Guys please
I have some question:
How to found a gateway by the ID number?
How to found a gateway by frequency - like 915Mhz or 433mhz near by me
How to scan gateway, or how to access this one?
I cannot found this answers, sorry if this s simple.
thanks
LoRaWAN gateways (or at least those operating class A, which is what TTN supports) are not something that you can “scan for”
Rather, the way LoRaWAN works is that a node transmits in accordance with the LoRaWAN spec.
Any in-range gateways complying with that spec receive and report the signal to a server.
If a server recognized the node (or join request) and a response is appropriate, it commands the gateway that reported the best received signal (or the gateway that reported the best signal and is available to transmit) to transmit that reply.
If no reply is appropriate, there is no feedback to the node at all.
Transmitted replies have no gateway identifying information in them at all.
Thus the only real way to detect gateways is to query a database of available gateways, or to operate a node and see which gateways participate in reporting it through the backend.
Sorry, I don’t want to be rude. My original idea is to do a system more smart to scan or check the gateway nearby. Like a blind scan. Not my intention to bad, my apologies for those feel bad. My censorious apologies again.
You’re welcome to design your own radio network incorporating your own protocol and discovery ideas, but that network would not be TTN.
As a practical matter, I’d recommend spending some time understanding existing schemes before you strike out on your own.
apart from what @cslorabox describes, there is not a “more smart” way to check things that in principle only receive data, unless stimulated with properly configured packets (that is, according to the LoRaWAN standard). If you stand in the forest and just listen, you will not hear other people that are just listening. If you scream in the forest, you may know some other people are there only if someone decides to answer. If your scream is like an animal (that is, no or different protocol), no one will greet you.
One thing you might do, with great patience, is to just wait for ISM signals, and try to understand whether they are LoRaWAN, of the kind a gateway may send in response to some other node asking for joining the network. Not sure how they could be recognized (I know how to learn it, but it’s your job 
). However, keep in mind that, in the same frequencies, you have a lot of other protocols running, from remotes to different uses of LoRa, different networks, and even if you are able to classify LoRaWAN packets, you will not know who and where is the gateway.
On the other side, if you do all of this “smart” waste of time just to access a gateway, you do not need it: any TTN gateway will simply accept your packets (because you do not access a gateway: it’s not something you have to ask permission to start a connection).
Likely, you have in mind a networking model that is not the one of LoraWAN 
(which is not perfect, of course, but thoroughly studied).
Install your own Gateway, you will than have access to it and have the benefit of helping the rest of the community.
As others has written, the only way you can “scan” for gateways is by having a node send packets, and listen for responses in the ttn-console.
I have a map doing that on https://kartoteket.alslug.dk/ttn/beacons.html#kort (to be moved to a new address i a short time)
We have a number of nodes sending on SF7-SF12 once an hour, recording the received packets and drawing a map.
Another solution if run/drive around with a tracker connected to TTN-mapper,but that only gives SF7 coverage.
You’re not able to “scan” but after a while you’ll get an idea on what your gateway-coverage is at a number of given locations. My approach also gives an idea on the coverage when there is no SF7 coverage.
/Henning