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#11
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Modification of the receiver is not an option for several
reasons......... - The Earth and solar system make alot of noise on these frequencies. I suspect the receiver is designed to be somewhat insensitive in order to avoid problems with noises generated by Mother Nature. - The schamatic of the dog collar is not available, the manufacturer chose to make type acceptance documents 'private'. There is a record of the receiver, but all details are unavailable to the public. - The receiver assembly is in an enclosure that can't be opened, probably to insure operation if the collar gets dunked in water (some dogs enjoy swimming). It also appears to be potted, the black epoxy is visible in the port provided for adjusting the correction level). - A That being said, it might still be easier to increase the sensitivity of the receiver. What type of antenna is on the dogs collar? Also - what is the brand and model of this unit? It might make tracking down the soultion a bit easier. |
#12
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On Tue, 29 Mar 2005 13:02:28 GMT, AB2RC
wrote: Also what would happen if the collar lost the xmitter signal due to other reasons (dog goes behind a trash can/metal shed/other large metal object)? Hi Alex, At 17KHz this is virtually impossible. It would be like trying to hide behind a house in Aceh when the wave came in. 73's Richard Clark, KB7QHC |
#13
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On 2005-03-29, Richard Clark wrote:
On Tue, 29 Mar 2005 13:02:28 GMT, AB2RC wrote: Also what would happen if the collar lost the xmitter signal due to other reasons (dog goes behind a trash can/metal shed/other large metal object)? Hi Alex, At 17KHz this is virtually impossible. It would be like trying to hide behind a house in Aceh when the wave came in. Forgot about the frequency there for a minute ... 17khz is a very long wave Either way, the whole concept of this specific device seems sort of backwards for it's intended purpose. -- Alex / AB2RC Linux is user friendly, however it is not idiot friendly |
#14
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Is there a webpage of the manufacturer which contains any details of the
device in question? A picture can be worth a 1000 words.... Regards -- Hay, if'n ya'll cun't konstructivly partecipete in this har disscusion, haw aboot speel-checkin it fer me? "Richard Clark" wrote in message ... On Mon, 28 Mar 2005 13:27:45 -0500, Albert wrote: I'd like to increase the range without spending much money-so I want something quick and dirty:: Hi Albert, Hmm, more range? You should be able to fry that puppy within a country mile if you do that. Perhaps you should describe your goal instead of your intended method. 73's Richard Clark, KB7QHC |
#15
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I Hope I misunderstood or you have thought about it:
If the collar shocks the dogs when it stops receiving the transmitter's signal... What is going to happen to the dog when the transmitter eventually stops working (exhausted batteries, mains cut or simple malfunction)? Toni |
#16
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John,
If you have broadband, I can send the files to you. There is nothing on the manufacturers website. It's all on the FCC website, although the schematic is marginally readable as it was scanned at low resolution. Let me know if your email address in your usenet post is correct and whether you can receive the large files. A Is there a webpage of the manufacturer which contains any details of the device in question? A picture can be worth a 1000 words.... Regards |
#17
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Ahhh! Then there must also be a transmitter in the collar to "answer
back" to the stationary transmitter? If so, maybe the thing works on the amount of time calculated for the signal to travel round trip. A radar mile (2 miles round trip) is about 12 microseconds, if I recall. Rountrip at 90 feet would be something like 183 nanoseconds. If THIS is how the unit works, running a kilowatt wouldn't make a difference. It would require changing the interval time that the transmitter waits for check-back. Maybe I'm making this too complicated It must be simpler and then I would think they would use something other than 17 KHz....interesteing!! Scott Albert wrote: Scott, Your question brings much complication to a matter that should be easy to answer. I'll do my best to avoid getting bogged down in the explanation. The transmitter has a very long range, much longer than 90 feet. I believe the dogs collar hears the signal for a very long distance. But, that the collar does not issue a correction if the dog wanders past the range of the transmitter. If the collar acted in this manner, it would preclude the dog from RE-ENTERING the protected area from the outside of the 90 foot range. In order for the collar to initialize, it must hear the transmitter (initially). If the transmitter is turned off, and the collar is turned on, no corrections are issued. Also, if the collar is properly initialized and operating, abruptly turning off the transmitter DOES NOT result in a correction being issued. Corrections are only issued IF the dog is in the intermediate zone, which appears to be a 3 foot wide area. This type of operation is necessary to safeguard the dog, even though it complicates the hardware some. At 16 kilohertz with horrendously inefficient transmitting antennas, I doubt there would be an FCC problem, especially with a modest boost in ERP. The Earth and the solar system generates much noise on those frequencies as well, we could probably increase the transmit power quite a bit without creating problems. Hope this helps. A On Tue, 29 Mar 2005 12:09:27 +0000, Scott wrote: I auume these thing work in reverse of conventional thinking. I assume that as long as the receiver is receiving a signal, the dog does not get shocked. If it strays too far and the receiver loses the signal...ZAP! However, modifying the transmitter would violate its Part 15 certification and the owner might be the one to get the ZAP (from the FCC)... Scott |
#18
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Nothing but a little receiver and a buzzer in the belt. The wire
radiates and the lil bitty receiver detects it and the little dog regrets his closeness to his boundaries. Butch Scott wrote: Ahhh! Then there must also be a transmitter in the collar to "answer back" to the stationary transmitter? If so, maybe the thing works on the amount of time calculated for the signal to travel round trip. A radar mile (2 miles round trip) is about 12 microseconds, if I recall. Rountrip at 90 feet would be something like 183 nanoseconds. If THIS is how the unit works, running a kilowatt wouldn't make a difference. It would require changing the interval time that the transmitter waits for check-back. Maybe I'm making this too complicated It must be simpler and then I would think they would use something other than 17 KHz....interesteing!! Scott Albert wrote: Scott, Your question brings much complication to a matter that should be easy to answer. I'll do my best to avoid getting bogged down in the explanation. The transmitter has a very long range, much longer than 90 feet. I believe the dogs collar hears the signal for a very long distance. But, that the collar does not issue a correction if the dog wanders past the range of the transmitter. If the collar acted in this manner, it would preclude the dog from RE-ENTERING the protected area from the outside of the 90 foot range. In order for the collar to initialize, it must hear the transmitter (initially). If the transmitter is turned off, and the collar is turned on, no corrections are issued. Also, if the collar is properly initialized and operating, abruptly turning off the transmitter DOES NOT result in a correction being issued. Corrections are only issued IF the dog is in the intermediate zone, which appears to be a 3 foot wide area. This type of operation is necessary to safeguard the dog, even though it complicates the hardware some. At 16 kilohertz with horrendously inefficient transmitting antennas, I doubt there would be an FCC problem, especially with a modest boost in ERP. The Earth and the solar system generates much noise on those frequencies as well, we could probably increase the transmit power quite a bit without creating problems. Hope this helps. A On Tue, 29 Mar 2005 12:09:27 +0000, Scott wrote: I auume these thing work in reverse of conventional thinking. I assume that as long as the receiver is receiving a signal, the dog does not get shocked. If it strays too far and the receiver loses the signal...ZAP! However, modifying the transmitter would violate its Part 15 certification and the owner might be the one to get the ZAP (from the FCC)... Scott |
#19
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Hi Scott,
I suspect you are making it more complicated than it is. I have the schematic for the transmitter, which is the part that stays indoors and needs AC line power. The only receiver is the receiver in the collar. There has to be some logic in the collar though because it has to initialize (won't issue corrections unless it hears the transmitter when the receiver is first turned on). After the collar is initialized, it will not issue corrections if the dog (somehow) gets outside the 90 foot area and tries to re-enter. This means that once the collar loses the signal completely, it won't issue a correction when the collar acquires the signal again. If the transmitter is powered down completely (after proper initialization) the collar will not issue a correction either. So, it's a smart receiver and is well thought out. But, all these functions can occur as the result of logic contained within the collar mounted receiver. Last night, I looked at the signal using spectrum lab's vlf receiver program. When I zoomed in on the transmitters signal, I noticed that there were sidebands occurring every 15 hz. I will post another message with more details. A PS.................. The vlf transmitter frequency is around 17 Khz. At first, this seemed like an odd choice for a wireless fence. But, I've done much research into vlf, and hte frequency selection makes much more sense now! VLF is used because the signal penetrates the ground better, meaning that the received signal strength doesn't vary much if the dog goes swimming or during a rain storm. Also, the signal strength changes very little if the dog tries to crawl 'under' the fence. The signal strength stays about the same if the dog turns towards or away from the transmitter as well. It also doesn't matter whether the dog walks behind a tree or obstacles such as small buildings, dog houses or trash cans. Because the wavelength is so long, these obstacles don't impact the field strength much. A vhf/uhf transmitter would have very serious drop outs with these types of obstacles. It must be simpler and then I would think they would use something other than 17 KHz....interesteing!! |
#20
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On Wed, 30 Mar 2005 08:31:08 -0500, Albert wrote:
Last night, I looked at the signal using spectrum lab's vlf receiver program. When I zoomed in on the transmitters signal, I noticed that there were sidebands occurring every 15 hz. I will post another message with more details. Hi Albert, This could be an ID modulation to serve the receiver's logic. In other words, correction is based upon both signal strength AND modulation. Thus the received signal strength has to fall to a certain level that is still above noise level (not complete drop-off) to insure that corrections are not applied due to power failure at the transmitter (and to allow registration at power-up). VLF is used because the signal penetrates the ground better, This was what I described as the subterranean communications channel used in the trenches of WWI. I would still suggest a power boost over building a ground dipole. The design of the amp is trivial, and kits are available to do the job for less than $20. 73's Richard Clark, KB7QHC |
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