ANC_4TW8x11a TIMEWAVE ANC 4 Noise Canceller Manual

User Manual: Pdf TIMEWAVE-ANC-4-noise-canceller-Manual

Open the PDF directly: View PDF .
Page Count: 22

ANC-4

ANTENNA NOISE CANCELLER

for Reducing

Locally-Generated Noise

Instruction Manual

Revision 2.1 March 12, 2003

TIMEWAVE TECHNOLLOGY INC.

LIMITED ONE YEAR WARRANTY

This warranty is extended only to the original purchaser of the ANC-4.

If your ANC-4 fails in normal use because of a defect in workmanship or materials

within one year of the date of purchase, we will repair or replace (at our option)

the equipment at our factory without charge to you. Timewave will pay for the

return of the warranty-repaired unit to you.

First, double check your connections and operating procedure. If you're certain

that the unit is faulty, notify Timewave Customer Service immediately. If

Timewave is unable to resolve the problem by telephone or email, we will give

you an RMA number and ask you to return the unit. You must pay all shipping

and insurance charges for returning the unit to our factory.

We cannot be responsible for damage caused by accidents, abuse, misuse,

improper installation, or unauthorized attempts to repair the unit.

Timewave service work performed in connection with this warranty is warranted

to be free from defects in materials and workmanship for 30 days from the date

of rerpair. All other terms of the limited warranty apply to the service warranty.

Contact Timewave Customer Service by telephone at (651) 489-5080 or by FAX

at (651) 489-5066.

Mailing and shipping address is 501 W. Lawson Ave., St.Paul, MN 55117-4771.

email: sales@timewave.com

techsupport@timewave.com

service@timewave.com

web: www.timewave.com

TIMEWAVE MAKES NO OTHER WARRANTY, EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED

TO THE IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

WARRANTY

WHO IS COVERED

WHAT WE WILL DO

WHAT YOU MUST DO

WHAT IS NOT

COVERED

SERVICE WARRANTY

HOW TO CONTACT

TIMEWAVE

CONTENTS

SECTION 1

SECTION 2

BRIEF DESCRIPTION ............................................................... 1

QUICK OPERATION ................................................................. 3

Connect Power ................................................................................ 3

Connect Noise Antenna .................................................................. 3

Connect Outside Antenna ............................................................... 3

Connect Unit to Receiver Antenna Connector ................................ 3

Connect to Station Ground ............................................................. 3

Turn On Power ............................................................................... 3

Control Settings .............................................................................. 3

Tune in Noise on the Receiver........................................................ 3

Adjusting for Minimum Noise ........................................................ 4

High Frequency Operation (Over 20 MHz) .................................... 5

Reducing Hang Time For Break-In CW Or

AMTOR/PACTOR Use ......................................................... 5

Broadcast Station Notch ..................................................................5

Broadcast Band Filter.......................................................................5

CONNECTIONS .......................................................................... 8

Power Requirements ....................................................................... 8

Vehicular Operation ....................................................................... 8

Main Antenna Input ........................................................................ 8

Radio Input ..................................................................................... 8

Noise Antenna ................................................................................ 8

CONTROLS & INDICATORS ................................................... 9

NOISE PHASE Control .................................................................. 9

PHASE RANGE pushbutton .......................................................... 9

FREQ RANGE pushbutton ............................................................. 9

NOISE GAIN Control .................................................................... 9

OPERATION .............................................................................. 10

Local Noise ................................................................................... 10

Active Antenna ............................................................................. 10

General Operating Hints ............................................................... 11

TECHNICAL INFORMATION ............................................... 12

Specifications................................................................................ 12

TROUBLESHOOTING ............................................................. 13

GENERAL THEORY OF OPERATION ................................ 15

SECTION 3

SECTION 4

SECTION 5

SECTION 6

SECTION 7

SECTION 8

FIGURES

FIGURE 1

FIGURE 2

FIGURE 3

FIGURE 4

FIGURE 5

FIGURE 6

FIGURE 7

Front Panel Controls ....................................................................... 6

Rear Panel Connectors.................................................................... 6

Connection Diagram ....................................................................... 7

Printed Circuit Board Parts Placement ......................................... 16

Principle of Operation .................................................................. 16

Block Diagram ................................................................................17

Schematic Diagram .........................................................................18

SECTION 1

BRIEF

DESCRIPTION

The ANC-4 is an rf device which is designed to provide cancellation of

locally generated noise from signals received by a primary antenna. This

unit is employed right at the antenna connector of the receiver or

transceiver to cancel locally generated noise, such as power line noise,

computer noise, TV-generated interference, etc., before it gets into the

receiver and affects the receiver AGC circuits. This will allow the

reception of signals well below the noise level induced by the local

interference.

To cancel locally generated interference, the interference signal must be

detected and its phase and magnitude adjusted so that it matches the

offending interference, but is 180 degrees out of phase, effectively

cancelling the interference. This scheme is particularly effective at

reducing local power line noise or other locally generated noise types.

This unit may be used with any receiver or transceiver with rf power

output of 250 Watts PEP or less. An rf detector built into the unit

automatically bypasses the network whenever transmit rf is detected.

The unit is NOT designed to be used at the output of a high power linear

power amplifier, but must be installed at the lower rf level of the

transceiver, if transmitting is anticipated. In other words, if you use a

linear amplifier, place the ANC-4 between the transceiver and the linear

amplifier.

Controls are provided on the front panel to allow adjustment of both the

phase and magnitude of the local interference, providing extremely deep

cancellation of the offending interference.

The unit connects between the main station antenna and the receiver

antenna connector. The DC power mating connector for the ANC-4 is

supplied with each unit. UHF (SO-239, which mates with a PL-259 plug)

connectors are used for the outside antenna and the output to the

receiver. A short wire antenna and a short collapsible whip are supplied

with each unit to act as a noise pickup antenna. These will generally be

satisfactory for eliminating noises generated around the operating

position or in the house, but are generally not large enough to eliminate

noises generated outside the home, such as power line noise. For noises

generated outside the home, we recommend that you mount a small noise

dipole (6 feet of wire each side of center) outside perhaps down in the

shrubs or some other area a foot or two above ground, and broadside to

the noise source, such as parallel to power lines. Feed the noise probe

at the center with coaxial cable, shielded wire or even lampcord and

connect it to the NOISE ANTENNA connector J1, located on the rear

of the ANC-4, using an RCA plug. (Connect the center conductor of

shielded wire or one side of the lampcord to the center pin of the RCA

phono plug, and the shield or other dies of the lampcord to the ground

side of the RCA plug.) If you use the whip supplied with the unit, it may

be mounted through a hole in the top over and screwed onto a threaded

stud. DO NOT OVERTIGHTEN. The short wire antenna supplied

connects to an RCA jack on the rear panel of the unit. Any noise antenna

that works, including combinations of horizontal and vertically polarized

antennas, may be used.

The ANC-4 can be used to cancel ignition noise, alternator whine or

other noise types found in an automobile. To provide sufficient noise

signal to the unit, it may be necessary to run a wire from the NOISE

ANTENNA connector into the engine compartment to act as a noise

pickup. It will probably be necessary to readjust the NOISE PHASE and

NOISE GAIN controls when changing from one band to another, but the

settings should hold over an entire Amateur band.

The ANC-4 may be used as an active antenna by plugging the noise antenna

(or a longer wire antenna) into the noise antenna jack and using the NOISE

GAIN control to increase the antenna output. See Section 5 ACTIVE

ANTENNA. The unit may also be used as a diversity combiner to null

interfering signals. See Section 5.

This section lets you get “on the air” with the ANC-4 as quickly and as

simply as possible. Refer to the Connection Diagram Figure 3. See the

following sections of this manual for more detailed information. Refer

to Figures 1 and 2 for location of front and rear panel connectors and

controls.

The ANC-4 operates from a nominal +12VDC power source. Plug an

AC to 12VDC adapter into the ANC’s DC IN (J4) jack on the rear panel.

The unit is protected for reverse polarity, so no damage will result if the

correct polarity is not observed, but the unit will not operate. If you solder

on your own power plug, be sure to check for the correct polarity - center

terminal is positive - before connecting to the ANC-4. Use the Timewave

ANC-1 or similar AC-to-DC adapter with at least 300 mA current

capacity. The power input mating connector is coaxial, 2.1mm ID and

5.0 to 5.5mm OD, center positive. A mating plug is included with the

unit. (Older JPS ANC-4 units use a 2.5 mm ID power connector).

Connect the Noise Antenna, using either the short wire antenna or the

collapsible whip antenna (both supplied with the unit) or your own noise

antenna, to the unit. NOTE: The two noise antennas supplied with the

unit are likely to be effective only for noise generated within the

operating area or room and will not be adequate for reducing power

line or other noises generated outside the home. See Section 3 for

outside noise antenna suggestions. The whip mounts through the hole

in the top of the case and screws onto a terminal on the internal printed

circuit board. The wire antenna comes with an RCA phono plug and

plugs into the phono jack (J1) on the rear of the unit. This jack is also

used to connect your own noise antenna, if desired. The RCA phono

connector provided with the wire antenna may be used to connect your

own outside noise antenna by unsoldering the wire and connecting the

coax center conductor to the center pin of the RCA connector and the

coax shield to the outside of the RCA connector. Use the shortest length

for the noise antenna that will provide a good null with the NOISE GAIN

control in its mid range.

Using a UHF connector, connect the outside antenna to the MAIN ANT

connector (J3) on the rear of the unit.

Using a UHF connector and coaxial cable, connect the unit from the

RADIO connector (J2) on the rear of the unit to the receiver or

transceiver rf input or ANTENNA connector.

Connect the rear panel ground connector to your station ground. This

will reduce the effect of hand capacitance on the settings as you null out

the local noise.

Turn on the ANC-4’s POWER switch. The yellow LED next to the

switch should be illuminated.

Set the NOISE PHASE control to the full CCW position. Set the PHASE

RANGE pushbutton in the “IN” (“A”) position. Set the FREQ RANGE

pushbutton in the “IN” (LO) position. Turn the NOISE GAIN control

fully CCW to ZERO.

Tune your receiver to a frequency in the 3 to 4 MHz band (80 Meters).

Find a spot where you hear only the noise level. If the noise is generated 3

CONTROL SETTINGS

TUNE IN NOISE ON

THE RECEIVER

SECTION 2

QUICK

OPERATION

CONNECT POWER

CONNECT NOISE

ANTENNA

CONNECT OUTSIDE

ANTENNA

CONNECT UNIT TO

RECEIVER ANTENNA

CONNECTOR

CONNECT TO

STATION GROUND

TURN ON POWER

locally, such as close-by power lines, computers, TV, etc., you should

be able to adjust the NOISE PHASE and NOISE GAIN controls to

reduce the noise level considerably. If the noise you receive is not

generated locally, the unit will probably have little effect on your noise

level.

Turn the NOISE GAIN control slowly CW (clockwise) while observing

the receiver “S” meter. Note when the noise level changes, either

increase or decrease. Now adjust the NOISE PHASE control until you

see the “S” meter dip. If you do not see a dip or rise in the “S” meter

reading, try changing the PHASE RANGE pushbutton to the “OUT”

(“B”) position and readjust the NOISE PHASE control. One position of

the PHASE RANGE pushbutton provides a NOISE PHASE range from

0 to 180 degrees, while the other position provides a NOISE PHASE

range from 180 to 360 degrees. One of the settings of the PHASE

RANGE button will provide the proper phase so that a good null can be

attained. Readjust the NOISE GAIN and NOISE PHASE controls

alternately until the local noise has been cancelled. If you cannot obtain

a null, follow the procedure given in the following paragraphs to

determine if adequate noise is being picked up by the noise antenna. If

you obtain a null of the noise, but it is not as deep as you believe it should

be, try changing the polarity of the noise antenna to agree with the

polarity of your main station antenna. Although the vertical whip may

do a good job of cancelling the noise regardless of the main antenna

polarity, better performance (deeper nulls) can be obtained in some

cases when the main antenna and the noise antenna have the same

polarity. When a null has been reached, you now hear the noise level you

would have if no local noise was present, because you have just

cancelled the locally-generated noise. Now you will hear signals that

you didn’t know were there before. Or you’ll get good copy on signals

that you couldn’t quite hear because they were in the noise level.

If your receiver does not have an “S” meter, listen carefully to the noise

level. When you hear the noise level increase with noise from the noise

antenna, switch to the NOISE PHASE control and listen for the null in

the noise. Switch between the NOISE PHASE and NOISE GAIN

controls to attain the local noise null. The null obtained is normally good

for most of, if not the entire band in which you’re listening. If you go to

a new frequency, you will probably have to readjust the settings on the

NOISE PHASE and NOISE GAIN controls to recancel the local noise.

If you cannot obtain a satisfactory null in the noise, make the following

check to determine if adequate noise is being picked up by the noise

antenna.

(1) Turn both NOISE PHASE and NOISE GAIN controls fully CCW.

(2) Note the S meter reading on noise received from the main antenna.

Also listen to the character of the noise.

(3) Disconnect the main antenna and increase the NOISE GAIN in a CW

direction until the S meter reads the same as it did with noise from the

main antenna. Listen to the noise to be sure it sounds the same as it did

in step 2 above. If you cannot get the S meter reading high enough to

equal the reading taken in step 2, the noise antenna length must be

increased to pick up enough noise to properly cancel that received by the

main antenna.

(4) If the character of the noise is not the same in step 3 as it was in step

4, you may need to place an outside noise dipole to pick up the noise.

Feed the output from this outside probe through shielded wire or coaxial

cable to the NOISE ANT connector on the rear of the ANC-4.

ADJUSTING FOR

MINIMUM NOISE

For operation at frequencies above 20 MHz, the FREQ RANGE pushbutton

should be in the “OUT” ( HI) position. This centers the network so that it will

operate properly at these higher frequencies. If you have trouble getting a good

null at high frequencies, try placing the FREQ RANGE switch in the LO

position and readjust the NOISE PHASE and NOISE GAIN controls. All

other adjustments should be made as noted above to cancel the local noise. The

unit will cancel local noise down to about 100 KHz and up to about 80 MHz.

To reduce the Time to Return to Receive Mode When RF is Not Present,

parallel resistor R29 with 22k, 1/4W. This can easily be done internally by

changing jumper J1 (DELAY) from position 1-2 (NORMAL), to position 2-

3 (FAST). This will decrease the relay hang time from 500 msec to

approximately 7 msec.

If a local broadcast station overloads the NOISE ANTENNA amplifiers, it can

be sharply attenuated with a tunable trap, C27 and L2. To activate the trap,

connect the jumper JP2 to position 1-2. By adjusting the variable capacitor,

station frequencies in the 1000 to 1600 kHz range can be trapped. To trap a

station with a frequency between 800 kHz and 1000 kHz, install a 22 pF

capacitor between E1 and E2 on the printed circuit board. If the offending

station has a frequency below 800 kHz, install a 47 pF capacitor between E1

and E2. To deactivate the tunable trap, place the jumper JP2 in position 2-3.

To attenuate signals from local broadcast stations that are picked up by the

external noise antenna, place Jumper JP3 for the BCB Filter in position 1-2.

This places a high pass filter with at least 50 dB attenuation in the stop band

in series with the noise antenna. If one particular station is so strong that it still

comes in despite the high pass filter, use the BCB TRAP to notch it out. See

paragraph above. To deactivate the BCB Filter, place jumper JP3 in position

2-3.

BROADCAST

STATION NOTCH

REDUCING HANG

TIME FOR BREAK-

IN CW OR AMTOR/

PACTOR USE

HIGH FREQ

OPERATION

(Over 20 MHz)

BROADCAST BAND

FILTER

Figure 2

Rear Panel Controls

TIMEWAVE

Figure 1

Front Panel Controls

Figure 3

Connection Diagram

NOISE

ANTENNA

+12VDC

FROM

POWER

SUPPLY

RADIO

ANTENNA

INPUT

OUTSIDE

MAIN

ANTENNA

This section gives detailed information on the connections to the ANC-

4. The unit is quite simple to connect and use, but for best results, follow

the guidelines in this manual. See Figure 2 for Rear Panel Connections.

The ANC-4 operates from +11VDC to +16VDC and requires about 300

mA. Power can be supplied from any filtered DC source. An AC to

12VDC adapter is available from JPS Communications at slight additional

cost.

The ANC-4 may be operated directly from the power system of any

12VDC negative ground vehicle.

The MAIN ANT input (J3) connector is a UHF (SO-239) type for use

with coaxial rf cables, such as RG-8 or RG-58. This connector serves as

the rf input from the outside or station antenna system.

The RADIO (J2) connector is also a UHF (SO-239) type for use with

coaxial rf cables, such as RG-8 or RG-58. This connector provides the

output from the antenna to the receiver. When the ANC-4 power is off,

the MAIN ANT is bypassed directly to the RADIO connector.

The NOISE ANTENNA connector on the rear panel (J1) is an RCA

phono jack for connecting the short wire noise antenna or your own noise

antenna to the ANC-4. A hole in the top cover of the unit allows the short

collapsible whip noise antenna to be screwed into a threaded adapter on

the pc board inside the unit. This antenna picks up locally generated

noise to the exclusion of desired long distance signals, and is used as a

reference signal which can be varied in magnitude and phase for

cancellation of the local noise. Keep in mind when selecting which noise

antenna to use that you may get deeper noise nulls by having the same

polarization on both the noise antenna and the main antenna. In either

case, the noise antenna should be kept as short as possible to provide a

good noise null with the NOISE GAIN control in its mid range.

If sufficient noise cannot be picked up by the noise antenna supplied

with the unit, it may be necessary to install a noise dipole or noise

probe outside to more clearly pick up the noise. A noise dipole of 3

to 6 feet either side of center, fed with shielded wire or coaxial cable, will

generally suffice. The dipole should be turned broadside (parallel) to the

noise source and should be located 2 to 4 feet above ground, perhaps in

shrubs around the house, but where it can "see" the power lines or other

noise source. This will prevent it from receiving much if any of the

desired signal. After installation, perform the test in the SECTION 2,

ADJUSTING FOR MINIMUM NOISE to be sure that adequate noise

pickup is available from the noise antenna. It is most desirable to have

the matching noise level occur when the NOISE GAIN control is

somewhere in its middle range. Otherwise, the null may be obscured if

it occurs too close to either end of the control.

SECTION 3

CONNECTIONS

POWER

REQUIREMENTS

VEHICULAR

OPERATION

MAIN ANTENNA

INPUT

RADIO INPUT

NOISE ANTENNA

This section explains the operation of the ANC-4 controls. See Figure 1

for the location of Front Panel Controls.

The NOISE PHASE control adjusts the phase angle of the signal from the

noise antenna to 180 degrees for maximum cancellation of the local noise.

The PHASE RANGE pushbutton provides two different networks to

allow greater range of adjustment of the NOISE PHASE control to achieve

the deepest null of local noise interference. When the button is pushed in,

the phase network is in the “A” position, which is used for most situations.

When the button is out, the phase network is in the “B” position. No

position on this switch is more “right” than the other. The proper or “right”

position is that which gives the best null. The FREQ RANGE button can

be used in conjunction with this pushbutton to give even greater phase

nulling range at low frequencies by placing it in the HI position.

The FREQ RANGE pushbutton extends the frequency range over which

the NOISE PHASE and NOISE GAIN controls are effective. In the “IN”

position (LO), the network is set for frequencies below 20 MHz. In the

“OUT” position (HI), the network is set for frequencies above 20 MHz.

Note that the HI position is also usable for low frequencies and may be

required if a satisfactory phase null cannot be obtained with the switch in

the LO position.

The NOISE GAIN control adjusts the level of the signal picked up by the

noise antenna so that the magnitude of the offending interference can be

cancelled. When the ANC-4 is used as an active antenna, this control

adjusts the gain of the antenna.

NOISE GAIN

SECTION 4

CONTROLS &

INDICATORS

NOISE PHASE

CONTROL

PHASE RANGE

PUSHBUTTON

FREQ RANGE

PUSHBUTTON

This section describes the operating procedure for best results with the

ANC-4.

When the unit is connected as shown in Figure 3, locally generated noise

can be cancelled, in many cases completely. The controls and switches

should be manipulated as follows: (Refer to Figure 1).

1. Use your receiver “S” meter as a noise level indicator.

2. Set the NOISE PHASE control initially fully CCW and turn the NOISE

GAIN control fully CCW. Set the PHASE RANGE pushbutton “IN” to

the A position, and the FREQ RANGE pushbutton “IN” to the LO

position for frequencies below 20 MHz, or release it to the “OUT” or

HIGH position for frequencies above 20 MHz. (See "adjusting for

Minimum Noise" in Section 3 for further discussion.)

3. Slowly increase the NOISE GAIN control clockwise until a change,

increase or decrease, in the “S” meter reading is just noted.

4. Now adjust the NOISE PHASE control until a null is noted on the “S”

meter.

5. Alternately adjust the NOISE GAIN and NOISE PHASE controls until

the best null is obtained. If interaction due to hand capacitance is noted,

ground the case of the ANC-4 to your system ground.

6. If a good null cannot be obtained with the PHASE RANGE pushbutton

in the A (in) position, release the pushbutton to the B position and

readjust. A null should be obtained in one of the two PHASE RANGE

switch positions. Remember that the “right” switch position is that which

gives the best null.

7. For the deepest noise nulls, it may be necessary to change the noise

antenna polarity (horizontal or vertical) to be the same as that of the main

antenna.

8. When changing bands, it will probably be necessary to readjust the

network to reduce the noise on the new band. Normally, the adjustment

will hold over a frequency range of several kilohertz without requiring

readjustment. So if you adjust the noise cancellation in any one ham band,

it will generally hold throughout that band. However, different noise

sources may be present in different parts of the same band, so that some

readjustment may be required if this occurs.

9. If a null cannot be obtained using the noise antennas supplied with the

unit, you may have to install an external noise antenna. SECTION 2,

ADJUSTING FOR MINIMUM NOISE provides a test which will

determine if adequate noise is being provided by the noise antenna.

SECTION 3, NOISE ANTENNA gives some hints for an external noise

antenna and where it should be physically located.

The ANC-4 can be used as an active antenna by using the whip antenna

provided with the unit (See Figure 2). The NOISE GAIN control can then

be used to provide amplification of the signals received by the antenna.

ACTIVE ANTENNA

SECTION 5

OPERATION

LOCAL NOISE

For active antenna use, do not connect an antenna to the MAIN ANTENNA

connector.

As an alternative, a wire antenna can be connected to the rear panel NOISE

ANTENNA connector, J1. Best results will be obtained by using the longest practical

length of wire for this antenna.

When used as an active antenna, set the NOISE PHASE control fully clockwise for

best results. Set the FREQ RANGE pushbutton to agree with the frequency band in

which you are operating. The position of the PHASE RANGE pushbutton is not

important.

Following are some helpful hints for operating with the ANC-4:

!To prevent damage to the ANC-4 when an antenna tuner is used,

simply turn off the power on the ANC-4 until the tuning process

is complete.

!If the PHASE GAIN control is too close to either the CCW or CW

end,merely adjust the noise antenna length to center the control. In

other words, keep the noise antenna length to the minimum required

to get a good null while keeping the NOISE GAIN control in its mid

range.

If you use an antenna tuner, wait until the antenna has been properly matched

before adjusting the ANC-4 for local noise null.

If the local noise is not stronger in the noise antenna than it is in the main antenna,

adjusting for a null will likely reduce the desired signal as well. It is desirable

to have the noise antenna as close to the noise source as possible for best

performance, so an external noise antenna may be required.

DO NOT connect the noise antenna to a high gain outside antenna unless a series

attenuator is used. Unless the signal is attenuated, the received signals will

overload the internal amplifier and will cause intermodulation distortion. The

loss in signal strength through the attenuator can be made up by adjusting the

NOISE GAIN control.

You will likely find that the ANC-4 will make operation of a DSP noise reducer,

such as the Timewave DSP-599zx., much more effective because the ANC-4

will eliminate noise before it gets into the receiver and affects the receiver AGC

circuits.

If you are situated close to an AM broadcast station, you may need to trap the BC

signal to prevent overload of the noise amplifier in the ANC-4. A tunable trap

is included on the pc board to eliminate BC station interference. See Section 2,

BROADCAST BAND NOTCH for further information. If more than one

station is involved, merely place jumper JP3 in position 1-2. This engages a

highpass filter which attenuates the broadcast band by at least 50 dB.

NOTE: If the NOISE GAIN is set too high, the ANC-4 will introduce noise

instead of removing it. Noise cancellation is dependent upon a good balance

between the NOISE PHASE and NOISE GAIN controls.

If two antennas are available and located with space diversity, you can use the

ANC-4 to null interfering stations as shown in figure below.

In order to obtain the best noise null, it may be necessary to change the noise

antenna polarization (horizontal or vertical) to be the same as that of the main

station antenna. 11

GENERAL

OPERATING HINTS

Operating Frequency Range 500 kHz to 80 MHz

(usable down to 100 kHz)

Signal Loss, Main Ant. to Radio 6 dB

Rf Input Level, Main Antenna 3 Vrms maximum

Maximum Transmit Rf Power 250 W PEP or Average

Through Unit

Time to Switch to Bypass When 7 mSec, typical

Transmit Rf is Detected

Time to Return to Receive Mode Approx. 500 msec or 7 msec, typical

When Rf is Not Present intenally selectable, (hang time)

Typical Local Noise Types Power Line Noise, Computer Noise,

TV Noise, etc.

Noise Cancellation Typically 40 dB or greater

Front Panel POWER switch, POWER LED,

PHASE RANGE switch, NOISE

PHASE control, FREQ RANGE

switch, NOISE GAIN control.

Rear Panel Power Input, Noise Antenna Input,

Main Antenna Input, Radio Output

Input Power +11 VDC to +16 VDC @ 150 mA,

reverse polarity protected

Size 1.7"H x 6"W x 4.3"D

(4.3cm x 15.2cm x 10.9cm)

Weight 2 pounds (.91 kG)

Temperature Ranges Operating: -20oC to +55oC

Storage: -40oC to +85oC

Humidity Up to 95% @ +55oC

SECTION 6

TECHNICAL

INFORMATION

SPECIFICATIONS

Symptom Possible Fault

POWER ON LED Check AC power source, polarity and power line connections.

does not light. Check for proper seating of plug in DC power jack

Unit comes on, but Check all antenna connections on rear panel. Make sure

no signals heard cables go to correct connectors in Receiver

Noise received cannot Received noise may not be locally generated. Follow nulling

be nulled instructions carefully. Make sure you try both settings of PHASE

RANGE switch and the FREQ RANGE switch when nulling if

difficulty is noted. If frequency is above 20 MHz, set the FREQ

RANGE switch to the HI position. NOISE GAIN control may be set

too high initially. The noise antenna length may be too great,

particularly if the noise is severe. Shorten the noise antenna length

until a satisfactory null can be obtained with the NOISE GAIN

control in its mid range. Change the noise antenna

polarization (horizontal or vertical) to agree with that of the main

station antenna. If you can approximate the location of the noise

source, place a short external noise antenna as close to the source

as you can, or use a short dipole facing toward the noise source as

a noise antenna. NOTE: The short whip and short wire noise

antennas supplied with the unit are not adequate to cancel

local power line noise or other noise generated outside the

home. You will need to install an outside antenna. See

Section 3, NOISE ANTENNA for suggestions on antenna size

and location. If problem persists, contact Timewave Customer

Service Department.

Noise received on noise antenna is too low. Noise received on noise

antenna is different from that received by main antenna. To determine

if this is the case, perform the following procedure:

(1) Connect up the unit as described in the manual. Turn the unit

power on.

(2) Turn both the NOISE PHASE and NOISE GAIN controls fully

CCW.

(3) Now with the main antenna connected, note the S meter reading

and listen to the character of the noise (is it a "buzz" or a "crackle",

etc.?)

(4) Disconnect the main antenna from the ANC-4.

(5) Turn the NOISE GAIN control CW until it is somewhere in its

mid-range and observe the S meter reading. Is it as high as the

reading obtained in step 3? Is the character of the noise the same as

SECTION 7

TROUBLE-

SHOOTING

Noise received cannot

be nulled.

that heard in step 3? If the answer to

both questions is "YES", you should be able to arrive at a satisfactory

null of the noise. (Hint: When you reach the same S meter reading as before,

leave the GAIN where it is, reconnect the main antenna and try to null with

just the NOISE PHASE control. You may have to alternate between PHASE

and GAIN a few times to get the deepest null.) If the answer to either question

is "NO", then a null probably cannot be achieved.

(6) If the noise sounds the same in steps 3 and 5, but you can't get a high

enough S meter reading from the noise antenna alone, you need a longer

noise antenna or need to locate the noise antenna closer to the noise source.

(7) If you can get a similar S meter reading, but the noise sounds different in

step 5 from what it sounds like in step 3, your noise antenna is picking up

noise that is not being heard by the main antenna and the noise antenna must

be relocated so that it DOES pick up the noise appearing on the main antenna.

(For instance, your outside antenna may be receiving noise from power lines,

while the indoor noise antenna may be picking up noise from a nearby

computer, noise which is not heard by your main antenna). In most cases, a

simple short dipole can be placed outside in shrubs or some other low area,

but in view of the noise source, if possible. The noise antenna is then fed to

the ANC-4 NOISE ANTENNA jack (rear of the unit) with shielded wire.

Repeating the above tests will let you determine if you will be able to null the

main antenna noise or not. Some adjustment of noise antenna length or

SECTION 8

GENERAL

THEORY OF

OPERATION

(See Figure 5)

position may improve the null.

Figure 6 is a block diagram of the ANC-4 showing the elements that are used to cancel

locally generated noise from the signal received by the station main antenna system.

The station antenna picks up noise, both locally and remotely generated, as well as desired

signals and passes everything directly to the receiver. If the noise level is strong enough,

it will take over the receiver AGC system and reduce the receiver gain for weaker desired

signals, masking them. The detected audio output then contains mostly noise information

unless the desired signal is of sufficient strength to overcome the noise signal amplitude.

This reduces the number of signals actually heard by the operator to those stronger than

the received noise level. When the noise level from local sources, such as power lines,

computers, etc., is strong enough to give high “S” meter readings on the receiver, the

number of intelligible signals received by the operator is greatly reduced when compared

to what could be heard if the local noise level could be overcome. Now DSP noise

reduction devices can allow the operator to improve the intelligibility of signals close to

or in the noise level, but cannot “dig out” those signals which have been masked by the

local noise. The ANC-4 provides a means to allow the operator to cancel the local noise

and let him hear those signals previously masked by that noise.

The signal from the MAIN antenna is combined in a special network with a signal from

the NOISE antenna. The MAIN antenna signal contains desired information as well as

noise. The NOISE antenna signal, which contains mostly the local noise, is amplified and

passed through a phase shift network so that its phase can be adjusted to 180 degrees

compared to the MAIN antenna signal. Front panel controls, NOISE PHASE and NOISE

GAIN, let the operator adjust the NOISE antenna phase and gain to just equal the noise

signal magnitude picked up by the MAIN antenna, but shifted 180 degrees in phase. Two

phase shift networks (PHASE) are incorporated to give maximum flexibility and cover

most local noise situations. A switch (FREQ RANGE) is also provided to tailor the noise

cancellation network for operation at frequencies above 20 MHz. The HI range on this

switch is also usable at lo frequencies and provides an additional phase shift network

which may be required if a satisfactory phase null cannot be obtained with either PHASE

switch position. The combined signals, with the local noise cancelled, are passed on to

the receiver via the RADIO connector on the rear panel. The networks in the ANC-4 allow

cancellation of local noise up to an operating frequency of about 80 MHz or so.

Desired Signal + Atmospheric Noise + Local Noise - Local Noise =

Desired Signal + Atmospheric Noise

When properly adjusted, 50 dB reduction of the locally generated noise is possible,

leaving only the normal atmospheric noise level existing on the band. (Observing the “S”

meter readings before and after local noise cancellation will make this apparent.) Signals

that were masked by the local noise can now be heard. Now that the local noise has been

removed from the received signal, a DSP noise reducer is much more effective when

operating at the audio end of things. Just by eliminating or reducing noise, listening

fatigue can be greatly reduced.

RADIO

ANC-4

J1 J2 J3

Noise

Ant

LOCAL NOISE DESIRED SIGNAL

Strong

Weaker

Main

Ant

Figure 5

Principle of Operation

Figure 4

Printed Circuit Board Parts Placement

For those who have access to the Internet, Timewave may be contacted at

Email: techsupport@timewave.com

service@timewave.com

sales@timewave.com

Timewave also has a Home Page on the World Wide Web

http://www.timewave.com

Here you may register a product, view a specification sheet and photo,

request the latest product catalog, view product FAQs, and

read about product upgrades when available.

Feel free to email us if you have technical questions

or comments about your Timewave product.

Phase

Shift

Network

Hybrid

Combiner

Detector

Figure 6

Block Diagram

Phase A/B

NOISE

ANTENNA

MAIN

ANTENNA

(or Linear Amp)

To Radio

NOISE

PHASE

R12

NOISE

GAIN

NOISE

AMP

+12

Note:

Relay shown in

transmit/power off

position

D D

C C

B B

A A

+12V

Title

Size Document Number R ev

Date: Sheet of

A.05300

ANC-4 Antenna Noise Canceller

Timewave Technology Inc.

St. Paul, MN 55117

11Wednesday, March 12, 2003

FREQ

ANT

RADIO

MAIN

DC IN

+12V

POWER

SOURCE

PHASE

YELLOW

GAIN

RANGE

NOISE

PHASE

USE JP1 TO ADJUST DECAY TIME AFTER KEY-UP:

JUMPER PINS 1 & 2 FOR NORMAL DECAY

JUMPER PINS 2 & 3 FOR FAST DECAY

USE JP2 FOR BC BAND TRAP

JUMP 1 & 2 TOGETHER FOR BC BAND TRAP

JUPM 2 & 3 TOGETHER TO DISABLE TRAP

USE JP3 FOR BCB FILTER

JUMP 1 & 2 TOGETHER FOR BC BAND FILTER

JUMP 2 & 3 TOGETHER TO DISABLE FILTER

NOISE

ANT

1W 1W 1W

R29

.1u

47uH

CR5

1N5711

R38

22k

C30

150pF

C29

100pF

C28

120pF

R15

4124

R14

2.2K

C25

100uF

C32

270pF

C11

.1u

C31

560pF

R13

4.7K

R31

500

1 3

NOISE ANT

JP3

BCB

FILTER

OUT IN

R18

R19

47K

C26

.1u

R20

47K

R21

47K R22

47K

DS2Y-DPDT

CR3

4148

CR4

4148

C14

.1u

CR9

1N5711

C21

R17

820uH

R12

500

1 3

BEAD

J310

R10

51 R37

1K C8

.1u

47p

.1u

TP4

R23

R24

CR12

1N5231B

JP2

BCB

TRAP

OUT

R26

100p

R11

C27

5-25pF

10p

R25

47uH

TP2

CR7

4148

C17

.1u

SW DPDT

CR6

4148

R27

10K

C22

10n

R28

100K

C23

10n

C18

2N7000

CR10

4004

C24

1000u

CR11

POWER

R36

R30

10M

2N7000

TP1

C19

2.2u

C16

C10

.1u

JP1

DECAY

FAST

NORM

R16

100

C12

.1u

C13

.1u

100K

CR8

4148

100 1W

J310

R32

47K

TP3

R33

47K

300

R34

47K

270K CR2

4148

R35

47K

CR1

4148

ANC_4TW8x11a TIMEWAVE ANC 4 Noise Canceller Manual

Navigation menu

Versions of this User Manual:

Views

Navigation