Datum Systems PSM-4900L Application Manual Download

Page: 14 / 14

L-Band IF Application Guide

Page L-Band - 14

Demod LNB, Command [87h], Read Change Flags (Hybrid & L-Band Only)

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

Byte 0

LnbPwr

Reserved

IOut

IMax

IMin

Ref

LoFrq

Byte

1 Spare Spare Spare Spare Spare Spare Spare Spare

Byte

2 Spare Spare Spare Spare Spare Spare Spare Spare

Byte

3 Spare Spare Spare Spare Spare Spare Spare Spare

Demod LNB, Read Flags

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

Byte

4 PwrEn0 PwrEn1 PwrEn2 RefEn0 RefEn1 RefEn2 Spare

Spare

Byte

5 Spare Spare Spare Spare Spare Spare Spare Spare

Byte

6 Spare Spare Spare Spare Spare Spare Spare Spare

Byte

7 Spare Spare Spare Spare Spare Spare Spare Spare

Demod LNB, Read Bytes

Bytes 8-9

Reserved

Bytes 10-11

Reserved

Bytes 12-13

LNB Current Out, Signed 16b, (0 to >500), 1mA Increments

Bytes 14-15

LNB Current Max, Signed 16b, (5 to 500), 1mA Increments

Bytes 16-17

LNB Current Min, Signed 16b, (5 to 500), 1mA Increments

Bytes 18-23

LNB LO Frequency, Unsigned 48b, (0 to 50,000,000,000), 1Hz Increments

Bytes 24-33

Spare

Demod LNB, Write Enable Flags

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

Byte

BucPwr

0 0 0

IMax

IMin

Ref

LoFrq

Byte

0 0 0 0 0 0 0 0

Byte

0 0 0 0 0 0 0 0

Byte

0 0 0 0 0 0 0 0

Demod LNB, Write Flags

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

Byte

4 PwrEn0 PwrEn1 PwrEn2 RefEn0 RefEn1 RefEn2 Spare

Spare

Byte

5 Spare Spare Spare Spare Spare Spare Spare Spare

Byte

6 Spare Spare Spare Spare Spare Spare Spare Spare

Byte

7 Spare Spare Spare Spare Spare Spare Spare Spare

Demod LNB, Write Bytes

Bytes 8-9

Bytes 10-11

Bytes 12-13

Bytes 14-15

LNB Current Max, Signed 16b, (5 to 500), 1mA Increments

Bytes 16-17

LNB Current Min, Signed 16b, (5 to 500), 1mA Increments

Bytes 18-23

LNB LO Frequency, Unsigned 48b, (0 to 50,000,000,000), 1Hz Increments

Bytes 24-33

Spare

[PwrEn2-PwrEn0]

= LNB Power, 3b, 0=Disabled, 1=Enabled

[RefEn2-RefEn0]

= LNB 10MHz Ref, 3b, 0=Disabled, 1=Enabled

Summary of Contents for PSM-4900L

Page 1: ...MHz of Transmit RF spectrum and 950 MHz of Receive RF spectrum without any converter settings Aside from the many advantages using L Band as an inter facility link frequency results in the need to carefully consider the components frequencies and construction techniques used to insure proper operation Part of the purpose of this addendum is to spell out those areas where special care must be used ...

Page 2: ... and 950 MHz receive range to accommodate as many satellite range converter LO schemes as possible One scheme seems to be fairly common for C Band ODUs using a BUC transmit LO of 4900 MHz while the LNB uses an LO of 5150 MHz The PSM 4900L provides two methods of specifying transmit and receive frequencies Added transmit and receive parameter inputs are provided for the transmit BUC and receive LNB...

Page 3: ...h side LO for both C and L Band transmit frequencies For a C Band BUC using a High side LO going from 950 1450 MHz to 5925 6425 MHz the LO frequency would be 7375 MHz 950 6425 MHz There would be an inversion in the transmit output spectrum Notice also that the highest transmit output frequency results from using the lowest L Band modem transmit frequency The same schemes are possible at Ku Band fr...

Page 4: ...date a wide range of cable length and LNB gains The LNB gain minus the cable loss should always fall within the range of 40 dB to 70 dB of overall gain As long as this gain is achieved the demodulator will function properly at all data rates from 1 2 kpbs to 4 92 Mbps requiring no further system level engineering For example a typical data grade LNB has a gain of approximately 60 dB This would all...

Page 5: ...to 90 MHz 4 bytes in binary command Is 950 to 1750 MHz 5 bytes in binary command OR 800 MHz of RF frequency range when the LO input not 0 Demodulator Carrier Frequency Was 50 to 90 MHz 4 bytes in binary command Is 950 to 1750 MHz 6 bytes in binary command OR 950 MHz of RF frequency range when the LO input not 0 3 0 Designing and Setting up an L Band Station The equipment complement at any station ...

Page 6: ...ut The typical input power required for full power output varies between 20 and 30 dB Maximum phase noise levels need to be determined based on the data rates being used Frequency stability Determined by externally applied 10 MHz reference oscillator Typically requires an approximate 1 part in 107 OCXO for C or Ku Band operation This represents a possible 600 Hz error at 6 GHz or 1 4 kHz at 14 GHz...

Page 7: ...rrier would require approximately 2 parts in 107 stability minimum This is 1200 Hz at 6 GHz transmit frequency A Ku Band BUC would require 1 part in 107 stability for a 32 kbps data rate Higher data rates would require less stability The typical BUC level requirement for the reference input is usually somewhere between 5 and 3 or 5 dBm from a sine wave oscillator The PSM 4900 output is nominally 3...

Page 8: ...f setting the antenna size The demodulator uses a sliding AGC window with an approximate AGC range of 55 dB at any given data rate As the data rate is decreased the AGC window moves down to accommodate the decreasing signal level The transmit levels must be carefully controlled however Most BUCs have no internal gain control and therefore represent a fixed gain block The output power is thus direc...

Page 9: ...rift frequency limits there might be a tendency for the receive to attempt locking to its own transmit signal 4 Considering the L Band IF range is 800 MHz or more spanning close to an octave the variation in loss between the high and low ends of the IF range may be significant A nominal design point may be to allow for 10 to 15 dB of total cable losses and select cable that will reliably achieve t...

Page 10: ... cable types The maximum length that RG214 would be used assuming the approx 15 dB loss criteria would be 150 ft or 50 meters Times LMR 400 cable would be usable over 300 ft At less cost Both of these examples assume that the DC loss of the BUC power is within tolerance For many receive applications RG6 cable is a good choice The typical DC resistance of 0 405 inch class 50 Ohm cables such as RG21...

Page 11: ...endently Forward Error Correction Optional Turbo Product Codes Optional Concatenated Reed Solomon Viterbi k 7 Rates 1 2 3 4 or 7 8 Standard and Short Block n 126 k 112 t 7 or n 219 k 201 t 9 or programmable with depth of 4 or 8 FEC Viterbi or TPC Rates Selectable 1 2 3 4 or 7 8 Data Rates Programmable at FEC rate 1 2 without IBS mux or R S option 1 2 kbps to 1 230 kbps BPSK 2 4 kbps to 2 460 kbps ...

Page 12: ... WARNING It may be difficult in many programming languages to generate a 6 byte number representation for binary programming of the modem Like the front panel controls the remote control procedures for specifying transmit and receive IF frequencies are dependant upon wether a BUC and or LNB LO frequency has been supplied If a non zero frequency has been input from any source then the transmit and ...

Page 13: ... 5 to 600 10mA Increments Bytes 16 17 BUC Current Min Signed 16b 5 to 600 10mA Increments Bytes 18 23 BUC LO Frequency Unsigned 48b 0 to 50 000 000 000 1Hz Increments Bytes 24 33 Spare Mod BUC Write Enable Flags Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Byte 0 BucPwr 0 VMin 0 IMax IMin Ref LoFrq Byte 1 0 0 0 0 0 0 0 0 Byte 2 0 0 0 0 0 0 0 0 Byte 3 0 0 0 0 0 0 0 0 Mod BUC Write Flags Bit 0 Bi...

Page 14: ...0 1mA Increments Bytes 16 17 LNB Current Min Signed 16b 5 to 500 1mA Increments Bytes 18 23 LNB LO Frequency Unsigned 48b 0 to 50 000 000 000 1Hz Increments Bytes 24 33 Spare Demod LNB Write Enable Flags Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Byte 0 BucPwr 0 0 0 IMax IMin Ref LoFrq Byte 1 0 0 0 0 0 0 0 0 Byte 2 0 0 0 0 0 0 0 0 Byte 3 0 0 0 0 0 0 0 0 Demod LNB Write Flags Bit 0 Bit 1 Bit 2...

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Datum Systems PSM-4900L, Application Manual

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