SRS FS725 Owner's manual

FS725 Rubidium Frequency Standard

Operation and Service Manual

1290-D Reamwood Avenue

Sunnyvale, California 94089

Phone: (408) 744-9040 • Fax: (408) 744-9049

email: [email protected] • www.thinkSRS.com

Version 1.3 (12/21/2015)

FS725 Rubidium Frequency Standard

Table of Contents 1

FS725 Rubidium Frequency Standard

Table of Contents

Specifications 3

Q2GK2GP R

D:-1G'=*1)5 ;

()*:'=*1)5 ;

S)1):*5 T

Overview 6

Operation 8

=-,): <

U*:+%2K <

7-11)JG8-1 <

3(3'81PG:2+)1GP #

D:)V2)1J4'7-1G:-5 !$

!'KKP'81K2G !!

Monitor and Control 14

3)GG81L'2K'(3"R" !;

S)GG81L'7-11)JG). !;

W)PG81L'J-11)JG8-1 !T

W):+81*5'K:-L:*+ !T

(2N8.82+'3G*GP !X

D*JG-:4'3)GG81LP'G*N !B

/1*5-L'Y*52)P'G*N !<

!'KKP'J-1G:-5'G*N !<

7-5-:).'N-E)P !<

D85)'Z)12 !#

[)5K'Z)12 !#

W):+81*5'K:-L:*+ !#

Calibration 20

U8G>'*'9:)V2)1J4'J-21G): "$

U8G>'*'!'KKP':)9):)1J) ""

W8+)%G*L'-99P)G'K*:*+)G): ";

Circuit description

=(3!$'J-11)JG-: "T

!'KKP'81K2G "T

\-JH'*1.'!'KKP'-2GK2G "X

(3%"R"'81G):9*J) "X

D:-1G'K*1)5'\]&P "X

=-,):'P2KK58)P "B

!$'Z[^'-2GK2G "B

T'Z[^'-2GK2G "<

38L1*5P'G-'-KG8-1'J*:.P "<

QKG8-1'J*:.P "<

Component parts list

D3B"T'+*81'N-*:. R$

D3B"T'-KG8-1'N-*:. R!

D3B"T'>*:.,*:) R"

Circuit Schematics 35

Z*81'N-*:.'@!_"A RX

Z*81'N-*:.'@"_"A RB

QKG8-1'N-*:.' R<

Addendum: PRS10 Manual

2 Table of Contents

FS725 Rubidium Frequency Standard

Specifications 3

FS725 Rubidium Frequency Standard

Specifications

Standard outputs W,-'!$'Z[^'P81)',*0)P6'-1)'T'Z[^'P81)',*0)6'-1)'!'KKP

,8G>'!$'`P',8.G>

Optional outputs aK'G-'R'.8PG:8N2G8-1'+-.25)P6')*J>',8G>'9-2:'!$'Z[^6'-1)'T

Z[^6'*1.'-1)'!'KKP

1 pps output "IT'Y'81G-'T$'b'6'T'Y'81G-'>8L>'8+K).*1J)6'!$'`P'K25P)',8.G>

Sine outputs $IT'Y:+P6'c!$d'@!I;!'YKK'-:'eB'.f+A

Phase noise g%!R$'.fJ_[^'F'!$'[^

(5 MHz & 10 MHz) g%!;$'.fJ_[^'F'!$$'[^

g%!T$'.fJ_[^'F'!'H[^

g%!TT'.fJ_[^'F'!$'H[^

Spurious g%!$$'.fJ'@,8G>81'!$$'H[^A

Harmonics g%X$'.fJ

Return loss h"T'.f'F'!$'Z[^

Accuracy cT'× !$%!!'

Aging gT'× !$%!!'@+-1G>546'*9G):'!PG'+-1G>A

gT'× !$%!$'@4)*:546'*9G):'98:PG'4)*:A

Allan variance g"'× !$%!!'@!'PA

g!'× !$%!!'@!$'PA

g"'× !$%!"'@!$$'PA

Holdover B"'>-2:'3G:*G2+'!'@!×!$%!!A

Frequency retrace cT'i!$%!!'@B"'>:P'-99'G>)1'B"'>:P'-1A

Settability gT'× !$%!"

Trim range c"'× !$%#'@K-G'-:'N4'$%T'Y&7'81K2GA

c$IT'KK+'@08*'(3%"R"A

Warm-up time gX'+812G)P'@G8+)'G-'5-JHA

gB'+812G)P'@G8+)'G-'!'i'!$%#A

4 Specifications

FS725 Rubidium Frequency Standard

Front Panel Indicators

Power jQ1k',>)1'/7'K-,):'8P'*KK58).

Locked jQ1k',>)1'9:)V2)1J4'8P'5-JH).'G-':2N8.82+'>4K):981)'G:*1P8G8-1

1 PPS input f581HP',8G>')*J>'!'KKP':)9):)1J)'81K2G'*KK58).'G-':)*:'K*1)5

1 PPS sync jQ1k',>)1'!'KKP'-2GK2G'8P'P41J>:-18^).'G-',8G>81'c!`P'-9'!'KKP'81K2G

Receive f581HP'j-1k',>)1'(3%"R"'J>*:*JG):P'*:)':)J)80).'N4'D3B"T

Send f581HP'j-1k',>)1'(3%"R"'J>*:*JG):P'*:)'P)1G'N4'D3B"T

Rear Panel Connections

FREQ ADJ $%T'Y&7'G-'*.l2PG'9:)V2)1J4'N4'e_%'$I$$"'KK+'@1-:+*554

21J-11)JG).A

1 PPS Input Q1) !$$'Hb'81K2GI'()V28:)P'7ZQ3'5)0)5'K25P)P'@$%T'Y&7IA O9'*1

)EG):1*5'!'KKP'81K2G'8P'*KK58).6'5-JH'8P'+*81G*81).'N)G,))1'G>)'!'KKP

81K2G'*1.'!'KKP'-2GK2G',8G>'J-+K2G):'*.l2PG*N5)'1*G2:*5'G8+)'J-1PG*1G

9:-+'<'+812G)P'G-'!<'>-2:PI'@&)9*25G'8P'"I"T'>-2:PIA

10 MHz Out W,-'8P-5*G).'T$'b'!$'Z[^'P81)'-2GK2GP

5 MHz Out Q1)'T$'b'T'Z[^'P81)'-2GK2G

1 PPS Out Q1)'T$'b'K25P)'-2GK2GI

Optional ]*J>'-KG8-1'N-*:.'K:-08.)P'9-2:'!$'Z[^6'-1)'T'Z[^'*1.'-1)'!'KKP

-2GK2GPI'aK'G-'R'N-*:.P'+*4'N)'81PG*55).'*G'G>)'G8+)'-9'-:.):I

Relays Z*E'J2::)1G6'R/I'3=&W6'1-:+*554%-K)1'-:'1-:+*554%J5-P).I'Z*4'N)

,8:).'81'K*:*55)5',8G>'-G>):':)5*4P'G-'j,8:)%-:k'*'P81L5)'*5*:+I

Rb Lock ()5*4'PG*G2P'+*GJ>)P'9:-1G'K*1)5'j\-JH).k'\]&I

1 PPS ()5*4'PG*G2P'+*GJ>)P'9:-1G'K*1)5'j!'KKP'P41Jk'\]&

RS-232 #'K81'J-11)JG-:'J-198L2:).'*P'&7]6'#X$$'N*2.I'/'U81.-,Pm'7-1G:-5

K:-L:*+'8P'K:-08.).I

Specifications 5

FS725 Rubidium Frequency Standard

Environmental

Operating temperature e!$'n7'G-'e;$'n7

Storage temperature %TT'n7'G-'e<T'n7

Temperature stability o9_9'gc!'× !$%!$'''@e!$'n7'G-'e;$'n7A

Magnetic field' o9_9'g'c"'× !$%!$'9-:'!'S*2PP'98)5.':)0):P*5

Relative humidity #Td'@1-1%J-1.)1P81LA

General

AC Power #$'G-'!R"'Y/7'-:'!BT'G-'"X;'Y/76';B'G-'XR'[^6'T$'Y/

Dimensions <ITk'E'RITk'E'!Rk'@U[\A

Weight #'5NP

Warranty Q1)'4)*:'K*:GP'*1.'5*N-:'-1'+*G):8*5P'*1.',-:H+*1P>8K

6 Overview

FS725 Rubidium Frequency Standard

Overview

W>)'D3B"T'8P'*'PG*1.%*5-1)'!$'Z[^'9:)V2)1J4'PG*1.*:.',8G>'*1')PG8+*G).'"$%4)*:'*L81L'-9

5)PP'G>*1'$I$$T'KK+I'W>)'218G'81G)L:*G)P'*1'3(3'=(3!$'(2N8.82+'D:)V2)1J4'3G*1.*:.6'*

2180):P*5'/7'81K2G'K-,):'P2KK546'*1.'.8PG:8N2G8-1'*+K5898):P'81'*'>*59%,8.G>'"a'J>*PP8P'@RITk

>)8L>GAI'W>)'218GpP'5-,'*L81L')58+81*G)P'G>)'1)).'9-:'*1')EG):1*5'9:)V2)1J4':)9):)1J)'81'+*14

*KK58J*G8-1Pq'>-,)0):'218GP'J*1'K>*P)%5-JH'G-'*1')EG):1*5'!'KKP'S=3'P8L1*5'9-:'*L)5)PP

K):9-:+*1J)'-:'K):8-.8J'J*58N:*G8-1'*P':)V28:).I

W>)'D3B"T'K:-08.)P')EJ)KG8-1*554'5-,'K>*P)'1-8P)'T'Z[^'r'!$'Z[^'P81)'-2GK2GP'*P',)55'*P

*'5-,%l8GG):'!'KKP'-2GK2GI'W>)'!$'Z[^'-2GK2GP'>*0)'*'K>*P)'1-8P)'-9'g%!R$'.fJ_[^'*G'!$[^

-99P)G'9:-+'J*::8):6'.:-KK81L'G-'gs!TT'.fJ_[^'*G'!$'H[^'-99P)GI'W>)'/55*1'Y*:8*1J)'8P'5)PP

G>*1'"E!$%!!'*G'-1)'P)J-1.'*1.'"'× !$%!"'*G'!$$'P)J-1.PI'W>)'!'==3'WW\'-2GK2G'>*P'5)PP'G>*1

!1P'-9'l8GG):'*1.'+*4'N)'P)G',8G>'!1P':)P-52G8-1I

W>)'PG*1.*:.'D3B"T'>*P'G,-'!$'Z[^'-2GK2GP6'-1)'T'Z[^'-2GK2G6'*1.'-1)'!'==3'-2GK2GI'aK

G-'G>:))'.8PG:8N2G8-1'+-.25)P'J*1'N)'*..).'G-'G>)'218GI']*J>'+-.25)'K:-08.)P'P8E'*..8G8-1*5

-2GK2GP?'9-2:'!$'Z[^'-2GK2GP6'-1)'T'Z[^'-2GK2G6'*1.'-1)'!'==3'-2GK2GI'U8G>'G>:))'+-.25)P

81PG*55).'G>)'D3B"T',855'K:-08.)'9-2:G))1'!$'Z[^'-2GK2GP6'9-2:'T'Z[^'-2GK2GP6'*1.'9-2:'!

==3'-2GK2GP6')*J>',8G>'G>)'P*+)'5-,'K>*P)'1-8P)6'>*:+-18J'.8PG-:G8-1'*1.'l8GG):I

/1'(3%"R"'81G):9*J)'*55-,P'9-:'.8:)JG'J-++218J*G8-1',8G>'G>)'=(3!$'(2N8.82+'9:)V2)1J4

PG*1.*:.I'W>8P'81G):9*J)'8P'2P).'9-:'9:)V2)1J4'J*58N:*G8-16'!'==3'G8+81L6'PG*G2P'.)G):+81*G8-16

*1.'G-'*PP8PG'81'G>)')0*52*G8-1'-9'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:.'*P'*'J-+K-1)1G'9-:

Q]Z'*KK58J*G8-1PI'/'U81.-,P'*KK58J*G8-1'K:-L:*+'8P'K:-08.).I

D3B"T',855'G8+)%G*L'G>)':8P81L').L)'-9'*'2P):'P2KK58).'!'KKP'81K2G6',>8J>'2P2*554'J-+)P'9:-+

*'S=3':)J)80):I'W>)'218G'J*1'K>*P)%5-JH'G-'G>8P'81K2G'G-'J*1J)5'5-1L%G):+'*L81LI''W>)'G8+)%G*L

:)P25GP'+*4'N)':)*.'N*JH'08*'G>)'(3%"R"'81G):9*J)I'W8+81L'8P':)9):)1J).'G-'G>)'5)*.81L').L)

-9'G>)'!'KKP'-2GK2G'K25P)I'W>)'!'KKP'-2GK2G'K25P)',855'N)'+-0).'81G-'J-81J8.)1J)',8G>'G>)

2P):'P2KK58).'!'KKP'81K2G'*9G):'"TX'81K2G'K25P)PI'W>):)*9G):6'G>)'=(3!$',855'*.l2PG'8GP

9:)V2)1J4'G-'+*81G*81'G>)'K>*P)'5-JH'N)G,))1'G>)'!'KKP'81K2G'*1.'G>)'!'KKP'-2GK2GI'W>)'K>*P)

5-JH'*5L-:8G>+'2P)P'*1'*.l2PG*N5)'1*G2:*5'G8+)'J-1PG*1G'@9:-+'*'<'+812G)P'G-'!<'>-2:PA',>8J>

+*4'N)'*.l2PG).'08*'G>)'(3%"R"I

W,-'*5*:+':)5*4P'*:)'K:-08.).'G-'P8L1*5'G>)'PG*G2P'-9'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:.

*1.'8GP'P41J>:-18^*G8-1'G-'*1')EG):1*5'!'KKP'81K2GI'f-G>':)5*4P'*:)'3=&W'K:-08.81L'N-G>

1-:+*554%-K)1'*1.'1-:+*554%J5-P).'-K):*G8-1I'3)0):*5'G>-2P*1.'=(3!$P'>*0)'N))1'-K):*G81L

81'0*:8-2P'Q]Z'*KK58J*G8-1P',8G>'*'.)+-1PG:*G).'ZWfD'P)0):*5'>21.:).'G>-2P*1.'>-2:P'*1.

P-'*'+*5921JG8-1'-9'G>)'=(3!$'8P'0):4'2158H)54I'O1'G>)')0)1G'-9'*'9*852:)'G>)'*5*:+':)5*4',855

*JG80*G)'N2G'G>)'!$'Z[^'-2GK2G',855'N)'K:-08.).'N4'G>)'218GpP'-0)18^).'37%J2G'!$'Z[^

J:4PG*5'-PJ855*G-:',8G>'G4K8J*5'*L81L'-9'$I$T'KK+_4)*:I

W>)'D3B"T',855'981.'*KK58J*G8-1'*P'*1'*2G-1-+-2P'9:)V2)1J4'PG*1.*:.'81'08:G2*554'*14

J*58N:*G8-1'*1.'(r&'5*N-:*G-:8)P',>):)'K:)J8P8-1'G8+)'-:'9:)V2)1J4'+)*P2:)+)1GP'*:)'+*.)6

-:'81'*14'-G>):'9*J858G4':)V28:81L'*1'*JJ2:*G)'9:)V2)1J4'PG*1.*:.I'W>)'5-,'J-PG'-9'G>)'218G6

Overview 7

FS725 Rubidium Frequency Standard

G-L)G>):',8G>'8GP')EG:)+)54'5-,'*L81L6',855'*55-,'J2PG-+):P'G-'.)K5-4'K:)J8P8-1'9:)V2)1J4

:)9):)1J)P'G>:-2L>-2G'*'9*J858G4',8G>-2G'G>)'1)).'G-'81PG*55'J*N5)P'-:'*1G)11*PI

8 Operation

FS725 Rubidium Frequency Standard

Operational Description

Power

W>)'218G'8P'K-,):).'9:-+'G>)'/7'+*81PI'W>)'2180):P*5'81K2G'K-,):'P2KK54'*JJ-++-.*G)P

*14'0-5G*L)'81'G>)':*1L)P'#$'G-'!R"Y/7'-:'!BT'G-'"X;Y/7',8G>'*'9:)V2)1J4'81'G>)':*1L)'-9

;B'G-'XR[^I'W>):)'8P'1-'K-,):'P,8GJ>'*P'G>)'218G'P>-25.'N)'5)9G'j-1k'*55'G>)'G8+)I'W>)

:2N8.82+'9:)V2)1J4'PG*1.*:.'8P'-K):*G81L'*1.'-2GK2GP'*:)'*0*85*N5)',>)1)0):'/7'K-,):'8P

*KK58).I

Warm-up

W>)'9:-1G'K*1)5'j=QU](k'\]&'P>-25.'N)'-1',>)1)0):'K-,):'8P'*KK58).'G-'G>)'218GI'W>)

9:-1G'K*1)5'j\Q7t]&k'\]&'P>-25.'J-+)'-1',8G>81'P8E'+812G)P'*9G):'K-,):'8P'*KK58).'89'G>)

218G'8P'PG*:G).'9:-+':--+'G)+K):*G2:)I'U*:+%2K'*1.'5-JH81L',855'G*H)'5-1L):'89'G>)'218G'8P

PG*:G).'9:-+'*'5-,):'G)+K):*G2:)I'QK):*G8-1'-9'G>)'j\Q7t]&k'\]&'J-::)PK-1.P'G-'G>)'PG*G)

-9'G>)':)*:'K*1)5'j(f'\Q7tk'*5*:+':)5*4I'U>)1'K-,):'8P'98:PG'*KK58).6'G>)'j\Q7t]&k'\]&

,855'N)'-99'*1.'G>)'j(f'\Q7t]&k':)5*4',855'N)'81'G>)'j*5*:+k'K-P8G8-1I'Q1J)'G>)'218G

,*:+P'2K'*1.'5-JHP'8GP'J:4PG*5'-PJ855*G-:'G-'G>)':2N8.82+'K>4P8JP'K*JH*L)6'G>)'j\Q7t]&k

\]&',855'G2:1'-1'*1.'G>)'j(f'\Q7tk':)5*4',855'+-0)'G-'G>)'1-1%*5*:+'PG*G)I

W>)'-2GK2G'9:)V2)1J4',855'N)'*N-2G'"$$'KK+'N)5-,'1-+81*5',>)1'K-,):'8P'98:PG'*KK58).'G-'*

J-5.'218GI'W>)'9:)V2)1J4',855'L:*.2*554'J-10):L)'-1'!$'Z[^'*P'G>)'218G',*:+P'2KI'/9G):

*N-2G';'+812G)P'@G4K8J*554A'G>)'218G',855':)*J>'-K):*G81L'G)+K):*G2:)'*1.'5-JH'G>)'J:4PG*5

-PJ855*G-:'G-'G>)':2N8.82+'>4K):981)'G:*1P8G8-1I'U8G>81'P)0)1'+812G)P6'G>)'218G',855'N)'5-JH).

G-',8G>'$I$$!KK+'-9'!$'Z[^I

Connection to other instruments

/55'-9'G>)'-2GK2GP'-1'G>)':)*:'-9'G>)'D3B"T'>*0)'*'P-2:J)'8+K).*1J)'-9'T$'b'*1.'*:)'81G)1.).

G-'.:80)'T$'b'5-*.PI'381J)'G>)'-2GK2GP'>*0)'*'P-2:J)'8+K).*1J)'-9'T$'b6'G):+81*G8-1'81G-'*

T$'b'5-*.'8P'1-G'J:8G8J*5'81'+-PG'*KK58J*G8-1PI'S)1):*5546'G>)'*+K58G2.)',855'*KK:-E8+*G)54

.-2N5)'89'G>)'-2GK2G'8P'1-G'G):+81*G).'81G-'*'T$'b'5-*.I'=:-K):54'G):+81*G81L'81G-'*'T$'b'5-*.

,855':).2J)'J>*11)5%G-%J>*11)5'J:-PP%G*5H'*1.',855':).2J)'G>)'K:-N*N54'-9'+25G8K5)'G:8LL):81L

-1'G>)'!'KKP'-2GK2GI

O9'*'P81L5)'T'Z[^'-:'!$'Z[^'-2GK2G'8P'j.*8P4%J>*81).k'G-'P)0):*5'81PG:2+)1GP'8G',855'N)

8+K-:G*1G'G>*G'*55'-9'G>)'81PG:2+)1GP'>*0)'*'>8L>%8+K).*1J)'81K2G'@h!'HbA'*1.'G>*G'*'T$'b

G):+81*G-:'N)'K5*J).'*G'G>)'9*:')1.'-9'G>)'581)I'S)1):*5546'8G'8P'N)GG):'K:*JG8J)'G-'2P)'*'P)K*:*G)

-2GK2G'G-')*J>'81PG:2+)1G'G-'*0-8.'J:-PP%G*5H'*1.'*+K58G2.)'0*:8*G8-1P'.2)'G-'21J):G*81

5-*.81L'*1.'PG*1.81L',*0)P'*5-1L'G>)'581)I

Z*14'81PG:2+)1GP',>8J>'L)1):*G)'-:'+)*P2:)'K:)J8P)'9:)V2)1J8)P'-:'G8+)%81G):0*5P'>*0)'*'!$

Z[^'81K2G6'2P2*554'5-J*G).'-1'G>)':)*:'-9'G>)'81PG:2+)1GI'Z-PG'-9'G>)P)'81PG:2+)1GP'*JJ)KG'*

P81)'81K2G',8G>'G>)'*+K58G2.)'K:-08.).'N4'G>)'D3B"TI'3-+)G8+)P'*':)*:'K*1)5'P,8GJ>'-:'9:-1G

K*1)5'J-198L2:*G8-1'+)12'8P':)V28:).'G-'jG)55k'G>)'81PG:2+)1G'G-'2P)'G>)'!$'Z[^'81K2G'*P'*

Operation 9

FS725 Rubidium Frequency Standard

:)9):)1J)'81PG)*.'-9'2P81L'G>)'81PG:2+)1GpP'-,1'G8+)'N*P)I'O+K:-0).'*JJ2:*J4'J*1'N)

*J>8)0).'N4'2P81L'G>)'D3B"T'*P'*1')EG):1*5'G8+)'N*P)'G-'*55'-9'G>)'81PG:2+)1GP'81'*'K*:G8J25*:

5*N-:*G-:4I'O1'*..8G8-16'*55')::-:P'*PP-J8*G).',8G>'G>)'J*58N:*G8-1'-9'*1'81.808.2*5'81PG:2+)1GpP

G8+)'N*P)'*:)')58+81*G).I

Connection to SRS Instruments

SR620 Time Interval Counter. W>8P'81PG:2+)1G'8P'jG-5.k'G-'2P)'G>)')EG):1*5'!$'Z[^'81K2G

08*'G>)'9:-1G'K*1)5'7QuDOS'+)12I'W-'J-198L2:)'G>)'3(X"$'G-'2P)'*1')EG):1*5'G8+)'N*P)

K:)PP'G>)'3]\'H)4'81'G>)'7QuDOS'P)JG8-1'-1J)'G-'.8PK5*4'7QuDOS'+)12P6'G>)1'K:)PP'3]\

-1)'+-:)'G8+)'G-'P)5)JG'G>)'jJ/\k'+)126',>8J>',855'95*P>',>)1'P)5)JG).I'=:)PP'G>)'3]W'H)4

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G>)'7QuDOS'+)12'@81'G>)'37Q=]'/u&'7[/(W'P)JG8-1A'G-'P)5)JG'j:]/:k6',>8J>'8P'G>)':)*:

K*1)5'G8+)'N*P)'81K2GI'=:)PP'G>)'3]W'H)4'81'G>)'7QuDOS'P)JG8-1'-1J)'+-:)'G-'0):894'G>)

)EK)JG).'G8+)'N*P)'9:)V2)1J4'@T'Z[^'-:'!$'Z[^AI'=:)PP'G>)'*::-,'H)4P'G-'P)5)JG'G>)

9:)V2)1J4'-9'G>)'G8+)'N*P)',>8J>'4-2',855'N)'2P81LI

DS345 Synthesized Function Generator.

W>)'&3R;T'*2G-+*G8J*554'.)G)JGP'G>)'*KK58J*G8-1'-9'*1')EG):1*5'G8+)'N*P)'*1.'K>*P)'5-JHP'G-

8GI'/9G):'*KK5481L'*'T'Z[^'-:'!$'Z[^'P81)'G-'G>)':)*:'K*1)5'G8+)'N*P)'81K2G6'*'9:-1G'K*1)5

81.8J*G-:',855'G2:1'j-1kI

DG535 Digital Delay Generator

/':)*:'K*1)5'P,8GJ>'8P'2P).'G-'PK)J894'*1')EG):1*5'!$'Z[^'G8+)'N*P)'81K2GI'3-+)':)08P8-1P'-9

G>)'&STRT':)V28:).'*'!$'Z[^'PV2*:)',*0)'81K2G6'*1.'+*4'1-G'-K):*G)'K:-K):54',8G>'G>)'!$

Z[^'P81)',*0)'-2GK2G'9:-+'G>)'D3B"TI'W>)'2P):'P>-25.'0):894'K:-K):'-K):*G8-1'-9'G>)

&STRT',>)1'5-JH).'G-'*1')EG):1*5'G8+)'N*P)',8G>'*1'3(X"$'W8+)'O1G):0*5'7-21G):I

10 Operation

FS725 Rubidium Frequency Standard

Direct Frequency Control of the FS725

W>)'9:)V2)1J4'-9'G>)':2N8.82+'>4K):981)'G:*1P8G8-1'8P'*.l2PG).'08*'*'P+*55'+*L1)G8J'98)5.'81

G>)'K>4P8JP'K*JH*L)I'W>)'+*L18G2.)'-9'G>)'+*L1)G8J'98)5.'8P'P)G'N4'G>)'+8J:-J-1G:-55):'81'G>)

=(3!$I'W>)'9:)V2)1J4'-99P)G'8P'V2*.:*G8J'81'G>)'+*L1)G8J'98)5.'N2G'98:+,*:)'81'G>)'=(3!$

581)*:8^)P'G>)'*.l2PG+)1GI'W>)'+8J:-J-1G:-55):':)*.P'G>)'K-P8G8-1'-9'*'J*58N:*G8-1

K-G)1G8-+)G):'@*JJ)PP8N5)'-1'G>)'P8.)'K*1)5'-9'G>)'81PG:2+)1GA6'-:':)PK-1.P'G-'P-9G,*:)

J-++*1.P'08*'G>)'(3%"R"6'G-'P)G'G>)'+*L1)G8J'98)5.',>8J>'J-1G:-5P'G>)'-K):*G81L'9:)V2)1J4I

W>)'-K):*G81L'9:)V2)1J4'+*4'N)'.8:)JG54'J-1G:-55).'-0):'G>)':*1L)'-9'c$I$$"KK+'81'9-2:

,*4P?

!I f4'G>)'*.l2PG+)1G'-9'*'!T'G2:1'K-G)1G8-+)G):'*JJ)PP8N5)'-1'G>)'P8.)'-9'G>)'81PG:2+)1GI

W2:181L'G>)'K-G)1G8-+)G):'J5-JH,8P)',855'81J:)*P)'G>)'9:)V2)1J4'N4'*N-2G'$I$$"T[^'K):

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G-'P)G'G>)'9:)V2)1J4',8G>'*':)P-52G8-1'-9'!?!$%!"I'W>)'K*:*+)G):'>*P'*':*1L)'-9'c"$$$

,>8J>'*55-,P'9:)V2)1J4'J-1G:-5'-0):'G>)':*1L)'-9'c$I$$"'KK+I'W>)'K-P8G8-1'-9'G>)

9:)V2)1J4'*.l2PG+)1G'K-G)1G8-+)G):'8P'2P).'G-'P)G'G>)'3D'K*:*+)G):'21G85'*'3D'J-++*1.

8P':)J)80).'08*'G>)'(3%"R"'-:'21G85'K>*P)'5-JH81L'G-'*1')EG):1*5'P-2:J)'8P'*JG80*G).'N4'G>)

*KK58J*G8-1'-9'!'KKP'81K2GP'G-'G>)':)*:'K*1)5'fu7I'7-1G:-5'8P':)G2:1).'G-'G>)'K-G)1G8-+)G):

,>)1'G>)'K-,):'8P'J4J5).I'&)G*85P'*:)'*0*85*N5)'81'G>)'=(3!$'-K):*G8-1'*1.'P):08J)

+*12*5I

;I f4'P-9G,*:)'J*58N:*G8-1'08*'G>)'ZQ'@Z*L1)G8J'Q99P)GA'K*:*+)G):I'W>)'ZQ'K*:*+)G):'8P

P2++).'81'V2*.:*G2:)',8G>'G>)'3D'K*:*+)G):'G-'J-1G:-5'G>)'9:)V2)1J4'-9'-K):*G8-1I'/G'G>)

9*JG-:46'G>)'ZQ'K*:*+)G):'8P'J*58N:*G).'P-'G>*G'G>)'218G',855'-K):*G)'*G'!$'Z[^',8G>'*1

3D'0*52)'-9'$I'W>)'3D'K*:*+)G):'8P'P)G'N4')8G>):'G>)'K-G)1G8-+)G):'-:'08*'(3%"R"

J-++*1.P6'*1.',855'N)'^):-',>)1'G>)'K-G)1G8-+)G):'8P'J)1G):).I'W>)'ZQ'K*:*+)G):'+*4

N)'*.l2PG).'*1.':)G*81).'81'G>)'=(3!$']]=(QZ6'*55-,81L'9:)V2)1J4'J*58N:*G8-1'08*'G>)

(3%"R"I'&)G*85P'*:)'*0*85*N5)'81'G>)'=(3!$'-K):*G8-1'*1.'P):08J)'+*12*5I

Operation 11

FS725 Rubidium Frequency Standard

Using an External 1 pps Reference.

W>)'D3B"T'>*P'P2998J8)1G'*JJ2:*J4'@$I$$T'KK+')PG8+*G).'-0):'"$'4)*:PA'G>*G'+-PG'2P):P',855

1-G'1)).'G-'2P)'*1')EG):1*5'G8+81L':)9):)1J)I'[-,)0):6'9-:'J:8G8J*5'*KK58J*G8-1P':)V28:81L'*

9:)V2)1J4'*JJ2:*J4',>8J>'8P'N)GG):'G>*1'!i!$%#6'-:'G-'K:-08.)'J-1G812-2P'G:*J)*N58G46'G>)

D3B"T'+*4'N)'5-JH).'G-'*1')EG):1*5'!'KKP':)9):)1J)I

U>)1'*'K:)J8P)'!'KKP'P8L1*5'8P'*KK58).'G-'G>)'!'KKP'81K2G'-1'G>)':)*:'K*1)5'-9'G>)'D3B"T6'G>)

:2N8.82+'9:)V2)1J4'PG*1.*:.',855'K>*P)%5-JH'G-'G>)'P8L1*5I'W>)'!'KKP'P8L1*5'2P2*554'J-+)P

9:-+'*'S=3':)J)80):',>8J>'J*1'>*0)'*'5-1L%G):+'*JJ2:*J4'-9'*'9),'K*:GP'81'!$!"I'f)J*2P)'G>)

PG*N858G4'-9'G>)'!'KKP':)9):)1J)'81'G>)'P>-:G'G):+'J*1'N)'+2J>',-:P)'G>*1'G>*G'-9'G>)'=(3!$6

G>)'=(3!$'K>*P)%5-JHP'G-'G>)'!'KKP',8G>'*1'*.l2PG*N5)'G8+)'J-1PG*1G'-9'9:-+'<'+812G)P'G-'!<

>-2:P6',>8J>':).2J)P'G>)'1-8P)'-9'G>)':)9):)1J)'!'KKP'N4'*0):*L81LI

W>)':)*:%K*1)5'!'KKP'81K2G'G-'G>)'D3B"T'8P'*'>8L>'8+K).*1J)'81K2G'G>*G'8P'.8PJ:8+81*G).'N4'*

7ZQ3'3J>+8GG'G:8LL):6',8G>'*'G>:)P>-5.'-9'*N-2G'"ITY&7I'OG'8P'8+K-:G*1G'G-'K:-08.)'*'!'KKP

81K2G',8G>'7ZQ3'5)0)5P'@$%TY&7IA'W>)'!'KKP'81K2G'+*4'1-G',-:H':)58*N54',8G>'*'WW\'81K2G

-:'G>)'!'KKP'-2GK2G'9:-+'*1-G>):'81PG:2+)1G'@P2J>'*P'*1-G>):'D3B"TA'89'G>)'P8L1*5'8P

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G):+81*G).'81G-'T$'bIA

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1*1-P)J-1.':)P-52G8-1I'/'K:-K-:G8-1*5%81G)L:*5'K>*P)%5-JH'*5L-:8G>+'J-1G:-5P'G>)'9:)V2)1J4

-9'G>)':2N8.82+'9:)V2)1J4'PG*1.*:.'08*'G>)'K*:*+)G):'3D'@3)G'D:)V2)1J4AI'u-:+*5546'G>)'3D

K*:*+)G):'8P'P)G'N4'G>)'98:+,*:)':)*.81L'G>)'J*58N:*G8-1'K-G)1G8-+)G):I'[-,)0):6',>)1'*'!

KKP'P8L1*5'8P'P))16'G>)'K>*P)%5-JH'*5L-:8G>+'x>8l*JHPp'G>)'3D'K*:*+)G):'G-'K>*P)%5-JH'G>)

:2N8.82+'9:)V2)1J4'PG*1.*:.'G-'G>)'!'KKP'81K2GI

W>)'5-JH81L'*5L-:8G>+'-9'G>)'=(3!$'K:-J)).P'*P'9-55-,P?

•'W>)'!'KKP'=\\'8P')1*N5).',>)1'G>)'218G'8P'G2:1).%-1'-:':)PG*:G).'89'G>)'=\'K*:*+)G):'PG-:).

81'G>)'218GpP']]=(QZ'8P'j!kI'@W>8P'8P'G>)'.)9*25G'0*52)IA

•'W>)'=\\',855'N)L81'G-'J-1G:-5'G>)'9:)V2)1J4'-9'G>)':2N8.82+'9:)V2)1J4'PG*1.*:.',>)1'"TX

J-1P)J2G80)'jL--.k'!'KKP'81K2GP'@8I)I6'!'KKP'81K2GP',>8J>'*:)',8G>81'±"$;<'1P'-9'G>)'98:PG

G8+)%G*L':)P25G6'+-.25-'!'PA'*:)':)J)80).I

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J-81J8.)',8G>'G>)'5*PG'-9'G>)'"TX'G8+)%G*L'0*52)PI'W>)'9:-1G'K*1)5'j!'KKP'P41J>:-18^).k'\]&

,855'G2:1'-16'*P'G>)'!'KKP'81K2G'*1.'G>)'!'KKP'-2GK2G'*:)'1-,',8G>81'c!`P'-9')*J>'-G>):I

•'W>)'218G',855'5-JH'G>)'9:)V2)1J4'-9'G>)'=(3!$'G-'G>)'jL--.k'!'KKP'81K2G'K25P)PI'jf*.k'!

KKP'81K2GP'@!'KKP'81K2GP',8G>'G8+)%G*LP'L:)*G):'G>*1'!6$";'1P'9:-+'G>)'5*PG'jL--.k'!'KKP

81K2GA',855'N)':)l)JG).I'/'.8L8G*5'985G):'8P'2P).'G-'8+K5)+)1G'G>)'J5*PP8J*5'"1.'-:.):

12 Operation

FS725 Rubidium Frequency Standard

K:-K-:G8-1*5_81G)L:*5'K>*P)'5-JH'5--KI'W>)'-2GK2G'-9'G>)'.8L8G*5'985G):'J-1G:-5P'G>)'9:)V2)1J4'-9

-K):*G8-1'08*'G>)'3D'@P)G'9:)V2)1J4A'J-++*1.6',>8J>'8P'2K.*G).'-1J)'*'P)J-1.I

•'W>)'=\\',855'N)'*N-:G).'*1.':)PG*:G).'89'G>):)'*:)'"TX'J-1P)J2G80)'jN*.k'!'KKP'81K2GPI

@W>8P'J-25.'>*KK)1'89'G>)'!'KKP'81K2G'8P'+-0).'P2..)154'N4'+-:)'G>*1'!6$";'1PIA

W>)'G8+)'J-1PG*1G'-9'G>)'=\\'8P'P)G',8G>'G>)'=W'J-++*1.I'W>)'.)9*25G'0*52)'8P'<6'K:-08.81L'*

x1*G2:*5'G8+)'J-1PG*1Gp'-9'*N-2G'"I"T'>-2:PI'W>)'=W'0*52)'P>-25.'N)'P)G'G-'*'P+*55):'12+N):

89'G>)'!'KKP':)9):)1J)'8P'0):4'J5)*16'9-:')E*+K5)6'89'G>)'!'KKP':)9):)1J)'8P'K:-08.).'N4'*1-G>):

D3B"TI'aP81L'*'P+*55):'=W'0*52)',855':).2J)'G>)'K)*H%G-%K)*H'0*:8*G8-1P'@xP,8++81LpA

N)G,))1'G>)'!'KKP'81K2G'*1.'G>)'218GpP'!'KKP'-2GK2GI'U8G>'*'J5)*1':)9):)1J)'*1.'*'P>-:G'G8+)

J-1PG*1G6'G>)'!'KKP'-2GK2G'G4K8J*554'G:*JHP'G>)'!'KKP'81K2G',8G>81'*'c!1P',81.-,I

W>)'.)9*25G'G8+)%J-1PG*1G'-9'"I"T'>-2:P'8P'*KK:-K:8*G)'9-:'5-JH81L'G-'G>)'G4K8J*5'S=3':)J)80):I

[-,)0):6'89'G>):)'8P'*':*K8.'J>*1L)'81'G>)'*+N8)1G'G)+K):*G2:)',>8J>'J*2P)P'G>)'=(3!$'G-

J>*1L)'9:)V2)1J4'N4'!i!$%!!6'G>)'J>*1L)',855'1-G'N)'*KK:)J8*N54')99)JG).'N4'G>)'=\\'.2:81L

G>)'98:PG'>-2:6'*1.'-1)',-25.')EK)JG'G-'P))'*'.:89G'N)G,))1'G>)'!'KKP'81K2G'*1.'G>)'!'KKP

-2GK2G'-1'G>)'-:.):'-9'RX$$'i'!$%!!6'-:'RX'1PI

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.)K)1.81L'-1'G>)'818G8*5'9:)V2)1J4'-99P)G'N)G,))1'G>)'D3B"T'*1.'G>)'!'KKP':)9):)1J)I

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G>)'.)9*25G'=\\'G8+)'J-1PG*1G'-9'j=W<k'-:'"I"T'>-2:PI'U8G>'G>8P'G8+)%J-1PG*1G6'G>)'=\\

*5L-:8G>+'>*P'58GG5)')99)JG'-1'G>)'D3B"TpP'9:)V2)1J4'-9'-K):*G8-1'.2:81L'G>)'98:PG'>-2:'-9

K>*P)'5-JH81L6'*1.'G>)'!'KKP'-2GK2G',855'PG:*4'9:-+'G>)'!'KKP'81K2G'N4'*N-2G'RX$$'i'!$%#6'-:

RIX'`PI'W>8P'8P'5*:L):'G>*1'G>)'c!'`P'P41J>:-18^*G8-1',81.-,6'*1.'P-'G>)'218G',855'81.8J*G)

G>*G'8G'8P'1-G'P41J>:-18^).I'U8G>'G>)'.)9*25G'G8+)'J-1PG*1G6'G>)'218G',855'K255'8GP'!'KKP'-2GK2G'G-

,8G>81'G>)'c!'`P'P41J>:-18^*G8-1',81.-,',8G>81'*'9),'>-2:P6'*1.',855'G>):)*9G):'81.8J*G)'G>*G

8G'8P'K:-K):54'P41J>:-18^).I

Operation 13

FS725 Rubidium Frequency Standard

W>)'G*N5)'N)5-,'P>-,P'G>)'=\\'K*:*+)G):P'9-:'G>)'*55-,).'0*52)P'-9'G>)'=W'K*:*+)G):I'W>)

:8L>G%+-PG'J-52+16'ju*G2:*5'W8+)'7-1PG*1Gk6'8P'G>)'N)PG'+)*P2:)'-9'G>)'=\\':)PK-1P)

J>*:*JG):8PG8JPI'@W>)'0*52)P'P>-,1'*:)'9-:'G>)'.)9*25G'PG*N858G4'K*:*+)G):6'yz!IA

PT Parameter

Parameter

set by PT

command

Integrator Time-

Constant

(hours)

Integral Gain

(SF bits per

hour per ns

of time-tag)

Proportional

Gain

(SF bits per ns

of time-tag)

Natural Time-

Constant

Characterizes

PLL response

(hours)

0 0.07 -14.063 -3.95 0.14

1 0.14 -7.031 -2.80 0.20

2 0.28 -3.516 -1.98 0.28

3 0.57 -1.758 -1.40 0.40

4 1.14 -0.879 -0.99 0.56

5 2.28 -0.439 -0.70 0.80

6 4.55 -0.220 -0.49 1.12

7 9.10 -0.110 -0.35 1.59

8 18.20 -0.055 -0.25 2.25

9 36.41 -0.027 -0.17 3.18

10 72.82 -0.014 -0.12 4.50

11 145.64 -0.007 -0.09 6.36

12 291.27 -0.003 -0.06 8.99

13 582.54 -0.002 -0.04 12.72

14 1,165.08 -0.001 -0.03 17.99

D2:G>):'.)G*85P'-9'G>)'K>*P)%5-JH81L'*5L-:8G>+'*:)'K:-08.).'81'G>)'=(3!$'(2N8.82+

D:)V2)1J4'3G*1.*:.'+*12*5I

14 Monitoring and Control

FS725 Rubidium Frequency Standard

Monitoring and Control via the RS-232

/'U81.-,Pm'N*P).'K:-L:*+6'(NZ-16'8P'K:-08.).'-1'*'R{k'95-KK4'.8PJI'W>)'K:-L:*+'+*4

*5P-'N)'.-,15-*.).'9:-+'G>)'3(3',)N'P8G)'*G',,,IG>81H3(3IJ-+I''W>)'K:-L:*+'9*J858G*G)P

+-18G-:81L6'J-1G:-56'*1.'J*58N:*G8-1'-9'G>)'D3B"T'(2N8.82+'D:)V2)1J4'3G*1.*:.'08*'G>)

J-+K2G):pP'7QZ'K-:G'-0):'*'P):8*5'(3%"R"'81G):9*J)I

(21181L'G>)'O1PG*55'K:-L:*+',855'K5*J)'G>)'(NZ-1'8J-1'-1'G>)'&)PHG-K'*1.'81'G>)'3G*:G

=:-L:*+P'58PG'*1.'K5*J)'G>)'K:-L:*+'J-+K-1)1GP'81'G>)'9-5.):'j(NZ-1kI'W>)'@K:-08.).A

a181PG*55'2G858G4'P>-25.'N)'2P).'G-':)+-0)'G>)'K:-L:*+'*1.'8GP'8J-1P'9:-+'4-2:'J-+K2G):I

34PG)+':)V28:)+)1GP'81J52.)'|!T$Z[^'=)1G82+'-:'J-+K*:*N5)6'U81.-,Pm'#T'-:'5*G):6'*1.

*1'*0*85*N5)'7QZ'K-:GI

W>)'.)9*25G'7QZ'K-:G'8P'7QZ!I'O9'4-2:'J-+K2G):'2P)P'7QZ!'*P'*'+-2P)'K-:G6'4-2',855

1)).'G-'J>*1L)'G>)'7QZ'K-:G'G-'7QZ"I

W>)'D3B"T'2P)P'G>)'=(3!$':2N8.82+'9:)V2)1J4'PG*1.*:.6'*5P-'+*129*JG2:).'N4'3G*19-:.

()P)*:J>'34PG)+PI'/55'J-++*1.P'P)1G'G-'G>)'D3B"T'*:)'K*PP).'.8:)JG54'G-'G>)'=(3!$I'/55

J-++*1.P':)J)80).'9:-+'G>)'D3B"T'J-+)'.8:)JG54'9:-+'G>)'=(3!$I'u-'N299):81L'-:'985G):81L

-9'J-++*1.P'8P'K):9-:+).'N4'G>)'D3B"TI'W>)'=(3!$'-K):*G8-1'*1.'P):08J)'+*12*56',>8J>'8P

*1'*..)1.2+'G-'G>8P'.-J2+)1G6'P):0)P'*P'*'K:-L:*++81L':)9):)1J)'9-:'G>)'D3B"TI

Setting up Communications

W>)'=(3!$'9:)V2)1J4'PG*1.*:.'J*1'J-++218J*G)'-K):*G81L'*1.'J*58N:*G8-1'P)GG81LP6'P2J>'*P

5-JH'81.8J*G-:P6'P8L1*5'5)0)5P6'>)*G):'J-1G:-5'PG*G2P6'!'KKP'G8+)'G*LP6'PG*G2P'95*LP6'*1.

J*58N:*G8-1'K*:*+)G):PI'W>8P'K:-08.)P'G>)'P4PG)+Pp'81G)L:*G-:',8G>'G>)'*N858G4'G-'+-18G-:'*1.

J-1G:-5'G>)'-K):*G8-1'-9'G>)'=(3!$I

7-++218J*G81L',8G>'G>)'=(3!$'8P'1-G':)V28:).'81'+-PG'*KK58J*G8-1PI'W>)'=(3!$'J-+)P'9:-+

G>)'9*JG-:4'J*58N:*G).'G-'cTi!$%!!6'*1.'G>)'D3B"T'K:-08.)P'9:-1G'K*1)5'\]&P'G-'81.8J*G)

K-,):6'5-JH6'*1.'!'KKP'P41J>:-18^*G8-1I

}-2'+*4',*1G'G-'J-++218J*G)',8G>'G>)'=(3!$'G-'*JJ)PP'*.0*1J).'9)*G2:)P'-:'9-:')0*52*G8-1

-9'G>)'=(3!$'81'*1'Q]Z'*KK58J*G8-1I'D-:'81PG*1J)6',>)1'5-JH81L'G>)'=(3!$'G-'*1')EG):1*5'!

KKP':)9):)1J)'4-2'+*4',*1G'G-'-KG8+8^)'G>)'G8+)'J-1PG*1G'*1.'5-JH'+-.)'-9'G>)'.8L8G*5'=\\

G-'+*GJ>'G>)'PG*N858G4'J>*:*JG):8PG8JP'-9'4-2:':)9):)1J)I

Getting Connected

W>)'=(3!$'2P)P'G>)'(3%"R"'K:-G-J-5'9-:'J-++218J*G8-1I'Z-PG'J-+K2G):P'>*0)'-1)'-:'+-:)

J-++218J*G8-1P'K-:GP'9-:'G>8P'K2:K-P)I'W-')PG*N58P>'J-++218J*G8-1',8G>'G>)'=(3!$'4-2',855

1)).'*'PG*1.*:.6'PG:*8L>G%G>:-2L>'#%K81'(3%"R"'J*N5)'J-11)JG).'N)G,))1'4-2:'J-+K2G):pP

J-++218J*G8-1P'K-:G'*1.'G>)'&f#'J-11)JG-:'-1'G>)'N*JH'-9'G>)'D3B"TI

Q1J)'G>)'J*N5)'8P'81'K5*J)6'4-2'1)).'G-'G)55'G>)'P-9G,*:)',>8J>'7QZ'K-:G'4-2',855'N)'2P81L'G-

J-++218J*G)',8G>'G>)'D3B"TI'W>8P'8P'.-1)',8G>'G>)'K255'.-,1'58PG'N-E'5-J*G).'81'G>)'2KK):

Monitoring and Control 15

FS725 Rubidium Frequency Standard

:8L>G'K-:G8-1'-9'G>)'+*81',81.-,I'aP)'G>)'K255'.-,1'58PG'N-E'G-'P)5)JG'G>)'7QZ'K-:GI'D-:

+-PG'J-+K2G):P'G>8P',855'N)')8G>):'7QZ!'-:'7QZ"I'Z*H)'P2:)'G>*G'G>)'j7-11)JG).k'N-E'8P

J>)JH).I'W>8P',855'*JG80*G)'G>)'J-++218J*G8-1P'K-:GI

Testing the Connection

W)PG'G>)'J-11)JG8-1'N4'P)1.81L'*'J-++*1.'G-'G>)'=(3!$'G-'P))'G>*G'8G':)PK-1.P'K:-K):54I

W4K)'G>)'J-++*1.'O&~'*1.'K:)PP'g]uW](hI'W>)'=(3!$'P>-25.':)PK-1.',8G>'8GP'8.)1G898):

PG:81LI'/'G4K8J*5'PJ:))1'P>-G',8G>'*55'G>)'K):G81)1G')5)+)1GP'K-81G).'-2G'8P'P>-,1'N)5-,I

RS-232 Communications

aP)'G>)'G*N'5*N)5).'(3%"R"'7-++218J*G8-1P'G-'P)1.'J-++*1.P'G-'G>)'=(3!$'+*12*554I'W>8P

G*N'8P'+)*1G'G-'K:-08.)'G>)'2P):',8G>'*1')*P4'+)G>-.'9-:'+*12*554'G4K81L'J-++*1.P'G-'G>)

=(3!$I'W-'2P)'8G6'+*H)'P2:)'G>*G'G>)'K:-K):'J-++218J*G8-1P'K-:G'8P'P)5)JG).6'*1.'G>*G'G>)

j7-11)JG).k'N-E'8P'J>)JH).I'Q1J)'G>*G'8P'J-+K5)G)6'P)1.81L'*'J-++*1.'G-'G>)'=(3!$'8P'*P

P8+K5)'*P'G4K81L'8G'81'*1.'K:)PP81L'g]uW](hI

D-:')*P)'-9'81G):K:)G*G8-16'J-++*1.P'G>*G'4-2'G4K)',855'N)'9-:+*GG).'81'boldI'()PK-1P)P

9:-+'G>)'=(3!$',855'>*0)'1-:+*5'9-:+*GG81LI't))K'81'+81.'G>*G'G>)'=(3!$',855'1-G':)PK-1.

G-'*55'J-++*1.PI'OG'-154':)PK-1.P'G-'V2):4'J-++*1.P•-1)P')1.81L',8G>'*'V2)PG8-1

+*:H'@~AI

Q1)'8+K-:G*1G'K-81G'G-'H))K'81'+81.'8P'G>*G'J-++*1.P'J*1'-154'N)')1G):).'-1'G>)'5*PG'581)I

\81)P'*N-0)'G>)'5*PG'581)'P>-,'G>)'K:)08-2P'J-++*1.P'P)1G'*1.':)PK-1P)P':)J)80).I'W>)P)

581)P'J*1'1-G'N)'-0):,:8GG)1I'Q154'G>)'5*PG'581)'8P'*0*85*N5)'9-:'G4K81L'81'1),'J-++*1.PI

16 Monitoring and Control

FS725 Rubidium Frequency Standard

[):)'8P'*'P*+K5)'PJ:))1'P>-G'K-81G81L'-2G'G>)'K):G81)1G'8G)+P'-9'81G):)PGI

Rb Stats

W>)'G*N'5*N)5).'(N'3G*GP'8P'2P).'G-'+-18G-:'08:G2*554'*55'-9'G>)'=(3!$pP'P)GG81LPI'W-'08),'G>)

J2::)1G'=(3!$'P)GG81LP6'J58JH'-1'G>)'(N'3G*GP'G*N6'+*H)'P2:)'G>*G'G>)'P)5)JG).

J-++218J*G8-1P'K-:G'8P'J-::)JG6'*1.'J58JH'G>)'j7-11)JG).k'J>)JH'N-E'G-')1*N5)'G>)

J-11)JG8-1I'W>)'PJ:))1'P>-25.'9855'81',8G>'G>)'J2::)1G'=(3!$'P)GG81LPI'W>)'P)GG81LP',855'N)

J-1G812-2P54'2K.*G).'21G85'4-2'.8PJ-11)JG'9:-+'G>)'J-++218J*G8-1P'K-:G'N4'J58JH81L'-1'G>)

j7-11)JG).k'J>)JH'N-E'*'P)J-1.'G8+)'G-'21J>)JH'8GI

Monitoring and Control 17

FS725 Rubidium Frequency Standard

/'P*+K5)'PJ:))1'P>-G6'G*H)1',>85)'G>)'=(3!$',*P',*:+81L'2K6'8P'P>-,1'N)5-,I

W>)'PJ:))1'8P'.808.).'81G-'G>:))'+*81'P)JG8-1P'5*N)5).'D*JG-:4'3)GG81LP6'/1*5-L'Q2GK2G

Y*52)P6'*1.'!'KKP'7-1G:-5I']*J>'P)JG8-1'>*P'G>:))'J-52+1PI'W>)'98:PG'J-52+1'J-1G*81P'G>)

J-++*1.'1*+)6'G>)'P)J-1.'J-1G*81P'G>)'J2::)1G'0*52)'-9'G>*G'K*:*+)G):6'*1.'G>)'G>8:.

J-1G*81P'*'N:8)9'.)PJ:8KG8-1'-9'G>)'K*:*+)G):I'7-5-:).'N-E)P'>8L>58L>G'0*:8-2P'K*:*+)G):P'G>*G

*:)'-2G'-9'G>)'1-:+*5'-K):*G81L':*1L)I'W>)'G>:))'P)JG8-1P'*1.'G>)'+)*181LP'-9'G>)'J-5-:).

N-E)P'*:)'N:8)954'.)PJ:8N).'N)5-,I'D-:'.)G*85).'.)PJ:8KG8-1P'-9')*J>'-9'G>)'J-++*1.P6

J-1P25G'G>)'=(3!$'+*12*5I

Factory Settings

W>8P'P)JG8-1'81J52.)P'J*58N:*G8-1'0*52)P'*1.'K*:*+)G):P'9-:'J-1G:-5581L'G>)'9:)V2)1J4'-9'G>)

=(3!$I'W>)'+-PG'8+K-:G*1G'K*:*+)G):'>):)'8P'j\Qk6',>8J>'81.8J*G)P',>)G>):'G>)'=(3!$'>*P

5-JH).'G-'G>)'(N'*G-+8J'>4K):981)'G:*1P8G8-1I'O1'G>)'PJ:))1'P>-G6'G>)'0*52)'-9'\Q'8P'^):-6

81.8J*G81L'G>*G'G>)'218G'>*P'1-G'4)G'5-JH).'G-'G>)'*G-+8J'G:*1P8G8-1I'OG'8P'>8L>58L>G).',8G>'*

N52)'N-E'G-'81.8J*G)'G>*G'G>8P'0*52)'8P'5-,):'G>*1'1-:+*5I

18 Monitoring and Control

FS725 Rubidium Frequency Standard

Analog Output Values

W>8P'P)JG8-1'J-1G*81P'G>)'J2::)1G'0*52)P'-9'"$'81G):1*5'0-5G*L)'G)PG'K-81GP',8G>81'G>)'=(3!$I

W>)P)'0*52)P'*55-,'4-2'G-'+-18G-:'G>)'>)*G):P6'G)+K):*G2:)P6'K-,):'P2KK58)P6'K>*P)'5-JH

5--KP6'*1.'5*+K'J>*:*JG):8PG8JP'-9'G>)'=(3!$I'O1'G>)')E*+K5)'PJ:))1'P>-G6'G>)'0*52)P'/&T6

/&X6'*1.'/&B'*:)'>8L>58L>G).',8G>':).'N-E)P'G-'81.8J*G)'G>*G'G>)'>)*G):P'*:)'*G'+*E8+2+

K-,):I'Y*52)P'/&!!6'/&!"6'*1.'/&!R'81.8J*G)'G>)'J2::)1G'0-5G*L)P'-1'G>)'G)+K):*G2:)

P)1P8G80)'G>):+8PG-:PI'Y*52)P'/&!!'*1.'/&!R'*:)'>8L>58L>G).',8G>':).'N-E)P'G-'81.8J*G)'G>*G

G>)P)'0-5G*L)P'*:)'*N-0)'1-:+*5I'O1'G>)'*N-0)'PJ:))1'P>-G6'/&!"'8P'1-G'>8L>58L>G).'N)J*2P)

G>)'J)55'>*P'*5+-PG':)*J>).'G>)'J-::)JG'-K):*G81L'G)+K):*G2:)I'[8L>58L>G).'N-E)P'*:)'*'1-:+*5

-JJ2::)1J)'.2:81L'G>)',*:+%2K'-9'G>)'=(3!$I

1 pps Control

W>8P'P)JG8-1'J-1G*81P'J*58N:*G8-1'K*:*+)G):P'G>*G'J-1G:-5'G>)'=(3!$pP'N)>*08-:',>)1'5-JH81L

G-'*1')EG):1*5'!'KKP':)9):)1J)I'O1'G>)')E*+K5)'PJ:))1'P>-G6'=W'8P'>8L>58L>G).',8G>'*'N5*JH'N-EI

W>8P'8P'+)*1G'G-'81.8J*G)'G>*G'8GP'J2::)1G'0*52)6'!;6'8P'.899):)1G'9:-+'G>)'0*52)'PG-:).'81

]]=(QZ6',>8J>'8P'G>)'0*52)'8G',855'>*0)'*G'PG*:G'2KI'O1'G>8P'K*:G8J25*:'J*P)6'G>)'J-++*1.

=W!;',*P')1G):).'+*12*554'81'G>)'(3%"R"'7-++218J*G8-1P'G*N'G-'J>*1L)'G>)'J2::)1G'0*52)

-9'=W'9:-+'<'G-'!;I'W>)'0*52)'9-:'WW6'G>)'5*PG'0*58.'G8+)'G*L6'8P'N5*1H'N)J*2P)'G>)'218G'>*P'1-G

4)G':)J)80).'*'K25P)'-1'8GP'!'KKP'81K2GI'U>)1'*'K25P)'8P':)J)80).6'G>)'WW'J-++*1.',855':)K-:G

G>)'G8+)'.899):)1J)'81'1*1-P)J-1.P'N)G,))1'G>)'81K2G'K25P)'*1.'G>)'!'KKP'-2GK2GI

Colored Boxes

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1-:+*5'-K):*G81L':*1L)I'W>8P'+-PG'J-++-154'-JJ2:P'*G'PG*:G'2K6',>85)'G>)'218G'8P',*:+81L

2KI'/9G):'*N-2G'!T'+812G)P'-9'-K):*G8-16'G>)'218G'P>-25.'N)'92554',*:+).'2K6'*1.'*55':).'*1.

N52)'N-E)P'P>-25.'.8P*KK)*:I'/9G):'G>)'818G8*5',*:+2K6'G>)'*KK)*:*1J)'-9'*'J-5-:).'N-E

G4K8J*554'P8L1*5P'P-+)G>81L'212P2*5'G>*G'P>-25.'N)'5--H).'81G-I'O9'G>)'218G',*P'N)81L'-K):*G).

81'*1'-0)16'9-:')E*+K5)6'G>)'218G'+*4'1-G'N)'*N5)'G-'K:-K):54':)L25*G)'G>)'G)+K):*G2:)P'-9'G>)

J:4PG*56'J)556'*1.'5*+KI'a1.):'G>)P)'J8:J2+PG*1J)P6'-1)',-25.')EK)JG'N52)'N-E)P'G-'*KK)*:

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'@f52)A'Y*52)'8P'5-,):'G>*1'1-:+*5I

'@f5*JHAY*52)'8P'.899):)1G'9:-+'G>)'0*52)'PG-:).'81']]=(QZ

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SRS FS725 Owner's manual

SRS FS725 Owner's manual

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