Testing of Main Indices of Signal Repeater

Testing of Main Indices of Signal Repeater

Testing concerning about the main indices of mobile communication signal repeater should consider the accuracy of testing and also the cost of testing and as well as possibility of easy and convenient operation of testing.

1. Testing of rated output power, maximum gain, gain adjustment range and AGC range of signal repeater

When testing the rated output power, the attenuation from output port of cell phone jammer to the input port of watt meter should be considered.

Many other indices should be tested at the power specified by the manufacturer of signal repeater, therefore, when the manufacturer determines the maximum output power, influence on other indices (such as the intermodulation, stray emission and so on) should be considered.

2. Testing of bandwidth, fluctuation in band and suppression beyond band of signal repeater

The sweeping frequency testing should be adopted as much as possible. The network analyzer (vector net and standard net) should be used or the frequency spectrum analyzer with tracking generator can be utilized. The latter one is recommended for its dynamic range is big and it can reduce the types of instruments to be tested so that the cost can be cut.

After connecting with the tracking generator, the center frequency should be adjusted to the center frequency of the signal repeater to be tested. The width of sweeping frequency should be adjusted to three times or seven times of band width of signal repeater to be tested (it is independent on the band width to be tested and magnification will be higher if the band width is narrow).

The output level should be adjusted to the input level of the signal repeater to be tested which is Lin. The reference level of the frequency spectrum analyzer should be adjusted to the almost full scale. The response curve of the filter will appear on the screen of frequency spectrum analyzer. The band width, fluctuation in band and suppression beyond band can be read with labels.

When testing the fluctuation in band, it is suggested that the input level Lin should be reduced to completely expose the fluctuation in band. When testing the suppression beyond band, if the dynamic range of the testing instrument is not big enough, the spot frequency testing method can be adopted.

The signal repeater should have the function of remote monitoring and controlling. The cell phone jammer is installed in the remote area. Some manufacturers will allocate a cell phone for the signal repeater. The cell phone number can be used to form the network management system of the signal repeater itself. But the price will be a little bit high.

When the signal repeater is not large in quantity, it is unnecessary to purchase the network management system. The easiest and most effective method is using the cable to lead the remote function to the ground through the RS232 port. And then, it is unnecessary to clime up the iron tower every time checking and inspection are performed to the signal repeater.

The signal repeater should have the function of fault and alarm recording. The signal repeater should have record of power off, overload of power amplification and whether there appears the self excitation or not.