System Description of the Arbitrary Waveform GeneratorFunction Generator Switching ModesFeature Summary Pulse GeneratorPhase Arbitrary Waveform ModeInt Clock / Ext Clock / Lock Master Lock slave mode Continuous/Triggered modeWaveform Function Generator ModeFunction Gen Wave Pos Ramp Rep Freq 100,000 Hz 000 mV Repetition FrequencyPositive Only Pulse Generator ModeDuty Cycle Saving Arbitrary Waveforms Using WAVELOAD.EXEDownloading arbitrary waveforms Cwaveload /COMx /y /baudz filename.extUsing your own program Floating Point Format Data FormatsRules for Floating Point format Time & Value Floating Point Format Example #2Digital Format Integer Format Rules for Hexadecimal format Hexadecimal FormatExample The data value E468 is handled as follows Rules for Binary format Binary FormatExample Arb Multiple Units LockingGenerator Starting Address = Number of waveform points * Phase Offset More on Phase OffsetsPhase Resolution Waveform Size RestrictionsExample Arb Program Program Listing ARB.BASClose System Subroutines Return Print #1, a Send integer value to 4070A Return Return Wiring Diagram DC Operation Option4070A Specifications Operating ModesSoftware CD RemoteHardware Setup Appendix aCLS CLS Print Print Subroutines END SUB Television Remote Control Example Appendix BCLS Make sure a 4070A is attached to the serial port Print Limited Two-Year Warranty Service Information Savi Ranch Pkwy Yorba Linda, CA 92887 USA TEL