Comtech EF Data SNM-1001 - Manual (Page 5)

Preface SNM-1001 Network Control Modem
iv Rev. 1
CHAPTER 3. OPERATION .............................................................................................. 3–1
3.1 Front Panel ....................................................................................................................................................... 3–1
3.1.1 LED Indicator............................................................................................................................................ 3–2
3.1.2 Front Panel Keypad Option....................................................................................................................... 3–2
3.2 Clocking Options.............................................................................................................................................. 3–2
CHAPTER 4. THEORY OF OPERATION ........................................................................ 4–1
4.1 Modulator ......................................................................................................................................................... 4–1
4.1.1 Specifications ............................................................................................................................................ 4–3
4.1.2 Theory of Operation .................................................................................................................................. 4–3
4.2 Demodulator..................................................................................................................................................... 4–5
4.2.1 Specifications ............................................................................................................................................ 4–6
4.2.2 Theory of Operation .................................................................................................................................. 4–6
4.2.3 Viterbi Decoding Theory .......................................................................................................................... 4–7
4.3 Monitor and Control ....................................................................................................................................... 4–9
4.3.1 Non-Volatile Memory ............................................................................................................................... 4–9
4.3.2 Remote Interface Specification ................................................................................................................. 4–10
4.3.3 M&C Theory of Operation........................................................................................................................ 4–10
4.3.4 Remote Interface Configuration ................................................................................................................ 4–10
4.3.5 Modem Defaults........................................................................................................................................ 4–10
4.4 Digital Interfaces.............................................................................................................................................. 4–12
4.4.1 EIA-422/449 Interface............................................................................................................................... 4–12
4.4.1.1 Functional Description ..................................................................................................................... 4–12
4.4.1.2 Specification..................................................................................................................................... 4–14
CHAPTER 5. MAINTENANCE......................................................................................... 5–1
5.1 System Checkout.............................................................................................................................................. 5–1
5.1.1 Modulator Checkout.................................................................................................................................. 5–2
5.1.2 Demodulator Checkout ............................................................................................................................. 5–3
5.1.3 Test Points................................................................................................................................................. 5–6
5.1.3.1 Modulator Test Points ...................................................................................................................... 5–6
5.1.3.2 Demod/M&C/Interface Test Points.................................................................................................. 5–7
5.2 Fault Isolation .................................................................................................................................................. 5–8
5.2.1 Modulator Faults ....................................................................................................................................... 5–10
5.2.1.1 Continuous Mode ............................................................................................................................. 5–10
5.2.2 Demodulator Faults ................................................................................................................................... 5–11
5.2.2.1 Burst Mode ....................................................................................................................................... 5–11
5.2.3 Transmit Interface Faults .......................................................................................................................... 5–11
5.2.4 Receive Interface Faults ............................................................................................................................ 5–11
5.2.4.1 Burst Mode ....................................................................................................................................... 5–11
5.2.5 Common Equipment Faults....................................................................................................................... 5–12
5.3 Module Identification ...................................................................................................................................... 5–13