TEK SME Signal Generator

Features

The SME Signal Generator supplies the complex signals required for the development and testing of digital mobile radio receivers. It's capable of generating all signals used in the main TDMA radio networks in line with relevant standards regarding the type of modulation, data format, TDMA structure and frequency hop patterns. The SME is also useful in the analog signal world of conventional signal generators.

The SME covers a frequency range from 5 kHz to 6 GHz. They can be tailored to your requirements by means of a wide variety of options with emphasis either on digital modulation, analog applications or expansion into a universal signal generator.

With the DM Coder (standard on SME03E, Opt. 11 all other models) the SME provides a variety of network-specific digital modulation modes:

The SME has been designed to allow for the integration of future types of modulation and networks.

Frequency and phase changes are produced by DDS (direct digital synthesis). The frequency and phase response are therefore synthesizer-accurate. There is no drift at the carrier frequency. The DM coder is provided standard in the SME03E.

The modulation spectrum stands out for its high spectral purity. Sidebands are well below permissible levels at the frequency spacing relevant for adjacent-channel measurements. Filters other than the standard ones may be used for varying the modulation spectrum (for GMS network: filters with BxT = 0.2, 0.3, 0.5). With GFSK modulation for DECT, non-standard deviations may be set to allow in-depth receiver tests.

The data signals for modulation are applied externally or supplied by the internal data generator. Bit rates are selectable with FSK; they are network-specific for other types of modulation.

Data Generator: The data generator supplies freely programmable data signals and Pseudo Random Bit Sequence (PRBS) signals in line with CCITT. For PRBS signals, five sequence lengths between 2⁹ - 1 and 2²³ - 1 are selectable. Up to ten different data signals can be stored.

Level and Frequency Hopping Synchronous with Data Signal: In addition to the data signal, the data generator supplies a burst and level switch signal. The burst and level switch signals are programmed bit-parallel with the data signal via list entries. The burst signal serves for controlling fast level changes (>80 dB) or frequency changes (<0.5 ms).

The internal level switch signal can be replaced by an external logic signal. The signal switches the level in selectable steps with a rise/fall time <10 µs and enables level variations of up to 20 dB (overrange up to 40 dB).

Amplitude Modulation: The modulation frequency range is DC to 100 kHz. Particularly noteworthy is the extremely low incidental phase modulation with AM, which plays an important role in AM sensitivity tests on FM receivers.

Frequency Modulation (with Opt. 05): The modulation frequency range is DC to 2 MHz. The maximum selectable deviation for modulation frequencies above 500 kHz linearly decreases to 25% at 2 MHz. In the FM DC mode, there's virtually no drift. This allows the digital signaling of receivers by means of analog frequency modulation.

Phase Modulation (with Opt. 05): Phase modulation ranges from DC to 100 kHz. This wide span allows, for instance, tests on phase-sensitive circuits or the generation of PSK modulation with freely selectable phase deviation.

Pulse Modulation (SME02 Opt. 03, SME03 Opt. 08, SME06 Opt. B9): The pulse modulation capability featuring an on/off ratio better than 80 dB and a rise/fall time shorter than 10 ns makes the SME an ideal choice for radar applications. The optional pulse generator allows pulsed signals to be produced without an external source.

Three optional modulation sources are available in addition to the standard fixed-frequency LF generator source:

LF Generator (Opt. 02): The LF generator is a synthesizer up to 500 kHz. In addition to sinewave, squarewave and triangular signals, it also supplies a noise signal. If two LF generators are installed in the unit, multitone signals can be generated.

Multifunction Generator (Opt. 06): This generator operates in a range up to 1 MHz. It produces the same signals as the optional LF generator and, in addition, stereo multiplex and VOR/ILS modulation signals.

Pulse Generator (Opt. 04): The pulse generator generates single and double pulses required for radar receiver testing. It can only be used in conjunction with the pulse modulator module, into which it's integrated.

Simultaneous modulation is required for simulating the complex signals used in modern communications and radar systems. The SME is capable of simultaneous DM, AM, FM (jM) and pulse modulation.

With AM and FM, multitone modulation can be affected either by means of the internal and an external modulation signal or, if two LF generators are provided, by means of two internal signals.

Convenient Sweeping in List Mode: Operation is extremely easy thanks to a well thought-out operating concept featuring a large LCD display and menu guidance. All parameters and conditions selectable for a specific function are logically arranged in a single display. Looking up functions in a manual is a thing of the past.

In the list mode, frequency and level settings are made by means of values stored in lists which may contain up to 4,096 pairs of frequency and level. This mode allows the frequency response of cable connections, amplifiers, TEM cells, etc., to be compensated in the signal generator, a particularly useful feature in EMC measurements.

The list mode may be executed either automatically with presettable dwell time, in single-step operation, or by means of external triggering (for frequency hopping applications). List mode is not provided in the SME03E.

Memory Sequence for Automatic Sequence Control: Up to 50 instrument settings can be stored in a non-volatile memory. After programming the sequence of measurements and the step time in a list, the sequence can be started.

External Triggering: In addition to automatic control, the list mode, memory sequence, RF, AF and level sweep functions may also be triggered by an external signal. This facility enables synchronous operation with other units.

Compensation of External Frequency Response: The frequency response of external cables can be compensated by entering level correction values for up to 100 frequency points. The correction values for the frequencies between these points are determined by means of interpolation. The frequency response correction will be active in any operating mode as well as during sweeps.

Calibration of the unit is required every three years. Calibration values are loaded via the RS-232-C or the IEC/IEEE-bus interface to ensure frequency and level accuracy to specifications. The unit doesn't need to be opened, nor are there any mechanical adjustments to be made.

For maintenance and calibration, precise data on the instrument status are needed. Using the built-in test equipment, the SME Series provides data without any extra equipment required. The signal generator status is continuously monitored. The SME signals malfunctions and deviations from nominal values by means of a message on the display screen.

The optional SME-K2 software allows you to easily program complex frame structures. Preprogrammed data sequences for most important telecommunications systems are provided so that you can quickly make measurements on the device-under-test. Communication standards GSM, NADC, DECT, PDC and PCS1900 are supported with SME-K2.

Specifications

Minimum Frequency	5  kHz
Maximum Frequency	3  GHz
Frequency Resolution	0.1  Hz
Frequency Switching Time	10  ms
Time base stability	0.000001  /yr
Minimum Output	-144  dBm
Maximum Output	13  dBm
Output Resolution	0.1  dB
Output Accuracy	2  dB
Output Impedance	50  ohm
Minimum Single-Side-Band Noise	-140  dBc/Hz
Maximum Single-Side-Band Noise	-120  dBc/Hz
Harmonics (noise)	-30  dBc
Non-harmonics (noise)	-80  dBc
Modulation	AM,FM

Ordering Information

TEK SME Signal Generator

Opt. 01/SM-B1 - Reference Oscillator OCXO.

Opt. 02/SM-B2 - LF Generator.

Opt. 03/SM-B3 (SME02) - Pulse Modulator.

Opt. 04/SM-B4 (Opt. 03, Opt. 08 or Opt. 09 required) - Pulse Generator.

Opt. 05/SM-B5 - FM/_phiM Modulator.

Opt. 06/SM-B6 - Multifunction Generator.

Opt. 08/SM-B8 (SME03) - Pulse Modulator.

Opt. 09/SM-B9 (SME06) - Pulse Modulator.

Opt. 11/SME-B11 - DM Coder.

Opt. 12/SME-B12 - DM Memory Expansion.

Opt. 19/SME-B19 - Rear Connectors for RF and AF.

Opt. 41/SM-B41 - Flex Protocol.

Opt. 42/SM-B42 - POCSAG Protocol.

Opt. B50/SME-B50 - High Speed CPU.

19 in. Rack Adapter - Order ZZA-94.

Service Kit - Order SMZ2.

SME-K2 - TDMA Frame Setup Software for SME Series.

Opt. D1 - Cal Data Report.

Opt. D3 - Test Data (requires Opt. C3).