The Great Debate

Perhaps in the old days the question was, what came first, the chicken or the egg? In underground dog fencing, the question is always: which is better, AM, FM or DM? My response to this ongoing debate is written under the FAQ's section, however, I would like to entertain my followers with how my competitors fight over this silly question. Enjoy the read! I laugh when I read this over and over again. I'm sorry, but I can be a bit of a geek. Surprisingly enough, I cannot seem to find what Invisible Fence® uses. They are smart to stay out of this ridiculous battle of nonsense.


The DogWatch® answer:


The Truth about Digital Modulation

Certain Hidden Fence companies advertise their products as offering DM, or “Digital Modulation”. They describe this as the most modern and up-to-date radio transmission technology for Hidden Fence systems. The “next generation” that is newer & better than even FM radio.


The educated customer needs to be informed that this is nothing more than marketing hype on the part of these organizations. Please, don’t be misled…


Digital Modulation (DM) is a radio signal processing technology used to send and receive information over FM (Frequency Modulation), or AM (Amplitude Modulation) radio waves. It's commonly used today in almost any device that performs some type of communication. Everything from cell phones to Hidden Fences function by sending "digitally modulated" signals over an FM or AM radio band. Although DM is based on AM/FM radio technology, it is NOT a next generation replacement for it. Rather...


Digital Modulation is the "digital" form of AM/FM radio.

Everyone is familiar with the differences between AM and FM radio. It’s widely known that FM signals are far more clear and secure than AM signals. This is why FM music plays over the radio with no static (at all...) and fire/police departments, air traffic controllers, etc. all communicate exclusively over FM channels. Bottom line; digital FM is superior to digital AM.


When applied to a Hidden Fence system, digital AM based systems are constantly subjected to interference inherent to that technology. The end result is a digital AM system that's prone to "misfire", shocking your pet indiscriminately. This can lead to a confused and frightened animal.


A digital FM Hidden Fence system doesn’t respond to radio wave interference and therefore is safest for your pet.

Digital Modulation (DM) is the radio signal processing technology used by ALL Hidden Fence products available on the market today. No matter if the product is based on AM or FM radio, DM is the technology used to process the transmissions. There is nothing special or unique about the use of DM within the Hidden Fence industry. All products available today use this technology.


The reason certain Hidden Fence companies make a big deal about offering Digital Modulation is because their products are actually AM radio based.

Since digital AM radio is inferior to digital FM, these companies are forced to use marketing hype in an attempt to compete against the ONLY Hidden Fence company in the entire industry that offers an FM radio based product; DogWatch®. By drawing attention to a commonly applied technology (DM) and making it “sound” like an advancement that differentiates their product, these companies are attempting to divert attention away from their greatest weakness; an AM radio based product.


Fortunately, an educated customer will see right through this. DM is NOT a next generation, "advanced" radio technology being offered by specific Hidden Fence companies. Rather…


ALL Hidden Fence companies use Digital Modulation throughout their entire product line(s).

Your car radio is a good illustration of this. Installed in each (late model) automobile is a “digital” AM/FM radio. Regardless if the channel you tune to is AM or FM a “digital” (DM) radio is processing the incoming signal, providing you with something to listen to.


Also, no matter who manufactured your car (Ford, BMW, Toyota, etc), the radio is using a form of Digital Modulation to interpret the AM or FM radio signals. What makes one car radio sound better than another often comes down to simply tuning it to an FM station rather than an AM station. Similarly…


What makes one Hidden Fence product better than another is simply the type of radio modulation it uses; FM vs. AM…


The Pet Stop® response:

by John J. Purtell, President, Perimeter Technologies, Inc.


Yes, it’s confusing. Because your car radio is clearer on FM than it is on AM it’s natural to assume that it’s better in pet fences too. That’s just not so!


Pet fences are not car radios. Most do not use just an AM or FM signal. For example Pet Stop uses a pattern of signals to create a unique code so that the dog collars only activate when it “sees” the Pet Stop signal. This prevents false activations, which is critically important for your pet’s safety. This coding is called DM, or "Digital Modulation" and we overlay that coding on an AM signal, just like airports do in sending landing signals to airplanes.


So do not be confused because one company touts FM as superior. It’s not superior. It’s only because they would be violating US Patent Law by doing it otherwise.



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