Comtech EF Data SNM-1001 User 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