Growing up in the country we had a long, wooded driveway. You’d never know who was coming up the drive: could it be a delivery person, the mailman, or perhaps someone wanting to cause mischief. I wish we had a product like the Dakota Alert Driveway Monitor to keep an eye on things and indicate when a vehicle was creeping up the drive.
Dakota Alert produces a full line of driveway monitor and alert products. Some of their devices are direct connect with a cable or run off as an unlicensed FCC Part 15 device. But I think their most powerful and useful alerts are their MURS radio band alert monitors and devices.
Combining the alert products with the Multi Use Radio Service (MURS) has a couple of distinct advantages. The MURS band is an unlicensed radio band designed for business and personal communication with radios up to 4 watts. It also allows for the use of detachable external antennas to increase the range of the transmitting devices. Where the low power devices may only work for a few hundred feet, with the right equipment and conditions a MURS transmitter can give a mile or more of coverage. Combine this with the ability to use multiple transmitters and off the shelf hand-held radios, and you’ll be able to create quite the security perimeter around your property.
[pq]An external antenna, like the KB9VBR MURS Antenna works wonders at increasing the Dakota Alert Monitor’s range [/pq]
To make the Dakota Alert MURS Driveway Monitors useful for longer ranges, you will want to replace the stock antenna with something higher profile and higher gain, like the MURS J-Pole antenna. This antenna has 3db of gain, twice that of the standard whip antenna supplied with the device, and you can mount it in a higher profile location to get the signal above obstructions. The copper antenna can even be painted to help camouflage it and blend into the surroundings.
There are two options on using external antennas with the Dakota Alert MURS driveway alert devices: either putting the antenna on the transmitter or on the receiver. If you are planning to use a handheld radio to monitor the alerts, then you’ll want the external antennas attached to the alert transmitters. While this may cut your range, it will give you the ultimate in flexibility especially if your work takes you around various point on your property.
If you are planning to use the MURS base station to monitor one or multiple alert devices, I’d install the external antenna on a mast and connect it to the base. The transmitter(s) can continue to use their stock antennas as a the high profile receiving antenna should be able to hear all the transmitters along your property (although a far remote transmitter may require an external antenna, it depends upon distance and terrain).
Connecting the antennas to the transmitters or receivers is easy; you’ll need two parts, both of which are available at Radio Shack. First is a BNC to PL-259 adapter, RS part number #278-120 and some RG-58 coax cable with PL-259 connectors RS part number 278-967. Attach the antenna to a pole, mast, or even a fence post driven into the ground. I recommend a mast of at least 10 feet to make the antenna most effective. If you are attaching the antenna to a base station, then mounting the antenna 20-30 feet would give you your best range. If you don’t have a tower, a chimney mount or tripod roof mount may be a couple of good options.
The Dakota Alert MURS Driveway monitors are great for announcing the arrival of any vehicle coming up your drive. Their motion sensors can also be used to monitor outbuildings and warehouses. By adding an external antenna to the transmitters and/or receivers you can extend their range and have reliable coverage over your entire campus or property.