6 Intermodulation attenuation

11.263GPPBase Station System (BSS) equipment specificationPart 4: RepeatersRelease 1997TS

6.1 Test purpose

To verify that the level of intermodulation products, generated in non-linear elements of the repeater, in the presence of two RF input signals, do not exceed the specified limits.

6.2 Test case

The repeater shall be set to maximum gain. Two continuous sinusoidal RF signals shall be fed to the input antenna port of the repeater using a combining device. The frequencies of both RF signals shall be within the repeater’s operating band. The spacing between both RF signals shall be the minimum possible spacing applied in a network, i.e. 600 kHz.

The level of both RF input signals shall be increased, until the maximum rated output power per channel, as declared by the manufacturer, is reached.

In case of a repeater only supporting one channel, one RF input signal shall be set to the operating frequency and the other RF input signal at an offset of 400 kHz to either side successively. In this case the input signal at the repeaters operating frequency shall be increased, until the maximum rated output power per channel, as declared by the manufacturer, is reached. The second signal shall be set to the same input level.

The level of the third order intermodulation products shall be measured by means of a selective measurement device presenting to the repeater a load with an impedance of 50 ohms.

The test shall be repeated with both RF input signals increased by 10 dB each.

NOTE: In this case, the automatic gain (level) control may reduce the gain to a value less than maximum gain in order to keep the maximum rated output power per channel, as declared by the manufacturer.

An average power measurement shall be performed using a bandwidth of 3 kHz.

The measurements shall apply to all antenna ports of the repeater.

Test environment: Normal

6.3 Conformance requirement

The maximum level of intermodulation product shall be not greater than:

‑36 dBm (250 nW) in the frequency band 9 kHz – 1 GHz

‑30 dBm (1µW) in the frequency band 1 GHz – 12,75 GHz

6.4 Reference requirement

GSM 05.05 [6] annex E