Hidden Fence brand® - Dog Fence and Dog fencing Containment Solutions,
was pioneered by Hidden Fence in Australia. We offer the only Professional Grade,
full service electric dog fence solutions in Australia and New Zealand.

FM vs AM on (digital modulation)

Electronic dog fence containment systems all use a modulated radio signal to transmit through a cable which surrounds a boundary.

Since 1990, all regulated, FCC and ACA approved brands of containment systems use DM (Digital Modulation).

All manufacturers of containment dog fence products (Except Hidden Fence) use DM (digital Modulation) on AM (amplitude modulation) carrier waves.

ONLY Hidden Fence brand by DogWatch has the Patent on DM carried by FM.


Types of DM-AM signals:

  • Pulse Amplitude Modulation (PAM) Used by most manufacturers of perimeter fence.  
  • Pulse-Duration Modulation (PDM) (Morse Code) Used by one manufacturer.
  • Pulse-Code Modulation (PCM) Used by one manufacturer.
  • Pulse Position Modulation (PPM)

Types of DM-FM signals:

  • Modulating Wave ( FM Radio, Police, Fire and Aircraft Communications)
  • Phase Modulation – (PM)
  • Frequency Speed Spectrum (Cell Phones)
  • Frequency Shift Keying  (FSK; US Emergency Alert system) and Hidden Fence


  • FM receivers ignore AM signals. (televisions, Air Con Compressors, motors, etc. emit AM signals).
  • FM receivers can work in electrical noise environment without disruption.
  • Output power remains constant with the amount of modulation.
  • Less risk of receiving partial signal.
  • Eliminates risk of false correction from other sources.

If any environmental factors such as Air Conditioning compressors, garage door openers, driveway gates, pool filters, etc are factors on your property, then only an DM-FM Hidden Fence System allows for non-activation of a receiver collar around these utilities.

Below are diagrams of what happens to DM-AM wave patterns when experiencing electrical noise (a motor or compressor starting).


As seen above, …FM FSK DM wave patterns don’t get disrupted by electrical noise or interference.

This is realised when you are listening to a car radio on an FM Radio station and can still hear your program clearly when travelling under a bridge or tunnel; whereas an AM radio station will “blank or phase out” when experiencing the same conditions.

Only Hidden Fence brand by DogWatch offers you this technology.

When dealing with a training tool or behavioural modifier, precision and accuracy is paramount to preserving animal welfare.


Beware of unregulated dog fence containment fences from online auction sites!

Your dogs behaviour and welfare may be at risk!

Disclaimer & Laws

Hidden Fence brand® should not be confused with Invisible Fence® or Invisible Fencing® which are products and registered trademarks of Invisible Fence, Inc. sold in the US.
© 2000-2014 DogWatch Inc. All rights reserved. No photographs, illustrations or text can be reproduced in any form without the express written consent of DogWatch Inc. Dog Fence.
© 2002-2014 Hidden Fence. All rights reserved. No photographs, illustrations or text can be reproduced in any form without the express written consent of Canine Containment Company Pty Ltd. DogWatch, DogWatch logos, FastReact ™, Automemory ™, Safelink ™, Performance ™, Scoot ™, PowerPak ™, Pet-Friendly ™, are all registered trademarks of DogWatch, inc. Dog Fence.
© 2002-2014 Hidden Fence brand experts in pet containment guaranteed is a registered logo trademark.
© 2010-2014 Dog Stop by Hidden Fence brand is a registered logo trademark of Hidden fence brand.
© 2002-2014 Canine Containment Company Pty Ltd. All rights reserved. DogWatch Hidden Fence Systems, The Hidden Fence Company and The Hidden Fence Company logos are all Registered trademarks of the Canine Containment Company Pty Ltd.

Licenced web domains to Hidden Fence d/b/a Canine Containment Company Pty Ltd include the following: www.hiddenfence.com.au, www.hiddenfence.co.nz, www.invisiblefence.com.au, www.remotetrainers.com.au, www.bigleash.com.au, www.invisibledogfence.com.au, www.hiddendogfence.com.au, www.invisblefence.co.nz

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