The Type CD-1 is a classical implementation of a matched-filter, Integrate & Dump coherent demodulator. It is capable of demodulating ASK, FSK, BPSK, QPSK, Offset-QPSK (OQPSK) and 8QAM coherently in the presence of additive noise from bit rates of 4, 8, 16, 32 and 64kbps.
The input modulation sourced from the Type MOD-1 Signal Modulator is added to noise produced from the Type NS-1 Noise Source then downconverted to baseband. The result is integrated and then compared to an adjustable or fixed-comparison (FSK MARK to FSK SPACE) threshold. For 2 and 3 bits/symbol modulation types such as QPSK, OQPSK and 8QAM, a selectable on-board symbol synchronization circuit is used to correct for bit timing.
A separate I and Q-Channel integrator adjustment is provided to set the proper integration levels prior to sampling. An on-board RMS power detector is also included that allows one to set the correct signal and noise power.
The Type CD-1 includes tutorials on integration and integration results for different types of modulation or integration on noise alone.
Both I-Channel and Q-Channel conversion to baseband and I and Q integrator outputs are provided (BNC connectors).
The Type CD-1 interfaces with the Type MOD-1 Signal Modulator whereby recovered 8-bit PCM and CVSD digital audio can be looped back for testing under various SNR conditions. The Bit Error Ratio (BER) can be measured by connecting the Type BER-1 BER Measurement board directly to the Type CD-1 Integrate & Dump Coherent demodulator and BER results can be compared to theory while varying the signal-to-noise (SNR) ratio. Input power requirements are +/- 12 VDC @ 500mA, maximum. Power is supplied from Type MOD-1 Signal Modulator board. DC power inputs are polarity protected.
The Type CD-1 Integrate & Dump Coherent demodulator comes with:
- Technical Manual that covers Configuration, Operation, General Theory, Block Diagrams, Schematic Diagrams along with design philosophy. 120 pages, 45 Figures, 10 Tables. Parts List.
- Three, 3-foot RG-58/BNC 50-ohm cables
- One, 3-foot +/- 12 VDC power connection cable
- 25, 2-pin configuration jumpers
- Type CD-1 board outline is (width x depth) 11" x 12" (279.4 x 304.8mm)