| Product overview

Space TT&C system (the full name of which is 'Space Tracking Telemetry and Command System') is an important technical system in the whole space network system. The system is used for real-time monitoring of spacecraft flight orbit and telemetry information, and controlling of the working state of the target spacecraft subsystem, which is an important support and guarantee for the good on-orbit operation of spacecraft.

Unified microwave TT&C system modulates signals with different functions, such as control, voice, speed measurement, ranging, etc., to subcarriers with different frequencies in the phase modulation form, and then converts up them to the same carrier, and transmits them to on-orbit spacecraft through uplink. Similarly, the information in the downlink signal forwarded by the spacecraft is also modulated at different subcarriers. After the receiver demodulates the downlink signal, each group of subcarriers is separated by band-pass filters with different center frequencies. Finally, each group of subcarrier signals can be demodulated to get different functional signals.

Different from the previous single function, the unified microwave TT&C system with separated components can modulate signals with different functions to the same carrier. In this way, the ground device is not only simplified, but also the mutual interference between signals is avoided. What's more, the antennas on the spacecraft are greatly reduced, which is of far-reaching significance for reducing the mass of the spacecraft and improving electromagnetic compatibility.

The TT&C baseband device includes several independent modules: IF transmitting module, IF receiving module and signal processing module. IF transmitting module includes analog of IF signal generation, IF gain control, and analog of noise source; IF receiving module includes automatic gain control (AGC) and multiple band-pass filters; the signal processing module is used to realize the functions of signal sidetone ranging, synchronization, demodulation, decoding and data output.

| Typical application

● Provide ranging, speed measurement, telemetry, remote control, telemetry, bit synchronization, frame synchronization, analog modulation and other functions.

● Provide the functions of carrier level measurement, carrier frequency shift, Doppler measurement, Eb/N0 measurement, BER measurement and spectrum display.

● Support USB(UXB) system signal modulation and demodulation, and support sidetone ranging.

● The monitoring of integrated TT&C baseband device is implemented through the Internet port of TCP/IP protocol. Any PC or workstation used in the local area network can monitor and control the integrated TT&C baseband device.

● The integrated TT&C baseband device supports receiving and sending data through Gigabit network port.

| Main technical indicators

Input IF data

1) Input frequency: 60.0 MHz - 78.0 MHz

2) Input signal bandwidth: 50 - 90 MHz

3) AGC range: -15 dBm to -105 dBm

4) IF input level measurement: resolution: 0.5 dB

5) Accuracy: 2 dB

6) AGC time constant: 0.1 ms, 1 ms, 10 ms, 100 ms

7) Capture range: ± 10 kHz to ± 500 kHz

8) Number of physical input ports: 3 groups (one active and one standby in each group)

9) Type of input connector: SMA-F

10) Impedance of input connector: 50 Ω

Auxiliary input data

1) Number of input port: 2

2) Input signal: baseband signal or IF signal

3) Input bandwidth: baseband: 0 - 20 MHz

4) Input signal level: baseband: 0.1 - 0.5 Vpp, IF: 0 to -20 dBm

5) Input impedance: 50 Ω;

Telemetry demodulation

1) PM demodulation

 - PLL bandwidth: 30 Hz - 3000 Hz

 -Carrier capture: automatic (FFT analysis, ASB), or manual.

 - Capture threshold: C/N0=20dB.Hz

 - Capture time: less than 1 s

 - Maximum Doppler speed: 50 kHz/s (C/N0 > 50dB.Hz, 2 Bn = 1,000 Hz)

 -Doppler measurement: provide data through TCP-IP

2) FM demodulation

 - IF bandwidth: 5 kHz, 10 kHz, 15kHz, 30 kHz, 50kHz, 100 kHz, 150 kHz, 300 kHz, 500 kHz, 1 MHz, 1.5 MHz,

3 MHz, 5 MHz, 10 MHz

 - AFC time constant: 1 ms, 10 ms, 100 ms, 1000 ms

 -Frequency discriminator parameters: 1 to 16

3) Subcarrier demodulation

 - BPSK SCF: 40 Hz - 128 kHz

 - Number of subcarriers: 2

 - Bit rate: 10 bps - 25 kbps

 - PCM bit type: NRZ-L/M/S, BP-L/M/S, BP-L/M/S

 - Capture threshold: Eb/N0 ≤ 0dB

 - BER deterioration: ≤ 1dB

Data processing

1) Frame-level processing

 -Frame synchronizer: 8 - 64 bits, which can be set as required

 -Time scale accuracy: ±50 μs (1 PPS input)

 -Real-time data processing capability: 32 parameters

 -Telemetry data storage: hard disk

 - Frame synchronization strategy: SYN: 0 - 7 bits,

 CTL: 0 - 7frames,

 LTS: 0 - 7frames,

 SLIP: 0, 1, 2 bits

IF modulation

1) Number of modulators: 1 group (one active and one standby)

2) Modulation mode: FM, PM

3) Subcarrier modulation mode: BPSK

4) Carrier frequency: 60.0 MHz - 78.0 MHz

5) Signal modulation: modulate four parameters at the same time

6) Signal generator modulation: provide functions of measurement and control, ranging, analog and emulation, and external input

7) Input signal: internal or external analog baseband signal

8) Frequency shift: 0 MHz to ±5 MHz

9) Modulation data: 0 radian - 2.5 radian

10) Output level of main port: 0 dBm to -80 dBm

11) Output level setting accuracy: ≤ ±1 dBm

12) Output level of standby port: -20 dBm±1 dBm

13) Carrier suppression: ≤-60 dBc when output is made at 0 dBm

14) Phase noise: less than 0.5° RMS, within 1 MHz band

15) Frequency scanning: range: ±1 kHz to ±1 MHz, rate: 1 kHz/s to 175 kHz/s, and offset: 0 to 1 MHz

Waveform

1) Subcarrier modulation mode: FSK, BPSK

2) PCM bit type: NRZ-L/M/S, BP-L/M/S

3) Subcarrier frequency: 40 Hz - 125 kHz

4) Bit rate: 10 bps - 10 kbps

5) Monotone frequency for remote control: 100 Hz - 100 kHz

6) Idle pattern: the content can be set, and the length can be set from 1 to 32 bits

7) Guide length: the length can be set from 0 to 224

8) Support burst and recurrent modes

9) Support sending of local instructions

10) Support the network instruction format verification

Satellite ranging

1) Ranging tone standard: ESA, ESA-like, USB, DFH

2) Ranging code standard: ESA

3) Ranging tone bandwidth: less than or equal to 100 kHz

4) Ranging tone demodulation: 2-order digital PLL

5) PLL bandwidth: 0.1 Hz - 8 Hz

6) Ranging resolution: 1 ns

7) Noise deterioration: less than the theoretical value by 0.5 dB

Doppler measurement

1) Measurement technology: Data is obtained by tracking the phase change of the PLL of the IF receiver

2) Measurement speed: 13.1072 ms

3) Measurement sample rate: it can be programmed from 0.1 s to 10 s by users

Simulation and test

1) Telemetry analog

 - Carrier modulation: PM, FM;

 - Subcarrier modulation: BPSK (sine wave)

 - Telemetry analog source: pseudo-random sequence, local ASCII file, telemetry playback file, Ethernet data packet

 - BER test: automatic file or PN code BER measurement

 - PCM bit type: NRZ-L/M/S, BP-L/M/S

 - Code rate and subcarrier: symmetrical with each downlink

2) Noise generator

 - Number of noise channels: 1

 - Noise bandwidth: ≥ 40 MHz

 - C/N0 range: 20 dB.Hz - 100 dB.Hz

Timing system and reference input

1) Time code: IRIG-B(AC)

2) Amplitude: 6Vpp

3) Reference input: 5 MHz / 10 MHz / 100 MHz

4) Impedance: 50 Ω

5) Amplitude: 0.5 V to 5 V, DC max = ± 4 V

| Physical characteristics

Size: W 19-inch, H 4 Unit

Power supply: 90 VAC -265 VAC, 47 - 63 Hz

Operating temperature: 10℃ - 40℃

Storage temperature: -20℃ to +60℃

Relative humidity: 85%, no condensation

MTBF: 50,000 hours

The equipment can meet both of EU (2004/108/CEE) and (73/23/CEE) safety standards