Rohde & schwartzsml01-data 电路图.pdf

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1、Signal Generator SML01 Top-class economy generator Despite its amazingly attractive purchase price, the new Signal Generator SML01 (FIG 1) comes up with a variety of technical benefi ts. For example, it features a wear-free electronic attenuator guaranteeing short level setting times. Users in produ

2、ction and servicing, EMC testing and design alike will highly appreciate this feature. In frequency synthesis too, our engineers have taken new approaches and created a spectrally pure synthesizer with extremely short setting times previously only found in high-end equipment. Modulation: classic mod

3、es SML01 generates amplitude-, fre- quency- and phase-modulated RF sig- nals in the frequency range 9 kHz to 1.1 GHz just what is needed in all classic receiver measurements. Of course the FM modulator provides stereo modulation too with the aid of an external signal. To generate sinusoidal modulati

4、on sig- nals, an AF generator is built into SML01 covering the frequency range 0.1 Hz to 1 MHz. Its output signal is brought out at a separate connector and thus available for external applica- tions. For two-tone modulation the AF generator can be operated in conjunc- tion with an external signal s

5、ource. Pulse modulation for EMC applications or measurements in the radar IF range? Again no problem for SML01: adding the option SML-B3, these functions are easily implemented. SML-B3 not only comprises a high-grade pulse modula- tor but also a fully equipped pulse generator whose signal is brought

6、 out at an extra output. All modulation modes can be operated simultaneously. Only frequency and phase modulation cannot be combined since they are generated by the same modulator. FIG 1 Great inner qualities and surprisingly compact outward appearance: the 19” case of SML01 is only 88 mm high and 4

7、50 mm deep. This makes the generator an attractive signal source for rack or desktop applications. Operation is by “EasyWheel” (FIG 2) Frequency synthesis: like the “big boys” In terms of frequency accuracy and spectral purity, SML01 is equal to high- end Rohde & Schwarz signal genera- tors in every

8、 way. Frequency setting is crystal-controlled with 0.1 Hz resolu- tion. Fitted with option SML-B1 (OCXO reference oscillator), SML01 satisfi es even the most stringent frequency accu- racy requirements. Particularly noteworthy is SSB phase noise (FIGs 3 and 4). A typical value of 128 dBc (at 1 GHz,

9、20 kHz from carrier, 1 Hz bandwidth) was simply unknown to date in this instrument class. FIG 3 shows a typical characteristic at 1 GHz for carrier offsets 1 Hz to Photo 43 412/3 Articles 8 News from Rohde&Schwarz Number 165 (1999/V) RadioFans.CN 收音机爱 好者资料库 FIG 2 The operating concept of SML01 is th

10、e same as that of Microwave Signal Generator SMR*: just turn the wheel to go to a desired menu item, then press it to open the correspond- ing submenu 10 MHz. This excellent noise perform- ance just like the outstanding spurious suppression of typically 76 dBc was achieved by sophisticated direct di

11、gital frequency synthesis (DDS). This concept at the same time means short frequency setting times (typ. 7 ms) for SML01. FIG 3 further shows broadband noise of typically 150 dBc (at 2 MHz from carrier), which meets the most exacting demands. Level: electronic setting The tough conditions of day-to-

12、day use in production are a measure of the worth of any signal generator. Here, precision and speed and above all maximum reliability are called for. This applies in particular to the attenuator in the output path of the signal generator. While mechanical attenuators, which are frequently used, full

13、y meet require- ments in terms of level accuracy, they leave a great deal to be desired when it comes to setting speed and service life. Not so SML01: its electronic attenu- ator handles any number of setting operations without any wear and this with typical setting times of 5 ms. And because of the

14、 excellently devised fre- quency response compensation of the RF level by means of the SML01 micro- processor, level accuracy (typ. 0.5 dB) well matches that of any signal gen- erator using a mechanical attenuator (FIG 5). The remaining RF level specifi cations are quite impressive too. For example,

15、 levels from 140 dBm to +13 dBm can be set in 0.1 dB steps with over- range even up to +19 dBm. Of course, neither a mechanical nor an electronic attenuator performs level setting without interruption. SML01, therefore, like signal generators with a mechanical attenuator, offers the “non-interruptin

16、g” level setting mode, allowing level vari- ation by typically 30 dB. This makes SML01 an ideal choice for squelch tests. Applications: fi t in every respect Receiver measurements These measurements belong to the clas- sic applications of SML01. Featuring low residual FM of typically 0.5 Hz (at 1 GH

17、z, weighting bandwidth 0.3 kHz to 3 kHz to CCITT) and low SSB phase noise as well as high spurious suppres- sion, the signal generator is ideal for all in-channel measurements on receiv- ers. This also applies to its use as a noise source outside the receive channel. Here the low broadband noise is

18、an additional advantage. Since SSB phase noise is very low even at several hundred kHz from the carrier, blocking measurements pose no problem. Sensitivity measurements call for high level accuracy, especially at low RF levels. The signal generator should also feature adequate RF shielding in partic

19、ular with unshielded receivers or equipment with an integrated antenna (eg pagers). SML01 fully meets both requirements. EMC measurements EMC measurements, such as of elec- tromagnetic susceptibility, are usually carried out with a power amplifi er connected after SML01. The ampli- fi er is extremel

20、y sensitive to fast level changes such as overshoots or drop- outs, which may even cause damage. The following two characteristics of SML01 are, therefore, particularly valu- able: level changes are practically with- out overshoots, and the non-interrupting level setting prevents RF level dropouts d

21、uring level changes (FIG 6). 0 20 40 60 80 100 120 140 160 1101001 k10 k100 k1 M10 M f Hz L (f) dBc/Hz FIG 3 Typical SSB phase noise at 1 GHz Turn Click 150 145 140 135 130 125 120 115 1100 f MHz 100090080070060050040030020010010 dBc/Hz FIG 4 Typical SSB phase noise versus carrier frequency (20 kHz

22、from carrier) Articles News from Rohde&Schwarz Number 165 (1999/V) 9 RadioFans.CN 收音机爱 好者资料库 Condensed data of SML01 Frequency range 9 kHz to 1.1 GHz Resolution 0.1 Hz Setting time 10 ms Harmonics 30 dBc Spurious 70 dBc SSB phase noise 122 dBc/Hz (f = 1 GHz, carrier offset 20 Hz) Residual FM to CCIT

23、T (f = 1 GHz) 80 dB Rise/fall time 20 ns AF generator 0.1 Hz to 1 MHz Pulse generator (option SML-B3) Pulse period 100 ns to 85 s Reader service card 165/02 Due to the widespread use of digital radiotelephones, growing importance attaches to testing the immunity of these units to high-frequency elec

24、tromagnetic fi elds. The European draft standard ENV 50204 specifi es a relevant test method. The method can basically be implemented with an SML01 fi tted with an optional SML-B3 pulse modulator. The measurement is carried out using a pulse-modulated carrier frequency of 900 MHz 5 MHz, with the pul

25、se generator set to a period of 5 ms and a pulse width of 2.5 ms. In this way the generator simulates interference caused by TDMA signals. Servicing SML01 is compact and lightweight. And another plus for fi eld use: it can be controlled both via an IEEE bus inter- face and a serial RS-232-C interfac

26、e. This allows straightforward operation from a notebook PC without an IEEE bus card. In the servicing of transceivers or trans- mitters, there is a risk of RF power being inadvertently applied to the gen- erator RF output. SML01 has a protec- tive circuit integrated in its output that prevents the

27、unit from being damaged (this applies to reverse power up to 50 W). * Kraemer, Wilhelm: Microwave Signal Gen- erators SMR Microwave in handy size. News from Rohde & Schwarz (1999) No. 162, pp 46 FIG 5 (top): Typical level accuracy at 0 dBm FIG 6 (right): Level sweep over range of 25 dB All in all: a

28、n investment you will not regret When it comes to reliability, SML01 makes no compromises either. Should a fault ever occur, the built-in diagnos- tic system helps to drastically reduce repair times. So SML01 is a safe invest- ment, not only due to the favourable purchase price but also to the low f

29、ollow-up costs and the long calibration interval of at least three years. Wilhelm Kraemer 10 5 0 5 10 15 TR Center 1 GHz 30 ms/ RBW1 MHzRF Att40 dB VBW1 MHz SWT300 msUnitdBm Ref Lvl 11 dBm 1VIEW 1 dB 0.5 dB 0 dB 0.5 dB 1 dB 0 Hz500 MHz1 GHz Articles 10 News from Rohde&Schwarz Number 165 (1999/V) RadioFans.CN 收音机爱 好者资料库