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The Model 531N is not a perfect receiver in this regard, but it

does yield useful

comparative

readings. When switched to read

AM noise, the upper

DEMOD METERING

bargraph

(7)

gives a

relative

indication of the demodulated AM component. This

metered value does

not

have linear-dB scaling. What is

heard

the headphones (or via the rear-panel

AM NOISE

output con-

nector) will have the greatest significance in exposing incidental

AM noise in the FM carrier.
It is important to have a strong signal for AM noise measure-

ments. As you listen off-air and tune among local stations, the

amount of ‘non-synchronous’ background noise (noise

not

as-

sociated with the transmitted program) will vary quite a lot.

What you want to listen for

the program-related noise, which

should have only odd-order harmonic content. The 531N can

be used as a tool in tuning transmitter stages for minimum

program-related ‘garbage’; just remember that what you hear

through the headphones or with an audio monitor is more im-

portant that what is displayed on the meter.
Though the 531N can prove an effective tool in monitoring and

minimizing AM noise, an off-air measurement should not be

considered a substitute for a dedicated broadband AM-noise

measuring set connected directly to the FM transmitter. We

acknowledge the

Radio Design Labs ACM-3

as the definitive

such device and recommend it as an excellent aid in transmitter

stage tuning.

Audio Loss

Alarm

It is important to realize that in FM broadcasting an

AUDIO

LOSS

alarm is meaningless in the absence of an RF carrier. It is

the nature of FM receivers to put out a ‘white noise’ (hiss) level

that can exceed normal program peak values when no carrier is

received. The 531N indicates

AUDIO LOSS

for a ‘dead air’ or

missing channel situation, but will not give an alarm when no

station at all is tuned in. In the case of carrier failure, a

LOW

SIGNAL

alarm would be dispatched.

AUDIO LOSS

alarm is triggered when the peak level of either

program channel falls below –10dB on the

DEMOD METERING

meters

(7)

for an interval of time programmed as described be-

low. The

AUDIO LOSS

alarm lights the panel indicator

(26)

provides a rear-panel closure to ground for remote indication,

and dispatches SMS/text or email notifications through the Web

interface.
Cycle the

SELECT

button

(14)

to light the

A-LOSS

indicator

(23)

The digital readout

(12)

now shows the delay interval, in se-

conds, between audio loss and the alarm. This delay can be

programmed with the

ADJUST

buttons

(13)

from 1 second to

120 seconds (2 minutes).

Содержание 531N

Страница 1: ...531N FM Modulation Analyzer with Networking Installation User Guide www inovonicsbroadcast com ...

Страница 2: ......

Страница 3: ...ffective with Serial No 3200 Inovonics Inc 5805 Highway 9 Felton CA 95018 Tel 831 458 0552 Fax 831 458 0554 Register online at www inovonicsbroadcast com PRODUCT REGISTRATION RECORD 531N Serial No __________________ Purchase Date _____________________ Warranty Registered Web Reg Date __________ By ____________ ...

Страница 4: ......

Страница 5: ...ort Miscellaneous BLOCK DIAGRAM 11 Section II INSTALLATION UNPACKING AND INSPECTION 12 MOUNTING 12 Rack Requirement Heat Dissipation AC MAINS POWER 11 Mains Voltage Selector Mains Fuse Power Cord RADIO FREQUENCY INTERFERENCE RFI 13 Location Ground Loops RF INPUTS 13 Antenna Input and Antennas Direct RF Input RF Input Switching COMPOSITE MULTIPLEX CONNECTIONS 14 Composite Output Composite Input Com...

Страница 6: ...TERFACE SETUP 20 PANEL CONTROLS AND INDICATORS 20 THE READOUT SECTION LEFT SIDE 21 Phones Carrier Modulation Demod Metering THE RECEIVER SECTION RIGHT SIDE 22 Digital Readout Freq Station Presets 1 6 Signal Level Multipath Stereo Forced Mono De Emphasis Subcarrier Measurement Audio Loss Peak Flasher Alarm Indicators Network Settings MEASUREMENT PITFALLS AND LIMITATIONS 25 Signal Strength Multipath...

Страница 7: ...rimary DNS HOOKING UP 34 COMPLETING THE NETWORK SETUP 34 The Network Page ACCESSING THE 531N REMOTELY 36 Dynamic DNS SNMP OPERATION 37 SNMP Overview SNMP Security SNMP Traps SNMP Ports Downloading the MIB File Further Study EMAIL PREFERENCES 39 Mail Server Setup Saving and Testing TIMEKEEPING 40 ADMINISTRATIVE SETTINGS 41 Password Lost Password Hard Reset The Hardware Profile Errata Section V 531N...

Страница 8: ...STATISTICS 48 SIGNAL ALARMS 49 Peak Overmodulation Audio Loss Low Signal and Multipath EMAIL AND TEXT MESSAGE NOTIFICATIONS 51 THE ALARM LOG 52 Alarm Log Capacity Downloading and Clearing the Alarm Log Section VI UPDATING THE 531N THE FIRMWARE UPDATER 53 Warning Firmware Update Files Running the Firmware Updater Updating the Web Interface Pages APPENDIX INOVONICS WARRANTY INSIDE BACK COVER ...

Страница 9: ...cts to validate readings and simplify antenna align ment Synthesized tuning with a digital readout and six sta tion presets memories to compare one s own signal with those of market companions An exclusive synchronous incidental AM noise meas urement utility to aid in transmitter alignment Selective display of common data and analog subcarri er injection levels Panel indicators tally outputs and e...

Страница 10: ...et ter than 65dB below 100 modulation with de emphasis applied Distortion 0 075 THD at 400Hz with 100 modula tion and no de emphasis Stereo Separation Refer to Figure 3 Crosstalk Measurement M S and S M crosstalk measurement is by the stereo sum difference method Refer to Figure 4 De Emphasis May be turned on and off from front panel or with Web interface internal jumper for 50µs or 75µs Program A...

Страница 11: ...SCELLANEOUS AC Mains Requirements 105 130VAC or 210 260VAC 50 60Hz 20W Size H 3 in 89mm W 19in 483mm D 12in 305mm Weight 14lbs 6 35kg shipping weight Environmental Continuous operation guaranteed at ambi ent temperatures between 32 F 0 C and 122 F 50 C 0 95 relative humidity non condensing altitudes to 10 000ft 3048m Conformances EN50081 1 EN50082 1 93 68 EEC 2002 95 EC Figure 1 Amplitude Response...

Страница 12: ...10 Figure 3 Typical Stereo Separation Figure 4 Typical Crosstalk Measurement Limits BLOCK DIAGRAM Figure 5 a simplified Block Diagram of the Model 531N Modulation Ana lyzer appears on the following page ...

Страница 13: ... 11 ...

Страница 14: ...OTE Many users choose first to familiarize them selves with equipment on the bench or at their desk in which case they may immediately turn to Section III that describes 531N setup and use Do please refer back to this section how ever to confirm proper physical installation and interconnec tion with other station equipment MOUNTING Rack Requirement The 531N mounts in a standard 19 inch equipment r...

Страница 15: ...e detachable IEC type power cord supplied with the 531N is fitted with a North American standard male plug If you need to replace the mains plug with another you will find that the individual cord conductors are color coded in one of two ways US standards specify black for AC hot white for AC neutral return and green for earth ground European CEE standards specify brown for AC hot blue for AC neut...

Страница 16: ...nna or DIR direct high level in puts COMPOSITE MULTIPLEX CONNECTIONS Composite Output The rear panel MPX OUT connector is a direct output from the FM demodulator An internal buildout resistor sets the source impedance at 100 ohms This output is intended for oscillo scope monitoring or for feeding outboard analysis equipment with high impedance bridging inputs Observe good laboratory practice and a...

Страница 17: ... R measurements CONTROL AND TALLY TERMINALS The GPIO interface for remote control and alarm connections is a 16 terminal tie down strip The screw terminal part of this strip unplugs from the chassis to make wiring and servicing more convenient Simply grab the plastic part that protrudes from the back panel and give it a hard pull Remote Preset Selection The six front panel STATION PRESETS may be r...

Страница 18: ...mote hookup which in cludes a carrier loss indication that would be difficult to ignore Figure 6 Suggested Remote Alarm Connection DE EMPHASIS SELECTION The 531N accommodates both the 75 microsecond Western Hemisphere and 50 microsecond Europe and Asia FM broad casting pre emphasis standards De emphasis that is appropri ate to the shipping destination is set at the factory but this is easily chang...

Страница 19: ...jacent channel signal But by allowing repetitive peaks to drive modu lation consistently past the legal limit the broadcaster is court ing the wrath of his regulatory agency The FCC s Measurement Method One reliable guideline in determining just how far you dare go with respect to total carrier modulation is with an awareness of how at least one government authority monitors a broadcast er s signa...

Страница 20: ...ard with the front panel assembly Just behind this cable below IC17 you ll find a 4 position jumper strip labeled JP2 The jumper shunt can be pulled off and replaced in any of 4 positions each position identified in the PC board legend Figure 8 at the top of the following page shows proper shunt placement for each integration selection 100µs Integration 200µs Integration 500µs Integration 1ms Inte...

Страница 21: ... reasoning the availability of more complex and more expensive audio processing equipment is a testament to its belief and to the paranoia and shortsighted ness of station ownership and management Aggressive audio processing and the accurate measurement of resulting carrier deviation are interwoven in broadcasting to day But the high degree of technical capability that we now have at our disposal ...

Страница 22: ...anufacture prior to a networking utility being added We thus recommend starting with front panel setup as this method not only gives the immediate gratification of a hands on experience but is necessary for initiating network connectiv ity in the first place PANEL CONTROLS AND INDICATORS The following overview of the Model 531N front panel is keyed to the coded front panel photographs that appear ...

Страница 23: ...ent with 100 corresponding to 75kHz carrier devia tion This display is quasi peak responding and it updates and holds the highest peak momentarily as a single glowing segment above the dynamic display When both the POS DEV 3 and NEG DEV 4 indi cators are lighted the highest deviation in either polarity is displayed This is the default measure ment mode By cycling the SELECT button 6 the display ma...

Страница 24: ... displayed on the upper of the bargraph readout pair and the lower readout is blanked Although a meter reading of 0dB does correspond to 100 carrier amplitude modulation meter scal ing is not the annotated linear dB function below this point and the measurement should be consid ered a relative more less one When AM NOISE 10 is selected the incidental AM component is heard in the headphones THE REC...

Страница 25: ...ative indica tion of incoming RF signal strength Generally three or more display segments must be lighted for valid modulation readings The LOW SIGNAL alarm 26 will light when the RF level is too low NOTE If all SIGNAL LEVEL readout 17 segments including the top most are lighted the receiver should be considered overloaded for purposes of AM noise measurement only Total modulation readings will re...

Страница 26: ...on shows up on the CARRIER MODULATION display 2 The SUB PILOT indicator 5 lights and percent injection may be read against the scale markings below the bargraph Subcarrier levels may also be read with acceptable precision using the FFT baseband spectrum display available through the Web interface This is dis cussed on Page 45 23 AUDIO LOSS Loss of program audio gives a front panel indica tion 26 a...

Страница 27: ...erpart Nevertheless random noise does result in a certain amount of dither at carrier zero crossings which translate to jitter in the time domain that can sabotage accurate measurement of total carrier deviation The basis for FM receiver sensitivity specifications dates to the early days of monaural FM broadcasting Tuners from this era boasted sensitivities in the low microvolt range Honest and fo...

Страница 28: ... A multipath alarm comes on when more than a couple of the MULTIPATH bargraph segments are lighted The associated alarm is preset to the maximum value of multipath distortion that can be tolerated for an accurate to tal mod reading Composite Clipping A small amount of well regulated hard clipping of the com posite waveform is a common technique with broadcasters to secure maximum modulation effici...

Страница 29: ...A more directional antenna may solve the problem or a band pass filter may be required at the primary frequency or a trap at the interfering frequency A GUIDED TOUR OF 531N OPERATION The short hands on tutorial that follows walks you through setup and typical operation of the Model 531N using the front panel controls and readouts The additional features available using the Web interface are discus...

Страница 30: ...to minimize multipath pickup Neither the LOW SIGNAL nor the MULTIPATH alarm indicators 26 should light If either alarm condition is indicated choose another station or connect a roof mounted antenna When the 531N is in actual Mod Monitor service the two signal quality warning indicators 26 must be off if measurements are to be trusted This usually calls for a rooftop antenna with a rotator for mea...

Страница 31: ...sistently meeting a deviation goal Using this feature as the intended alarm on the other hand requires that the trip level be set somewhat above the maximum modulation point Again if the processor is set to hold peaks at precisely 100 an alarm value of 102 might be selected This would represent a value that should never be attained in normal oper ation one that would indicate a legitimate fault Pi...

Страница 32: ...off to get a meaning ful measurement of any residual 38kHz component What shows on the display when program information is present is low frequency stereo difference information Demod Metering The default mode for DEMOD METERING 7 displays left and right channel program material with the LEFT RIGHT indicator 8 lighted Use the SELECT button 11 to cycle the DEMOD METERING display 7 to show stereo su...

Страница 33: ...in will turn de emphasis back on As you cycle program de emphasis on and off you may notice that although the audio sounds quite different the left and right channel program audio displays 8 do not change much if at all Despite a very audible difference there is very little musical energy at the high frequencies It s the subtle overtones that are boosted out of proportion without proper de emphasi...

Страница 34: ...onsidered a substitute for a dedicated broadband AM noise measuring set connected directly to the FM transmitter We acknowledge the Radio Design Labs ACM 3 as the definitive such device and recommend it as an excellent aid in transmitter stage tuning Audio Loss Alarm It is important to realize that in FM broadcasting an AUDIO LOSS alarm is meaningless in the absence of an RF carrier It is the natu...

Страница 35: ...Press the NETWORK SETTINGS button once again to return to a readout display of dHCP The IP Address With dHCP showing on the readout press the right hand AD JUST button to bringIP onto the display Press NETWORK SETTINGS once and the first address group of the current IP will appear very probably the digits192 If the IP address is to be assigned manually DHCP would have been set to OFF and you would...

Страница 36: ...should see the main Now Playing Webpage on your screen as shown here A header at the top of the page and a Menu list on the left are common to all 531N Web pages The header displays the tuned frequency alarm status indicators signal quality readouts and the remote listening utility COMPLETING THE NETWORK SETUP Before we get to the interesting everyday useful aspects of the 531N Web interface let s...

Страница 37: ... the particular hardware of your 531N and cannot be changed You are free to change the Hostname from the factory assign ment to whatever you wish The Hostname allows the user to assign a unique ID to the equipment Once you are on the same network this is what you enter into a Windows browser ad dress bar to connect a Windows computer tablet or mobile de vice to the 531N The HTTP Port has a default...

Страница 38: ...atic IP ad dress then it is a simple matter to address the 531N from any where Just type the IP address and port number into your browser as shown in this example http 55 76 38 170 2345 But if your ISP issues you a dynamic IP which is most often the case this mandates Dynamic DNS operation using the ser vices of an IP forwarding provider Dynamic DNS It would not be possible to address equipment be...

Страница 39: ...ion right onto the screen and click Save This will allow you to access your 531N with a dynamic IP ad dress SNMP OPERATION SNMP Overview SNMP or Simple Network Management Protocol allows other TCP UDP IP equipment on the same Local Area Network LAN to communicate directly with the 531N and for the 531N it self to initiate an alarm on the network The 531N will interface directly with a network cont...

Страница 40: ...nhibits communicaton between the 531N and the SNMP Manager Click the arrow to the right of Disabled to view operating choices Changing the Mode to Read Only allows the 531N to be interro gated by the SNMP Manager so that 531N settings meters RDS data and alarms can be integrated with other equipment on the network ...

Страница 41: ...usu al Windows manner The MIB file is in plain text and may be read with Windows Notepad Further Study The foregoing discussion of SNMP operation is purposely ab breviated SNMP is a complex utility managed exclusively by whatever SNMP Manager the monitoring equipment is em ployed Refer to published instructions for the SNMP Manager in setting up the 531N From the active 531N SNMP browser screen yo...

Страница 42: ...en the Time Time Zone Web screen to set up the internal timekeeping function of the 531N Correct timekeeping is es sential for tagging alarm notifications and for meaningful Alarm Log listings Select your offset from Universal Coordinated Time operation on planet Earth is assumed here using the Time Zone Hours slider When this is set correctly local time will show at the top of the window You may ...

Страница 43: ...periodically downloading and saving a Hardware Profile which retains all the setup data and can be uploaded back to the 531N This procedure is described in due course Of course the old lost password is part of the Hardware Profile so you must edit this file before uploading it otherwise you ll be back to where you started The snapshot at the right shows the very bottom of the Hardware Profile wher...

Страница 44: ... to a Downloads folder unless you are asked for a specific save to location The file has a default name of 531Nsettings ini To upload a saved Hardware Profile to your 531N first click Browse to locate the saved profile on your computer and then click Upload Hardware Profile This will replace all setup parameters that are currently loaded and running in your unit Errata At the bottom of the Admin W...

Страница 45: ...ould be running the Web interface setup of which was covered in the previous Section THE WEB SCREEN HEADER All Web screen pages present the common header shown here At the far left is the frequency of the currently tuned station Next is the audio streaming utility Remote Listening Click the loudspeaker icon in the header to listen to the station from a remote location Two audio quality options are...

Страница 46: ...anada so these two are re lated in those countries Elsewhere Callsign will be blank PS the Program Service Name is an 8 character field where sta tions call letters or street name for display on any RDS radio faceplate The PS field is often dynamic to scroll song artist and title information in this area Radio Text is a 64 character field that is displayed by some ra dios but not by all This field...

Страница 47: ... shown as Empty or already has an entry The Web screen directly re flects the six STATION PRESETS buttons on the front panel Just click any Station Preset to tune immediately to that fre quency GRAPHS AND METERING MPX Spectrum Display The first item under Graphs Metering is MPX FFT This pre sents a spectrum display of the composite MPX baseband sig nal demodulated from the off air signal or the pl...

Страница 48: ... the first example shows a densely modulated program audio signal with an apparently wide soundstage or stereo image very probably the result of stereo enhancement by the station s audio processor The central image is of a station ID between music cuts which has no appreciable L R component a monaural program for all intents and purposes Note that the plot is pretty much a 45 degree diagonal line ...

Страница 49: ...n accordance with the selected display period Mod provides a first order measure of program loudness as the amount of time that program peaks spend at or near the maximum modulation value is a persua sive indication of program audio density In the example above this station looks to be pretty well within US modulation guidelines A highly processed Babyface track was playing at the graph start poin...

Страница 50: ...a wealth of information about the RDS subcarrier being received Here is an example of the RDS utility put to good use by a station About the only thing that this station does not transmit is the local Time Many stations elect not to send time data rather than risk sending incorrect time or the wrong DST or UTC off set info which tends to make listeners quite irate The RT fields indicate that this ...

Страница 51: ...an important section of the 531N Web interface utility that requires thoughtful setup Also the time stamp feature for email notifications and the Alarm Log depends on Internet time plus the proper time off set and relationship to DST Correct time setup should be con firmed before proceeding here Internet time setup was ex plained on Page 40 Peak Overmodulation The front panel Peak Flasher is dupli...

Страница 52: ...eshold fixed at about 10dB with respect to 0dB on the peak responding DEMOD METERING scale This means that dead air or a missing channel will trig ger an alarm Nearly any broadcast for mat even classical music programming will con tain peaks that reach the Audio Loss trigger point Nonetheless to avoid unnecessary alarms from short instances of dead air or pianissimo passages a Time On Sec setting ...

Страница 53: ...e Web screen click the ar row at the right of the Recipient box This will display a pull down list showing all potential recipients of alarm messages In the example the first recipient is selected an SMS text messaging address for Ron Smith the station s Chief Engineer Now select the various alarm notifications and logs that will be automatically dispatched by text message to the C E This is shown...

Страница 54: ...een sent to Ron s phone immediately and these three will remain in the log until cleared Alarm Log Capacity Status is a notation of how full the log is at the moment Alt hough the log is capable of containing a couple of thousand events it might be important to know when you have accumu lated a certain number of entries The Email when full slider sets up an independent email noti fication when the...

Страница 55: ...wnload Alarm Log This opens a browser dialog box where the log may be opened immedi ately with a de fault text reader or the csv file download for ar chiving or for fur ther analysis with a spreadsheet program Click Clear Alarm Log to purge all entries ...

Страница 56: ... A bootloader is a simple software routine that runs on any PC connected to the same network as the 531N Refer to Section IV for specifics on assuring a connection between the 531N and your computer This must be a wired LAN connection for both the PC and for the 531N Attempting to use a Wi Fi link will almost guarantee failure Warning A firmware update will restore the 531N to factory defaults All...

Страница 57: ...own here advising that the Firmware Updater does not yet find the 531N Click OK to start the firmware updating utility and display its main screen The bootloader window outlines the firmware update process in three easy steps The first step advises that the 531N must it self be in the boot loader firmware update mode Simply hold down the two SELECT buttons 6 and 11 on the left side of the 531N fro...

Страница 58: ... Hardware Profile to reclaim all user setup parameters Page 42 Updating the Web Interface Pages If a new version of firmware calls for a Webpage update there will be an extra Webpage Uploader exe file in the Firm ware Update folder The snapshot at the right shows this file identified with an arrow Immediately after the firmware update is bootloaded while the 531N is in communication with your comp...

Страница 59: ... 57 ...

Страница 60: ...modification or if the serial identifi cation label has been removed or altered III TERMS OF WARRANTY Inovonics Inc products are warranted to be free from defects in materials and workmanship A Any discrepancies noted within THREE YEARS of the date of delivery will be repaired free of charge or will be replaced with a new or remanufactured product at Inovonics option B Parts and labor for factory ...

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