MURS Modifications

[Lowdown3]

So the factory is getting caught up finally... and after everyone else gets theirs I'm thinking about getting a few more for myself and working on some modifications to the MATS.

Some ideas I've thought about-

*Wiring a small solar panel in to the unit with 5-10' of cable that could charge rechargeable batteries in the MAT. The panel could be placed higher up in a tree or something for better camoflague. This might negate having to go out and change batteries on the units. That being said I have some in regular operation that it's been easily 4 months that I haven't had to change the batteries that alert every day.

*An external antenna setup to perhaps help range. I'm thinking the freqs may be close enough that a 2 meter J pole type antenna may work? Maybe a 10 or 20 foot hank of coax and the J pole up 10 or 20 feet running from the MAT may increase range? Thoughts?

*More camo mods- easy enough to spray paint them to match the surroundings but I'm thinking about a little more than that on the next couple.

*IR indicator- it would be nice to tie in an IR LED mounted on the outside of the unit to turn on when the alert is activated. At night through NV it might cut down on the time to view and check which unit was going off.

Thoughts?

[justanothergunnut]

LOL great minds think alike.. Im not a radio guy but do have 15 years experience in low voltage applications like security,automation,cctv etc. I have been toying around with the idea of adding a connection bus to the main board where the NO/NC (normally open/normally closed) tie down is. You could simply clip the two wires for the contact closure from the motion detector then lay them down on a added multi tap bus bar. This way you could add additonal detectors. You could add door contact sensors, vibration sensors, light sensors. even geophones. The nice thing about it is you can wire either in series or parallel. For example you could add multiple motion detectors to cover a larger area or another configuration would be hooking up a motion and a geophone in parallel so BOTH devices must be tripped to send a alarm status. This would decrease false alarms inherent in both sensors. The geophone wouldnt set off the alarm when a tree limb falls and the motion wouldnt set off the alarm when a coyote walks by. by sensitivity adjustment and placement of both units you could get a pretty decent false alarm rejection %.. This was the foundation platform for my idea on updating the Vietnam era intrusion set.

SSHHH don't tell any one.. now im gonna see my DAkota mod all over the net...

[Lowdown3]

Well damn! Good stuff! Your going all out with it and I like it!

Any way to trigger a wireless camera to start sending video back to a monitor? Now that would be the bizzoommb!

[justanothergunnut]

Well damn! Good stuff! Your going all out with it and I like it!

Any way to trigger a wireless camera to start sending video back to a monitor? Now that would be the bizzoommb!

Yeah thats not a problem either.. the wire coming off the motion detector is simply a contact closure switch. run that into a powered relay between the power supply and the camera using a ELk brand timer/relay module and you could have the motion detector turn on the camera for just about any period of time you want. You could also if you wanted to get real crazy add a RF relay into the mix and remotely turn on or off the cameras and IR floods.. Power becomes the issue but realistically you could easily hide a small 12v security battery in a weatherproof enclosure that could power the whole setup.. Add in your hidden solar panel and you could place it and forget about it.

[kev80]

That is great idea. Have you set one up yet.

[justanothergunnut]

I may post pics of the proto type but will more than likely do a short video of it in operation then send it to someone for testing and further opinions.. They may decide to post a video or they may not.. it will be up to them.. I am currently working on which out door PIR I want to use. Considerations are error rejection and power consumption. 9-12 vdc at around 75-150 milliamps is normal. but the kicker is how good is the units on board program for dealing with outdoor stuff.. IE temp variations, rain, snow, wind, all the normal stuff.. That is phase one, pretty simple and I have several out door rated PIR's in my stash of perimeter defense goodies to choose from already. Standard security sytem vibration sensors and door contacts are easily integrated into the system and would require no additional testing. Phase two will be building the proto type for the geophone sensor. There are many options available off the shelf however here the key is to find one that operates at the same voltage of 12 vdc or less and has adjustable sensitivity that is field apropriate. Too sensitive like the ones used in a seismograph and the bottom end is way too sensitive, you need a unit with more "head room". The output of the geophone will have a variable voltage output depending on sensed vibration say 1-5 volts so you need to hook the output voltage to a adjustable relay that has a range that matches the output of the geophone. So the relay kicks at the sensitivity you need it too, adjust the relay input to match the sensitivity of the geophone. For example you measure a human walking at 30 feet from the geophone and it outputs 1.7 volts so you have to turn the dial on the relay module to trigger the contact closure at 1.7 volts. When the contact closure occurs it triggers the MURS radio which sends the signal. Not terribly difficult just time consuming to find and match the correct components. They exist and the project is VERY do able but the geophone accessory will require the most trial and error by far. Of course cost for the geophone option will not be insignificant. Preliminary estimates put it at around $125-175 per sensor.

[justanothergunnut]

Any ideas would be good. Especially wish list type stuff for solving perimeter security needs. A idea I may look into is using a magnetometer ( metal detector) tons of ideas and not a lot of time so the geophone vibration sensor will decently come first.

[tech]

I'm just wondering how you are going to listen to ensure the frequency is clear before transmitting. No license does not equal no rules.

[1Admin]

I'm just wondering how you are going to listen to ensure the frequency is clear before transmitting. No license does not equal no rules.

Can you refer to what your talking about????

[qrprat77]

Can you refer to what your talking about????

If you cause unintentional harmful interference to another service user, you can invite The Man into your life. However, since MURS is pretty much line of sight, the risk of intereference is minimized. Know where you are transmitting (frequency wise) and know what frequencies others use around you (listen/monitor).

[tech]

If you cause unintentional harmful interference to another service user, you can invite The Man into your life. However, since MURS is pretty much line of sight, the risk of intereference is minimized. Know where you are transmitting (frequency wise) and know what frequencies others use around you (listen/monitor).

Exactly what I was referring to...if you're in the middle of nowhere with noone else around for miles, then the chances of interference is minimal. But if you are just on the other side of the trees about a quarter mile from someone else that is using MURS frequencies (remember that they ARE still used by some businesses) then trouble is waiting to find you.

Just sayin' - be sure to know before "Uncle Charlie" comes knockin'... ;)

[justanothergunnut]

If the use of a security device that transmits on MURS frequencies is a violation of FCC rules regarding unintentional harmful transmissions because you can't control exactly when it may transmit why would the FCC allow such a device to be marketed and sold by the thousands or tens of thousands. If their use carries with it such a risk of offending uncle charlie then how does Dakota Alert sell them???? Just curious,, it sounds somewhat like a "technical " violation that is more theory than practice... Also I would like to add Dakota alert systems and the mods I am experimenting with are to be used at a time when the FCC will be the LAST thing im worried about..

[tech]

From the owners manual:

This device complies with Part 15 of the FCC rules, Operation of this
device is subject to the following conditions: 1. This device may not
cause harmful interference. 2. This device must accept any interference,
including interference that may cause undesired operation.

As with nearly all radio products, it is the end user's responsibility to ensure that there are no issues created by the use of the item.