Realistically, you're not going to be able to create a remote-control with cell-phone like range. There are only certain frequency ranges available for use without licensing the spectrum. Those all have strict limitations on either how they're used (CB-band radios) or on how much power they can emit (wifi, bluetooth and other devices using the scientific and instrument band). As such, the only frequency bands which they can use for this purpose aren't going to allow powerful enough transmissions to be picked up a couple of miles away. Thus, increasing the range is not feasible.
What could potentially be done would be to build a similar device which acts as a blue-tooth device and some custom software for a cell-phone such that you could use a computer to send commands to the cell phone which would then send commands to the device. However, that would probably have to be a different device from the one that they have built and there are also a bunch of difficulties in getting the software onto the cell phone. Or alternately, you could build a device which communicates via WiFi and use a cell-phone which does tethering or a mifi in order to have the device be on the internet. So, I do think that you could realistically build a device which could do something like that, but it would be a whole separate device from the one they have built. Maybe, if this project is successful for them, you could get them to tackle it as a next project (if they would agree to doing another project), but I'm sure that they won't be able to modify this product in that way.
We have to make a distinction between activating the receiver from a cell phone (which you can already do if you can see a website from your cell phone and the receiver is within DL2K-LINK range) and using a cell phone as a DL2K-LINK replacement.
The main issue with the latter is that as you say there would need to be a bluetooth connection between the receiver and the cell phone and the DL2000 does not use bluetooth. Choice of RF technology is mainly determined by battery consumption. We made the battery last 3 months, this would never have been possible with a bluetooth device.
So what is the range like?
In line of sight if you transmit with the DL2K-LINK you may be able to get a 1 mile range. But that's meaningless, because there will be obstacles, always... If the wearer turns away that already reduced signal by 1/3rd or more because the human body is mostly water which absorbs RF very well. So in practice the DL2K-LINK will reach anywhere inside an average home and probably outside in the garden if you have one. Same as your Wi-fi router.
The target with the remote control which is less powerful than the DL2K-LINK was to get it to work well enough that the wearer could be facing the other way and be 20 meters away and packets would still be delivered 100% of the time. We achieved that goal. It's a pretty awesome result considering battery life, technology available and legal limits.
We never had the target of reaching a wearer miles away. We know it can be done, but only by making considerable compromises in battery life and/or receiver size.
A bluetooth version of the DL2K-LINK would not really need greater battery life than any other normal bluetooth device. It could be independent from both the cellphone and the DL2000 and simply carried by the male along with the cellphone. Putting the device into close range dog mode would ensure that the male could not turn it off or leave it out of range. It could then satisfy these requirements without compromising the battery life of the DL2000 itself (or even require any modification to the existing design) and simply be recharged at night like you would do with any other normal bluetooth device.
Cell phone charge lasts a few days at most. DL2000 battery has 1/3rd the capacity (and size) and lasts 3 months. Technology changes fast but last time we checked it was impossible to get the same battery life with bluetooth.
I was referring to a bluetooth version of the DL2K-LINK, not the DL2000. The DL2000 would not need bluetooth so it should not affect the battery life of the DL2000.
I have made a similar post over on one of the blogs, but I think a wonderful follow on device would be a bluetooth interface. You could have an app running on his phone that talks to the bluetooth which in turn talks to the receiver.
If you've sent him to the store and the phone app sees that his gps position isn't along the path to and from the store, it gives him a reminder not to stray. Or if he's taking too long, it'll give him the necessary encouragement to pick up the pace.
If he's out doing stuff and it's time for him to come home, just send a message to the phone app to start coaxing him to head home (checking against gps position all the while).
Yeah, the battery may only last a couple of days, but that's the same story with the phone battery too.
Personally, I would willingly sacrifice battery life for the additional power of control this would provide. I can understand how others might not share this willingness. I also expect that many would agree with me, however. Could this possibly become an optional feature?
In open air the wearer will disappear from your sight before the remote stops working.
Look at old blog posts, there's one called "crossing the pond"... demonstrates reception 100-200 meters away.
Indoors it's a completely different story, but the signal will still go through 1 brick wall most of the time. Sometimes 2 brick walls.