C/N Measurement

The R&S FSH offers a carrier/noise (C/N) measurement for determining the ratio of carrier power to noise power or carrier power to noise power density. The R&S FSH supports three different modes for carrier power measurement. In the CW TX mode, the R&S FSH determines the power of an unmodulated carrier. In the digital TX mode, it determines the channel power of a reference channel, as is common with digitally modulated carriers (e.g. the DAB, DVB, DVB-T, DVB-H and J.83/A/B/C standards). Furthermore, the ATSC standard for digital terrestrial television with 8VSB modulation is supported. In the analog TV mode, the R&S FSH measures the peak power of the vision carrier with amplitude-modulated TV signals.

Channel-power measurements

The channel-power measurement function is for determining the power in a transmission channel specified by the user. After a few preliminary settings have been made, a single keystroke starts the R&S FSH3s spectrum measurement inside the channel, using a resolution bandwidth that is small relative to the channel bandwidth. The R&S FSH3 then integrates the measured values indicated by the trace to obtain and display the total power. All the settings required for the digital mobile radio standards 3GPP WCDMA, cdmaOne, CDMA2000 1x are predefined ready for use.

Directional power measurement

The Directional Power Sensors R&S FSH-Z14 and R&S FSH-Z44 turn the R&S FSH into a full-fledged directional power meter with a frequency range of 25 MHz to 1 GHz and 200 MHz to 4 GHz. The R&S FSH can then simultaneously measure the output power and the matching of transmitter system antennas under operating conditions. The power sensors measure average power up to 120 W and normally eliminate the need for any extra attenuators. They are compatible with the common standards GSM/EDGE, 3GPP WCDMA, cdmaOne, CDMA2000 1x, DVB-T and DAB. Additionally, the peak envelope power (PEP) can be determined up to a maximum of 300 W.

Fieldstrength Measurement

When measuring electric field strength, the R&S FSH takes into account the specific antenna factors of the connected antenna. Field strength is displayed directly in dBµV/m. In addition, frequency-dependent loss or gain of, for example, a cable or an amplifier can be corrected. For quick and easy result analysis, the R&S FSH provides two user-definable limit lines with automatic limit monitoring.

Locating EMC weak spots

The Near-Field Probe Set R&S HZ-15 is a diagnostic tool for locating EMC weak spots on printed boards, integrated circuits, cables, shieldings and other trouble spots. The Near-Field Probe Set R&S HZ-15 can handle emission measurements from 30 MHz to 3 GHz. Its sensitivity can be enhanced by adding the Preamplifier R&S HZ-16, which has a frequency range up to 3 GHz, a gain of approx. 20 dB and a noise figure of 4.5 dB. In combination with the R&S FSH, the preamplifier and near-field probe set are a cost-effective means of analyzing and locating sources of interference during development.

Measurement with Channel Tables

Channel tables make it possible to tune the R&S FSH using channel numbers as an alternative to frequency entry. The channel number is displayed instead of the center frequency. This makes operation simple by offering users channel assignments they are accustomed to from familiar TV and mobile radio applications. The channel tables are generated with the R&S FSH View software and loaded into the R&S FSH. The software comes with TV channel tables for virtually the entire world. Up to 15 different frequency bands can be easily defined within a channel table. The R&S FSH can even handle gaps in channel numbering or with assigned frequencies (as usually occur with TV channel assignments, for example). Alternatively, a channel table can be defined directly on the instrument by entering the first channel number together with the associated frequency, the number of channels and the channel spacing. ( Available for all R&S FSH models as standard, requires at least firmware 7.0 )

Power measurements

When the accessory Power Sensor R&S FSH-Z1 or R&S FSH-Z18 is fitted, the R&S FSH3 is transformed into a high-precision RF power meter with a maximum frequency of 8 GHz or 18 GHz. As with thermal sensors, the true RMS value of the measured signal is obtained over the whole measurement range irrespective of the signal waveform. This is particularly relevant when measurements are made on modulated signals because no additional measurement errors are introduced. The measurements are straightforward, which is very important for digitally modulated signals such as 3GPP. The large measurement range which covers 200 pW to 200 mW (equivalent to a dynamic range of 90 dB) turns the R&S FSH3 with the R&S FSH-Z1 or R&S FSH-Z18 into a universal RF power meter.

Receiver Mode

When equipped with the firmware option R&S FSH-K3, the R&S FSH can be operated as a receiver for monitoring and precompliance EMC applications. Measurements are performed at a predefined frequency with a user-selectable measurement time. In the scan mode, the R&S FSH sequentially measures each level at various frequencies defined in a channel table. The channel tables are generated with the R&S FSH View software and loaded into the R&S FSH. The screenshot on the right shows, for example, a measurement of the level assignment in the GSM uplink band displayed as vertical lines. In addition, the CISPR bandwidths 200 Hz, 9 kHz, 120 kHz and 1 MHz are available for RFI emission measurements. The R&S FSH offers peak, average, RMS and quasi-peak detectors. (Available for all R&S FSH models with installed R&S FSH-K3 keycode and firmware >= 7.0)