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CDM-550T Satellite Modem (Viterbi/Sequential/RS/Turbo) Installation and Operation Manual (For Firmware V1.19 or higher) Part Number MN/CDM550T.IOM Revision 1.3...
4. To ensure that the product is not damaged during shipping, pack the product in its original shipping carton/packaging. 5. Ship the product back to Comtech EF Data. (Shipping charges should be prepaid.) For more information regarding the warranty policies, see Warranty Policy, p. xii.
Table of Contents Customer Support ..............................iii Overview of Changes to Previous Edition ....................... viiiviii About this Manual ............................. viiiviii Conventions and References ..........................viiiviii Metric Conversion............................viiiviii Cautions and Warnings ........................... viiiviii Recommended Standard Designations ......................... ixix Reporting Comments or Suggestions Concerning this Manual................ixix Safety Notices ................................
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Preface CDM-550T Satellite Modem Compatibility ..............................1–3 New in This Release............................1–4 CHAPTER 2. INSTALLATION..................2–1 Unpacking ..............................2–1 Mounting ..............................2–1 Configuration..............................2–2 Select Internal IF Loop ..........................2–2 Connect External Cables..........................2–2 CHAPTER 3. FUNCTIONAL DESCRIPTION ............. 3–1 CHAPTER 4. PHYSICAL DESCRIPTION ..............4–1 Front Panel..............................4–2 Rear Panel ..............................4–3...
About this Manual This manual provides installation and operation information for the Comtech EF Data CDM-550T satellite modem. This is a technical document intended for earth station engineers, technicians, and operators responsible for the operation and maintenance of the CDM-550T.
The user should observe the following instructions: Fuses The CDM-550T is fitted with two fuses - one each for line and neutral connections. These are contained within the body of the IEC power inlet connector, behind a small plastic flap.
The equipment is not designed for connection to power system which has no direct connection to ground. The CDM-550T is shipped with a line inlet cable suitable for use in the country of operation. If it is necessary to replace this cable, ensure the replacement has an equivalent specification.
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CDM-550T Satellite Modem Preface Immunity: EN 50082 Part 1 - Generic immunity standard, Part 1: Domestic, commercial and light industrial environment. In order that the Modem continues to comply with these standards, observe the following instructions: • Connections to the transmit and receive IF ports (BNC female connectors) should be made using a good quality coaxial cable - for example RG58/U (50 ohm) or RG59/U (75 ohm).
Disclaimer Comtech EF Data has reviewed this manual thoroughly in order that it will be an easy-to- use guide to your equipment. All statements, technical information, and recommendations in this manual and in any guides or related documents are believed...
Standard Features IF port impedance is selectable from the front panel. Users may choose between the universal standard of 50 ohms or the less frequently used 75 ohms. The CDM-550T offers both impedances in the same unit as a standard feature.
1.1.1 AUPC An important innovation in the CDM-550T is the addition of Automatic Uplink Power Control (AUPC). This feature enables the modem to automatically adjust its output power to maintain the Eb/No of the remote end of the satellite link constant. This provides protection against rain fading, a particularly severe problem with Ku-band links.
Compatibility For 1:1 applications the CDM-550T is supported by a low-cost external switch, the CRS- 100. For Hub applications, the CDM-550T is supported by a low-cost 1:N switch, the CRS-200. Its fast acquisition time makes it attractive for both demand-assigned and fixed-assigned SCPC applications.
5/16 - both operating in BPSK only. • If you do not have Version 1.15, or higher, installed in your CDM-550T, please contact the factory for a free upgrade. Please note the following two new features provided in the Version 1.10 firmware: 1.
Mounting If the CDM-550T is to be mounted in a rack, ensure that there is adequate clearance for ventilation. The CDM-550T does not include a cooling fan, so care must be taken that too many units are not mounted on top of each other. The limit is four units, and then a blank 1U panel must be inserted to allow sufficient airflow around the units.
CDM-550T Satellite Modem Note that the CDM-550T is very light - under 7 lbs (3.2 kgs), and very short - 12 ins (305 mm). For this reason, it has not been designed to have rack slides mounted to the side of the chassis.
Chapter 3. FUNCTIONAL DESCRIPTION The CDM-550T has two fundamentally different types of interface - IF and data. The data interface is a bi-directional path which connects with the customer’s equipment (assumed to be the DTE) and the modem (assumed to be the DCE). The IF interface provides a bi-directional link with the satellite via the uplink and downlink equipment.
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Functional Description CDM-550T Satellite Modem This page is intentionally blank. 3–2 Rev. 1.3...
Chapter 4. PHYSICAL DESCRIPTION The CDM-550T is constructed as a 1U high rack-mounting chassis, which can be free- standing, if desired. Rack handles at the front facilitate removal from and placement into a rack. Figure 4-1 shows the front and rear panels of the modem.
Physical Description CDM-550T Satellite Modem Front Panel On the front panel of the unit is the Vacuum Fluorescent Display (VFD), keypad, and eight LED indicators. The user enters data via the keypad, and messages are displayed on the VFD. The LEDs indicate, in a summary fashion, the status of the unit.
Physical Description Rear Panel External cables are attached to connectors on the rear panel of the CDM-550T. These comprise the IEC line input connector, the Receive and Transmit IF connectors, the Data connector, Alarms connector, Remote Control connector, and Auxiliary Serial connector.
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Physical Description CDM-550T Satellite Modem The pinout details for this connector are provided in the next section. The Remote Control connector is a 9 pin 'D' type female (DB9-M). Access is provided to remote control ports of the modem, both RS232 and RS485. The pinout details for this connector are provided in the next section.
Chapter 5. CONNECTOR PINOUTS Data Connector 25 Pin ‘D’ Type Female Table 5-1 Data Connector - 25 Pin ‘D’ Type Female Generic Signal description Direction EIA-422/ V.35 EIA-232 Circuit EIA 530 Shield Shield Transmit Data A DTE to Modem SD A SD A Receive Data A Modem to DTE...
CDM-550T Satellite Modem Connector Pinouts Auxiliary Serial Connector - HE1402 3 Pin Header Table 5-4 Auxiliary Serial Connector - HE1402 3 Pin Header Description EIA-232 Transmit Data (Output) Ground EIA-232 Receive Data (Input) PIN NUMBERING: Looking at the rear panel, pin 1 is on the right-hand side : •...
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Connector Pinouts CDM-550T Satellite Modem This page is intentionally blank. 5–4 Rev. 1.3...
FRONT PANEL OPERATION Description The user can fully control and monitor the operation of the CDM-550T from the front panel, using the keypad and display. Nested menus are used, which display all available options, and prompt the user to carry out a required action.
Menu Trees Figure 6-2 shows the menu structure of the CDM-550T. The detailed screens and menus will now be described. Note: The ‘level’ of the menu (how far down into the structure) is indicated by how far the screen is indented from the left.
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CDM-550T Satellite Modem Front Panel Operation Figure 6-2. Principle Menu Trees Rev. 1.3 6–3...
Front Panel Operation CDM-550T Satellite Modem 6.2.2 Select SELECT: CONFIG TEST INFO MONIT STORE/LD UTIL ODU The user is presented with the following choices: CONFIG (Configuration) This menu branch permits the user to fully configure the unit. TEST This menu branch permits the user invoke one of several test modes (loopbacks, for example).
‘all ones’ as an idle pattern. However, by convention, the ‘all ones’ condition is taken to be the Alarm Indication Signal (AIS). The CDM-550T monitors for the AIS condition, and if desired, this alarm may be masked. IMPED (Impedance) This menu sub-branch permits the user to define the impedance at the IF connectors, either 50 or 75 ohms.
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Front Panel Operation CDM-550T Satellite Modem 6.2.3.1 (CONFIG) TX (Transmit) TX: MOD FREQ DATA ON/OFF PWR SCRAM CLK TSI The sub-branches available are: (CONFIG, TX) MOD (Modulation) SELECT TX MODULATION: BPSK QPSK OQPSK (ENTER) Select BPSK, QPSK, or Offset QPSK modulation, using the LEFT/RIGHT arrow keys, then press ENTER.
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, TX) DATA (Data Rate) EDIT TX DATA RATE: 2048.000 kbps(PRESS ENT) Edit the transmit data rate. This is accomplished by selecting the digit to be edited, using the LEFT/RIGHT arrow keys. The value of the digit is then changed using the UP/DOWN arrow keys.
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, TX, FEC) Select Viterbi, Sequential, Viterbi + concatenated Reed-Solomon, Sequential + concatenated Reed-Solomon, or None, using the LEFT/RIGHT arrow keys, then press ENTER. If the Turbo Codec option is installed, the following menu will be displayed:...
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CDM-550T Satellite Modem Front Panel Operation TX TURBO:3/4(Q) 21/44(B) 5/16(B) 3/4(OQ) (ENTER) (CONFIG, TX, FEC, RATE) FEC Rate (Turbo Only) Select Rate 3/4 (QPSK), Rate 21/44 (BPSK ONLY) Rate 5/16 (BPSK ONLY) or Rate 3/4 (OQPSK) encoding rate, using the LEFT/RIGHT arrow keys, then press ENTER.
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, TX, PWR) MODE OUTPUT POWER LEVEL MODE: MANUAL AUPC (ENTER) Select the output power level mode, either Manual or AUPC, then press ENTER. If the user selects MANUAL, the following menu is displayed:...
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, TX, PWR, MODE) AUPC TARGET EbNo MAX RANGE ALARM DEMOD-UNLOCK(ENT) Select either TARGET EbNo, MAX RANGE, ALARM or DEMOD-UNLOCK. The user should then press ENTER. (CONFIG, TX, PWR, MODE, AUPC) TARGET EbNo EDIT TARGET MIN EbNo OF REMOTE MODEM:9.9dB (ENT)
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, TX, PWR, MODE, AUPC) ALARM SELECT ACTION AT MAXIMUM TX POWER: NONE TX ALARM Select the action that will occur if the AUPC causes the maximum output power level to be reached, either NONE or TX ALARM. Then press ENTER.
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Select INT (Internal), EXT (External) or LOOP-TIMED, using the LEFT/RIGHT arrow keys, then press ENTER. INTERNAL indicates that the CDM-550T will supply a clock to the DTE, which is derived from its internal high-stability source. EXTERNAL indicates that the CDM-550T expects to receive a clock from the DTE, to which the unit can phase-lock its internal circuits.
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, TX) TSI (Transmit Spectral Invert) SELECT TRANSMIT SPECTRAL INVERSION: OFF ON(ENTER) Select either OFF or ON, using the LEFT/RIGHT arrow keys, then press ENTER. When in the ON position, and QPSK is selected, the transmit spectrum is inverted (which is the same as reversing the direction of phase rotation in the modulator).
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, RX) FRQ (Frequency) EDIT RX FREQUENCY: 72.2345 MHz (PRESS ENT) Edit the receive frequency. This is accomplished by selecting the digit to be edited, using the LEFT/RIGHT arrow keys. The value of the digit is then changed using the UP/DOWN arrow keys.
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Front Panel Operation CDM-550T Satellite Modem However, if the Reed-Solomon Codec option is installed, the following menu will be displayed: SELECT FEC TYPE: VIT SEQ VIT+RS SEQ+RS NONE (ENT) Select Viterbi, Sequential, Viterbi + concatenated Reed-Solomon, Sequential + concatenated Reed-Solomon, or None, using the LEFT/RIGHT arrow keys, then press ENTER.
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, RX, FEC, RATE) FEC RATE (TURBO ONLY) RX TURBO: 3/4(Q) 21/44(B) 5/16(B) 3/4(OQ) (ENTER) Select Rate 3/4 (QPSK), Rate 21/44 (BPSK ONLY) Rate 5/16 (BPSK ONLY) , or Rate 3/4 (OQPSK) decoding rate, using the LEFT/RIGHT arrow keys, then press ENTER.
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The CDM-550T can be operated with independent transmit receive and transmit data rates. Even in this configuration, where RX data rate <> TX data rate, the output clock for the buffer will be phase locked to the transmit clock.
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, RX) BUF (Buffer size) EDIT RX BUFFER SIZE: +/-4096 BITS (PRESS ENT) Edit the size, in bits of the Plesiochronous/Doppler Buffer. The value is changed using the UP/DOWN arrow keys. The user should then press ENTER. Values of +/- 256, 512, 1024, 2048 and 4096 bits are possible.
Front Panel Operation CDM-550T Satellite Modem (CONFIG) FRAME (Framing Mode) SELECT FRAMING MODE: TRANSPARENT FRAMED (ENT) The sub-branches available are: (CONFIG, FRAME) TRANSPARENT No framing is selected. No overhead is added, and the unit will be compatible with other manufacturer’s equipment, when operating in a ‘standard’...
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, FRAME, FRAMED) EDMAC-ON SELECT EDMAC MODE: MASTER SLAVE (ENTER) Select either MASTER or SLAVE, using the LEFT/RIGHT arrow keys, then press ENTER. An EDMAC MASTER is a unit which is local to the M&C computer, and which passes messages, via the overhead, to a distant-end modem.
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, FRAME, FRAMED, ON) EDMAC SLAVE EDIT THIS UNIT'S ADDRESS 0245 (SEE HANDBOOK)(ENT) Edit the address of this SLAVE unit. This is accomplished by selecting the digit to be edited, using the LEFT/RIGHT arrow keys. The value of the digit is then changed using the UP/DOWN arrow keys.
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, LOCAL) If LOCAL is selected then remote control will be disabled. Remote monitoring is still possible. (CONFIG, REMOTE) If REMOTE is selected then the following sub-menus will be displayed: If the unit has not been defined as an EDMAC SLAVE then:\...
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, REMOTE, INTFC) If INTERFACE is selected: ELECT. INTERFACE: RS232 RS485-2W RS485-4W (ENT) Select RS232, RS485 (2-wire), or RS485 (4-wire), using the LEFT/RIGHT arrow keys, then press ENTER. At this point the user will be further prompted to enter the bus address.
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CDM-550T Satellite Modem Front Panel Operation 6.2.3.5 (CONFIG) MASK (Alarm mask) ALARM MASK: Eb/No RX-AIS BUF-SLIP TX-AIS Select AGC, Eb/No, RX-AIS, BUF-SLIP, or TX-AIS, using the LEFT/RIGHT arrow keys, then press ENTER. One of the following sub-menus will be displayed:...
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Front Panel Operation CDM-550T Satellite Modem (CONFIG, MASK) RX-AIS SEL RX-AIS ALARM MASK: ACTIVE MASKED(PRESS ENT) Select either ACTIVE or MASKED, using the LEFT/RIGHT arrow keys, then press ENTER. If the user selects ACTIVE, then a Receive Traffic fault will be generated whenever the demodulator senses that the ‘all ones’...
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CDM-550T Satellite Modem Front Panel Operation (CONFIG, MASK) TX-AIS SEL TX-AIS ALARM MASK: ACTIVE MASKED(PRESS ENT) Select either ACTIVE or MASKED, using the LEFT/RIGHT arrow keys, then press ENTER. If the user selects ACTIVE, then a Transmit Traffic fault will be generated whenever the transmit circuitry senses that the ‘all ones’...
Front Panel Operation CDM-550T Satellite Modem 6.2.4 TEST TEST: NORM TX-CW TX-1,0 IF] DIG] I/O] RF] (ENT) Select NORM, TX-CW, TX-1,0, IF LOOP, DIG LOOP, I/O LOOP or RF LOOP, using the LEFT/RIGHT arrow keys, then press ENTER. This sub-menu permits the user to select the following test modes:...
Front Panel Operation CDM-550T Satellite Modem 6.2.5 INFO (Information) INFO:ID TX RX BUFF EDMAC REMCONT MASK MISC(ENTER) Select ID, TX, RX, BUFF, EDMAC, REMCONT, MASK, or MISC using the LEFT/RIGHT arrow keys, then press ENTER. These screens display information on the current configuration of the unit.
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CDM-550T Satellite Modem Front Panel Operation 6.2.5.3 (INFO) RX (Receive information) Rx: 70.0000 512.000 SEQ B R3/4 BUFF +/-23k I The information displayed here is as follows: Top line: Receive Frequency Receive Data Rate FEC Decoder type (VIT = Viterbi, SEQ = Sequential, VRS=Viterbi + Reed-...
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Front Panel Operation CDM-550T Satellite Modem 6.2.5.6 (INFO) REMCONT (Remote Control information) REM-CONTROL:ON RS485-4W ADDRESS: 0001 19200 BAUD This screen shows if the unit is in LOCAL or REMOTE mode, and gives details of the electrical interface type selected, the unit’s address, and the baud rate selected.
CDM-550T Satellite Modem Front Panel Operation 6.2.6 MONIT (Monitor) MONITOR:ALARMS RX-PARAMS STORED-EVENTS STATS AUPC Select ALARMS, RX-PARAMS, STORED EVENTS, STATS, or AUPC or using the LEFT/RIGHT arrow keys, then press ENTER. If the user selects ALARMS, the following sub-menu is displayed: 6.2.6.1...
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Front Panel Operation CDM-550T Satellite Modem (MON, ALARMS) RECEIVE (Receive alarms) RX TRAFFIC: AGC ALARM REDUCE COMPOSITE I/P LVL The screen will indicate if there are any Receive Traffic Faults. If not, it will display ‘NONE’. Pressing ENTER takes the user back to the previous menu.
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CDM-550T Satellite Modem Front Panel Operation If the user selects STORED EVENTS, the following sub-menu is displayed: 6.2.6.3 (MONIT) STORED EVENTS STORED EVENTS: VIEW CLEAR ALL (PRESS ENTER) Select VIEW or CLEAR ALL, using the LEFT/RIGHT arrow keys, then press ENTER.
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Front Panel Operation CDM-550T Satellite Modem If the user selects STATS, the following sub-menu is displayed: LINK STATISTICS: VIEW CLEAR CONFIGURE (ENTER) MONIT) STATS (Link Statisics) Select VIEW, CLEAR, or CONFIGURE, using the LEFT/RIGHT arrow keys, then press ENTER. If the user selects VIEW, the following screen is displayed:...
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CDM-550T Satellite Modem Front Panel Operation Notes: If the demod has lost lock during the measurement interval, the minimum Eb/No will show ‘LOSS’ rather than indicate a value. However, the average value (while the demod was locked) will still be calculated and shown. If, on the other hand, the demodulator has been unlocked for the entire measurement interval, the average Eb/No will also show ‘LOSS’.
Front Panel Operation CDM-550T Satellite Modem 6.2.6.4 (MONITOR) AUPC FRAMING NOT ENABLED! (PRESS ENTER) If AUPC is selected, and the modem is in Framed mode, the following sub-menu is displayed: AUPC: REMOTE EbNo=14.0dB TX POWER INCREASE=2.2dB The top line displays the value of Eb/No of the demodulator at the distant end of the satellite link.
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CDM-550T Satellite Modem Front Panel Operation 6.2.7.1 (STORE/LD) STORE STORE CONFIGURATION TO LOCATION: (ENTER) Select the location to store the current configuration to, using the UP/DOWN arrow keys, then press ENTER. Locations 1 through 10 are available. If the selected location does not contain a previously stored configuration, the...
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Front Panel Operation CDM-550T Satellite Modem 6.2.7.2 (STO/LD) LOAD LOAD CONFIGURATION FROM LOCATION: (ENTER) Select the location to load a configuration from, using the UP/DOWN arrow keys, then press ENTER. Locations 1 through 10 are available. If the selected location contains valid data, the following screen will be...
CDM-550T Satellite Modem Front Panel Operation 6.2.8 UTIL (Utility) UTILITY: SET-RTC DISPLAY MAN-1:1 RECENTER-BUF ID Select SET-RTC, DISPLAY, MAN-1:1, RECENTER-BUF, or ID, using the LEFT/RIGHT arrow keys, then press ENTER. This sub-menu permits the user to select from a number of different utility...
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Front Panel Operation CDM-550T Satellite Modem 6.2.8.2 (UTIL) MAN-1:1 (Manual 1:1 switchover) PRESS ENT TO FORCE THIS UNIT TO STDBY (1:1 ONLY) If the unit is part of a 1:1 redundant pair of modems, and this unit, is currently on-line, pressing ENTER will cause the unit to switch to standby.
Eb/No). This is not true of the Sequential decoding method, as explained in the section below. Note that in BPSK mode, the CDM-550T only permits a coding rate of 1/2. Because the method of convolutional coding used with Viterbi, the encoder does not preserve the original data intact, and is called non-systematic.
RS decoder do not exceed its capacity to correct those errors. In the case of the CDM-550T, two RS code rates are used. A 220,200 code is used in transparent modes, and a 200,180 code is used in framed (EDMAC) modes. (220,200 means that data is put into blocks of 220 bytes, of which 200 bytes are data, and 20 bytes are FEC overhead.) These two codes were chosen because they fit well into Comtech EF...
This may be due to the carrier-recovery circuits, or the synchronization threshold of the primary FEC device, or both. In the CDM-550T, and Rate 1/2 operation, this threshold is around 4 dB Eb/No. Below this value, operation is not possible, but above this value, the error performance of the concatenated RS system produces exceptionally low error rates for a very small increase in Eb/No.
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However, with Firmware Version 1.15 (and later) Comtech EF Data has introduced two further code rates - Rate 21/44 BPSK (very close to Rate 1/2) and Rate 5/16 BPSK (very close to Rate 1/3).
In many cases, FEC methods which provide increased coding gain do so at the expense of increased processing delay. However, with TPC, this increase in delay is very modest. The table below shows, for the CDM-550T, the processing delays for the major FEC types, including the three TPC modes:...
There are occasions where a user may wish to operate a satellite link with no forward error correction of any kind. For this reason, the CDM-550T offers this uncoded mode for all three modulation types - BPSK, QPSK and OQPSK. However, the user should be aware of some of the implications of using this approach.
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However, if uncoded operation is used, there is no way to recognize a data false lock. The demodulator will indicate that it is correctly locked, but the data out will not be correct. Comtech EF Data strongly cautions users when using uncoded operation. If the acquisition sweep width exceeds one quarter of the symbol rate, there is a very high probability that the demodulator will false lock.
Chapter 8. OFFSET QPSK OPERATION Offset QPSK modulation is a variation of normal QPSK, which is offered in the CDM- 550T. Normal, bandlimited, QPSK produces an RF signal envelope which necessarily goes through a point of zero amplitude when the modulator transitions through non- adjacent phase states.
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Offset Qpsk Operation CDM-550T Satellite Modem The demodulator must re-align the I and Q symbol streams before the process of carrier recovery can take place. For various reasons this makes the process of acquisition more difficult. The two consequences of this are: 1) Acquisition may be longer, especially at low data rates.
ASYNCHRONOUS OPERATION Introduction The CDM-550T supports asynchronous RS232 in addition to synchronous RS232 formats. This is useful, for example, in connecting two computers together, via their serial ports, at opposite ends of a satellite link. There are, however, some restrictions and limitations when using this mode, and the user may have to experiment a little in order to get reliable communication.
EIA-232 Data Interface - Asynchronous Operation CDM-550T Satellite Modem Setup The setup required for this mode is remarkably simple. Select RS232 as the interface type, and then select the required baud rate for both transmit and receive data rates. Detection of the asynchronous mode is fully automatic. If no clock is detected, asynchronous mode is assumed, and the internal circuitry is switched accordingly.
Chapter 10. CLOCKING When dealing with satellite modems, the subject of clocking can be a complex issue. This section describes the various clocking options which are available with the CDM-550T. 10.1 Transmit Clocking There are four transmit clocking modes in the CDM-550T. EIA-422/449 signal mnemonics will be used for illustration, but the description applies equally to V.35, and...
10.1.4 Loop-Timed, RX<>TX (Asymmetric Loop Timing) The CDM-550T incorporates circuitry which permits loop timing when the TX and RX data rates are not the same. In this case the clock frequency appearing at ST will be whatever the TX data rate is programmed to, but phase-locked to the demodulator’s receive symbol clock.
10.4 Loop Timing With Sync EIA-232 The CDM-550T distinguishes between synchronous and asynchronous EIA-232 by detecting clock activity on the TX Clock pin of the interface. If no clock is detected, it is assumed that the mode is asynchronous. Therefore, if loop timing is employed in a synchronous EIA-232 application, it is essential to provide an external loop between the ST and TX clock pins.
Chapter 11. EDMAC CHANNEL 11.1 Theory Of Operation As explained earlier, EDMAC is an acronym for Embedded Distant-end Monitor And Control. This is a feature which permits the user to access the M&C features of modems which are at the distant-end of a satellite link. This is accomplished by adding extra information to the user’s data, but in a manner which is completely transparent to the user.
EDMAC Channel CDM-550T Satellite Modem of the descrambler, 3 output errors are generated. However, there is an alternative when the data is in a framed format. In this case, a different class of scrambler may be used - one which uses the start of frame information to start the scrambling process at an exact known state.
CDM-550T Satellite Modem EDMAC Channel path on the satellite link. The EDMAC Master assembles the complete packet, and transmits the response back to the M&C Computer. Apart from the round-trip satellite delay, the M&C Computer does not see any difference between local and distant-end units - it sends out a packet, addressed to a particular unit, and gets back a response.
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Chapter 12. AUTOMATIC UPLINK POWER CONTROL 12.1 Introduction Automatic Uplink Power Control (AUPC) is a feature whereby a local modem is permitted to adjust its own output power level in order to attempt to maintain the Eb/No at the remote modem. ! ! ! IMPORTANT WARNING ! ! ! The user MUST obtain permission from the Satellite Operator to use this feature.
Automatic Uplink Power Control (AUPC) CDM-550T Satellite Modem 12.2 Setting AUPC Parameters 1) The user, under the menu (CONFIG, FRAME) first ensures that Framed mode is selected. EDMAC may be disabled, or the unit may be defined as an EDMAC Master or Slave.
CDM-550T Satellite Modem Automatic Uplink Power Control (AUPC) 12.2.3 Alarm This parameter defines how the user wants the modem to act if, under AUPC control, the maximum power limit is reached. The two choices are: NONE (no action) TX ALARM (generate a TX alarm) The default setting is NONE.
Automatic Uplink Power Control (AUPC) CDM-550T Satellite Modem 12.4 Monitoring The remote demodulator’s value of Eb/No can be monitored at all times, either from the front panel (MONIT, AUPC) or via the remote control interface. The resolution of the reading is 0.2 dB. For all values greater than or equal to 16 dB, the value 16.0 dB will be displayed.
Chapter 13. FLASH UPGRADING The CDM-550T eliminates the need for updating firmware by physically replacing EPROMs. Instead, the CDM-550T modem uses ‘flash memory’ technology internally, and new firmware can be uploaded to the unit from an external PC. This makes software upgrading very simple, and updates can now be sent via the Internet, E-mail, or on disk.
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Summary Of Specifications CDM-550T Satellite Modem None: Uncoded BPSK/QPSK/OQPSK Viterbi: k=7, per IESS 308/309 BPSK: Rate 1/2 QPSK/OQPSK: Rate 1/2, Rate 3/4 and Rate 7/8 Sequential: k=36 (Rate 1/2) per IESS 309 k= 63 (Rate 3/4) per IESS 309 k= 87 (Rate 7/8)
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CDM-550T Satellite Modem Summary Of Specifications Clock tracking range ± 100 ppm min VITERBI BER Rate 1/2 Rate 3/4 Rate 7/8 Guaranteed Guaranteed Guaranteed Eb/No: performance (met in the presence Eb/No: Eb/No: (typical value in of two adjacent (typical value in...
CDM-550T Satellite Modem Summary Of Specifications 14.6 Async Overhead Electrical Interface EIA-232 (Rx Data, Tx Data, and ground no flow control) 8 data bits, no parity, 1 stop bit, (8-N-1) – full duplex Async format Baud Rates Main channel data rate versus async channel baud rate (All modes except 21/44 and 5/16 Turbo) <50 kbps - option disabled...
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Summary Of Specifications CDM-550T Satellite Modem Typical Coarse AGC voltage Characteristic Composite input level Alarm Threshold For input levels < -40 dBm AGC functions are performed in the digital demod For Symbol Rates >300 ksym/sec IF BW = 3.5 MHz For Symbol Rates >...
Chapter 15. REMOTE CONTROL 15.1 Introduction This section describes the protocol and message command set for remote monitor and control of the CDM-550 Modem. The electrical interface is either an EIA-485 multi-drop bus (for the control of many devices) or an EIA-232 connection (for the control of a single device), and data is transmitted in asynchronous serial form, using ASCII characters.
Remote Control CDM-550T Satellite Modem In the other direction, on the other pair, each target has a tri-stateable line driver connected, and the controller has a line-receiver connected. All the line drivers are held in high-impedance mode until one (and only one) target transmits back to the controller.
Remote Control CDM-550T Satellite Modem 15.5.3 Instruction Code This is a three-character alphabetic sequence which identifies the subject of the message. Wherever possible, the instruction codes have been chosen to have some significance. For example TFQ for transmit frequency, RMD for receive modulation type, etc. This aids in the readability of the message, should it be displayed in its raw ASCII form.
CDM-550T Satellite Modem Remote Control Second, if the controller sends an instruction to set a parameter to a particular value, then, providing the value sent in the argument is valid, the target will acknowledge the message by replying with TFQ= (with no message arguments).
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CDM-550T Satellite Modem Remote Control Parameter Command Arguments for Description of arguments Response to Command Query Response to query Type (InstructionC Command or (note that all arguments are ASCII numeric codes, that is, (target to controller) (Instruction (target to controller)
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2550 is CDM-550T, no Reed-Solomon or Turbo 3550 is CDM-550T with Reed-Solomon Codec 4550 is CDM-550T with Turbo Codec fitted (Rate 3/4 QPSK only - S/W Version less than 1.15) 5550 is CDM-550T with Turbo Codec fitted (Rate 3/4 QPSK,...
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Appendix A. CABLE DRAWINGS The EIA-530 standard pinout (provided on the CDM-550T) is becoming more popular in many applications. However, there are still many occasions when, especially for existing EIA-422/449 and V.35 users, a conversion must be made. For these situations, the following two cable drawings show EIA-530 to EIA-422/449 DCE conversion, and EIA-530 to V.35 DCE conversion.
Appendix B. Eb/No MEASUREMENT Although the CDM-550T calculates and displays the value of receive Eb/No on the front panel of the unit, it is sometimes useful to measure the value using a spectrum analyzer, if one is available. Rev. 1.3...
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Eb/No Measurement CDM-550T Satellite Modem The idea is to accurately measure the value of (C+N)/N, (Carrier + Noise/Noise) and this is accomplished by tuning the center frequency of the Spectrum analyzer to the signal of interest, and measuring the difference between the peak spectral density of the signal (the flat part of the spectrum shown) and the noise density.
Appendix C. Async Overhead Option Introduction For many applications the EDMAC channel provides an excellent solution to the problem of communicating with a modem (and possibly a transceiver) at the distant end of a satellite link. However, the EDMAC information remains internal to the equipment, and is not presented to the outside world.
Async Overhead Option CDM-550T Satellite Modem Electrical Interface The electrical interface is 3-wire EIA-232 (Rx Data, Tx Data, and ground). No flow control is provided. The async character format is fixed at 8 data bits, no parity, 1 stop bit, (8-N-1), full duplex.
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SPECIALS menu. The FACTORY sub-menus contain features and operating modes that may be specific to particular customers of Comtech EF Data, and includes diagnostic modes that may, in certain circumstances, render the modem inoperable. It is our policy, therefore to require a special combination of keystrokes for FACTORY access, which we do not publish.
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Index Data Connector - 25 Pin ‘D’ Type Female ... 5–1 About this Manual ...........viii Data Interfaces ............1–3 Address ..............15–3 Data Interfaces ............14–4 Alarm..............12–3 Demod Unlock ............12–3 Alarms Connector - 15 Pin ‘D’ Type Male... 5–1 Demodulator Specifications ........14–2 Approvals..............
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CDM-550T Satellite Modem Monitor and Control of the KST-2000A Satellite Terminal Addendum A (For Modem Firmware V1.20 or higher) Part # MN/CDM550T.AA1...
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Disclaimer Comtech EF Data has reviewed this Addendum thoroughly in order that it will be an easy-to-use guide to your equipment. All statements, technical information, and recommendations in this manual and in any guides or related documents are believed reliable, but the accuracy and completeness thereof are not guaranteed or warranted, and they are not intended to be, nor should they be understood to be, representations or warranties concerning the products described.
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Table of Contents ODU Operation via a CDM-550T Modem Front Panel Comprising Firmware ≥ ≥ ≥ ≥ 1.20 ........1 Menu Trees .................................. 3 Select .................................... 3 ODU....................................3 (ODU,ENABLE) Selections............................4 (ODU,ENABLE) CONFIG (Configuration) ......................4 (ODU,ENABLE,CONFIG) TRANSMITTER ......................4 (ODU,ENABLE,CONFIG,TRANSMITTER) FREQUENCY ................
KST-2000A Satellite Terminal. The user can fully control and monitor the operation of Comtech EF Data’s KST- 2000A Satellite Terminal from the front panel, using the keypad and display of a CDM-550T modem.
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CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 The keypad has six keys, the functions of which are described below: → → → → Moves the cursor to the right, when it is displayed ← ← ← ←...
(Utility) This menu branch permits the user to perform miscellaneous modem functions, such as setting the Real-time clock, adjusting the display brightness, etc. (Outdoor Unit) This permits the user to monitor and control a Comtech EF Data KST- 2000A Transceiver, if connected.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.3 (ODU,ENABLE) Selections ODU SELECT: CONFIG INFO STATUS (ENTER) The user is prompted to select 1 of 3 sub-menu branches using the [←] [→] keys, then press <ENTER>. 1.2.4 (ODU,ENABLE)
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.7 (ODU,ENABLE, CONFIG,TRANSMITTER) ATTEN (Attenuation) EDIT ODU TX ATTENUATION: 15.00 dB (PRESS ENTER) The user is prompted to edit the transmit attenuation. This is accomplished by selecting the digit to be edited, using the [←] [→] keys. The value of the digit is then changed using the [↑] [↓] keys.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.12 (ODU,ENABLE, CONFIG) RECEIVER ODU RX: FREQUENCY ATTEN (PRESS ENTER) This menu item is used to select which ODU Receiver parameter is to be modified. Use the [←] [→] keys, then press <ENTER>.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.14 (ODU,ENABLE, CONFIG,RECEIVER) ATTEN (Attenuation) EDIT ODU RX ATTENUATION: 15.00 dB (PRESS ENTER) The user is prompted to edit the receive attenuation. This is accomplished by selecting the digit to be edited, using the [←] [→] keys. The value of the digit is then changed using the [↑] [↓] keys.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.19 (ODU,ENABLE, CONFIG) MISCELLANEOUS KST MISC: AGC REF-ADJUST (ENTER) This menu item is used to select miscellaneous ODU parameters for modification. Use the [←] [→] keys, then press <ENTER>. 1.2.20...
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.29 ODU,ENABLE,INFO) FW (Firmware) FIRMWARE INFO: M&C FW: 9364-1- VER: 01.01.01 Note: The blinking cursor is on the M&C. Use the [↑] [↓] keys to view additional firmware information for the Up Converter, Down Converter, and HPA.
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CDM-550T Satellite Modem Monitor and Control of the KST-2000A Satellite Terminal Addendum A (For Modem Firmware V1.20 or higher) Part # MN/CDM550T.AA1...
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Disclaimer Comtech EF Data has reviewed this Addendum thoroughly in order that it will be an easy-to-use guide to your equipment. All statements, technical information, and recommendations in this manual and in any guides or related documents are believed reliable, but the accuracy and completeness thereof are not guaranteed or warranted, and they are not intended to be, nor should they be understood to be, representations or warranties concerning the products described.
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Table of Contents ODU Operation via a CDM-550T Modem Front Panel Comprising Firmware ≥ ≥ ≥ ≥ 1.20 .........1 Menu Trees...................................3 Select .....................................3 ODU ....................................3 (ODU,ENABLE) Selections ............................4 (ODU,ENABLE) CONFIG (Configuration) ......................4 (ODU,ENABLE,CONFIG) TRANSMITTER......................4 (ODU,ENABLE,CONFIG,TRANSMITTER) FREQUENCY................4 (ODU,ENABLE,CONFIG,TRANSMITTER) ATTEN (Attenuation) ..............5 (ODU,ENABLE,CONFIG,TRANSMITTER) OUTPUT ..................5...
KST-2000A Satellite Terminal. The user can fully control and monitor the operation of Comtech EF Data’s KST- 2000A Satellite Terminal from the front panel, using the keypad and display of a CDM-550T modem.
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CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 The keypad has six keys, the functions of which are described below: → → → → Moves the cursor to the right, when it is displayed ← ← ← ←...
(Utility) This menu branch permits the user to perform miscellaneous modem functions, such as setting the Real-time clock, adjusting the display brightness, etc. (Outdoor Unit) This permits the user to monitor and control a Comtech EF Data KST- 2000A Transceiver, if connected.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.3 (ODU,ENABLE) Selections ODU SELECT: CONFIG INFO STATUS (ENTER) The user is prompted to select 1 of 3 sub-menu branches using the [←] [→] keys, then press <ENTER>. 1.2.4 (ODU,ENABLE)
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.7 (ODU,ENABLE, CONFIG,TRANSMITTER) ATTEN (Attenuation) EDIT ODU TX ATTENUATION: 15.00 dB (PRESS ENTER) The user is prompted to edit the transmit attenuation. This is accomplished by selecting the digit to be edited, using the [←] [→] keys. The value of the digit is then changed using the [↑] [↓] keys.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.12 (ODU,ENABLE, CONFIG) RECEIVER ODU RX: FREQUENCY ATTEN (PRESS ENTER) This menu item is used to select which ODU Receiver parameter is to be modified. Use the [←] [→] keys, then press <ENTER>.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.14 (ODU,ENABLE, CONFIG,RECEIVER) ATTEN (Attenuation) EDIT ODU RX ATTENUATION: 15.00 dB (PRESS ENTER) The user is prompted to edit the receive attenuation. This is accomplished by selecting the digit to be edited, using the [←] [→] keys. The value of the digit is then changed using the [↑] [↓] keys.
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.19 (ODU,ENABLE, CONFIG) MISCELLANEOUS KST MISC: AGC REF-ADJUST (ENTER) This menu item is used to select miscellaneous ODU parameters for modification. Use the [←] [→] keys, then press <ENTER>. 1.2.20...
CDM-550T Satellite Modem Revision 0 KST-2000A FSK Remote Operation MN/CDM550T.AA1 1.2.29 ODU,ENABLE,INFO) FW (Firmware) FIRMWARE INFO: M&C FW: 9364-1- VER: 01.01.01 Note: The blinking cursor is on the M&C. Use the [↑] [↓] keys to view additional firmware information for the Up Converter, Down Converter, and HPA.
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