Modulators, Uplink RF, IF & Sub-Carrier

Model 793 Multimode Modulator
Model 793 Multimode Modulator

The Model 793 Multimode Modulator is a B/S/QPSK subcarrier generator and modulator, a PM/FM/AQPSK subcarrier generator and modulator, a programmable psuedo-random number (PRN) data generator and an IRIG-106 code converter with convolutional encoding and V.35 and V.35M data randomizing. The unit can be phaselocked to an external station reference frequency.

The B/S/QPSK modulator accepts externally supplied data and clock, or the internally generated PRN data and clock. The selected data source is used to BPSK, QPSK or SQPSK (Staggered QPSK) modulate a subcarrier which is tunable to 10 MHz The B/S/QPSK output is internally connected as a selectable modulation input to the FM/PM modulator.

The PRN bit rate is tunable to 10 Mbps and the PRN generator may be programmed to output a pseudo-random pattern up to 223-1 bits in length or one of several preset recirculating word patterns. Modulation data can be selectively processed by a differential code converter, convolutional encoder (rate ½, K=7, 9) and a V.35 data randomizer.

The B/S/QPSK Modulation can be turned off to provide a continuous wave (CW), sinusoidal subcarrier output. The modulator output level is adjustable from -20 dBm to +10 dBm. Modulation data and clock are output via the unit rear panel.

The FM/PM/AQPSK modulator can output an AQPSK (Asynchronous QPSK), PM or FM modulated subcarrier. In the AQPSK modulation mode, the modulator accepts two externally supplied asynchronous TTL data and clock inputs. Two independent differential code converters can process the modulation data. I/Q channel unbalance is programmable up to 30 dB permitting adjustment of the ratio of energy per bit (Eb) to noise density (N0) for two modulation channels of unequal modulation data rates. When set for frequency modulation (FM) mode or linear phase modulation (PM) mode, the modulator accepts up to two analog inputs that are linearly summed prior to modulation. The FM/PM/AQPSK subcarrier is tunable to 20 MHz. Modulation can be turned off to provide a continuous wave (CW) subcarrier output. The modulator output level is adjustable from -20 dBm to +10 dBm.

  1. Tunable Modulated Subcarriers
  2. B/S/QPSK Modulation Data Rates to 6.25 Mbps
  3. AQPSK Modulation Data Rates to 7.5 Mbps / Input
  4. FM Modulation Index 0 to 10 MHz/V
  5. PM Modulation Index 0 rad to 3.14 rad/V
  6. Code Converters IRIG-106
  7. PRN Data Generator
  8. Data Randomizer V.35 / V.35M
  9. Convolution Encoder

B/QPSK MODULATOR
External Modulation Inputs:
Data (DC to 6.25 Mbps)
Clock (0° clock for code conversion)
TTL signal levels (50 ohms)

Internal PRN Generator:
Data and Clock:
(to 9,999,999.99 bps)
Pattern:
Selectable 2N-1 (N=7, 9, 11, 15, 20 or 23) maximal length patterns, or fixed pattern selections (1000, 1010, zeros, ones), or fully programmable taps

Pre-modulation Data Processing:
Input Code conversion (Requires 0° clock):

NRZ-L/M/S; BiPhase-L/M/S; DM-M/S BYPASS (no conversion)
Data Randomizer (Requires 0° clock):

V.35 (CCITT), V.35M (Intels at)Selectable ON or OFF
Convolutional Encoder (Requires 0° clock):

Rate ½, k=7 constraint length (k=9 optional) Selectable ON or OFF

Sub-Carrier Generator
Frequency:
Tunable 0.00 Hz to 9,999,999.99 Hz
Resolution:
0.01 Hz
Frequency Accuracy:
+/- 100 ppm
Harmonic Suppression:
>35dB @ 10 MHz

B/QPSK Modulator Output:
BPSK:
Non-coherent, 0 / 180 phase shift, sine wave, or
QPSK:
0 / 90 / 180 / 270 phase shift, sine wave, or
SQPSK:
(Staggered QPSK)
CW:
No modulation
Output Level:
-20.0 dBm to +10.0 dBm into 50 Ohms
Resolution:
0.1 dBm
Output on/off control
Front panel test port @ +10 dBm (2.0 Vpp into 50 Ohms)

Other Outputs:
Modulation Data and Clock:
Code converted to NRZ -L/M/S, BiPhase-L/M/S, DM-M/S
Randomized, Convolutionally Encoded with 0° Clock
Polarity and on/off control of data and clock

Remote Control
IEEE STD 488 GPIB and RS232 Serial Interface

PM/FM/AQPSK MODULATOR
AQPSK Data and Clock Inputs:
Data:
A and B
Clocks:
Asynch A and B, or Common (A Clock)
TTL signal levels
Input data rates:
DC to 7.5 Mbps

AQPSK Pre-mod Data Code Conversion:
NRZ-L/M/S; BiPhase-L/M/S; DM-M/S or BYPASS

FM/PM Modulation Inputs:
External or internal B/QPSK modulator output.
Second external input sums with primary source.
Interface:
2 Vpp into 50 Ohms, max. aggregat

Sub-Carrier Generator:
Frequency:
Tunable 0.00 Hz to 20.00 MHz
Resolution:
0.01 Hz
Frequency Accuracy:
+/- 100 ppm
Harmonic Suppression:
>35dB @ 20 MHz

Modulator Output:
AQPSK:
Four phase angles, sine wave I/Q unbalance, 0.0 dB to 30.0 dB
FM:
Linear frequency modulation Mod. index, 0.0 Hz to 10 MHz per Volt
PM:
Linear phase modulation Mod. index, 0.0 rad to 3.14 rad per Volt
CW:
No modulation Output Level: -20.0 to +10.0 dBm into 50 Ohms
Resolution:
0.1 dBm
Output on/off control
Front panel test port @ +10 dBm

Reference Frequency
Used to phase-lock subcarriers to station reference frequency.

Input:
Selectable, 1 MHz, 2 MHz, 5 MHz or 10 MHz
Level:
TTL or 4 Vpp max.
Input Impedance:
50 Ohms

Output:
Selectable, 1 MHz, 2 MHz, 5 MHz or 10 MHz
Level:
TTL into 50 Ohms

Local Front Panel Control
High contrast Vacuum Fluorescent (VF) display
2-line by 40-character format
Twenty (20) position momentary -action keypad

Support:
Virtual Instrument Remote Control Application Software and integration support is available. Call GDP Space Systems Marketing and Sales for your specific requirements.