UNAOHM
12
NG500 (Rev. 0)
Figure 4 Connections to check the frequency response of a device under test
Example
If you wish to measure the gain of a channel amplifier, such as channel 23 covering the
frequency range from 486 to 494 MHz (8MHz bandwidth device) :
1)
Make sure the amplifier accepts 80 dBµV + 10 log (8) = 89 dB without getting into saturation
at its input (see Appendix). Compatibility of this kind is important since the noise generator
supplies 80 dBµV each 1MHz bandwidth.
2)
Apply the NG500 generator signal directly to the input connector of the FSM set to 90 dBµV
full scale and 1 MHz bandwidth, as per Figure 4. Check for a reference level say, at
81 dBµV
.
Connect now the amplifier under test between the NG500 and the FSM (with the same 1MHz
bandwidht), as per Figure 4, and take the level reading (for example,
96 dBµV
).
The amplifier gain will correspond to the dB difference between the two measurements, that is:
dB gain = dB measurement – dB reference = 96 – 81 =
15 dB
.
Figure 4 legenda:-Dispositivo sotto test = Device under test (DUT).
-Misuratore di campo = Field Strength Meter (FSM).
