Datum Systems PSM-500L Bedienungsanleitung PDF herunterladen (Seite 5)

Datum Systems PSM-500, 500H & 500L VSAT/SCPC Modem Specification

Rev. 0.86

A-5

The basic modem design includes separate synthesized transmit and receive interfaces, flexible

clocking options and on-board Viterbi Forward Error Correction (FEC). The on-board standard data

interface is programmable for either RS-449, V.35, V.36, EIA-530/A or synchronous RS-232, while

a separate Serial Control Port allows external monitor and control of all variable functions and

parameters from either a terminal device or control computer. Front panel control and display

allows full operation of the unit without external devices.

The modem includes an internal microprocessor for controlling all transmit and receive functions

and user display control. The processor also accepts commands from and responds to the Serial

Control Port. The processor stores its current configuration in non-volatile memory for proper

power-up recovery of the last state. The incorporation of an embedded processor allows intelligent

modem features such as smart reacquisition of a lost carrier, real Eb/No and BER display and full

interactive monitor and control of the modem. This control can be translated to a PC running

terminal emulation software for full screen terminal display.

A second internal Digital Signal Processor, or DSP, gives the modem acquisition capabilities

significantly faster than a standard modem at lower data rates. It does this by mathematically

determining the location of a carrier based upon sampled, digitized data input.

The modem design incorporates a unique combination of reliability, cost and flexibility. The design

uses large scale proprietary ASIC/FPGA devices to reduce the complexity and cost to a minimum

while providing full flexibility. The modulation and demodulation is accomplished directly at the IF

frequency without heterodyning, eliminating all adjustments.

Modulator Specifications

IF Output

Output Frequency Range: Standard & Hybrid.50.000 to 90.000 MHz. (100 to 180 MHz Optional)

L-Band ................... 950 to 1750 MHz

Tuning Method: ................................................ Via internal synthesizer.

Output Level Control:.......................................Programmable in 0.1 dB steps over 40 dB from

.......................................................... +5 to -35 dBm, +3 dBm max at 50Ω standard unit

Output Level Accuracy/Stability: ...................... ± 0.5 dB over 0 - 50°C @ any level or frequency

..........................................................± 0.25 dB over any 10°C range.

Output Impedance: Standard..................... Programmable 50 or 75Ω.

L-Band .......................50Ω.

Output Return Loss: Standard & Hybrid ........20 dB minimum

L-Band ..........................10 dB minimum, 14 dB typical

Output Burst Control: ....................................... Contact factory for burst definition and capability.

Output Burst Off Isolation.................................>60 dB

Modulation Technique:..................................... BPSK, QPSK, OQPSK, 8PSK, 8QAM or 16QAM Selectable.

Spectral Density:..............................................The modulated band shall be -3 dB at the

.......................................................... Nyquist frequency of the symbol rate, then

.......................................................... approximating an n=8 Butterworth filter

.......................................................... response.

Spurious Output: Standard & Hybrid .........< -50 dBc from 2 to 200 MHz.

L-Band ..........................< -50 dBc from 400 MHz to 5000 MHz

Harmonic Output: Standard & Hybrid ......... < -50 dBc.

L-Band ..........................< -50 dBc up to –10 dBm out, -40 dBc at +5 dBm.

Phase Balance:................................................< 1 degree.

Transmit Synthesizer

Tuning Step Size:............................................. 1 Hz steps.

1 2 3 4 5 6 7 8 9 10 ... 31 32

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