GSM Initialisation

Using Arduino General Electronics
1

I hope someone can help with this, ive got a rather strange thing that happens when i try to initialise my GSM module. The situation arises when using different power mediums but i dont know why. The situation is basically like this:

  • When powering the Arduino and GSM via PC through USB, the GSM module connects to the network perfectly fine.
  • When powering the Arduino and GSM via external battery pack through USB, the GSM module cant connect to the network.
  • When powering the Arduino and GSM via 2.1mm DC jack, the GSM module cant connect to the network.

I've been trying to work out why it wants to be connected to the PC to work properly. My first thought it the current requirement however the DC jack would provide more than the PC anyway (12V 400mA suppply).

If anyone can help then it will be much appreciated.

EDIT, SOLVED:
Turns out a 5 V 1 A external pack doesnt work however a 5.1 V 1 A and a 5.15 V 2.1 A external pack both work so it seems to be the voltage which begs the question as to why my 12 V supply isnt giving the arduino enough juice

2

GSM peak current requirements are lots(*) more than the average supply current, your
supply must be able to deliver the peak current requirement of the GSM module
or the supply voltage will just drop.

(*) perhaps 2A. Some GSM boards have extra decoupling to help when the
supply is inadequate, if not then you need a supply that can provide the peak
current comfortably.