A.2. SwitchingSignalSelector

disableLOBlanking

disableLocalBlanking

A.3. LO1

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

Receiver

restFrequency

ifCenterFreq

switchDeltas

restFrame

velocityDefinition

tolerance

phaseCalCtl and phaseCalMode

A.4. IFRack

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

receiver

analog_power_level

filter_select

S9 ... S12 (transfer switches)

A.5. ConverterRack

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

CMInput

ABselect

CMOutput

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

Gfrequency

A.6. ActiveSurface

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.

correctionSelect

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

A.7. AnalogFilterRack

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

"Sampler Filter" (wideband) Connections

"Converter Filter" Connections

A.8. DCR

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

Switching phase table information will be sent from the scan coordinator, so there is no need to set explicitly 'switching_signals_master', 'switch_period', 'number_phases', 'phase_start', 'cal_state', 'sig_ref_state', or 'blanking'.

Bank and Channel

CyclesPerIntegration

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:

A.9. Spectrometer

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

As is the case for all backends, the switching phase tables parameters are not directly set by the configurator, but by the Scan Coordinator.

configuration

relative_bandwidth

slow_samplers

fast_samplers

number_slow_samplers

switching_signals_select

slow_samplers_level

requested_integration_time

polarization

How to choose the configuration

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)

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

Note: the sampler assignment column shows which samplers are assigned to which banks, for example, '01' means samplers 0 and 1 are assigned to bank A; '01_23' means samplers 0 and 1 are assigned to bank A and samplers 2 and 3 are assigned to bank B.

A.10. SpectralProcessor

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

Note that NIF = Nwin x #beams
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.

SpectralProcessor connections

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 the single-beam receivers (Rcvr8_10 and lower frequencies), signals are routed to both converter racks. If there is a bad module in converter rack A (CM1-8), then an alternate route is to use rack B.

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.

A.11. BCPM

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.

BCPM Connections

Receivers

Prime Focus