** Managers **

- A.1 ScanCoordinator
- A.2 SwitchingSignalSelector
- A.3 LO1
- A.4 IFRack
- A.5 ConverterRack
- A.6 ActiveSurface
- A.7 AnalogFilterRack
- A.8 DCR
- A.9 Spectrometer
- A.10 SpectralProcessor
- A.11 BCPM
- A.12. Receivers: PrimeFocus, Rcvr1_2, Rcvr2_3, Rcvr4_6, Rcvr8_10, Rcvr12_18, Rcvr18_26, Rcvr40_52

** return to main Configuration document.
**

Likewise, the receiver parameter will be passed on to the IFRack and the LO1 managers.

There is some importance in the order in which parameters are set. First set 'subsystemSelect', so that subsequent parameters will be inherited by the devices that need them. When setting the switching parameters, first set the number of phases, then the blanking, then the others.

When finished setting all parameters, do a 'regChange', not 'activate', 'start', or 'prepare'. (For all other managers, do a 'prepare')

Table A.1.1. Scan Coordinator | |
---|---|

YGOR Parameters | Depends on Keyword(s) |

receiver | Receiver |

subsystemSelect | Receiver, Backend |

switching_signals_master | Backend |

number_phases | Swmode |

phase_start | Swmode |

sig_ref_state | Swmode, Backend, Vframe |

cal_state | Swmode |

blanking | Swmode, Swtype, Backend |

switch_period | Swper |

** subsystemSelect **

- Always include the Antenna, Receiver, LO1, IFRack, IFManager, and Measurements.
- If the receiver is Rcvr8_10 or higher frequency, include the active surface.
- Include the converter rack, unless the only backend is DCR_IF or DCR_PF.
- Always include the DCR, in addition to any other back end.
- Include the backend manager if there is one.
- If the backend is the Spectrometer or DCR_AF, include the analog filter rack.

** switching_signals_master **

Set this to the backend, with a few exceptions:

Table A.1.2. | |
---|---|

Backend | switching_signals_master |

DCR | DCR |

SpectralProcessor | SpectralProcessor |

Spectrometer | Spectrometer |

BCPM | DCR |

GBPP | DCR |

BCPM&SP | SpectralProcessor |

Radar | DCR |

VLBI | VLBA_DAR |

** number_phases, phase_start, sig_ref_state, cal_state **

These parameters all depend on the Switching Mode, as
listed in the table.

Table 4.1.3. | ||||
---|---|---|---|---|

Swmode | number_phases | phase_start | sig_ref_state | cal_state |

tp (not Spectral Processor or local Vframe) | 2 | [0.0, 0.5] | ['Sig', 'Sig'] | ['NoNoise', 'Noise'] |

tp (Spectral Processor and non-local Vframe) | 2 | [0.0, 0.5] | ['Sig', 'Ref'] | ['NoNoise', 'Noise'] |

tp_nocal | 1 | [0.0] | ['Sig'] | ['NoNoise'] |

sp | 4 | [0.0, 0.25, 0.5, 0.75] | ['Sig', 'Sig', 'Ref', 'Ref'] | ['NoNoise', 'Noise', 'NoNoise', 'Noise'] |

sp_nocal | 2 | [0.0, 0.5] | ['Sig', 'Ref'] | ['NoNoise', 'NoNoise'] |

** blanking **

- If Swmode is 'tp_nocal', blanking = 0.0
- If Backend is VLBI or Obstype is Pulsar, blanking = 0.0
- If Swtype is 'fsw' and Backend is SpectralProcessor, blanking = 0.04
- If Vframe is not Local, and Backend is SpectralProcessor, blanking = 0.04
- For all other cases, blanking = 0.002

** switch_period **

YGOR Parameters | Keyword(s) |
---|---|

selSigRef | Backend |

selAdvSigRef | Backend |

selCal | Backend |

selBlanking | Backend |

disableLOBlanking | Backend, Vframe, Swtype |

disableLocalBlanking | Backend |

** disableLOBlanking **

** disableLocalBlanking **

Several parameters are always set the same way; for these there is nothing in the "Keyword" column.

Table A.3.1. LO1 Parameters | ||
---|---|---|

YGOR Parameters | Keyword(s) | Comments |

receiver | Receiver | |

loConfig | -- | Set to 'TrackA_BNotUsed' |

restFrequency | Restfreq | |

ifCenterFreq | Restfreq, Deltafreq, Nwin | See Section 6.0 |

switchDeltas | Swfreq, Swtype | If Swtype is not 'fsw' set to zeros. |

sourceVelocity | (Vlow+Vhigh)/2 | |

restFrame | Vframe | |

velocityDefinition | Vdef | |

tolerance | Backend, Nchannels | |

phaseCalCtl | Obstype, Phasecal | VLBI only |

phaseCalMode | Obstype, Phasecal | VLBI only |

subsystemSelect | ----- | set to [1,1,0,1] |

useOffsets | ----- | set to 'false' |

autoSetLOPowerLevel | ----- | set to 1 |

testToneFreq | ----- | set to 17000.0 |

testTonePowerLevel | ----- | set to -110 db |

Table A.3.2. restFrame values | |
---|---|

Vframe | LO1 restFrame |

topo | Local |

bary | Barycentric |

lsrk | KinematicalLSR |

lsrd | DynamicalLSR |

galac | Galactocentric |

cmb | CosmicBackground |

Table A.3.3. velocityDefinition values | |
---|---|

Vdef | LO1 velocityDefinition |

rad | Radio |

opt | Optical |

rel | Relativistic |

If the Obstype is VLBI and Phasecal keyword is 'M1' or 'M5', then phaseCalCtl is set to 'on', and phaseCalMode is set to 'M1' or 'M5'. Otherwise, phaseCalCtl should be 'off'.

If phaseCalCtl is 'on', then the switches that route the phase cal signal to the receiver must also be set.

Table A.4.1. IF Rack Parameters | ||
---|---|---|

YGOR Parameters | Keyword(s) | Comments |

receiver | Receiver | |

analog_power_level | Receiver, Bandwidth | |

filter_select | Bandwidth, Nwin, etc. | |

laser_auto_level_control | Set all to 'swOn' | |

subsystemSelect | Set all to ones. | |

noise_bandwidth | Set to 'narrowband' | |

S9 ... S12 | Transfer switches: See Section 7.0 |

For Gregorian receivers, the IF filters are set to the smallest value that includes "BWTOT", as explained in Section 6.0. But if BWTOT is greater than 1280 MHz, set the filter to 1280.

For simplicity, set all filters in the filter_select array the same.

Eight frequency synthesizers (G1, G2, ... G8) provide a second downconversion frequency (LO2) to two converter modules each. 'Gfrequency' is the list of these frequencies.

Table A.5.1. Converter Rack Parameters | ||
---|---|---|

YGOR Parameters | Keyword(s) | Comments |

CMInput | Receiver, Beam | |

ABselect | Receiver, Beam | |

CMOutput | Backend, Bandwidth | |

Gfrequency | Receiver, Backend, Bandwidth,
Nwin, Restfreq, Dfreq, Vlow, Vhigh, Vdef |
Refer to Section 6.0 |

Glevel | --- | Set them all to 10 |

Table A.5.2. : CMInput | ||
---|---|---|

A | B | Converter Modules |

OpRcvr1 | OpRcvr2 | 1, 2, 3, and 4 |

OpRcvr3 | OpRcvr4 | 5, 6, 7, and 8 |

OpRcvr5 | OpRcvr6 | 9, 10, 11, and 12 |

OpRcvr7 | OpRcvr8 | 13, 14, 15, and 16 |

Table A.5.3. | ||
---|---|---|

CMOutput[n] | Filter | Destination |

1 | All Pass | Analog Filter Rack : Bandwidth = 200 or 800 MHz |

2 | 500-1000 MHz | VLBI or Radar backends |

3 | All Pass | unused |

4 | 550 MHz Low-pass | Analog Filter Rack : Bandwidth = 12.5 or 50 MHz
Spectral Processor BCPM |

Note that certain backends (VLBI, BCPM, Radar) connect to only a few of the converter modules. One must consult the cabling file to find out which modules connect to which backends. The nominal setup is as follows:

- VLBI: CM1&5, CM9&13
- Radar: CM10&14
- BCPM1: CM4&8, CM12&16
- BCPM2: CM3&7, CM11&15

YGOR Parameters | Keyword(s) |
---|---|

receiver | Receiver |

correctionSelect | Receiver |

For receivers for frequencies 8 GHz and higher (i.e., X-band, Ku-band, K-band, Q-band, W-band), the active surface FEM model should be enabled, and the active surface manager should be in the Scan Coordinator. For lower frequency receivers (prime focus, L-, S-, and C- bands), the FEM model should be turned off and the Zero Points mode should be enabled.

For receivers of frequencies > 8 GHz, correctionSelect = [zero=1, fem=1, random=0]

There are two flavors of filter module:

- "Sampler Filters" handle the wide-band signals (200 or 800 MHz)
- "Converter Filters" handle the narrow-band signals (12.5 or 50 MHz)

The outputs of Sampler Filter modules 1 through 8 go to high speed samplers 1 through 8 in the Spectrometer.

There are 16 "Converter Filter" modules. Their inputs are connected to the "550MHz Lowpass" outputs of the Converter Rack modules. Converter filter module numbers 1-16 connect to corresponding numbered converter rack modules. Parameter 'CFFilter' sets the bandpass in these modules. Set CFFilter to 'wide' for 50 MHz and 'narrow' for 12.5 MHz.

Although the possibility exists of setting different bandwidths in different modules, we will not do this for this version of the configurator. All modules will be set the same.

Table A.7.1. AnalogFilterRack parameters | ||
---|---|---|

YGOR Parameters | Keyword(s) | Comments |

SGInput | Receiver, Beam | SGInput = 1(input from CR "A")
or 2(input from CR "B" |

SGFilter | Bandwidth | SGFilter = 'wide' for 800 MHz,
or 'narrow' for 200 MHz |

CFFilter | Bandwidth | CFFilter = 'wide' for 50 MHz,
or 'narrow' for 12.5MHz |

subsystemSelect | Set them all to 1 |

Table A.7.2. Wideband filter module connections | ||
---|---|---|

SGInput= 1 / 2 |
SF Module | Spectrometer Sampler Connection |

CM 1 / 9 | 1 | J1 |

CM 2 / 10 | 2 | J2 |

CM 3 / 11 | 3 | J3 |

CM 4 / 12 | 4 | J4 |

CM 5 / 13 | 5 | J5 |

CM 6 / 14 | 6 | J6 |

CM 7 / 15 | 6 | J6 |

CM 8 / 16 | 8 | J8 |

Table A.7.3. Narrow filter module connections | |||
---|---|---|---|

ConverterRack module |
AFR "Converter Filter Module |
Spectrometer Sampler Connection |
Sampler number |

1 | 1 | J9 | 0 |

2 | 2 | J10 | 1 |

3 | 3 | J17 | 8 |

4 | 4 | J18 | 9 |

5 | 5 | J13 | 4 |

6 | 6 | J14 | 5 |

7 | 7 | J21 | 12 |

8 | 8 | J22 | 13 |

9 | 9 | J25 | 16 |

10 | 10 | J26 | 17 |

11 | 11 | J33 | 24 |

12 | 12 | J34 | 25 |

13 | 13 | J29 | 20 |

14 | 14 | J30 | 21 |

15 | 15 | J37 | 28 |

16 | 16 | J38 | 29 |

Data comes to the DCR from three different devices, the IF Rack, the Prime Focus Receiver, and the Analog Filter Rack. For the purpose of configuring, we are considering only the IF Rack and Analog Filter Rack inputs, and are treating these cases as two different back ends, called "DCR_IF" and "DCR_AF".

The list of parameters that the configurator needs to be concerned with is listed in Table A.8.1.

Table A.8.1. DCR Parameters | |
---|---|

YGOR Parameters | Keyword(s) |

Bank | Receiver, Beam |

Channel | Receiver, Beam |

CyclesPerIntegration | Tint, Backend |

Table A.8.2 DCR Inputs | ||
---|---|---|

Device | Bank | Channels |

IF Rack | A | 1 - 8 |

AFR SG1 - SG8 (wide band channels) |
A | 9 - 16 |

AFR CF1,3,5,7,9,11,13,15 (narrow band channels) |
B | 9 - 16 |

If the DCR is not the switching signal master, then it is being used to monitor Tsys, so just set CyclesPerIntegration for one second integrations:

Although it is possible to set up different banks with different bandwidths and modes, we will not consider that. All spectra will have the same bandwidth and number of channels.

Table A.9.1. Spectrometer Parameters | |
---|---|

YGOR Parameters | Keyword(s) |

configuration | Bandwidth, Nwin, Beam,
Nchannels |

relative_bandwidth | Bandwidth |

slow_samplers | Nwin, Beam |

fast_samplers | Nwin, Beam |

number_slow_samplers | Nwin, Beam |

switching_signals_select | Swmode |

slow_samplers_level | Nlevels |

requested_integration_time | Tint |

polarization | Obstype |

Table A.9.2. ACS Configurations | ||
---|---|---|

Configuration | Num.Banks | Num.Quads per bank |

Spectrum_A1 | 1 | 1 |

Spectrum_A2 | 1 | 2 |

Spectrum_A4 | 1 | 4 |

Spectrum_A1_B1 | 2 | 1 |

Spectrum_A2_B2 | 2 | 2 |

Spectrum_A1_B1_C1_D1 | 4 | 1 |

If the Bandwidth is 12.5 MHz or 200 MHz, set this parameter to 'narrow'. Otherwise, set it to 'wide'. Set all banks the same.

For Bandwidth=200MHz, no more than 4 fast samplers may be assigned to a bank.

For Bandwidth=800MHz, no more than 2 fast samplers may be assigned to a bank.

Set them if using slow samplers, i.e., the Bandwidth is 12.5 or 50 MHz.

The TOTAL number of samplers is the number of spectral windows (Nwin) times the number of beams (Nbeams) times two (we always set up for dual polarization. Divide the total TOTAL number of samplers by the number of banks to get the number of samplers per bank. Set all banks to this number.

This enables the Spectrometer to respond to switching signals. Set all the internal enables to zeros (i.e., they are all disabled). Enable external Cal and external blanking. If Swmode is switched power, enable external SigRef. Set all banks the same.

Set them all to Nlevels (i.e., 3 or 9).

Set them all to Tint.

Set them all to zero for non-cross-polarization mode.

The allowed combinations of Nwin and number of beams for the slow samplers (of which we can use up to 16 at a time), are given in Table A.9.3.

Table A.9.3. Total number of samplers for Low-speed modes. | |||
---|---|---|---|

Nwin | one beam | two beams | four beams |

1 |
2 | 4 | 8 |

2 |
4 | 8 | 16 |

4 |
8 | 16 | X |

8 |
16 | X | X |

The next table shows which configuration to use for each choice of
Nwin and beam for the slow samplers.

In the table, beam designations B1, B2, B3, and B4 apply not only
to multi-beam receivers, but to any receiver at all. Each "beam"
indicates a pair of inputs to the IF Rack, as follows:

- B1 : IF Rack inputs S1,S3; (route thru conv. Rack A)
- B2 : IF Rack inputs S5,S7; (route thru conv. Rack B)
- B3 : IF Rack inputs S2,S4; (route thru conv. Rack A)
- B4 : IF Rack inputs S6,S8; (route thru conv. Rack B)

Sampler groups are designated as: G1 = (0-7); G2 = (8-15); G3 = (16-23); G4 = (24-31)

Table A.9.4. Low-Speed Configuration and sampler assignment. | |||||||
---|---|---|---|---|---|---|---|

Nwin | Beam | Total num. samplers |
Configuration | Levels | num.samplers per bank |
Sampler Group | Nchannels |

1 |
B1 | 2 | A1 A2 A4 A1 A2 A4 |
3-lev 3-lev 3-lev 9-lev 9-lev 9-lev | 2 | G1 | 32768 65536 131072 8192 16384 32768 |

1 |
B2 | 2 | same as for B1 | 2 | G3 | ||

1 |
B3 | 2 | same as for B1 | 2 | G2 | ||

1 |
B4 | 2 | same as for B1 | 2 | G4 | ||

1 |
B12 | 4 | A1_B1 A2_B2 A1_B1 A2_B2 |
3-lev 3-lev 9-lev 9-lev |
2 | G1_G3 | 32768 65536 8192 16384 |

1 |
B34 | 4 | same as for B12 | 2 | G2_G4 | ||

1 |
B1234 | 8 | A1_B1_C1_D1 A1_B1_C1_D1 |
3-lev 9-lev |
2 | G1_G2_G3_G4 | 32768 8192 |

2 |
B1 | 4 | A1 A2 A4 A1 A2 A4 |
3-lev 3-lev 3-lev 9-lev 9-lev 9-lev |
4 | G1 | 16384 32768 65536 4096 8192 16384 |

2 |
B2 | 4 | Same as 2 IFs, B1 | 4 | G3 | ||

2 |
B3 | 4 | Same as 2 IFs, B1 | 4 | G2 | ||

2 |
B4 | 4 | Same as 2 IFs, B1 | 4 | G4 | ||

2 |
B12 | 8 | A1_B1 A2_B2 A1_B1 A2_B2 |
3-lev 3-lev 9-lev 9-lev |
4 | G1_G3 | 16384 32768 4096 8192 |

2 |
B34 | 8 | Same as 2 IFs, B12 | 4 | G2_G4 | ||

2 |
B1234 | 16 | A1_B1_C1_D1 A1_B1_C1_D1 |
3-lev 9-lev |
4 | G1_G2_G3_G4 | 16384 4096 |

4 |
B1 | 8 | A1_B1 A2_B2 A1_B1 A2_B2 |
3-lev 3-lev 9-lev 9-lev |
4 | G1_G2 | 16384 32768 4096 8192 |

4 |
B2 | 8 | same as 4 IFs, B1 | 4 | G3_G4 | ||

4 |
B3 | 8 | same as 4 IFs, B1 | 4 | G1_G2 | ||

4 |
B4 | 8 | same as 4 IFs, B1 | 4 | G3_G4 | ||

4 |
B12 | 16 | A1_B1_C1_D1 A1_B1_C1_D1 |
3-lev 9-lev |
4 4 |
G1_G2_G3_G4 G1_G2_G3_G4 |
16384 4096 |

4 |
B34 | 16 | A1_B1_C1_D1 A1_B1_C1_D1 |
3-lev 9-lev |
4 4 |
G1_G2_G3_G4 G1_G2_G3_G4 |
16384 4096 |

8 |
B1 or B2 | 16 | A1_B1_C1_D1 A1_B1_C1_D1 |
3-lev 9-lev |
4 4 |
G1_G2_G3_G4 G1_G2_G3_G4 |
16384 4096 |

8 |
B3 or B4 | 16 | A1_B1_C1_D1 A1_B1_C1_D1 |
3-lev 9-lev |
4 4 |
G1_G2_G3_G4 G1_G2_G3_G4 |
16384 4096 |

Now for the fast samplers, i.e., Bandwidths of 200 or 800 MHz, Table A.9.5 shows the possible combinations of Nwin and number of beams. There are a maximum of 8 fast samplers.

Table A.9.5. Total Numbers of Fast Samplers. | |||
---|---|---|---|

Nwin | one beam | two beams | four beams |

1 |
2 | 4 | 8 |

2 |
4 | 8 | X |

4 |
8 | X | X |

Fast sampler configurations are listed in Table A.9.6.

Table A.9.6. Configurations for Fast Samplers. | ||||||
---|---|---|---|---|---|---|

Nwin | # beams | NSamp | Configuration | Bandwidth | Sampler assignment |
NChannels |

1 |
1 | 2 | A1 A2 A4 A1 A1_B1 A2_B2 |
200 200 200 800 800 800 | 01 01 01 01 0_1 0_1 |
8192 16384 32768 2048 4096 8192 |

1 |
2 | 4 | A1 A1_B1 A2_B2 A1_B1 A1_B1_C1_D1 |
200 200 200 800 800 |
0123 01_23 01_23 01_23 0_1_2_3 |
4096 8192 16384 2048 4096 |

1 |
4 | 8 | A1_B1 A1_B1_C1_D1 A1_B1_C1_D1 |
200 200 800 |
0123_4567 01_23_45_67 01_23_45_67 |
4096 8192 2048 |

2 |
1 | 4 | A1 A1_B1 A2_B2 A1_B1 A1_B1_C1_D1 |
200 200 200 800 800 |
0123 01_23 01_23 01_23 0_1_2_3 |
4096 8192 16384 2048 4096 |

2 |
2 | 8 | A1_B1 A1_B1_C1_D1 A1_B1_C1_D1 |
200 200 800 |
0123_4567 01_23_45_67 01_23_45_67 |
4096 8192 2048 |

4 |
1 | 8 | A1_B1 A1_B1_C1_D1 A1_B1_C1_D1 |
200 200 800 |
0123_4567 01_23_45_67 01_23_45_67 |
4096 8192 2048 |

The first table lists the YGOR parameters that the configurator needs to set. Following the table are descriptions of how each YGOR parameter relates to the configuration keywords. Finally, there is an explanation of how to connect the Spectral Processor to the GBT IF system.

A.10.1. Parameters set directly by configurator | |
---|---|

YGOR Parameters | Dependent on Keyword(s) |

processorMode | Obstype |

multiplierMode | spmode |

reqBandwidth | Bandwidth |

reqNumChan | Nchannels, Bandwidth, Nwin, Beam |

numSpectr | Nwin, Beam |

observeFreq | Nwin, Beam, Restfreq, Dfreq |

rfSideband | Receiver |

reqIF | (normally these are always 250 MHz |

sampleTime | Tint |

calPhase | always set to 0.0 |

calDuration | always set to 0.5 |

atodLevMode | set to 'ScanStart' |

balance | set to 'Balance' |

reqPulsarPeriod | set to Swper |

reqDispersionMeasure | set to zero |

polycoDatFile | optional user input in pulsar mode. |

The switching phase table and related information is set by the Scan Coordinator, and does not need to be set explicitly by the configurator. These parameters include: number_phases, cal_state, sig_ref_state, phase_start, blanking, switch_period, and switching_signals_master.

** processorMode **

** multiplierMode **

This is a parameter selected by the user. The values are
'Square', 'Cross', or 'SqrCross'. 'Square' means parallel polarization
products; 'Cross' means crossed polarization products;
'SqrCross' means both. See the table below for how
this relates to other parameters.

** reqBandwidth **

** reqNumChan and numSpectr **

The possible values for these parameters are listed in the
following table:

Table A.10.2. Spectrum Configurations | ||||
---|---|---|---|---|

Bandwidth | multiplierMode | NIF | reqNumChan | numSpectr |

40 MHz | Square or Cross | 1 | 1024 | 1 |

20 MHz | Square or Cross or SqrCross | 1 | 1024 | 1 |

20 MHz | Square or Cross | 2 | 512 | 2 |

10 MHz | Square, Cross, or SqrCross | 1 | 1024 | 1 |

10 MHz | Square, Cross, or SqrCross | 2 | 512 | 2 |

10 MHz | Square or Cross | 4 | 256 | 4 |

<= 5 MHz | Square, Cross, or SqrCross | 1 | 1024 | 1 |

<= 5 MHz | Square, Cross, or SqrCross | 2 | 512 | 2 |

<= 5 MHz | Square, Cross, or SqrCross | 4 | 256 | 4 |

For the case of NIF=2, the user has a choice of 512 or 256 channels (Nchannels). Otherwise the Bandwidth and NIFs dictate the number of channels. For standard configuration we will always choose 512 channels.

** observeFreq **

observeFreq is an array of NIF frequencies. Calculation of these frequencies is described in Section 6.0. Use "Flocal[i]" from Section 6.0 for spectral window i.

** rfSideband **

rfSideband is an array of size NIF containing the sideband designation (either 'Upper' or 'Lower') for each IF. These are the net sideband, and depend on the receiver:

** reqIF **

reqIF is an array of size NIF. For standard configurations (which is all that we are considering), all members are set to 250 MHz.

** atodLevMode and balance **

The configurator should always set these to 'ScanStart' and 'Balance' for the initial setup.

Here we make an attempt to explain the logic of connecting the SpectralProcessor to the GBT IF system.

The Spectral Processor has 8 inputs, designated A1,A2,A3,A4, and B1,B2,B3,B4. The "A" inputs connect to one polarization, usually X or LCP, the the "B" inputs to the other polarization. For normal dual-polarization observing, A1 and B1 are used for the first spectral window, A2 and B2 for the second, and so on. There is no flexibility in these assignments, i.e., one cannot use A2 and B2 for the first window. If using one spectral window one must always use A1 and B1; if using two windows, one must always use A1,A2, B1,B2; and so on.

The Spectral Processor inputs connect to an "A/B" switch to the outputs of the converter modules. The switch in the "A" position connects the 8 SP inputs to outputs of converter modules 1-8, and the "B" position to modules 9-16. Do not confuse the "A/B" switch with the "A" and "B" of the Spectral Processor inputs!!

Given a particular instance of the cabling file, there are only two ways to connect the Spectral Processor, one through Converter Rack A ("A/B" switch in "A" position), the other through Converter Rack B.

The following table describes how the GBT IF system connects to the Spectral Processor. It shows the typical use of converter modules, but keep in mind that the cabling file must be consulted to determine how the modules are actually cabled up. Polarization pairs (X,Y) or (LCP,RCP) are normally routed through fiber pairs (1,3), (2,4), (5,7), or (6,8), which can be selected by converter module pairs CM1&5, CM2&6, CM3&7, CM4&8, CM9&13, CM10&14, CM11&15, or CM12&16. The actual fiber pairs must be determined by consulting the cabling file in case one or more fiber drivers are out of service.

The output switch of the converter module in all cases is set to 'LPF550MHz'.

Table A.10.3. Spectral Processor Inputs | ||||
---|---|---|---|---|

Fibers | Polarization | Converter Modules | A/B Switch position | Spectral Processor Input |

1 or 2 | XL | CM1 | A | A1 |

3 or 4 | YR | CM5 | A | B1 |

1 or 2 | XL | CM2 | A | A2 |

3 or 4 | YR | CM6 | A | B2 |

1 or 2 | XL | CM3 | A | A3 |

3 or 4 | YR | CM7 | A | B3 |

1 or 2 | XL | CM4 | A | A4 |

3 or 4 | YR | CM8 | A | B4 |

5 or 6 | XL | CM9 | B | A1 |

7 or 8 | YR | CM13 | B | B1 |

5 or 6 | XL | CM10 | B | A2 |

7 or 8 | YR | CM14 | B | B2 |

5 or 6 | XL | CM11 | B | A3 |

7 or 8 | YR | CM15 | B | B3 |

5 or 6 | XL | CM12 | B | A4 |

7 or 8 | YR | CM16 | B | B4 |

For multi-beam receivers, typically each beam is routed through either rack A or B, but not both. Beams usually work in pairs which can be switched between if doing beam switching. One member of the pair goes through converter rack A (selected by A/B switch in A position), the other through rack B (selected by A/B switch in B position). Since the Spectral Processor can connect to either rack A or B, but not both, it cannot record both beams of a pair simultaneously.

There are two BCPMs, designated BCPM1 and BCPM2. Each can accept an input signal with a bandwidth of 192 MHz. With one BCPM, one spectral window can be observed. With two BCPMs, two spectral windows can be observed. The "normal" situation will be that spectral window #1 goes to BCPM1 and spectral window #2 goes to BCPM2. But at the moment, only BCPM1 is working, so only one spectral window is possible.

A complication is that BCPM2 will have the ability to collect cross-polarization data and BCPM1 does not. Some observers will want to use only BCPM2.

The first six YGOR parameters in the table are really the only configuration parameters, specified by user keywords. The remaining ones may change from one observation to the next. The table gives reasonable values to use for the initial setup.

Table A.11.1. BCPM Parameters | |
---|---|

YGOR Parameters | Keyword(s) |

submanagers_used | Nwin |

setif | Receiver |

center_frequency | Restfreq, Deltafreq |

channel_bandwidth | (user selected) |

sample_time | (user selected) |

sum_polarizations | (user selected) |

cal_used_flag | (initialize to 'no') |

operating_mode | (initially set to 'monitor') |

data_storage | (initially set to 'disk' |

file_size | (initialize to 60) |

base_name | (source name) |

target_name | (source name) |

** submanagers_used **

** setif **

** center_frequency **

This is an array of two frequencies, the first for BCPM1, the second for BCPM2. These are the two sky frequencies, Flocal[i], at described in Section 6.0.

Table A.11.2. BCPM Inputs | ||
---|---|---|

Polarization | Converter Module | BCPM: Input |

XL | 3 | BCPM2 : A1 |

YR | 7 | BCPM2 : A2 |

XL | 4 | BCPM1 : A1 |

YR | 8 | BCPM1 : A2 |

XL | 11 | BCPM2 : B1 |

YR | 15 | BCPM2 : B2 |

XL | 12 | BCPM1 : B1 |

YR | 16 | BCPM1 : B2 |

** Prime Focus **