Modules being used - sim800l and DHT22. (can be changed on your advice)
Board - arduino uno.
#Problem - No GSM signal inside the cold storage.
I can not solve the problem.
Case 1 - DHT inside, arduino and GSM outside. Minimum wire length would be 100ft(30m). As I learnt, DHT22 signal degrades even at 5m.
Case 2 - Everything Inside. I will get a U.fl to coaxial cable, take it 100ft outside, attach a SMA antenna. But as I learnt (everything I learnt is from electronics stackexchange , the GSM signal will not reach module.
Try a DS18B20 inside. One of those should be able to manage 100ft.
Another possibility is to have an Arduino inside and another outside communicating over serial. You could improve your chances of good data transfer with a low baud rate.
Wire capacitance degrades the signal over long lines, so twisted-pair or coax only adds to the problem. As 6V6 said, RS485 is a much more robust mode and designed for very long lines.
wildbill:
Try a DS18B20 inside. One of those should be able to manage 100ft.
Another possibility is to have an Arduino inside and another outside communicating over serial. You could improve your chances of good data transfer with a low baud rate.
@wildbill I just want to ask if it is possible to just put a 1k resistor as pullup? What if I tried 500ohms?