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Motorola GM1200E, Installation Manual

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Reducing Noise Interference in Mobile Two-Way Radio Installations

2-i

Chapter 2

Reducing Noise Interference in 

Mobile Two-Way Radio Installations

Table of Contents

Table of Contents

Paragraph

Page

1.0

Introduction ................................................................................................ 1

2.0

Noise Sources ............................................................................................ 1

2.1

Radiated Noise ............................................................................................ 1

2.2

Conducted Noise ......................................................................................... 2

2.3

Induced Noise.............................................................................................. 2

3.0

Operation of a Conventional Ignition System ......................................... 3

4.0

Detection of Noise Sources ...................................................................... 4

5.0

Noise Reduction Techniques .................................................................... 7

5.1

General ........................................................................................................ 7

5.2

Ignition System Interference ........................................................................ 7

5.3

Battery Connections .................................................................................... 8

5.4

Alternator/Generator Whine......................................................................... 9

5.5

Voltage Regulator Noise............................................................................ 10

5.6

Hood and Trunk Lid Noise ......................................................................... 10

5.7

Other Electrical Noises .............................................................................. 11

5.8

Wheel Static............................................................................................... 11

5.9

Ground Bonding......................................................................................... 11

5.10

Extender Radios ........................................................................................ 12

Summary of Contents for GM1200E

Page 1: ...European Publications Department RPG Fleet Hampshire England Issue May 1998 GM1200E Mobile Radio Installation Manual 68P64112B07 ...

Page 2: ...ii ...

Page 3: ...apter gives details on planning procedures for installing the radio Descriptions on the accessory connector and the internal connections for the databox radio are also provided 2 0 Reducing Noise Interference in Mobile Two Way Radio Installations Describes ways of reducing noise interference when installing the radios ...

Page 4: ...Table of Contents iv Installation Manual ...

Page 5: ...ing and Procedures 4 5 1 Installation Planning Mobile Radios 4 5 2 Installation Planning Antenna Mounting 4 6 0 Radio Mounting 5 6 1 Mounting Trunnion 5 6 2 DC Power Cable Installation 5 6 3 Mounting Trunnion Installation 6 6 4 Radio Mounting in an Automotive Dashboard 9 6 5 External Speaker Installation 10 6 6 Remote Mount Controlhead Installation 10 7 0 Accessory Connector Pin Functions 12 7 1 G...

Page 6: ...Table of Contents 1 ii Radio Installation ...

Page 7: ...d park before making or answering a call if driving conditions so require 2 0 Installation Safety Warning Installation of vehicle communication equipment should be performed by a professional installer technician qualified in the requirements for such installations Consider the occupants safety when you choose a location for the radio Do not mount the radio overhead or on a side wall unless you ta...

Page 8: ...e LP gas container in the trunk or other sealed off space within the interior of the vehicle The NFPA58 requires the following 1 Any space containing radio equipment shall be isolated by a seal from the space in which the LP gas container and its fittings are located 2 Removable outside filling connections shall be used 3 The container space shall be vented to the outside WARNING For vehicles equi...

Page 9: ... through 180 This useful feature provides multiple mounting options for the radio For example the radio may be mounted on either side of the vehicle transmission tunnel with the cooling fins of the radio against the side of the tunnel to facilitate the safest and ergonomically ideal position The control head is then positioned to provide most convenient user access To reverse mount the control hea...

Page 10: ... frequency energy levels higher than recommended by the American National Standards Institute ANSI In Metallic Body Vehicles with transmitters at any frequency having a power output in excess of 7 watts it is mandatory that when using a glass mount antenna the installation instructions covering the location of the antenna at the top of the front or rear window and the cable routing be followed exa...

Page 11: ...icle ground polarity before you begin installation to prevent wasted time and effort The 3 meter 10 feet DC power cable shipped with the radio is long enough for installation in most vehicles Begin the power cable installation in the following manner 1 Determine a routing plan for the power cable with reference to where the radio is to be mounted 2 Locate an existing hole with a grommet in the veh...

Page 12: ...ly to the battery may result in severe alternator whine interference Figure 1 2 Power Cable Assembly 6 3 Mounting Trunnion Installation 1 Select the location to mount your radio either on the Transmission Hump or Under the Dash see Figure 1 5 By mounting the trunnion on the transmission hump take care the transmission housing is not affected 2 Using the trunnion mounting bracket as a template mark...

Page 13: ... connector on the rear of the radio see Figure 1 4 8 Mount the microphone clip to a convenient spot near your radio 9 Plug the microphone into the control head connector Your microphone has a telephone type connector at the end of its cord 10 To complete your radio installation plug the power cable into the radio power connector see Figure 1 4 Figure 1 4 Connections to Radio rear Thumb Screw Trunn...

Page 14: ...Radio Mounting 1 8 Radio Installation Figure 1 5 Transmission Hump Mounting top and Below Dash Mounting bottom ...

Page 15: ...ut in the dashboard and if necessary enlarge it to the dimension shown in Figure 1 6 2 Insert the mounting frame into the cutout and bend the six tabs see Figure 1 7 to hold it in place Press the Bezel onto the mounting frame 3 Slide the radio into the mounting frame Figure 1 7 Mounting Frame Detail 4 Make necessary connections to the radio for the power antenna and accessory connector as shown in...

Page 16: ...ssory plug into the accessory connector of radio 6 6 Remote Mount Controlhead Installation To remove the front housing 1 Remove the control head from the radio using a flat blade screw driver Insert the screw driver in the recess between the control head and the radio Press until the side of the control head releases 2 Pull the control head away from the radio Remove the flex connector from the so...

Page 17: ...unt the trunnion with the supplied screws 2 Ensure the socket gaskets are in the back of control head and radio front housing and connect the remote mount cable to both connectors 3 Snap the control head into the mounting trunnion and fix it with the wing screws For more information on the remote mount kit please refer to the accessory chapter in the Basic Service Manual section 5 of the Product M...

Page 18: ... pin is as an external alarm output See Note 3 5 Flat_TX_Audio NPD Data Out This input is intended for injecting signals into the transmit path that should not be filtered e g the digital output of a modem The nominal input level is 150mVRMS for 60 deviation The impedance is greater than 25kohms 6 SCI Data In Bus This connects to the radio s SCI serial bus which is used for programming and tuning ...

Page 19: ...that the hook is a mechanical switch so the software will always debounce this input Also available on the microphone connector pin 3 15 RSSI This is an analog output which indicates the strength of the received signal 16 External Speaker Positive output of radio s audio PA see Pin 1 Note 1 Digital Input 4 7 kΩ Internal Pull Up Resistor to 5V Maximum Input Voltage accepted as Low 0 6V Minimum Inpu...

Page 20: ...ogic input to radio from terminal equipment Activation of line will immediately clear the call Note Application notes dealing with the functionality of NPD are given in Appendix C of the Basic Service Manual 7 2 Radio Power Up Down Power to the radio is via the supply line and the radio is normally switched on off using the On Off button however for a data radio this is not feasible The following ...

Page 21: ...until either the supply is removed or the IGNITION SENSE line is de activated It is recommended that during installation of the Databox radio the SUPPLY and IGNITION SENSE lines are linked together and connected to the switchable power supply This will allow the radio ON OFF to be controlled by activating and de activating the the switchable power supply Note The radio must be powered up using one...

Page 22: ... the appropriate accessory or technical manual for further information Refer to the Basic Service Manual chapter 3 for accessory service information CAUTION 1 DO NOT short pin 16 or 1 on the accessory connector to ground this may damage the radio CAUTION Ensure correct position of the accessory connector 4 86 85 12V 12V 4 86 85 Alternative Alternative Alarm Relay Alarm Relay 87 87 30 30 12V 12V ...

Page 23: ...Radiated Noise 1 2 2 Conducted Noise 2 2 3 Induced Noise 2 3 0 Operation of a Conventional Ignition System 3 4 0 Detection of Noise Sources 4 5 0 Noise Reduction Techniques 7 5 1 General 7 5 2 Ignition System Interference 7 5 3 Battery Connections 8 5 4 Alternator Generator Whine 9 5 5 Voltage Regulator Noise 10 5 6 Hood and Trunk Lid Noise 10 5 7 Other Electrical Noises 11 5 8 Wheel Static 11 5 9...

Page 24: ...Table of Contents 2 ii Reducing Noise Interference in Mobile Two Way Radio Installations ...

Page 25: ...duction provisions the manufacturer applies when AM AM FM or CB radios are installed as original equipment These radios are also subject to electrical noise interference and the manufacturer may install noise suppression components only upon those vehicles which require radio equipment at the time of manufacture These noise suppression components should be added in any first attempt to suppress no...

Page 26: ...erators voltage regulators or weak batteries Conducted noise can degrade both transmit and receive performance of a mobile radio 2 3 Induced Noise Induced noise enters the radio through the proximity of radio wiring to other wiring in the vehicle Electrical currents through the standard vehicular wiring can induce undesirable noise signals into the radio cabling and degrade communication simply be...

Page 27: ...m Figures 2 2 a mechanical circuit breaker the cam and points in the distributor opens the primary circuit of the ignition coil and high voltage is developed at the secondary This high voltage is synchronized and applied to each spark plug by the distributor Figure 2 2 Typical Vehicular Ignition System Simplified Schematic Diagram The battery is connected to the primary winding of the coil through...

Page 28: ... the effective noise suppression Use your available equipment to best advantage A pick up loop about one inch in diameter can be connected to a portable CB radio or a mobile radio being operated at a frequency similar to the installed radio frequency but from an isolated supply voltage The pick up loop can be moved throughout the vehicle with the radio used as a radiated noise detector Be sure the...

Page 29: ...se suppress the vehicle during a less noisy time of day or in a different quieter location 1 2 3 4 5 6 1 4 1 4 Notes 1 Noise reduction can only be achieved if components are grounded properly 2 Items not supplied in kit See auto parts dealer Generator Be sure that all the capacitors and the generator filed suppressor assembly are grounded properly This may require bonding straps for proper bypass ...

Page 30: ...rces cannot be turned on and off at will These sources will need to be attacked piecemeal on a trial and error basis alternator whine voltage regulators electric fuel pump etc Remember that induced noise can result from radio wiring being too close to other vehicle wiring This problem is most easily solved by proper cable routing at the time of installation Radiated noise must be attacked after co...

Page 31: ...ure that spark plug wires make good solid contact at each end and are routed as far as possible from low voltage leads 5 Many late model automobiles are equipped with a shield over the distributor points Check to see that this shield is properly positioned and securely attached 5 2 2 Available Noise Reduction Kits Motorola offers two noise reduction kits Model TLN8845A for alternator equipped vehi...

Page 32: ...r cap inserts as the rotor turns To suppress this noise use resistance ignition wire to connect the ignition coil to the distributor cap 5 3 Battery Connections The radio set power cable can pick up noise generated in the vehicle This can be minimised by connecting the power cable directly to the battery instead of the fuse block The battery acts like a large capacitor about one Farad for a 50 amp...

Page 33: ...t see figure 2 6 and 2 7 Figure 2 6 Generator Whine Suppression Figure 2 7 Alternator Whine Suppression Step 1 Step 3 Step 4 Caution Do not connect capacitor to field terminal Connect capacitor lead to armature post Connect wire lead to capacitor using lockwasher and nut Mount Capacitor 0 5µF Coaxial Type under generator ground screw Step 2 Disconnect wire dashed from armature post and connect to ...

Page 34: ...caused by friction in poorly bonded automobile hoods or trunk lids which causes static electricity to build up until arcing occurs This type of noise is suppressed using a Motorola Hood Wipers and Mounting Hardware Kit part of TLN8845A or TLN6252A Noise Reduction Kits which provides electrical bonding of the hood or trunk to the vehicle body while permitting them to be opened CAUTION Disconnect th...

Page 35: ...ss noise from this source using wheel static collector rings Motorola Part No 1K534254 regular type 1K653173 small type 5 9 Ground Bonding Static charges can build up on various parts of a vehicle if not properly bonded and cause noise through arcing This type of noise is suppressed by bonding the part using one inch wide ground straps keep them as short as possible Some common points where bondin...

Page 36: ...e noise impulse as it passes through the receiver Motorola radios with the Extender feature have additional circuitry which blanks the receiver for the duration of the undesired noise pulse so that annoying pops are not heard The Extender receiver effectively chops out the small portion of the message which contains pops This type of receiver is effective in areas where other noisy vehicle ignitio...

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