schematic gsm jammer
Hello,
Illegal as it may be to use jammers, from the technical discussion pov, I think that the jamming process depends on the following factors:
- distance or cell area to be jammed
- Power that the Base Station is transmitting at or its EIRP (depends on transmitter power and the antenna gain), and the height of its antenna
- Sensitivity of the receiver
- Losses for the wireless link
from the above you cn make a very simplified "link budget" and calculate the amount of power you need for your jammer.
For GSM I agree that you should jam the pilot channel of the cell (called the BCCH in GSM) as if jammed it will block all service in the cell, however this is the channel that is transmitted with the most power and it is always on (beacon channel). Other channels (traffic channels TCH) are transmitted on per need basis and have the ability to hop on several frequencies (one freq each time slot) so if you try to jam a TCH you may cause bad quality but not block the service.
To know which channel is the BCCH, you can use a trace mobile software, on old nokia phone there waqs a "netmonitor" software that showed you the signal level on your cell and neighbor cells.
For CDMA and its derivative (WCDMA, etc) the channels are wideband relatively (1.25 MHz (IS95) and 5 MHz(WCDMA) versus 200 Khz for GSM channels) and it is very tricky as the CDMA system is designed to extract the required signal from all the interference (users use the same frequency in the cell), however it can only extract the info as long as the total interference is below a certain level, by adding a certain amount of interference from your jammer you can easily block this channel, the problem being to have to generate a big bandwidth signal (up to 5 Mhz)
Regards