UltraScope Users Manual
Contents
1. 312 5kHz Note that UltraScope only has 220kHz usable signal bandwidth available due to limitations of the analog anti alias filters Therefore only the first 180 values are meaningful the rest fall into the analog filter transition band CAY Page 14 To convert each 5 digit FFT value to dB SPL sound pressure level use the following formula dB SPL integer value G 30500 where G is dependent upon the preamplifier gain setting that is output as part of the sequence G is also dependent upon whether the Microphone or Line Input is used which can also be determined from the sequence Select G according to the following table Input Gain 0dB Gain 10dB Gain 20dB Gain 30dB Microphone 124 114 104 94 Line Input 100 100 100 100 Table 2 G Value Lookup Table Note that the value of G does not change as a function of preamplifier gain when the Line Input is used since the preamplifier gain is not applied to the Line Input Also the dB SPL calculation will most likely NOT be accurate when the Line Input is used since the actual sensitivity of the connected device cannot be known However when the supplied ACO Pacific mic is used the calculated dB SPL will be fairly accurate generally within 2dB CAY Page 15 5 0 SPECIFICATIONS Input Connections Line Input Preamp Input Input Gain Stage Input Highpass Filter Equivalent Input Noise Bandwidth Frequenc2. The Mic Gain setting adjusts the preamplifier gain for the mic input it has no effect on the Line Input Selectable values include 0 10 20 and 30 dB Reducing the gain allows greater sound pressure levels to be accepted without clipping while increasing the gain allows lower sound pressure levels to be detected The input level options are listed below Applied Mic Gain Maximum Input SPL 0 dB 124 dB 10 dB 114 dB 20 dB 104 dB 30 dB 94 dB Table 1 Mic Gain vs Maximum Input SPL CAY Page 12 The Low Cut setting selects whether the built in 20kHz highpass filter is On or Off If on the filter is applied to the input signal and attenuates all human audible signals that are input from the mic before preamplification as specified by the Mic Gain setting This feature allows the gain to be applied to ultrasonic frequencies only thus avoiding clipping distortion in loud audible noise environments Note that like the Mic Gain setting the Low Cut setting has no effect on signals applied to the Line Input Demodulation selects whether double side band DSB upper side band USB or lower side band LSB amplitude demodulation is applied to the selected 10kHz frequency band Normally the DSB setting is recommended as better low frequency response can be obtained on the demodulated audio output In cases where single sideband modulation is suspected and or there are adjacent noise signals near the carrier frequenc
3. and a NiMH rechargeable battery pack with charger CAY Page 1 1 1 Dual and Single Side Bands A signal modulated onto an ultrasonic carrier will most likely take on one of two main forms These forms are referred to as Single Side Band SSB and Dual Side Band DSB amplitude modulation To explain these two forms of modulation some background in spectrum analysis is needed Magnitude Time Figure 1 Simple Sine Wave Figure 1 shows a simple sine wave In the frequency domain spectrum this sine wave is represented by two spikes about the zero axis representing the energy concentrated at the frequency of the sine wave A 1 KHz sine wave would be represented in the frequency domain by a single spike at 1 KHz above and below the baseband 0 Hz axis as shown in Figure 2 A more complex audio signal would have energy at many frequencies An example audio spectrum is shown in Figure 3 Magnitude 1 KHz 1 KHz Frequency 0 Figure 2 1 KHz Sine Wave Representation in the Frequency Domain CAY Page 2 Magnitude Frequency 0 Figure 3 Example Audio Spectrum An ultrasonic carrier looks very similar to the 1 KHz Sine Wave in the frequency domain except it will be at a much higher carrier frequency f generally one well in excess of 20000 Hz so that it is completely inaudible to humans Magnitude fo R fc Frequency Figure 4 Ultrasonic Carrier Frequency Spectrum Modulated audio on an ultrasonic carrier will look simi
4. is thorough the use of electronic equipment The traditional approach for sniffing out transmitters of this type is to connect an ultrasonic microphone to a general purpose spectrum analyzer and look for line spectra in the ultrasonic region The difficulties with this approach are twofold first though the spectrum analyzer can determine if an ultrasonic signal is present it cannot determine whether it is a benign signal such as that produced by a motion sensor or a malicious one that is being used as a covert communications path Second the equipment is generally bulky and AC powered which is difficult to manage and transport from room to room as needed for a thorough sweep To address these difficulties DAC has developed the UltraScope product UltraScope is a handheld battery powered ultrasonic acoustical analyzer which incorporates an ultrasonic mic and precise FFT spectrum analyzer along with a unique feature the ability to select a 10 kHz region of signal to demodulate to the audible band for listening This is a dramatic improvement over traditional technology because it allows the user to listen to the ultrasonic signal in question and determine its nature or origin Other features of the UltraScope include a Line Out connector to allow the user to record any signals of interest a large backlit LCD display for viewing the frequency spectrum and setting operating parameters a large user friendly keypad with rotary controls
5. 12V DC power The 12V DC Power connector is for powering the UltraScope unit with the included power supply unit The external power supply can both power the UltraScope unit and charge the rechargeable NiMH battery packs The batteries will continue to be charged when the unit is powered off The Line Out connector attaches to any 3 5mm mono or stereo plug For stereo plugs the signal will be present only on the left channel The output signal is a line level approximately 1Vims maximum level signal containing the demodulated audio of the selected frequency selecting the frequency is discussed in the Front Panel Functions section The Phones connector attaches to any standard 3 5mm stereo headphone connector To listen to the demodulated audio simply attach a standard pair of stereo headphones to this connector and adjust the loudness using the Volume connector on the front panel The RS 232 connector is for attaching the included RS 232 cable that has a standard 9 pin D shell connector on one end and a 3 5 mm stereo plug on the other This connector allows the connection of UltraScope to a PC for advanced data logging applications see Section 4 0 DATA LOGGING for further details on this feature CAY Page 7 2 3 Front Panel Functions BD UltraScope POWER DISPLAY ZOOM ON OFF MENU A UTILITY E MENU ADJUST VOLUME Figure 10 UltraScope Front Panel The front panel provides control for each of the Ult
6. L x 3 7 W Optional Pelican carrying case and accessory kit 9600 baud rate 1 stop bit no parity bits Outputs measurements in ASCII format in response to any character input see Section 4 0 Adaptor cable for connection to standard PC COM port supplied N Page 16 CAY Page 17 CAY Page 18
7. NPUT will appear at the top of the LCD display The spectrum of the input signal is plotted using the remainder of the display This spectrum is the frequency domain representation of the input signal and on a band by band basis shows the peak energy level of frequencies from 0 to 220 000 Hz at its lowest zoom level Using this display any ultrasonic carrier frequency will show up as a spike of higher energy within a particular band CAY Page 9 0 220KHC Figure 12 UltraScope Spectrum Display Use the Adjust knob to select which frequency is demodulated and output to the headphones and line output The cursor which is a vertical bar the full height of the display area can be moved using the Adjust knob and will graphically display the currently selected frequency and peak level To increase the currently selected frequency turn the Adjust knob in the clockwise direction To decrease the selected frequency turn the knob in the counter clockwise direction To change the step size by which the selected frequency is changed by the Adjust knob use the Coarse Fine button Each time the Coarse Fine button is depressed the step size will change and the new step size will be displayed on the LCD display Supported step sizes vary from 4 Hz finest adjustment to 10000 Hz most coarse adjustment The Zoom and Zoom buttons expand the viewed spectrum around the current cursor region This new range of frequencies being vi
8. ULTRASONIC LISTENING DEVICE UltraScope User s Manual Firmware Version 2 0 Technology to Make Listening Easier ULTRASONIC LISTENING DEVICE UltraScope USER S MANUAL Firmware Version 2 0 September 13 2001 DIGITAL AUDIO CORPORATION A DRI Company 5121 Holly Ridge Drive Raleigh NC 27612 Phone 919 782 6767 Fax 919 782 6766 TABLE OF CONTENTS 1O BACKORO UN D ss ee ee 1 1 1 Dual and Single Side Bands ENEE 2 1 2 Ultrasonic Acoustical Intensity oooooooccccnnnncccinnnaconocnononcconanananannnonnnnnnnnnnnnnnnnnnnos 5 20 ULTRASCOPEORERATIO Na ee ee eee eee ee a 6 2 17 Top Panel FUNCHONS ae er 6 2 2 Bottom Panel Functions dee dc ee elect feta 7 2 3 Front Panel FUNCIONS eebe Ee 8 2 3 1 Spectrum Viewing EE eessen 9 E Display AGA iea ie 11 23 3 MY EE 12 2 4 Powering the EE 13 3 0 ULTRASCOPE CALIBRATION EE 14 40 DATA LOGGING EE 14 3 0 SPEGIFISATIONS a rs 2 ya Ma EEE Eat 16 LIST OF FIGURES AND TABLES Figure 1 ul EE 2 Figure 2 1 KHz Sine Wave Representation in the Frequency Domain 2 Figure 3 Example Audio Gpechum EEN 3 Figure 4 Ultrasonic Carrier Frequency Spectrum ccccceceeeeeeeeeeeeeeneeeeeeeeeeeeeeeeeneees 3 Figure 5 Dual Side Band Modulated Audio een 3 Figure 6 Upper Single Side Band Modulated Audio 4 Figure 7 Lower Side Band Modulated Audio 4 Figure 8 UltraScope Top E TEE 6 Figure 9 UltraScope Bottom Panel 7 Figure 10 UltraScope Front EE Eeer ee 8 Figure 11 U
9. cts a line level signal of approximately of 800mV ms or less The Line In connector allows the UltraScope to be used with other signal detection and countermeasures products like Digital Audio Corporation s ProbeAMP By routing the line output from the ProbeAMP into the line input of the UltraScope carrier current devices can be detected on power lines and telephone lines and demodulated for listening If a stereo 3 5mm plug is used to connect a signal to the Line In connector note that only the left channel signal is actually accepted the right channel signal will be ignored by the unit The Preamp connector allows connection of the included ultrasonic microphone and or extension cable The connector is an industry standard Lemo microphone connector which provides an extremely reliable connection and is easily mated and unmated The microphone simply snaps into place as if it were an antenna The Enable Disable Backlight switch is used to allow or disallow illumination of the built in backlight on the front panel LCD To allow the backlight to be turned on and off via software control put the switch in the Enable position To ensure that the backlight remains off at all times put the switch in the Disable position CAY Page 6 2 2Bottom Panel Functions LINEOUT PHONES RS 232 E POWER Figure 9 UltraScope Bottom Panel The bottom panel allows for connection of the output audio signals RS 232 communications and
10. ewed is shown in the upper left corner of the LCD To zoom in increase the frequency resolution around the current cursor position depress the Zoom button To zoom out decrease the frequency resolution depress the Zoom button When initially powered on the UltraScope defaults to the lowest zoom level all frequencies displayed The second smaller Volume knob is used to change the listening level of the signal routed to the headphone jack To increase the listening level turn the knob clockwise To decrease the listening level turn the knob counter clockwise The new listening level as a percentage of maximum will be displayed momentarily on the LCD display each time the Volume knob is turned CAY Page 10 2 3 2 Display Menu The Display Menu button is used to access the menu which allows the user to alter how information is displayed on the graphical LCD Depressing this button will cause the Display Menu to appear as shown in Figure 13 From this menu the user can adjust the LCD contrast and the backlight mode BACK LIGHT AUTO CONTRAST 100 Figure 13 UltraScope Display Menu To select the Display Menu options use the Zoom and Zoom buttons Once the desired menu option is selected use the Adjust knob to change the value The Backlight mode option determines how the backlight is applied when the top panel Backlight switch is in the Enable position In the Auto mode the backlight will stay i
11. highly directional in nature which means that detection devices need to be pointed directly at such a device perhaps even within a narrow angular window in order to acquire the signal Hence a handheld portable device such as UltraScope is highly desirable as it is easily moved around and pointed in different directions To support operation in high intensity ultrasound environments UltraScope can accept acoustic energy as loud as 124dB SPL without clipping Also to allow additional gain to be applied to just the ultrasound in high audible noise environments UltraScope includes a 20kHz highpass filter which can be switched in and out of the circuit ahead of the preamplifier This allows the user to apply up to 30dB of additional gain to the ultrasound via the UTILITY MENU without introducing clipping distortion CAY Page 5 2 0 ULTRASCOPE OPERATION 2 1 Top Panel Functions ENABLE LINE IN PREAMP DISABLE BACKLIGHT NOT A HIGH WARNING VOLTAGE INPUT Figure 8 UltraScope Top Panel The top panel allows connection of the inputs to the UltraScope as well as control of the backlight for the LCD The Line In connector allows attachment of an 3 5 mm stereo plug to input an alternate signal other than the Preamp signal to be analyzed by the UltraScope If a signal source is connected to the Line In connector this input will be used instead of the Preamp connector signal The Line In expe
12. lar to Figure 5 This type of modulated audio is DSB as both the positive and negative frequency information is centered on the carrier frequency fc Magnitude fo 5 fe Frequency Figure 5 Dual Side Band Modulated Audio Note that the complete signal spectrum is symmetric about 0 Hz The UltraScope takes advantage of this symmetry and displays only the positive frequency spectrum on the LCD display since the negative frequency information is identical and contributes nothing extra to the analysis UltraScope s display plots the signal spectrum over a range of 0 Hz to 220 kHz which is approximately 10 times the range of human hearing CAY Page 3 Note also that the DSB signal that is centered about f is also symmetrical in effect an extra copy of the desired audio signal is being transmitted This duplication of information can be eliminated using SSB modulation thus improving the spectral and power efficiency of the transmission system SSB modulation is represented in the following figures Figure 6 shows upper side band USB modulated audio and Figure 7 shows lower side band LSB modulated audio Magnitude fe o fe Frequency Figure 6 Upper Single Side Band Modulated Audio Magnitude fo fe Frequency Figure 7 Lower Side Band Modulated Audio Note that USB modulated audio Figure 6 is a clear signal and simply needs to be frequency shifted to baseband 0 Hz for listening However LSB modulated audio is a
13. lluminated for 30 seconds after any knob or button activity To manually control the backlight simply set to On or Off as needed To ensure that the backlight remains off at all times simply set the Backlight hardware switch on the rear panel to the Disable position The Contrast option allows adjustment of the LCD display s contrast Increasing the contrast percentage will darken the LCD display while decreasing the percentage will lighten the display Adjust the contrast as needed for different lighting conditions Depressing the Display Menu button again will return the user to Spectrum Viewing Screen All Display Menu values will be retained in the UltraScope s flash memory upon power down CAY Page 11 2 3 3 Utility Menu The Utility Menu button is used to access a menu that allows the user to alter settings that affect the global operation of the device Depressing this button will cause the Utility Menu to appear as shown in Figure 14 From this menu the user can enable or disable the Low Cut filter adjust the Microphone Gain select the type of demodulation to be applied to the selected 10kHz region or select the number of averages to apply to the FFT analysis Mic GAIN 30 Low GUT OFF DEMODULATION AVERAGING O DSB Figure 14 UltraScope Utility Menu To select the Utility Menu options use the Zoom to and Zoom buttons Once the desired menu option is selected use the Adjust knob to alter the value
14. ltraScope Splash Screen ENNEN 9 Figure 12 UltraScope Spectrum Display Ae 10 eeler ET EE 11 Figure 14 UltraScope Utility Men 12 Table 1 Mic Gain vs Maximum InpuboP EE 12 Table 2 or le Lookup Table ee EE 15 1 0 BACKGROUND Ultrasonic vibrations are above the range of human hearing Ultrasound is typically considered to be all acoustic energy above 20 000 Hz Although humans cannot hear such high frequencies a number of other creatures including insects dogs and whales can Ultrasound is also exploited in various electronic products including sonar medical imaging high tech cleaning systems and industrial materials testing equipment Ultrasound can also be used to transmit signals through the air in a manner very similar to radio or infrared transmissions Signals containing audio data or other intelligence can be modulated onto ultrasonic acoustical carriers amplified and transmitted using specialized high frequency transducers If the transmitted acoustical signal is sufficiently strong it can travel outside the building where it can be recovered with the proper receiving equipment At the receiver the recovered signal can be demodulated and the audio or intelligence revealed Note that ultrasound produces no electromagnetic energy that would be detectable using an RF sweep receiver the vibrations are purely mechanical Since ultrasound is completely inaudible to the human ear the only way to detect ultrasound
15. lways spectrally inverted meaning that low and high frequency signals are transposed For intelligible listening then LSB modulated audio must be frequency inverted once it is frequency shifted to baseband UltraScope supports all three types of amplitude modulation DSB USB and LSB These modes can be selected via the UTILITY MENU CAY Page 4 1 2Ultrasonic Acoustical Intensity Practical ultrasound communication systems require a high intensity acoustical carrier particularly if the intent is to convey an audio signal from the inside of a building to the outside This carrier though completely inaudible can be in excess of 110dB SPL or roughly the same intensity as a burglar alarm when it is activated This means that any effective detection equipment needs to have sufficient dynamic range that it can accept the extremely intense acoustical signal that is present within the building as well as the relatively weak 40dB SPL or less residual acoustical signal that may be present outside the building The Ultrascope system offers approximately 100dB of dynamic range and is capable of distinguishing acoustical energy in the range of 20dB SPL to 120dB SPL High intensity sources of ultrasonic acoustical energy include such items as motion sensors insect repellers and audio countermeasures devices that are intended to defeat microphones Computer equipment as well as rotating machinery can also emit ultrasonic energy Such signals are
16. omes too low the LOW battery indicator will be shown at the upper left corner of the LCD display CAY Page 13 3 0 ULTRASCOPE CALIBRATION UltraScope is factory calibrated and should remain accurate as long as the supplied ACO Pacific ultrasonic mic is utilized with the unit If other mics are to be used or if the accuracy of the level measurements ever becomes suspect please return the unit along with the microphone to DAC for proper calibration 4 0 DATA LOGGING UltraScope s RS 232 interface allows computer logging of the FFT spectral data for subsequent analysis To utilize this feature simply connect the supplied DB 9 to 3 5mm adaptor cable to the RS 232 jack and connect the DB 9 end to the serial port of your PC Your logging software will need to be configured to operate as follows Baud Rate 9600 Number of bits 8 Parity None Stop Bits 1 Handshaking None To receive FFT data on the PC the logging software will need to send a single character to the UltraScope to trigger the data transmission The data will be configured as follows Microphone for Lineln Gain 30 preamplifier gain setting in dB Each Bin is 1220 7Hz 12345 first of 256 FFT points each one a 5 digit decimal integer 23456 e O 0 32100 256th FFT point The first FFT point output represents the DC 0 Hz band while subsequent points represent subsequent frequency bands at intervals of 1220 7 Hz e g OHZ 1220 7Hz 2441 4Hz
17. raScope s features The Power On Off button is used to turn the unit on or off To turn on the unit depress the Power On Off button To turn off the unit depress the Power On Off button again CAY Page 8 When the unit is initially powered on the first screen to appear momentarily on the LCD will be the splash screen Figure 11 displaying the firmware version number currently Version 2 0 An introductory audio clip will also be played on the headphone and line outputs The firmware is the software that runs internally on the UltraScope After the splash screen has disappeared the Spectrum Viewing Screen will appear UltraScope F 2001 Digital Audio Corp v2 Figure 11 UltraScope Splash Screen 2 3 1 Spectrum Viewing Screen The Spectrum Viewing Screen shown in Figure 12 displays the current spectrum of the input signal The current range of frequencies graphed is displayed in the upper left corner of the LCD display The frequency and instantaneous level of the band that is currently being demodulated and output via the headphones and line output is shown in the upper middle portion of the display the frequency and level are alternatively displayed at 2 second intervals The overall dB level of the input signal is displayed in the upper right corner of the display as well as graphically by the thick bar on the far right of the display If the input signal becomes too strong and an overload condition occurs I
18. y either LSB or USB should be used with the understanding that the demodulated audio will sound somewhat tinny due to low frequency rolloff below approximately 2 5kHz Averaging selects the amount of smoothing to apply to the FFT spectral data as it is being displayed Range of values is 0 10 in increments of 1 with 0 indicating no smoothing applied and 10 indicating that the average of the last 10 FFT frames is being displayed Note that the averager is peak sensitive in the case where 10 averages are applies if any of the last 10 FFT frames has a level that is higher than the current average value the average value gets set to that peak so that it is not missed by the user Depressing the Utility Menu button again will return the user to the Spectrum Viewing Screen All Utility Menu values will be retained in the UltraScope s flash memory upon power down 2 4 Powering the Unit The unit can powered from either a rechargeable NiMH nickel metal hydride battery pack one included by the 12 VDC AC adaptor included or by a 4 cell AA alkaline battery pack optional accessory Contact DAC for replacement battery packs AC adaptors or other optional accessories While the unit is being externally powered the NiMH battery pack if installed will also be recharged Four standard AA alkaline batteries can be used in the optional accessory battery pack Whenever the unit is powered by batteries and the battery voltage level bec
19. y Selectability Line Output Phones Output Power Packaging RS 232 Industry standard Lemo connector on Preamp Input Standard 3 5 mm stereo connector on Line Input Accepts either mono or stereo plugs 800mV ms Maximum input level gt 100 kilohm input impedance Only left channel connected when stereo plug used Typical 3mV or less input level from supplied ACO Pacific ultrasonic microphone 15 kilohm input impedance Supplies required 28VDC and 200VDC polarization voltages required by ACO Pacific mic 24dB to 54dB adjustable in 10dB increments Applied to preamplifier input only 20 kHz cutoff frequency Can be switched in and out as desired Applied to preamplifier input only Less than 1000 nVrms 100 220 000 Hz Any 10kHz region from 0 to 220kHz can be selected for listening Minimum step size of 4Hz allows precision tuning Either DSB USB or LSB demodulation can be selected 1Vims Nominal output level Capable of driving 1 kilohm or higher impedance load Standard 3 5 mm stereo connector accepts mono or stereo plugs Signal on left channel only when stereo plug is used 3 5 mm stereo phone jack drives standard 8 Ohms stereo headphones Monaural signal applied to both ears 9 18 VDC external DC power input 2 1 mm barrel plug positive tip NiMH battery pack Four AA standard alkaline batteries requires optional accessory pack Rugged ABS plastic housing approximately 1 Ib 2 1 H x 9 0
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