I’ll warn you right away that I don’t have much experience in radio engineering, and I don’t have one at all in the search for missing people, so it’s quite possible that my conclusions are based on false premises. I thought, is it worth it to write this article at all? But still, “keeping silent” would be wrong. Perhaps not in this form, but if the suggested thoughts will lead to an idea that can help someone return home - it's worth it.
So, briefly for those who have not read the article from the link above. There is a task - to find a person in the forest using modern technology. This article discusses the work of several teams and I will rely on some examples of their work in my reasoning.
In fact, there are two ways of searching - taking into account the active assistance of the victim (scattering beacons in the forest, one of which the victim must activate), or without such assistance (for example, combing the forest with quadrocopters). I will consider only the first approach. Although potentially, I think, the option of searching by robots is more preferable (at least by the fact that it allows you to find motionless people), but in this option you need to work on increasing the sensitivity of sensors, developing complex robots, training neural networks, etc. And in these matters I should offer there is nothing.
So, back to the lighthouses.
The beacons considered in the article consist of
LoRa, proprietary design board with attachments, mosfets, stabilizers, GPS module, rechargeable battery and 12 V siren
The idea is
- With the help of several aircraft-type drones, scatter a hundred or two small sound beacons over the forest. They connect into one network, where each unit is a radio signal repeater, and begin to make a loud sound. The lost person must hear it, find it, press the button and thus transmit a signal about his whereabouts.
So, we define the cons of the lighthouse from the article:
- The device is quite expensive, there are not cheap components (cost of about 3000r).
- The device is quite large, in a post a rather large radio-controlled aircraft could take away no more than 2 pieces at a time.
- The device’s battery will last for several hours, after which the lighthouse turns into a brick and needs to be found (since there is an array of coordinates).
The shared network and GPS in every beacon is cool, but it only works if there are rescuers nearby who are ready to catch the signals of this network. Then is she needed?
If the rescuers put something like a radar antenna that will scan the forest to the activated lighthouse, you only need to emit a signal, and it can be detected for tens of kilometers. By the time of the "response" (or simply by putting two "radar") - you can determine the coordinates of each lighthouse (by interrogating them in turn).
Thus, the design is simplified to an antenna, a transceiver and a siren. The cost is reduced at times, probably up to several hundred rubles (in circulation), the size is reduced, the "lifetime" is extended. Such lighthouses can be released much more, it will be much easier to find them.
Let's go further.
My opinion, with which many disagree (I think not one of those whose relatives disappeared in the forest), is that the lighthouse should be reusable. Collecting all the lighthouses after each search is extremely difficult and expensive.
Of course, clogging the forest is also not a matter, you must be able to find devices whose resource is running out. But still, in those places where people are often lost, several thousand lighthouses already scattered are much better than losing people.
So the sentence:
The lighthouse, probably a ball of bright colors, contains:
- The transceiver for communication with the base station can operate in a pulsed mode and, preferably, in talk mode.
- Battery
- Gyroscope
- Backlight
- Siren
- Receiving coil
A receiving coil is needed since the beacon is completely de-energized before starting work. The radar at the base station has enough power to create enough current in the receiving coil (at the resonant frequency) to turn on the device.
After switching on, the beacon (by default) switches to the search mode for people: once a minute, making a loud sound and blinking diodes. Optionally, between the signals, the beacon can listen to the surroundings and, with non-standard noise, start to signal more often or send a recording to the base. If the gyroscope signals the movement of the device, it establishes communication with the base station (including in talk mode), the base station transmits the coordinates to the rescuers.
An instruction is written on the device that if you are lost, you need to take the ball with you (even if it is silent). And wait for its activation, then shake to contact the help center. It is likely that people will often pick up such a ball before the start of the search and just carry it around. That will speed up the search many times, including helping to find some inactive victims (and also save battery on other lighthouses).
But what about the garbage? These balls will fill everything ...
There is a second mode for this. It is activated if the base station transmits a “maintenance” signal during device activation. In this case, it transmits information about its charge, the state of the sensors and, if a signal is received for a search, it starts “squeaking” on the air every few seconds to simplify searches.
To search for a device, you can use a miniature manual base station (similar to a metal detector only less). It makes it easy to find the device within a few hundred meters. Or several tens, if the device is completely discharged and only the receiving coil "responds".
This approach allows you to organize the collection of devices or the replacement of batteries by volunteers. And since after the initial placement of the beacons a map of their placement is compiled - then no beacon will disappear, even if it is completely defective, it is relatively easy to find and dispose of.
The obvious question to this scheme is the duration of the battery’s charge in the street (especially in cold weather). Here I can’t give a complete answer because I don’t know what are the options and how realistic this use is in practice.
Of course, it is desirable to equip the devices with solar panels for gradual recharging. Even indirect lighting will allow you to charge the battery in a few weeks, especially since the device does not use it at all in a “simple” mode. A more exotic option is to use the energy of daily temperature drops, but their efficiency is lower and the cost is higher.
In winter, the device will be in the snow, which is likely to prevent serious hypothermia, which could irreversibly damage its battery.
Of course, under the snow, the efficiency of the device will be extremely small (especially given the attenuation of the signal), but in winter there are much less "losses", and other types of search operations (for example, observation from copters) become much more effective, due to the lack of thick sheets .
There are other little things that can help someone. For example, it’s logical to build a compass in each lighthouse, but not the classic one that few people in Central Asia will be able to use, but just the arrow and the inscription “go there!”. Since the location of the beacons is known, the position of the arrow on the magnetized disk is naturally selected by rescuers based on a map of the area.
You can think of a lot more (for example, a whistle to call rescuers, and a lighter built into the body), but I think the idea is clear. I would be glad if someone finds it useful.
And to the rescuers - many thanks for your work! You are awesome!)
An important addition after publication.
The first comments after the publication of this post show that I could not clearly convey the main idea of ​​this article and the reason for its appearance. Many object to the lighthouses as a concept in general, but the article is not about that. Lighthouses have already been used by several teams in the searches described in the article by reference. Moreover, the team recognized as the best - also used beacons . Those. it is a technology that is already working and is already paying off. Obviously, there are other technologies, but they are not considered in this article.
The article describes only a way to optimize the use of beacons. Simplification of construction, cost reduction, increase in efficiency. In my opinion, you need to work on this, and if at least some ideas help the following teams work more efficiently - great. If someone thinks in the comments or other articles how to optimize the design even more - even better!
Finally, to the idea, which raises a lot of questions about not cleaning up the beacons after the searches. Obviously (this is discussed in the article), it makes sense for those places where people get lost often. Judging by past Lisa-Alert publications, there are relatively small forests (several hundred sq. Km.) Where people disappear almost every month. In this case, it makes sense to place the beacons at the beginning of the season, and assemble at the end, or even after a couple of years, if the design allows them to continue working for so long.
Lighthouses are not a panacea, this is just another tool that may be in service with the search team, and of course it is up to them to decide how and when to use it. I am sure that there are situations where this can be justified.
I did not describe any elementary things. For example, that lighthouses can be left in prominent places during searches, it is not necessary to drop them from the plane. Or that the "radar" can be installed on a search helicopter (in general, "radar" is just a name, in fact, its power will be many times less, and the device is simpler than with real radars). But most commentators do not even seem to read the article that they are commenting on, so there is simply no point in describing any little things. I think if there is a rational kernel in my idea, those who need it will notice it.